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  • 1
    Publication Date: 2024-06-06
    Description: Sponges (Porifera) are one of the most ancient animals present on the planet. They are aquatic, filter-feeding sessile metazoans that rely on asexual and sexual reproduction. These animals have a long history on Earth and had plenty of time to develop different reproductive strategies. Here, we review different aspects of the physiology of reproduction in Porifera. This chapter is divided into six sections. In the first section, we present general features of sponge reproduction, such as factors that trigger the onset of their reproduction, as well as the periodicity of their reproductive cycles. The molecular basis of the hormonal control of gametogenesis is presented although sponges have no endocrine system. The second section deals with gametogenesis, 2including how sex and the germline are determined and maintained in this group, how oocytes and spermatozoa are formed and nourished, and how they behave once released. The third section reviews different topics about the reproductive mode. Here, we discuss the dichotomy in reproductive mode: oviparity vs. viviparity, the spatial distribution of the reproductive elements in the sponge tissue, the effect of symbiosis in reproduction (and vice-versa), and energetic trade-offs during reproduction. The fourth section describes fertilization, and we cover the factors controlling the spawning events and how the sperm are attracted and recognized by the egg. The diversity of developmental modes, the molecular control of sponge embryonic development, and the maternal-embryo relationship are discussed in the fifth section. Finally, in the sixth section, the types of asexual reproduction, factors influencing budding, gemmulation, hibernation, and gemmule development are described. Knowledge about the physiology of reproduction of sponges is still fragmentary and based on studies in very few species. Consequently, there are many generalizations that need further investigation. However, evidence-based on morphological, experimental, and molecular data demonstrates that their physiology is not very different from that of other metazoans
    Type: Book chapter , PeerReviewed
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  • 2
    Publication Date: 2023-09-21
    Description: The Central and South Atlantic represents a vast ocean area and is home to a diverse range of ecosystems and species. Nevertheless, and similar to the rest of the global south, the area is comparatively understudied yet exposed to increasing levels of multisectoral pressures. To counteract this, the level of scientific exploration in the Central and South Atlantic has increased in recent years and will likely continue to do so within the context of the United Nations (UN) Decade of Ocean Science for Sustainable Development. Here, we compile the literature to investigate the distribution of previous scientific exploration of offshore (30 m+) ecosystems in the Central and South Atlantic, both within and beyond national jurisdiction, allowing us to synthesise overall patterns of biodiversity. Furthermore, through the lens of sustainable management, we have reviewed the existing anthropogenic activities and associated management measures relevant to the region. Through this exercise, we have identified key knowledge gaps and undersampled regions that represent priority areas for future research and commented on how these may be best incorporated into, or enhanced through, future management measures such as those in discussion at the UN Biodiversity Beyond National Jurisdiction negotiations. This review represents a comprehensive summary for scientists and managers alike looking to understand the key topographical, biological, and legislative features of the Central and South Atlantic.
    Type: Book chapter , PeerReviewed
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  • 3
    Publication Date: 2024-02-07
    Description: Long-term changes in the life history and behaviour of seabirds during the non-breeding season can reflect shifts in environmental conditions. However, long-term marine studies are scarce, particularly on southern hemisphere seabirds. Here, we used moult scores from 86 Brown Skuas (Stercorarius antarcticus lonnbergi), a large predatory seabird breeding on the Chatham Islands, Aotearoa/New Zealand to model both the timing and duration of primary feather moult. In addition, we analysed stable isotope values (δ13C and δ15N) from 62 modern (2014–16) and ten museum tail feathers. These data provide insights into the non-breeding behaviour of Brown Skua. Interestingly, our results show that the primary feather moult occurred prior to birds departing the colony, starting on average on 2 January ± 5 days (SE). The average start of primary feather moult occurred five days prior to the end of breeding (7 January ± 10 days (SD)) and 42 days before the birds departed the colony (13 February ± 11 days (SD)). The average duration of primary feather moult was 189 ± 14 days (SE). Importantly, low δ13C values in four females suggested that tail feather moult might also occur while skuas are at the colony. There was no difference in tail feather δ13C and δ15N values between any pairwise comparison of modern and museum years. However, values of δ15N from tail feathers sampled in 2014 were different from those sampled in 2015 and 2016. This large annual variation in δ15N values from tail feathers over such a short period makes long-term comparisons difficult to interpret, particularly between years with low sample sizes. While the stable isotope analyses of tail feathers are informative, we recommend future studies of skuas sample the primary coverts rather than tail feathers.
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  • 4
    Publication Date: 2024-02-07
    Description: Coarse woody habitat (CWH) is an important structural habitat in freshwater ecosystems. In natural lakes, CWH accumulates over centuries alongside the succession of littoral tree communities. Newly created gravel pit lakes have difficulties in accumulating CWH due to their young age. Additionally, CWH presence might be negatively affected by shoreline development, where wood is removed to facilitate recreational activities such as angling. We studied 26 gravel pit lakes with an age ≤ 55 yrs in Lower Saxony, Germany, to quantify CWH density and to understand the impact of environmental factors, including lake morphology, lake age, wind direction, abundance of riparian trees, and the presence or absence of fisheries management, on CWH density. We sampled small and large CWH in the littoral zone of the study lakes using a transect-based approach. Density of CWH was lower in German gravel pit lakes than in North American natural lakes. In gravel pit lakes, we detected increasing densities of small CWH with increasing numbers of large trees on the shore and with increasing littoral slopes in lakes managed for recreational fisheries. Large CWH density was positively affected by lake age, by the density of large trees on the shore and with wind from land, and again by steep littoral slopes in lakes managed for recreational fisheries. We recommend that recreational fisheries managers and individual anglers maintain CWH in shallow littoral zones to promote fish habitats in generally low-structured gravel pit lakes.
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  • 5
    Publication Date: 2024-02-07
    Description: Cambrian igneous rocks in the Takaka Terrane of New Zealand provide important constraints for geodynamic reconstructions of the Cambrian SE Gondwana margin. We provide field data and a comprehensive trace element and isotope dataset for such rocks from the upper Baton River area in northwest Nelson, New Zealand, including the first combined Hf-Nd isotope data for Takaka Terrane rocks. These submarine volcanic rocks, known as Mataki and Benson volcanics of the Devil River Volcanics Group, are both interbedded with Haupiri Group sediments, providing a previously not observed direct stratigraphic link between the two volcanic units. Incompatible element abundances of Mataki Volcanics display a full spectrum from subduction-modified back-arc-tholeiites to E-MORB type tholeiites. Initial Hf-Nd isotope compositions are coupled, spanning a range from MORB-like to OIB-like compositions. The MORB-like endmember (initial ϵNd +7 and ϵHf +13), taps moderately depleted asthenospheric mantle. If extrapolated to present-day composition, this depleted mantle endmember does not resemble modern Pacific-type mantle, suggesting formation in a back-arc basin separated from Pacific mantle by a continent-ward, intra-oceanic subduction zone. The enriched asthenospheric mantle endmember in the Mataki Volcanics may be an equivalent to the sources of Neoproterozic or middle Cambrian intra-continental flood basalts in central and SE-Australia.
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  • 6
    Publication Date: 2023-01-04
    Description: The prediction of a spatial variable is of particular importance when analyzing spatial data. The main objective of this study is to evaluate and compare the performance of several prediction-based methods in spatial prediction through a simulation study. The studied methods include ordinary Kriging (OK), along with several neural network methods including Multi-Layer Perceptron network (MLP), Ensemble Neural Networks (ENN), and Radial Basis Function (RBF) network. We simulated several spatial datasets with three different scenarios due to changes in data stationarity and isotropy. The performance of methods was evaluated using the Root Mean Square Error (RMSE), Mean Absolute Error (MAE) and Concordance Correlation Coefficient (CCC) indexes. Although the results of the simulation study revealed that the performance of the neural network in spatial prediction is weaker than the Kriging method, but it can still be a good competitor for Kriging.
    Type: Article , PeerReviewed
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  • 7
    Publication Date: 2024-01-08
    Description: Algae are the oldest representatives of the plant world with reserves exceeding hundreds of millions of tons in the world's oceans. Currently, a growing interest is placed toward the use of algae as feedstocks for obtaining numerous natural products. Algae are a rich source of polyphenols that possess intriguing structural diversity. Among the algal polyphenols, phlorotannins, which are unique to brown seaweeds, and have immense value as potent modulators of biochemical processes linked to chronic diseases. In algae, flavonoids remain under-explored compared to other categories of polyphenols. Both phlorotannins and flavonoids are inclusive of compounds indicating a wide structural diversity. The present paper reviews the literature on the ecological significance, biosynthesis, structural diversity, and bioactivity of seaweed phlorotannins and flavonoids. The potential implementation of these chemical entities in functional foods, cosmeceuticals, medicaments, and as templates in drug design are described in detail, and perspectives are provided to tackle what are perceived to be the most momentous challenges related to the utilization of phlorotannins and flavonoids. Moving beyond: industrial biotechnology applications, metabolic engineering, total synthesis, biomimetic synthesis, and chemical derivatization of phlorotannins and flavonoids could broaden the research perspectives contributing to the health and economic up-gradation.
    Type: Article , PeerReviewed
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  • 8
    Publication Date: 2024-02-07
    Description: Wetlands physical and biological processes are fundamental to the distribution and structuring of organic matter in sediments. This study investigated spatial and temporal changes in organic matter sources in sediments within the Nylsvley Wetland, South Africa across two seasons, five sites and three wetland zones and identified pertinent contributors to sediment organic matter. Results showed distributions were uneven throughout the wetlands, with the seasonal zone having slightly high sediment organic matter in the cool-dry season and the permanent zone had high sediment organic matter in the hot-wet season, whereas the temporary zone had low SOM concentrations. Significant differences in nutrient concentrations were observed across wetland zones and seasons for Phosphorous, Potassium, Calcium and Magnesium, with the seasonal zone tending to be the most nutrient-rich in the cool-dry season, and with permanent zone nutrient levels rising substantially in the hot-wet season. Sediment δ13C differed significantly among wetland zones, whereas δ15N was statistically similar. Autochthonous plants were the main sources of organic matter in sediments overall across sites and zones. This study’s findings help to better understand the distribution of organic matter in wetland ecosystems and the role wetland zones play in the seasonal provisioning of allochthonous inputs.
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  • 9
    Publication Date: 2024-02-14
    Description: Glacio-eustatic cycles lead to changes in sedimentation on all types of continental margins. There is, however, a paucity of sedimentation rate data over eustatic sea-level cycles in active subduction zones. During International Ocean Discovery Program Expedition 375, coring of the upper ∼110 m of the northern Hikurangi Trough Site U1520 recovered a turbidite-dominated succession deposited during the last ∼45 kyrs (Marine Isotope Stages (MIS) 1–3). We present an age model integrating radiocarbon dates, tephrochronology, and δ18O stratigraphy, to evaluate the bed recurrence interval (RI) and sediment accumulation rate (SAR). Our analyses indicate mean bed RI varies from ∼322 yrs in MIS1, ∼49 yrs in MIS2, and ∼231 yrs in MIS3. Large (6-fold) and abrupt variations in SAR are recorded across MIS transitions, with rates of up to ∼10 m/kyr occurring during the Last Glacial Maximum (LGM), and 〈1 m/kyr during MIS1 and 3. The pronounced variability in SAR, with extremely high rates during the LGM, even for a subduction zone, are the result of changes in regional sediment supply associated with climate-driven changes in terrestrial catchment erosion, and critical thresholds of eustatic sea-level change altering the degree of sediment bypassing the continental shelf and slope via submarine canyon systems.
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  • 10
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    Taylor & Francis
    Publication Date: 2024-05-23
    Description: The extent of our duties to mitigate climate change is commonly conceptualized in terms of temperature goals like the 1.5°C and the 2°C target and corresponding emissions budgets. While I do acknowledge the political advantages of any framework that is relatively easy to understand, I argue that this particular framework does not capture the true extent of our mitigation duties. Instead I argue for a more differentiated approach that is based on the well-known distinction between subsistence and luxury emissions. At the heart of this approach lies the argument that we have no budget of substantial, net-positive luxury emissions left. In a world in which dangerous climate change has begun, we must expect all further substantial, net-positive luxury emissions to cause harm. Since they lack the kind of justification needed for them to be nevertheless permissible, I conclude that we must stop emitting them with immediate effect. I also briefly discuss the difficult case of subsistence emissions and offer some first thoughts on the morality of a third category of emissions, what I call ‘transition emissions’.
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  • 11
    Publication Date: 2023-01-04
    Description: Whakaari/White Island is a partially submerged, offshore andesite island volcano, located at the northern end of the Taupō Volcanic Zone. Since the late 1960s, volcanic activity has alternated between quiescence, unrest, and eruption on short timescales. For this review we compiled extensive observational records, examined the rich scientific literature, and use newly acquired data, to understand the broad volcanic history and system dynamics. Based on recent bathymetry data, we propose a distinction exists between the Whakaari edifice and Te Paepae o Aotea/Volkner Rocks, which were previously considered to be part of the same edifice. Geochemical analyses of scoria samples from the island have been used to build a magma system model where dominantly andesitic-dacitic magma is periodically intruded by basalt. More dynamic processes are recorded in the hydrothermal system, where the location and activity of fumarolic features have been ephemeral and the crater lake has varied in scale over short time intervals. Eruptions of the dominantly andesitic magma have historically been small and range from phreatomagmatic through to magmatic, largely depositing ash and scoria to a restricted distance that is confined to the main crater floor. Phreatic eruptions are the most common eruption style, based on recently observed and monitored activity.
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  • 12
    Publication Date: 2023-01-04
    Description: Recently, the aeromagnetic survey with Unmanned Aerial Vehicle (UAV) for mineral exploration has become ubiquitous. They can fly at a lower speed, lower altitude, need fewer crew members, and are cost-effective compared to traditional manned aeromagnetic. With the development of drones, magnetometers were also developed, which reduced the cost, weight, size, and energy consumption of these sensors. One of these sensors is the magneto-inductive magnetometer. This study investigates the integration of the UAV with a magneto-inductive sensor. We have performed an aeromagnetic survey along with six profiles and compared them with the terrestrial magnetic survey using a proton precision magnetometer. We show that the magneto-inductive sensor can sense Earth’s magnetic field’s change up to less than 60 nT. These results show the promising potential of using the UAV equipped with the magneto-inductive sensor to prospect the magnetic ore deposits.
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  • 13
    Publication Date: 2023-01-04
    Description: Tephra deposits in Aotearoa New Zealand (ANZ) have been studied for 〉180 years. The now-global discipline of tephrochronology, which has some developmental roots in ANZ, forms the basis of a powerful chronostratigraphic correlational tool and age-equivalent dating method for geological, volcanological, palaeoenvironmental, and archaeological research in ANZ. Its utility is founded on the key principle that tephras or cryptotephras provide widespread isochrons in many different environments. In the first part of this article, we summarise the history of tephra studies in ANZ and then describe how tephras have been mapped, characterised, and correlated using field and laboratory-based methods. We document advances in geochemical fingerprinting of glass; tephra/cryptotephra detection and correlation by sediment-core scanning methods (e.g. X-radiography, CT imaging, XRF elemental analysis, magnetic susceptibility); statistical correlation methods; and dating of tephras/cryptotephras. We discuss the advent of ANZ cryptotephra studies (from mid-1970s) and their more-recent growth. The second part comprises examples of applications of tephrochronology in ANZ: climate-event stratigraphy (NZ-INTIMATE project); eruptive-event stratigraphy in the Auckland Volcanic Field; developments in the marine tephra record; advances in identifying, correlating, and dating old (pre-50 ka) tephras and weathered-tephra deposits; forming soils/paleosols on tephras; tephras and archaeology; Kopouatai bog tephrostratigraphy and palaeoenvironments; and volcanic-hazard assessments.
    Type: Article , PeerReviewed
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  • 14
    Publication Date: 2023-01-24
    Description: There is a significant interest in the usage of algae in everyday diet because of their positive influence on the gastrointestinal system due to the presence of high amounts of dietary fibres, while the presence of ω-3 fatty acids contributes to the protection of cardiovascular system. Algal derived polysaccharides are found in the food products as stabilisers, thickening agents and emulsifiers. In the cosmetic industry, algae are used in sunscreen, anti-age, anti-cellulite, moisturising and skin whitening products. These products can be used for the development of cosmeceuticals which contain algal derived bioactive compounds and they can exert a pharmaceutical therapeutic benefit. However, these compounds also have potential for being isolated and used for development of novel drugs against diseases, such as cancer, neurodegenerative disorders, and diabetes. Present review provides information about algal compounds incorporated into various food, cosmetic or medicinal products, as well as their potential for health improvement was evaluated.
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  • 15
    Publication Date: 2023-05-24
    Description: During World War I, an enormous amount of chemical and conventional munitions was fired. Many of these munitions did not explode and are still recovered in the soil of the regions where the war raged for several years. After the war, many of the remaining munitions were dumped in the sea as an easy way of removal. These unexploded and dumped munitions are still present so many years after the end of the war. The explosive material inside the munitions is more than 100 years old now. Samples were collected from some of these old munitions. These samples have been analyzed to determine their composition. The explosives typically used in World War I (TNT, DNT, DNB and picric acid) have been identified. It has been shown that the aged samples still contain their energy. They have not become more sensitive to friction or impact. For one the samples, it has been shown that it is still cap-sensitive and detonates normally. These results are important for any risk assessment involving old munitions.
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  • 16
    Publication Date: 2024-02-07
    Description: This article presents the results of a marine geophysical and sedimentological study carried out around Lesvos Island (NE Aegean) to investigate the potential of exploitable marine aggregate (MA) deposits that could be used for beach replenishment purposes. Sub-bottom profiler data showed a good prospect for potential coarse-grained deposits in two of the three surveyed areas around Lesvos. Grain size and mineralogical analysis of the surficial sediments revealed sands that could properly feed nourishment schemes for eroded beaches or artificial beach development. Observed MA volumes are considered adequate for renourishment operations, when the threat of projected sea-level rise is introduced. Environmental constraints, as well as human activities, are considered for the suggestion and prioritization of specific areas for detailed surveying before future exploitation.
    Type: Article , PeerReviewed
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  • 17
    Publication Date: 2024-02-07
    Description: Modelling the drift of marine debris in quasi-real time can be of societal relevance. One pertinent example is Malaysia Airlines flight MH370. The aircraft is assumed to have crashed in the Indian Ocean, leaving floating wreckage to drift on the surface. Some of these items were recovered around the western Indian Ocean. We use ocean currents simulated by an operational ocean model in conjunction with surface Stokes drift to determine the possible paths taken by the debris. We consider: (1) How important is the influence of surface waves on the drift? (2) What are the relative benefits of forward- and backward-tracking in time? (3) Does including information from more items refine the most probable crash-site region? Our results highlight a critical contribution of Stokes drift and emphasise the need to know precisely the buoyancy characteristics of the items. The differences between the tracking approaches provide a measure of uncertainty which can be minimised by simulating a sufficiently large number of virtual debris. Given the uncertainties associated with the timings of the debris sightings, we show that at least 5 items are required to achieve an optimal most probable crash-site region. The results have implications for other drift simulation applications.
    Type: Article , PeerReviewed
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  • 18
    Publication Date: 2024-02-07
    Description: Chirp sub-bottom profilers (SBP) provide centi-to-decimetre resolution, seismic data with applications for various geophysical and geological purposes. To verify the field application of imaging of a buried target with a cost-effective and easy-to-apply pseudo-3D Chirp SBP survey, we explored the buried site of an ancient wooden shipwreck off the west coast of Korea before underwater excavations. The survey was conducted using a commercial 2D Chirp SBP system with a newly devised recording system that preserved the true polarity of the chirp signal. To produce high-resolution 3D Chirp SBP data from 2D Chirp SBP datasets recorded by the novel system, an optimal data processing sequence, consisting of a first phase of 2D data processing and a second phase of 3D data processing was designed. The first, 2D phase, included the estimation of a source sweep signature, cross-correlation, and deconvolution using an inverse filter. The resulting resolution of the 2D Chirp SBP data was better than that of the enveloped data provided by the commercial acquisition system. The second phase of 3D data processing included gathering 3D datasets, redistributing of ping positions, and static correction. To improve the consistency of the seismic events and reduce the repetitive corrections (swell, tidal, tie, and residual corrections), a static correction was based on multi-beam echo sounder data. The amplitude variation near the shipwreck was clearly apparent in the time slice from the final pseudo-3D Chirp SBP dataset with a bin size of 2.0 m (crossline) × 0.6 m (inline). Through 3D rendering, the buried ancient shipwreck with dimensions of 5 m (width) × 12 m (length) × 2 m (depth) was imaged successfully.
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  • 19
    Publication Date: 2024-02-07
    Description: Riparian zones are important for the maintenance of aquatic ecosystem functional integrity, yet are considered to be particularly vulnerable to plant invasions. The role of terrestrial riparian plant invasions in compromising aquatic ecosystem processes is, however, still poorly understood. This issue is particularly relevant for temporary rivers, which are understudied compared to permanent river systems, despite their ubiquity and largescale contributions to biogeochemical processes. Here we experimentally assessed leaf litter breakdown dynamics in situ in a temporary river in arid southeastern Botswana, Southern Africa. We contrasted aquatic leaching and microbial and invertebrate litter breakdown contributions to the native leadwood Combretum imberbe and invasive river red gum Eucalyptus camaldulensis in the Lotsane River. Fine-mesh (detritivore exclusion) and coarse-mesh (detritivore inclusion) bags were separately filled with leaf litter from each species and deployed in the river during a hydroperiod (wet phase), with decomposition measured over a 6-week period. E. camaldulensis shed significantly more leachate than the native C. imberbe. Significantly more microbial and detritivore breakdown was, however, observed in native than in invasive leaf litter. Overall, invertebrates contributed little to biological leaf litter breakdown processes compared to microbial breakdown contributions. Although significantly higher in native leaves, low invertebrate numbers were found in leaf litter in the study. This study highlights the role of microbial contributions to detrital decay in temporary arid zone rivers, whereas invertebrate contributions were relatively minor. The study further contributes to our understanding of how invasive riparian plant species alter aquatic detrital pool dynamics in invaded temporary wetland ecosystems.
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  • 20
    Publication Date: 2024-02-07
    Description: Accurate and repeatable population estimates are key to establishing population trends and conservation status. Rako, or Buller’s Shearwater (Ardenna bulleri) is a seabird endemic to New Zealand that breeds only on the Poor Knights Islands, but forages throughout wider areas of the Pacific Ocean during the non-breeding season. The lack of threats on the breeding grounds and the wide foraging range of Buller’s Shearwaters makes them ideal sentinels of ocean health. Although they are commonly seen at sea and the population in the 1980s was thought to be around 2.5 million birds, other rapid land-based surveys suggested a much lower figure (~100,000 pairs on Aorangi), and no thorough population estimate has been undertaken to date. We calculated a population estimate for Buller’s Shearwater based on burrow counts and state of occupancy conducted at the Poor Knights during either the 2016–2017 or the 2017–2018 breeding seasons. We incorporated information on habitat availability and preference in population models. Our estimate of 78,645 (95% confidence interval 67,176–89,178) active burrows, broadly representing breeding pairs, is lower than some previously published assessments. This is a repeatable quantitative study of the Buller’s Shearwater breeding population, including breeding activity, and provides critical baseline data to determine population trends for this potentially important marine indicator species. © 2021 BirdLife Australia.
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  • 21
    Publication Date: 2024-02-07
    Description: Anthropogenic pressures on standing waterbody systems potentially result in changes to sediment and water qualities, and thus ecological community characteristics. We tested effects of drawdown on physical, water and sediment variables, as well as their effects on littoral macroinvertebrate community composition in two subtropical reservoirs. Water levels differed significantly between reservoirs and over time, with significant effects on several water chemistry parameters (e.g., pH, conductivity, Mg, Fe), whilst sediment properties were less affected. Significant effects of water level, site and macrophyte cover on macroinvertebrate community structures were not detected, however macroinvertebrate community structuring differed significantly over time. Redundancy analysis (RDA) highlighted that the first and second axes accounted for 45.6% of the total macroinvertebrate community and environmental variables relationship variance. Most of the sediment variables, such as Cu, Mg, Na and Pb and water chemistry (i.e., HCO3-), were positively associated with the first axis, while water temperature and pH were negatively associated with the first axis. The RDA variation partitioning showed that water and sediment chemistry variables accounted for 40.3% and 30.3%, respectively, of the total macroinvertebrate variation. The present study contributes to understandings of the interplays between water level, physico-chemical properties and community compositions in human-altered aquatic ecosystems.
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  • 22
    Publication Date: 2024-02-07
    Description: Despite the diversity and oftentimes large biomass of jellyfish in marine systems, their ecological role remains poorly understood. We here provide the first systematic review of studies on jellyfish trophic ecology in the Baltic Sea (a regional marine system under strong multiple global and regional anthropogenic pressures). In total, we identified 57 peer-reviewed publications, with notable taxonomic bias towards two species (Aurelia aurita; non-indigenous Mnemiopsis leidyi) and spatial bias towards five areas (Bornholm Basin, Kiel Bight, Kertinge Nor, Lim- and Gullmarsfjord). The studies provide evidence for diverse trophic roles of jellyfish as predators and as competitors of other jellyfish, zooplankton and fish species. In combination, the studies also highlight potentially large impacts via top-down (grazing) and bottom-up (nutrient excretion) effects, but also, strong spatio-temporal variability in the magnitude of these effects, depending on the occurrence of jellyfish blooms. Studies on the role of jellyfish as prey for fish, seabirds or marine mammals, and for benthic systems via food-falls, were limited or lacking for the Baltic Sea, despite increasing focus on these topics globally. Improved understanding of the temporal (seasonal, inter-annual, long-term) and spatial variability of blooms and corresponding trophic effects, would provide more systematic understanding of the ecological role of jellyfish in the spatio-temporally variable Baltic Sea. A broader spatial coverage, inclusion of more jellyfish taxa and under-studied early life history stages, as well as the implementation and continuation of long-term data series would represent important steps towards this goal.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 23
    Publication Date: 2024-02-07
    Description: Gonatus fabricii (Lichtenstein, 1818) is an ecologically important squid that spends its entire life cycle within the Arctic where it is the most abundant cephalopod. Due to the rarity of mature and reproducing females, it is unknown how many eggs females spawn (actual fecundity). Among 47,000 specimens studied between 2005 and 2019 one spent, degenerated and gelatinous female with a mantle length of 230 mm was caught in West Greenland in 2019. Examination allowed the first detailed description of fecundity and spawning pattern in the species. Oocyte development shows that the most considerable maturation of mid-vitellogenic oocytes to late vitellogenic and then to ripe stages occurs immediately after the first ripe oocytes appear in the ovary. There were no ripe oocytes in the ovary or oviducts. The ovary contained an estimated 6561 oocytes and 2551 post-ovulatory follicles and hence the total fecundity was 9112. This specimen of G. fabricii realised 28.0% of its potential fecundity which is comparable to Berryteuthis magister, which also belongs to Gonatidae, and lower than in the majority of studied deep-sea squids (including other gonatids). Spent females may provide clues as to where the major spawning areas of this abundant but poorly known squid are located.
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  • 24
    Publication Date: 2024-02-07
    Description: A recent analysis of observed oxygen changes shows a 2% decline in marine oxygen during the 50 years since 1960. However, these oxygen changes vary on time scales related to climate modes and by regions, including areas of increasing oxygen. Hence, any local oxygen change is related to various subsets of these drivers for the different regions and time scales. Here we provide an overview of drivers presently known for the different regions in the upper and deep ocean and the regional influence of climate modes, focussing on decadal and longer time scales for open ocean regions. We identify and compile regions where changes in solubility, stratification, decadal to multidecadal variability, source waters (either increases or decreases), overturning circulation or circulation-driven changes, and biological or nutrient stimulation have been shown to play a role in oxygen changes. The superposition and interaction of drivers and processes makes the decomposition of the impact on oxygen distribution difficult. Nevertheless, the description of the different drivers identified will help in better understanding the oxygen changes observed and lead to better verification of numerical models of future ocean oxygen levels.
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  • 25
    Publication Date: 2023-02-08
    Type: Article , PeerReviewed
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  • 26
    Publication Date: 2023-02-08
    Description: Understanding the physical and biogeochemical interactions and feedbacks between the ocean and atmosphere is a vital component of environmental and Earth system research. The ability to predict and respond to future environmental change relies on a detailed understanding of these processes. The Surface Ocean-Lower Atmosphere Study (SOLAS) is an international research platform that focuses on the study of ocean-atmosphere interactions, for which Future Earth is a sponsor. SOLAS instigated a collaborative initiative process to connect efforts in the natural and social sciences related to these processes, as a contribution to the emerging Future Earth Ocean Knowledge-Action Network (Ocean KAN). This is imperative because many of the recent changes in the Earth system are anthropogenic. An understanding of adaptation and counteracting measures requires an alliance of scientists from both domains to bridge the gap between science and policy. To this end, three SOLAS research areas were targeted for a case study to determine a more effective method of interdisciplinary research: valuing carbon and the ocean’s role; air-sea interactions, policy and stewardship; and, air-sea interactions and the shipping industry.
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  • 27
    Publication Date: 2023-02-08
    Description: Monowai is an active submarine volcanic centre in the Kermadec Arc, Southwest Pacific Ocean. Multi-beam data acquired during expedition SO225 aboard R/V SONNE in December 2012 indicates that the topography of the main stratocone has evolved significantly since the last survey in June 2011. Bathymetric measurements of the edifice reveal differences of up to 42 m in seafloor depth and indicate a net volume increase of ∼0.037 km3 across the summit area. Explosive volcanism observed onsite during the SO225 mapping campaign could be linked to a 20h-long swarm of unusually coherent T phase arrivals, suggesting that Monowai is a prime source of broadband seismic noise in the Southwest Pacific region during times of activity. Our findings further document the dynamic nature of volcanic processes at Monowai and have implications for future expedition planning.
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  • 28
    Publication Date: 2023-02-08
    Description: This study examined the residential perceptions of industrial activities in Ilupeju, Lagos, Nigeria. The relevance of distance decay theory, which postulates that the magnitude of effects of the outputs from an industrial establishment would decrease with increasing distance from the point of origin, was tested in the study. Global Positioning System was used to capture the coordinates of the identified firms in Ilupeju. Additionally, two different sets of structured questionnaire were designed; the first set, which was distributed among the industrialists, sought information on the types of waste generated among others while the second set was randomly distributed among the residents and was used to elicit information on the types of pollution emanating from the industries, socioeconomic benefits, among others. The result shows that there is a significant variation in the perceived effects as people living within 0.5 km to the industrial sites claimed to suffer more pollution than those living 1.5 km away from the industrial sites, which is consistent with the distance decay theory. On the other hand, the distance decay theory cannot explain socioeconomic impacts such as increase in living costs, among others as they are felt around the study area irrespective of distance away from the industrial sites.
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  • 29
    Publication Date: 2023-02-08
    Description: Dissimilatory iron reduction and sulfate reduction are the most important processes for anaerobic mineralization of organic carbon in marine sediments. The thermodynamics and kinetics of microbial Fe(III) reduction depend on the characteristics of the Fe(III) minerals, which influence the potential of Fe(III)-reducers to compete with sulfate-reducers for common organic substrates. In the present study, we tested different methods to quantify and characterize microbially reducible Fe(III) in sediments from a transect in Kongsfjorden, Svalbard, using different standard sequential endpoint extractions and time-course extractions with either ascorbate or a Fe(III)-reducing microbial culture. Similar trends of increasing ‘reactive Fe’ content of the sediment along the fjord transect were found using the different extraction methods. However, the total amount of ‘reactive Fe’ extracted differed between the methods, due to different Fe dissolution mechanisms and different targeted Fe fractions. Time-course extractions additionally provided information on the reactivity and heterogeneity of the extracted Fe(III) minerals, which also impact the favorability for microbial reduction. Our results show which fractions of the existing Fe extraction protocols should be considered ‘reactive’ in the sense of being favorable for microbial Fe(III) reduction, which is important in studies on early diagenesis in marine sediments.
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  • 30
    Publication Date: 2023-02-08
    Description: Microbial metabolisms in sediments play a pivotal role in marine element cycling. In hydrothermal sediments chemosynthetic microorganisms likely prevail, while in non-hydrothermally impacted sediment regimes microorganisms associated with organic matter decomposition are primarily recognized. To test how these microorganisms are distributed along the hitherto neglected transition zone influenced to different degrees by hydrothermal input we sampled four sediment sites: these were (i) near an active vent, (ii) the outer rim, and (iii) the inactive area of the Kairei hydrothermal field as well as (iv) sediments roughly 200 km south-east of the Kairei field. Chemistry and microbial community compositions were different at all sampling sites. Against expectations, the sediments near the active vent did not host typical chemosynthetic microorganisms and chemistry did not indicate current, extensive hydrothermal venting. Data from the outer rim area of the active Kairei field suggested microbially mediated saponite production and diffuse hydrothermal flow from below accompanied by increased metal concentrations. A steep redox gradient in the inactive Kairei field points towards significant redox driven processes resulting in dissolution of hydrothermal precipitates and intense metal mobilization. Local microorganisms were primarily Chloroflexi, Bacillales, Thermoplasmata, and Thaumarchaeota.
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  • 31
    Publication Date: 2023-12-12
    Description: Versatile peroxidase, a new family of ligninolytic peroxidases have catalytic properties of both lignin peroxidase and manganese peroxidase and has been isolated from citrus sinensis leaf extract which contains manganese peroxidase activity of 2.2 IU/ml and lignin peroxidase activity of 0.44 IU/ml. The overall recovery yield was 11 % with specific activity 1.0 IU/mg. Its molecular wt was found to be 24.60KDa. Km and Kcat value using veratryl alcohol and manganese sulphate as a substrate is 20 μM, 7.87sec and 12.5 μM, 13.84sec-1. The calculated pH optimum was 2.4 ± 0.1 for lignin peroxidase activity and 4.5 ± 0.1 for manganese peroxidase activity. The temperature optimum of the enzyme was 18°C for LiP and 25°C for MnP. Degradation of polyaromatic hydrocarbons like α-naphthol, β-naphthol, and 1,10-phenanthroline has been studied using UV/VIS spectrophotometer and cyclovoltameter at room temperature. Enzyme activity was inhibited by sodium azide and EDTA effectively.
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  • 32
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    In:  Marine Georesources & Geotechnology, 22 (1-2). pp. 103-114.
    Publication Date: 2017-07-20
    Description: The deep ocean floor between the Clarion and Clipperton fracture zones (NE equatorial Pacific) has the highest known manganese nodule abundance in the world oceans. A detailed analysis of MR1 (Mapping Researcher 1, 11–12 kHz) sonar images and free-fall grab data in the Korean manganese nodule field areas reveals a close relationship between side-scan sonar characteristics of the seafloor and manganese nodule abundance. Eight sonar facies are identified based on back-scattering intensity and distribution patterns. These sonar facies can be interpreted as (1) volcanic seamounts (facies I-1), (2) bounding faults of abyssal hills (facies I-2 and II-1), (3) lava flows or volcanoclastic mass-flow deposits around the volcanic seamounts (facies I-3 and II-2), (4) crests of abyssal hills (facies II-1), (5) abyssal troughs between abyssal hills (facies III-1), (6) relatively flat areas (facies II-3 and III-2). In the areas where facies II-1 (abyssal hill crests with thin sediment cover) and II-3 (relatively flat areas draped by thin sediments) are dominant, manganese nodules occur abundantly. In contrast, zones comprising facies III-1 (abyssal troughs with thick sediment cover) and III-2 (relatively flat areas covered by thick sediments) are characterized by low abundance of manganese nodules. This relationship between distribution of sonar facies and manganese nodule abundance implies that (1) the qualitative difference in acoustic reflectivity of long-range sidescan sonar with some ground truth data is useful for regional assessment of manganese nodule occurrence over wide areas in a reasonable time, and (2) seafloor topography and sediment thickness are important controlling factors for regional occurrences of manganese nodules.
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  • 33
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    In:  Marine and Freshwater Behaviour and Physiology, 37 (4). pp. 235-251.
    Publication Date: 2020-07-08
    Description: The torque generated by a rotating joint comprises the useful force exerted by the joint on the external environment, and both the magnitude and distribution of torque through the step cycle during walking are important variables in understanding the mechanics of walking. The mechanics of the American lobster (Homarus americanus) and snow crab (Chionoecetes opilio) during walking were modelled to examine the relative roles of flexor versus extensor apodeme–muscle complexes, investigate which legs of these decapods likely contribute the greatest to locomotion, determine scaling effects of torque generation, and assess the relative roles of various model variables on torque production. Force generated along the length of the apodeme by the muscle was modelled based on apodeme surface area, muscle stress, and muscle fibre pinnation angle. Torque was then calculated from this estimated force and the corresponding moment arm. The flexor apodeme–muscle complex is calculated to generate consistently greater forces than the extensor, and generally this results in flexor torque being larger than extensor, though the snow crab does illustrate the opposite in two of its legs. This greater torque generation in flexion suggests that, in addition to the pushing of the trailing legs, the pulling action of the leading legs may play a significant role, at least during lateral walking. Leg 4 of both species appears to generate greater torques and thus provide the greatest forces for locomotion. Torque generation as a function of body size shows a second order response due to the increase in apodeme surface area. The pinnation angle of the muscle fibre is found to be insignificant in force generation, apodeme surface area (representing muscle cross sectional area) likely plays the most influential role in total force production, and moment arm controls the distribution of this force through the step cycle. Muscle stress remain a largely unknown quantity however, and may significantly affect both magnitude and distribution through step cycle of forces, and thus torque. Despite the uncertainty associated with the muscle stress parameter, the modelled results fit well with previously published force measurements.
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  • 34
    Publication Date: 2015-01-22
    Description: Palaeoenvironmental records from permafrost sequences complemented by infrared stimulated luminescence (IRSL) and 230Th/U dates from Bol'shoy Lyakhovsky Island (7320'N, 14130'E) document the environmental history in the region for at least the past 200 ka. Pollen spectra and insect fauna indicate that relatively wet grass-sedge tundra habitats dominated during an interstadial c. 200–170 ka BP. Summers were rather warm and wet, while stable isotopes reflect severe winter conditions. The pollen spectra reflect sparser grass-sedge vegetation during a Taz (Late Saalian) stage, c. 170–130 ka BP, with environmental conditions much more severe compared with the previous interstadial. Open Poaceae and Artemisia plant associations dominated vegetation at the beginning of the Kazantsevo (Eemian) c. 130 ka BP. Some shrubs (Alnus fruticosa, Salix, Betula nana) grew in more protected and wetter places as well. The climate was relatively warm during this time, resulting in the melting of Saalian ice wedges. Later, during the interglacial optimum, shrub tundra with Alnus fruticosa and Betula nana s.l. dominated vegetation. Climate was relatively wet and warm. Quantitative pollen-based climate reconstruction suggests that mean July temperatures were 4–5 C higher than the present during the optimum of the Eemian, while late Eemian records indicate significant climate deterioration.
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  • 35
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    In:  International Journal of Remote Sensing, 25 (7-8). pp. 1449-1453.
    Publication Date: 2015-10-14
    Description: The Space Information Laboratory (SIL) of the Tropical Center for Earth and Space Studies of the University of Puerto Rico at Mayagu¨ ez (UPRM) has been collecting and processing satellite data since December of 1996. Satellite imagery from the Advanced Very High Resolution Radiometer (AVHRR) and the Sea viewing Wide Field of view Sensor (SeaWiFS) provides us with a new understanding of phytoplankton dynamics in the Caribbean region. SeaWiFS shows the intrusion of waters into the eastern Caribbean Sea from the Orinoco River during fall and from the Amazon River during spring–summer. Strong coastal upwelling in Venezuela produced by the trade winds during winter– spring is detected with the AVHRR. The satellite data suggest that these seasonal events may play an important role in phytoplankton fertilization of the eastern Caribbean Sea. SeaWiFS and hydrological data are also combined to evaluate the impact of hurricanes on phytoplankton distribution. The development of models for estimation of ocean primary productivity using SeaWiFS and AVHRR data is now in progress.
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  • 36
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    In:  International Journal of Remote Sensing, 25 (7-8). pp. 1337-1340.
    Publication Date: 2015-10-08
    Description: The hydrographic conditions in the south-east Atlantic were investigated during the cruise of R/V Poseidon in April 1999. The area of investigation covers the two major eastern boundary currents of the Southern Atlantic and its convergence in the Angola-Benguela Frontal Zone (ABFZ). Hydrographic measurements have been carried out in combination with current measurements and are supplemented with remote sensing data of sea surface temperature (SST) and wind stress. The Angola Current transported in its surface part less saline water from the great rivers in the north towards the ABFZ. At the same time, south of the front, strong coastal upwelling in the Benguela was observed. At the beginning of April 1999 the ABFZ was found at an unusual southern position. The rapid dynamic response of the ABFZ to wind forcing is discussed on the basis of satellite SST images combined with hydrographic measurements.
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  • 37
    Publication Date: 2016-06-14
    Description: Changes apparent in the arctic climate system in recent years require evaluation in a century-scale perspective in order to assess the Arctic's response to increasing anthropogenic greenhouse-gas forcing. Here, a new set of century- and multidecadal-scale observational data of surface air temperature (SAT) and sea ice is used in combination with ECHAM4 and HadCM3 coupled atmosphere-ice-ocean global model simulations in order to better determine and understand arctic climate variability. We show that two pronounced twentieth-century warming events, both amplified in the Arctic, were linked to sea-ice variability. SAT observations and model simulations indicate that the nature of the arctic warming in the last two decades is distinct from the early twentieth-century warm period. It is suggested strongly that the earlier warming was natural internal climate-system variability, whereas the recent SAT changes are a response to anthropogenic forcing. The area of arctic sea ice is furthermore observed to have decreased similar to8 x 10(5) km(2) (7.4%) in the past quarter century, with record-low summer ice coverage in September 2002. A set of model predictions is used to quantify changes in the ice cover through the twenty-first century, with greater reductions expected in summer than winter. In summer, a predominantly sea-ice-free Arctic is predicted for the end of this century.
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  • 38
    Publication Date: 2016-06-14
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  • 39
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    In:  Biofouling, 20 (1). pp. 43-51.
    Publication Date: 2019-03-06
    Description: Multiple antifouling strategies of marine organisms may consist of combinations of physical, chemical and mechanical mechanisms. In this study, the role of surface microtopography (〈500 mum) of different marine organisms, such as Cancer pagurus , Mytilus edulis , Ophiura texturata and the eggcase of Scyliorhinus canicula , has been investigated as a possible component of their defence systems. High resolution resin replicates of these natural surface structures were exposed to natural fouling in field experiments. Abundances of recruits were determined and compared to those on untextured, but otherwise identical, control surfaces to quantify the influence of the different microtopographies on fouling rates. Antifouling effects of microtopographies varied with type of microtopography and coloniser species. The surface microtopography of C. pagurus significantly rejected macrofoulers. The surface structures of the eggcase and O. texturata had repellent effects on microfoulers. Barnacle settlement was temporarily reduced on surface microtopographies of M. edulis and the eggcase. These results emphasise the promising non-toxic antifouling properties of microtextured surfaces
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  • 40
    Publication Date: 2017-05-03
    Description: Using thin-layer chromatography (TLC) bioautography, a total of 58 extracts from various organs (aerial parts, leaves, flowers, fruits, roots) of 16 Turkish plants were tested for their antibacterial, antifungal, acetylcholinesterase inhibitory, antioxidant, and radical scavenging activities. The hexane, CHCl3/CH2Cl2, water, and total MeOH extracts were used. No activity was observed against two Gram-negative bacteria (Escherichia coli and Pseudomonas aureginosa) and the yeast Candida albicans. However, 23 plant extracts, mostly the CHCl3/CH2Cl2 and H2O-solubles, inhibited the growth of all five Gram-positive bacteria tested, Micrococcus luteus, Bacillus subtilis, Bacillus cereus, Staphylococcus aureus, and Staphylococcus epidermidis. Of the active extracts, the CHCl3-soluble of the roots of Putoria calabrica (L. fil) DC (Rubiaceae) displayed the highest antibacterial potential. The majority of the CHCl3/CH2Cl2 crude extracts also appeared to inhibit acetylcholinesterase on TLC plates at 100 µg/spot concentration. Particularly active samples were the middle polarity extracts (CHCl3/CH2Cl2) of the leaves of Rhododendron smirnovii Trautv., R. ponticum L., and R. ungernii Trautv. (Ericaceae). β-Carotene, β-carotene/linoleic acid mixture, and 2,2-diphenyl-l-pieryhydrazyl (DPPH) solutions sprayed onto TLC plates were used for detecting antioxidant and radical scavenging properties of the crude extracts. Antioxidant and radical scavenging activities were found to be predominant in highly polar extracts. The water-solubles of all Rhododendron (Ericaceae) and Phlomis (Lamiaceae) species presented the most significant activity.
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  • 41
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    In:  Journal of Environmental Science and Health, Part B- Pesticides, Food Contaminants, and Agricultural Wastes, 39 (5-6). pp. 871-887.
    Publication Date: 2020-07-24
    Description: A lab-scale composting experiment was carried out using vegetable and flower stalks waste to study the effectiveness of ligno-cellulolytic microorganisms (LCMs) obtained from the previous isolation on composting process, especially on enhancement of biodegradation rate of these organic materials. The addition of LCMs to compost showed promised to be a valuable asset by rendering timely benefits in efficiency, maturity, and quality of the composting. This was evidenced by a significant increase of temperature, O2 consumption and CO2 emission, and population density of LCMs in compost mass compared with that of biotic (addition of culture of horse feces) and abiotic (1% molasses amendment) treatments, as well as control trial. The phytotoxicity assay showed that the substrate became mature after 60 days’ composting. The LCMs inoculation enhanced the biodegradation of the composting materials as evidenced by an increasing screening ratio (1.2 cm sieve pore) of 34.5% in the treated trail, compared with that of control, which elucidated that big advantage of adding selected inoculants over other treatment, and screening ratio is a reasonable index to compare the quality of different compost. However, the inoculation seemed to have no significant effect on the moisture content, pH, and the final organic carbon of the composting materials.
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  • 42
    Publication Date: 2021-09-01
    Description: The egg mass and embryos of the ommastrephid squid Nototodarus gouldi McCoy, 1888 are reported for the first time, their identity confirmed by mitochondrial 16S rDNA sequence determination. The egg mass is a free‐floating gelatinous sphere of at least 1.5 m diameter and contains an estimated several thousand randomly distributed eggs; similar egg masses recorded from north‐eastern New Zealand waters of 1.0–2.0 m diameter are reported. Observed fluctuations in populations for this and other squid species may be a partial result of trawl damage to the egg masses.
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  • 43
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    In:  Biotechnic & Histochemistry, 78 (3-4). pp. 191-199.
    Publication Date: 2017-06-27
    Description: Siliceous and calcareous sponges commonly are treated with acid to remove the spicules prior to embedding and cutting for histological investigations. Histology of spiculated sponge tissue represents a challenging problem in sponge histotechnology. Furthermore, fluorescence in situ hybridization (FISH), a key method for studying sponge-associated microbes, is not possible after acid treatment. For a broad range of siliceous sponge species, we developed and evaluated methods for embedding in paraffin, methylmethacrylate resins, LR White resin and cryomatrix. Different methods for cutting tissue blocks as well as mounting and staining sections also were tested. Our aim was to enable histological investigations and FISH without prior removal of the spicules. To obtain an overview of tissue and skeleton arrangement, we recommend embedding tissue blocks with LR White resin combined with en bloc staining techniques for large specimens with thick and numerous spicules, but paraffin embedding and subsequent staining for whole small specimens. For FISH on siliceous sponges, we recommend Histocryl embedding if the spicule content is high, but paraffin embedding if it is low. Classical histological techniques are used for detailed tissue examinations.
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  • 44
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    In:  Advanced Robotics, 17 (9). pp. 863-878.
    Publication Date: 2016-12-14
    Description: Fault tolerance is an important aspect in the development of control systems for multi-legged robots since a failure in a leg may lead to a severe loss of static stability of a gait. In this paper, an algorithm for tolerating a locked joint failure is described in gait planning for a quadruped robot with crab walking. A locked joint failure is one for which a joint cannot move and is locked in place. If a failed joint is locked, the workspace of the resulting leg is constrained, but legged robots have fault tolerance capability to continue walking maintaining static stability. A strategy for fault-tolerant gaits is described and, especially, a periodic gait is presented for crab walking of a quadruped. The leg sequence and the formula of the stride length are analytically driven based on gait study and robot kinematics. The adjustment procedure from a normal gait to the proposed fault-tolerant crab gait is shown to demonstrate the applicability of the proposed scheme.
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  • 45
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    In:  Journal of Natural History, 37 (11). pp. 1281-1327.
    Publication Date: 2018-06-01
    Description: The family Forskaliidae (Siphonophora, Physonectae) contains a single genus, Forskalia, whose species are, in general, poorly known. However, in recent years many Forskalia specimens have been collected by scuba divers or by using submersibles. These specimens have allowed a comprehensive review of the species within the genus to be carried out. In addition two new species are described.
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  • 46
    Publication Date: 2015-03-23
    Description: Permafrost deposits were studied along the Olenyeksky and the Arinsky distributaries in the western Lena delta using a multidisciplinary approach that included sedimentological, mineralogical, stable-isotope, and paleoecological analyses in order to reconstruct the Late Quaternary landscape and environmental history of this Northeast.
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  • 47
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    In:  Oceanography and Marine Biology: an Annual Review, 41 . pp. 115-159.
    Publication Date: 2015-12-11
    Description: This review provides an overview of the importance of beach accumulations of macrophytes and other organic beach-cast material on the ecology of sandy beach ecosystems. It describes the composition of these allochthonous subsidies, their abundance on beaches in relation to seasonal, lunar, tidal and spatial trends, their decomposition and utilisation by bacterial, meio- and macrofaunal communities. The paper then analyses the community structure and the species succession in both macrophyte wrack and carrion and reports the most important findings on individual wrack-inhabiting species (amphipods, isopods, dipterans). Other aspects, such as feeding and microclimatic preferences of certain species and their interactions in wracks, are also discussed. Links to vertebrate species and other secondary consumers that exploit beach-cast macrophytes and carrion as trophic resource are considered, and the importance of wrack in recycling nutrients to nearshore coastal ecosystems is stressed. The beneficial and detrimental effects of organic beach-cast material on both plants and animals of beach and nearshore communities and on the geomorphology of coastal beach-dune systems are pointed out. Another section is dedicated to human use of beach-cast macrophytes through harvesting of economically important species and of other stranded material through its exploitation for traditional reasons. The effects of harvesting on local faunal communities and on the stability of the dunes is discussed. A final section of the paper includes the positive and negative effects of man-made debris on sandy-beach ecosystems and briefly reviews the major findings.
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  • 48
    Publication Date: 2015-10-02
    Description: Current antifouling technologies rely on metal-based paints, but due to their toxicity, an expected worldwide ban of organotin-containing paints is now prompting the quest for safe and effective alternatives. One of these is antifouling coatings whose active components are naturally occurring compounds in marine organisms. A number of laboratory bioassays has been designed to search for antifouling compounds. However, there is no evidence to date that these assays provide results reproducible through ecologically realistic field experiments. Natural concentrations of the extracts from the Brazilian seaweeds Laurencia obtusa and Stypopodium zonale were tested in the laboratory through the 'mussel test' and in the field through the 'phytagel method' in order to compare the efficiency of these methods in assessing antifouling activity. L. obtusa extract significantly inhibited fouling in both the laboratory and field assays, while S. zonale stimulated fouling in both assays. Major compounds from the extracts were identified. The findings suggest that the 'mussel test' is a reliable time and cost-saving screening method for antifouling substances, although field assays are more sensitive for detection of their activity spectrum.
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  • 49
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    In:  European Journal of Phycology, 38 . pp. 171-180.
    Publication Date: 2017-09-12
    Description: Development of biomass and density in experimental monospecific stands of Fucus serratus, F. vesiculosus and F. spiralis was followed on Helgoland (southern North Sea) in plots with three different initial germling densities. As biomass increased over time, considerable mortality occurred. Mortality was significantly higher in stands with higher initial densities, leading to similar final densities. The self-thinning law, which describes boundary conditions for combinations of biomass and density of plants, was refuted in two ways for all three Fucus species: (i) several data points on a bi-logarithmic plane lay considerably above self-thinning lines with conventional parameters from terrestrial plant ecology; however, ‘overall boundaries’ (i.e. a self-thinning line that constrains all lines found) from terrestrial plant ecology were not significantly transgressed, (ii) lines fitted with principal components analysis (PCA) revealed a positive correlation between stand biomass and density. Reasons are proposed why seaweeds generally seem to show higher maximum biomass for a given density than terrestrial plants. Size distributions at the end of the experiment were positively skewed with high Gini coefficients that lay in the range found in other seaweed studies. Inequality decreased with individual mass and increased with density. Gini coefficients were highly correlated with other measurements of inequality (coefficient of variation, skewness).
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  • 50
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    In:  Tellus A: Dynamic meteorology and oceanography, 55 . pp. 426-437.
    Publication Date: 2016-06-14
    Description: The Baltic Sea Experiment BALTEX is the European regional project of GEWEX. The aim of BALTEX is to improve the knowledge of the water and energy cycle of the Baltic Sea including its catchment area (the BALTEX area). In this study the NCEP/NCAR reanalysis data (Kalnay et al. Bull. Am. Meteorol. Soc., 1996, 77, 437–471) are used to derive the mean atmospheric water budget over the BALTEX area. For this purpose the horizontal water vapour fluxes are calculated. In the long-term mean (here 1948 – 2000) the vertically integrated divergence of these fluxes must balance evaporation minus precipitation. The latter two are provided by the NCEP/NCAR reanalyses. The water budget over the BALTEX area is, however, not closed. An error estimation is performed. The divergence of the water vapour flux is corrected due to the mass balance correction technique (Alestalo, Tellus, 1981, 33, 360–371). Large differences are obtained between the precipitation given by the NCEP/NCAR reanalysis and by the analysis of the observations by Rubel and Hantel (Meteorol. Atmos. Phys., 2001, 77, 155–166). With these analysed precipitation data and the corrected divergence of the water vapour fluxes the imbalance of the water vapour budget could be remarkably reduced.
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  • 51
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    In:  Tellus A: Dynamic meteorology and oceanography, 55 . pp. 352-367.
    Publication Date: 2016-06-15
    Description: Precipitation and evaporation over the Baltic Sea are calculated for a one-year period from September 1998 to August 1999 by four different tools, the two atmospheric regional models HIRLAM and REMO, the oceanographic model PROBE-Baltic in combination with the SMHI (1 × 1)° database and Interpolated Fields, based essentially on ship measurements. The investigated period is slightly warmer and wetter than the climatological mean. Correlation coefficients of the differently calculated latent heat fluxes vary between 0.81 (HIRLAM and REMO) and 0.56 (SMHI/PROBE-Baltic and Interpolated Fields), while the correlation coefficients between model fluxes and measured fluxes range from 0.61 and 0.78. Deviations of simulated and interpolated monthly precipitation over the Baltic Sea are less than ±5 mm in the southern Baltic and up to 20 mm near the Finnish coast for the one-year period. The methods simulate the annual cycle of precipitation and evaporation of the Baltic Proper in a similar manner with a broad maximum of net precipitation in spring and early summer and a minimum in late summer. The annual averages of net precipitation of the Baltic Proper range from 57 mm (REMO) to 262 mm (HIRLAM) and for the Baltic Sea from 96 mm (SMHI/PROBE-Baltic) to 209 mm (HIRLAM). This range is considered to give the uncertainty of present-day determination of the net precipitation over the Baltic Sea.
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  • 52
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    In:  European Journal of Work and Organizational Psychology, 12 (3). pp. 257-287.
    Publication Date: 2020-06-17
    Description: The aim of this article is to give a contextual description of personnel selection in Europe, and to highlight some typical features and recent trends in practice and research. We begin with describing the socio-economic environment in which European personnel selection is embedded. Next, we take a closer look at the institutional settings in which personnel selection takes place and its underlying principles. Consequently we review and discuss recent empirical evidence on selection practices and methods, and interpret observed characteristics in terms of contextual differences. Looking at recent changes in the European organizational environment, we note that selection practices exhibit a certain degree of conservatism, and that selection research and theory are slow in addressing new issues. The lack of responsiveness to the changing context is attributed to a continued adherence to the "right man in the right place" paradigm. As an alternative paradigm we propose the "theatre model" of selection, which seems more suitable to tune personnel selection to current contextual demands. Finally, we present a view of the future agenda for European selection research.
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  • 53
    Publication Date: 2019-09-23
    Description: Cold seep environments such as sediments above outcropping hydrate at Hydrate Ridge (Cascadia margin off Oregon) are characterized by methane venting, high sulfide fluxes caused by the anaerobic oxidation of methane, and the presence of chemosynthetic communities. Recent investigations showed that another characteristic feature of cold seeps is the occurrence of methanotrophic archaea, which can be identified by specific biomarker lipids and 16S rDNA analysis. This investigation deals with the diversity and distribution of sulfate-reducing bacteria, some of which are directly involved in the anaerobic oxidation of methane as syntrophic partners of the methanotrophic archaea. The composition and activity of the microbial communities at methane vented and nonvented sediments are compared by quantitative methods including total cell counts, fluorescence in situ hybridization (FISH), bacterial production, enzyme activity, and sulfate reduction rates. Bacteria involved in the degradation of particulate organic carbon (POC) are as active and diverse as at other productive margin sites of similar water depths. The availability of methane supports a two orders of magnitude higher microbial biomass (up to 9.6 2 10 10 cells cm m 3 ) and sulfate reduction rates (up to 8 w mol cm m 3 d m 1 ) in hydrate-bearing sediments, as well as a high bacterial diversity, especially in the group of i -proteobacteria including members of the branches Desulfosarcina/Desulfococcus , Desulforhopalus , Desulfobulbus , and Desulfocapsa . Most of the diversity of sulfate-reducing bacteria in hydrate-bearing sediments comprises seep-endemic clades, which share only low similarities with previously cultured bacteria.
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  • 54
    Publication Date: 2015-01-22
    Description: Pollen data from a Levinson-Lessing Lake sediment core (74°28'N, 98°38'E) and Cape Sabler, Taymyr Lake permafrost sequences (74°33'N, 100°32'E) reveal substantial environmental changes on the northern Taymyr Peninsula during the last c. 32000 14C years. The continuous records confirm that a scarce steppe-like vegetation with Poaceae, Artemisia and Cyperaceae dominated c. 32 000–10300 14C yr BP, while tundra-like vegetation with Oxyria, Ranunculaceae and Caryophyllaceae grew in wetter areas. The coldest interval occurred c. 18000 yr BP. Lateglacial pollen data show several warming events followed by a climate deterioration c. 10500 14C yr BP, which may correspond with the Younger Dryas. The Late Pleistocene/Holocene transition, c. 10300–10000 14C yr BP, is characterized by a change from the herb-dominated vegetation to shrubby tundra with Betula sect. Nanae and Salix. Alnus fruticosa arrived locally c. 9000–8500 14Cyr BP and disappeared c. 4000–3500 14Cyr BP. Communities of Betula sect. Nanae, broadly distributed at c. 10000–3500 14Cyr BP, almost disappeared when vegetation became similar to the modern herb tundra after 3500–3000 14Cyr BP. Quantitative climate reconstructions show Last Glacial Maximum summer temperature about 4°C below the present and Preboreal (c. 10 000 14C yr BP) temperature 2–4°C above the present. Maximum summer temperature occurred between 10 000 and 5500 14C yr BP; later summers were similar to present or slightly warmer.
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  • 55
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    In:  European Journal of Phycology, 37 . pp. 1-17.
    Publication Date: 2017-01-04
    Description: A compilation of data on the elemental composition of marine phytoplankton from published studies was used to determine the range of C:N:P. The N:P ratio of algae and cyanobacteria is very plastic in nutrient-limited cells, ranging from 〈5 mol N:mol P when phosphate is available greatly in excess of nitrate or ammonium to 〈100 mol N:mol P when inorganic N is present greatly in excess of P. Under optimal nutrient-replete growth conditions, the cellular N:P ratio is somewhat more constrained, ranging from 5 to 19 mol N:mol P, with most observations below the Redfield ratio of 16. Limited data indicate that the critical N:P that marks the transition between N- and P-limitation of phytoplankton growth lies in the range 20–50 mol N:mol P, considerably in excess of the Redfield ratio. Biochemical composition can be used to constrain the critical N:P. Although the biochemical data do not preclude the critical N:P from being as high as 50, the typical biochemical composition of nutrient-replete algae and cyanobacteria suggests that the critical N:P is more likely to lie in the range between 15 and 30. Despite the observation that the overall average N:P composition of marine particulate matter closely approximates the Redfield ratio of 16, there are significant local variations with a range from 5 to 34. Consistent with the culture studies, lowest values of N:P are associated with nitrate- and phosphate-replete conditions. The highest values of N:P are observed in oligotrophic waters and are within the range of critical N:P observed in cultures, but are not so high as to necessarily invoke P-limitation. The C:N ratio is also plastic. The average C:N ratios of nutrientreplete phytoplankton cultures, oceanic particulate matter and inorganic N and C draw-down are slightly greater than the Redfield ratio of 6.6. Neither the analysis of laboratory C:N:P data nor a more theoretical approach based on the relative abundance of the major biochemical molecules in the phytoplankton can support the contention that the Redfield N:P reflects a physiological or biochemical constraint on the elemental composition of primary production.
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  • 56
    Publication Date: 2019-05-16
    Description: We investigated the effects of local nutrient enrichment, among-population variation in quality, and within-plant variation in quality on growth, development, and food consumption (total amount of food ingested) of the marine isopod Idotea baltica when fed Fucus vesiculosus. We found that the proximity of fish farms increased carbon/nitrogen ratio, but did not change the concentration of phlorotannins in the F. vesiculosus thallus. Algal diets taken from sites close to or far from fish farms did not affect the growth, development, or total amount of food ingested of I. baltica. Therefore, eutrophication may not necessarily decrease the level of plant resistance. We found that different F. vesiculosus beds vary in quality and led to differences in total amount of food ingested and production efficiency of I. baltica. The variation in quality of F. vesiculosus in different locations may generate variance in grazing pressure between the belts. Idotea baltica was most sensitive to within-plant variation, as the isopods grew more and had higher production efficiency on apical than basal parts of F. vesiculosus. Idotea baltica did not compensate for the lower quality of basal parts by increasing consumption. This may indicate that the low quality of the basal thallus is related to higher levels of secondary metabolites and not to lower levels of soluble sugars or nitrogen that might have encouraged compensatory consumption. Our results suggest that within-plant variation in the quality of the F. vesiculosus is more important for herbivores than possible environmental variation caused by eutrophication.
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  • 57
    Publication Date: 2019-07-01
    Description: Small-angle phase functions (0.05° 〈 θ 〈 20°) have been measured for turbid samples that were then used in a Monte-Carlo theoretical light-scattering model. The measured phase function yields excellent agreement between model predictions and long-path tank measurements.
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  • 58
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    In:  Tellus A: Dynamic meteorology and oceanography, 54 . pp. 406-425.
    Publication Date: 2016-06-14
    Description: The study investigates perspectives of the parameter estimation problem with the adjoint method in eddy-resolving models. Sensitivity to initial conditions resulting from the chaotic nature of this type of model limits the direct application of the adjoint method by predictability. Prolonging the period of assimilation is accompanied by the appearance of an increasing number of secondary minima of the cost function that prevents the convergence of this method. In the framework of the Lorenz model it is shown that averaged quantities are suitable for describing invariant properties, and that secondary minima are for this type of data transformed into stochastic deviations. An adjoint method suitable for the assimilation of statistical characteristics of data and applicable on time scales beyond the predictability limit is presented. The approach assumes a greater predictability for averaged quantities. The adjoint to a prognostic model for statistical moments is employed for calculating cost function gradients that ignore the fine structure resulting from secondary minima. Coarse resolution versions of eddy-resolving models are used for this purpose. Identical twin experiments are performed with a quasigeostrophic model to evaluate the performance and limitations of this approach in improving models by estimating parameters. The wind stress curl is estimated from a simulated mean stream function. A very simple parameterization scheme for the assimilation of second-order moments is shown to permit the estimation of gradients that perform efficiently in minimizing cost functions.
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  • 59
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    In:  Philosophical Magazine: A, 82 (10). pp. 1821-1829.
    Publication Date: 2022-01-19
    Description: Using dimensional analysis and finite-element calculations, several relationships that relate features of indentation loading and unloading curves to the hardness, the elastic modulus and the work of indentation are extended to conical indentation in elastic-plastic solids with various angles. These relationships provide new insights into indentation measurements. They may also be useful to the interpretation of results obtained from instrumented indentation experiments.
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  • 60
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    In:  Journal of Asian Natural Products Research, 3 (2). pp. 117-122.
    Publication Date: 2018-02-05
    Description: One kinds of glycolipid (SBI) have been isolated from the marine brown alga Sargassum hemiphyllum (Turn.) Ag. The structures of SBI have been determined as the sodium salt of 1-0-acyl-3-0-(6′-sulfo-α-D-quinovopyrannosyl) glycerol (acyl: tetradecanoyl, pentadecanoyl, 11-hexadecenoyl, hexadecanoyl, 10,13-octadecadienoyl, 9-octade cenoyl, 15-metylheptadecanoyl and 11-eicosenoyl 17:1.5:19:153:1:19:1:2) on the basis of chemical and spectral evidence and GC-MS analysis, respectively. Four constituents of the SBI were new compounds [the sodium salt of 1-0-(11″-hexadecenoyl)-3-0-(6′-sulfo-α-D-quinovopyrannosyl) glycerol, the sodium salt of 1-0-(10″,13″-octadecadienoyl)-3-0-(6′-sulfo-α-D-quinovopyrannosyl) glycerol, and the sodium salt of 1-0-(15″-metylhexadecenoyl)-3-0-(6′-sulfo-α-D-quinovopyrannosyl) glycerol, and the sodium salt of 1-0-(11″-eicosenoyl)-3-0-(6′-sulfo-α-D-quinovopyrannosyl) glycerol]. All compounds were isolated from marine brown alga for the first time.
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  • 61
    Publication Date: 2017-07-25
    Description: Seafloor morphology and ferromanganese nodule occurrence were studied using a multibeam side scan sonar (SeaBeam, 2000) and a deep-sea camera system in the Korea Deep-sea Environmental Study (KODES) area, northeast equatorial Pacific. Seafloor morphology and nodule abundance are highly variable even in this small study area. The NNE-SSW oriented hills are parallel and about 100–200 m high. Valleys are very flat-floored, while hilltops are rugged with depressions of tens of meters. Cliffs to about 100 m bound the valleys and the hills. The study area can be classified into three types based both on nodule occurrence and seafloor morphology, mostly G- and B-types and some M-type. G-type is characterized by high nodule abundance, ubiquitous bioturbation, and flat seafloor morphology, while B-type is characterized by irregular-shaped nodules, variable nodule abundance, occurrence of giant nodules and sediment lumps, rugged bottom morphology with depressions, and white calcareous surface sediments. Medium nodule abundance and a generally flat seafloor characterize M-type. G-type occurs mostly in the valley regions, while B-type is on the hilltop areas. M-type is located between the hilltop and the valley. Tectonic movement of the Pacific plate resulted in the elongated abyssal hills and cliffs. The rugged morphology on hilltops resulted from erosion and redistribution of surface siliceous sediments on hilltops by bottom currents, outcropping of underlying calcareous sediments, and dissolution of the carbonate sediments by corrosive bottom water undersaturated with CaCO3. Sediment eroded from the hills, which is relatively young and organic-rich, is deposited in the valleys, and diagenetic metal supply to manganese nodules in the valley area is more active than on the hills. We suggest that tectonic movement ultimately constrains morphology, surface sediment facies, bottom currents and sediment redistribution, bioturbation, thickness of the sedimentary layer, and other conditions, which are all interrelated and control nodule occurrence. The best potential area for mining in the study area is the G-type valley zones with about 3–4 km width and NNW-SSE orientation.
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  • 62
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    In:  North American Journal of Fisheries Management, 21 (1). pp. 1-9.
    Publication Date: 2020-06-19
    Description: The use of precautionary management actions within a fisheries context has generally been limited to reducing fishing mortality. By the use of quantitative models, overfishing thresholds can be determined and actions can be taken to reduce the probability of further population declines and to allow rebuilding. Within this context, four management approaches have been defined (i.e., preventive approach, corrective approach, precautionary approach, and precautionary principle) on the basis of levels of uncertainty in the information used to make decisions and the potential cost of errors as a result of those decisions. In this paper, I apply these approaches to developing a precautionary and adaptive habitat management framework. Fishing effort metrics are used to develop estimates of the area of seafloor impacted by fishing, and thresholds are proposed to trigger specific types of management actions. Information needs include the cumulative area impacted by all gears, the distribution of habitats and diversity of key taxa, effects of gears on habitat and patterns of diversity, and linkages between habitat and the dynamics of exploited populations. Incentives for the fishing industry that will improve the information available to make decisions and reduce the level of precaution required for managing exploitation of wild populations are discussed. This framework is a starting point for management agencies to develop precautionary and adaptive habitat management programs that promote both the sustainability of exploited populations and the maintenance of biological diversity.
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  • 63
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    In:  Tellus A: Dynamic meteorology and oceanography, 54 (3). pp. 299-316.
    Publication Date: 2019-09-23
    Description: Due to the ephemeral nature of the atmospheric conditions over the Baltic Sea, the flow field is highly variable, and thus, changes in the resulting circulation and upwelling are difficult to observe. However, three-dimensional models, forced by realistic atmospheric conditions and river runoff, have reached such a state of accuracy that the highly fluctuating current field and the associated evolution of the temperature and salinity field can be described. In this work, effects of remote and local atmospheric forcing on circulation and upwelling in the Baltic Sea are investigated. Changes in the characteristics of the large-scale atmospheric wind field over the central and eastern North Atlantic can be described by the North Atlantic Oscillation (NAO). The NAO is related to the strength and geographical position of weather systems as they cross the North Atlantic and thus has a direct impact on the climate in Europe. To relate the local wind field over the Baltic Sea to the large-scale atmospheric circulation, we defined a Baltic Sea Index (BSI), which is the difference of normalised sea level pressures between Oslo in Norway and Szczecin in Poland. The NAO is significantly related to the BSI. Furthermore, the BSI is highly correlated with the storage variation of the Baltic Sea and the volume exchange through the Danish Sounds. Based on three-dimensional model calculations, it is shown that different phases of the NAO during winter result in major changes of horizontal transports in the deep basins of the Baltic Sea and in upwelling along the coasts as well as in the interior of the basins. During NAO+ phases, strong Ekman currents are produced with increased up- and downwelling along the coasts and associated coastal jets, whereas during NAO− phases, Ekman drift and upwelling are strongly reduced, and the flow field can almost entirely be described by the barotropic stream function. The general nature of the mean circulation in the deep basins of the Baltic Sea, obtained from a 10-yr model run, can be described by the depth integrated vorticity balance derived from the transport equation for variable depth.
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  • 64
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    In:  International Journal of Geographical Information Science, 15 (8). pp. 763-784.
    Publication Date: 2021-07-13
    Description: Cephalopod stocks are of increasing economic importance. Cephalopod fisheries show marked inter-annual fluctuations unrelated to fishery landings and effort. Their population dynamics, particularly recruitment, are thought to be strongly susceptible to changes in environmental conditions. This arises in part from the short life cycle, resulting in poor buffering of the population against changing conditions. These characteristics make traditional approaches to stock assessment and fishery management inappropriate. GIS offers a tool to improve understanding of spatio-temporal trends in abundance and facilitate rational management. A cephalopod fishery geographical information system for Northeast Atlantic waters (CFGIS-NEA) was developed. The system covers the area from 28.0° W to 11.0° E, and 34.5° N to 65.5° N. It was designed for investigating cephalopod resource dynamics in relation to environmental variation. It is based on Unix Arc/Info, and PC ArcView, combined with the statistical software package S-PLUS and supported by a database in Microsoft Access. Environmental data (e.g. sea surface temperature and salinity, sea bottom temperature and salinity, and bathymetric data), cephalopod fishery, survey and biological data, from a variety of sources, were integrated in the GIS as coverages, grids, shapefiles, and tables. Special functions were developed for data integration, data conversion, query, visualisation, analysis and management. User-friendly interfaces were developed allowing relatively inexperienced users to operate the system. The spatial and temporal distribution patterns of cephalopod abundance by species, the spatial and temporal relationships between cephalopod abundance and environmental factors, and the spatial and temporal patterns of cephalopod fishing activity were analysed using a combination of visual (qualitative) and quantitative methods. Predictive empirical models, such as GAMs (generalized additive models), were developed for modelling cephalopod abundance using environmental variables.
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  • 65
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    In:  Sarsia, 86 (1). pp. 1-11.
    Publication Date: 2021-06-28
    Description: All seven known resident Arctic cephalopods were identified in the collections of the German RV Polarstern (1991, 1993, 1995, 1998) in the waters around Svalbard, northwards from the Kara Sea, in the Laptev and western East Siberian seas: sepia lids Rossia palpebrosa (depths 96–362 m) and R. moelleri (67–101, specimens identified with question mark also at the depths of 38 and 292 m), benthic octopuses Bathypolypus arcticus (180–362 m), Benthoctopus piscatorum (1580–2000 m), and Benthoctopus sibiricus (30m, a juvenile identified with question mark), cirrate octopod Cirroteuthis muelleri (3012–3310 m), and gonatid squid Gonatus fabricii (juveniles: in midwater, 300–500 m, in fish stomachs, 946–990 m). The latter two species are definitely circumpolar and panpolar (inhabiting the whole Polar Basin). The known ranges of R. pulpebrosa, R. moelleri, and B. arcticus are extended from the eastern coasts of Severnaya Zemlya and Vilkitsky Strait to western East Siberian Sea (R. palpebrosa: 150°E) or eastern Laptev Sea (R. moelleri: 130°E, B. arcticus: 135°E), the range of B. piscatorum is extended from West Spitsbergen Island to 91°E. Although gaps still exist in the known distributions of R. palpebrosa. R. moelleri and B. arcticus (these species are considered as West-Arctic or Atlanta-West-Arctic) between the eastern boundaries of their ranges in the Asian Arctic and western boundaries in the Canadian Arctic, there are little doubt that they are in fact circumpolar and widely eurybathic in the western sector of the Arctic but in the eastern sector distributed only at depths 〉 100–200 m (except R. moelleri: to 67 m). B. piscatorum is known at yet in western Arctic only and may be not circumpolar. Benthoctopus sibiricus is the East-Arctic (definitely not circumpolar) shallow-water benthic octopus having relations with the octopods of northwestern Pacific.
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  • 66
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    In:  Journal of Applied Animal Welfare Science, 4 (2). pp. 157-168.
    Publication Date: 2021-06-30
    Description: What is environmental enrichment? During the last several decades, zoos and aquariums have come to realize (perhaps belatedly) that animals kept in captivity need environmental enrichment for their well-being (Seidensticher & Forthman, 1998). Early zoos and aquariums tried to show as many animals as possible; hence, their exhibits were frequently small and bare to permit easy viewing, cleaning, and sterilization. Now, all have come to realize that captive animals need environmental enrichment for their health and for the education and increased expectations of visitors to zoos and aquariums.
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  • 67
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    In:  Marine Georesources & Geotechnology, 18 (1). pp. 43-76.
    Publication Date: 2017-05-09
    Description: The morphological features associated with Co-rich manganese deposits, the size variations of nodules, and the occurrence of different substrates have been analyzed, to evaluate the influence of various seabed slope angles on the distribution of these features. The coverage and size of the crusts depend on their surface morphology and seabed topography, resulting in cobble-type, lineated, or step-like outcrops. Small nodules (1–4 cm in diameter) dominate all seabed slopes, with a few locations having nodules ranging from 1 to 8 or 1 to 10 cm. Sediments invariably occur as substrates for nodules and as cover for crusts, their coverage being inversely proportional to that of the nodules and crust outcrops.
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  • 68
    Publication Date: 2017-07-06
    Description: A semi-quantitative assessment is made of the animals observed in archived videotapes taken from the research submersible Jago, during diamond mining and exploratory surveys off the mouth of the Orange River on the west coast of southern Africa (28°15′S, 29°11′S) in November 1996. The seabed environment is described and nekton associations with substratum features are identified. The area is characterized by heterogeneity to its physical and biological struture. The variety of observed nekton is low, and communities are dominated by goby Sufflogobius bibarbatus, juvenile hake Merluccius spp. and cuttlefish Sepia spp. (on soft substrata), as well as false jacopever Sebastes capensis and kingklip Genypterus capensis (on rocky substrata).
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  • 69
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    In:  International Geology Review, 42 . pp. 445-469.
    Publication Date: 2017-09-29
    Description: The chief host of cadmium in zinc deposits is sphalerite, the cadmium content of which depends on the type of deposit. Sphalerite from Mississippi Valley-type (MVT) deposits has high cadmium concentrations whereas sphalerite from exhalative deposits has low cadmium concentrations. The Cd content of sphalerite depends on the Cd/Zn ratio, ligand activities, and temperature of the ore-forming fluids. The combined effect of variation of temperature, pH, total activity of reduced sulfur, and activity of Cl- cannot by itself account for either Cd depletion (exhalative deposits) or Cd enrichment (MVT deposits). Variations in the Cd/Zn ratio of the fluid have a significant effect in determining that of sphalerite. Basinal brines, which can considered to be the recent equivalents of MVT fluids, have high Cd/Zn ratios, and active exhalative systems are characterized by low Cd/Zn ratios. Probably the differences in sphalerite composition between the different deposit types are less a function of temperature and ligand activities than Cd/Zn ratio of the ore-forming fluids. In the hydrothermal environment, the Cd/Zn ratio is generally not high enough to allow crystallization of cadmium sulfides (greenockite or hawleyite). The abundance of greenockite in the supergene alteration zone of hydrothermal zinc deposits can be explained on the basis of Zn scavenging by crystallizing smithsonite.
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  • 70
    Publication Date: 2020-05-28
    Description: A single living specimen of Stenocyathus vermiformis was collected with a grab from the distal rubble zone of a Lophelia bank at 276 m depth on the Sula Ridge, Norwegian Shelf.
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  • 71
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    In:  Tellus B: Chemical and physical meteorology, 51 (2). pp. 562-571.
    Publication Date: 2019-01-24
    Description: Recent progress in research of the global carbon cycle is reviewed and research needs for the immediate future are discussed, in light of the challenge posed to society to come to grips with the problem of man-made climate change. The carbon cycle in the oceans and on the land is reviewed, and how the atmosphere functions to couple them together. Major uncertainties still exist for any projection of the future atmospheric burden of carbon dioxide resulting from postulated emission scenarios of CO2. We present some ideas on how future policies designed to limit emissions or to sequester carbon can possibly be supported by scientific evidence of their effectiveness.
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    In:  Marine Georesources & Geotechnology, 18 (3). pp. 223-235.
    Publication Date: 2020-07-09
    Description: Particle fluxes were measured 7 m above the sea bottom during the predisturbance, disturbance, and postdisturbance periods by using time series sediment traps attached to seven deep-sea moorings deployed in the INDEX experiment site in the Central Indian Basin. The predisturbance particle fluxes varied between 22.3 to 55.1 mg m−2 day−1. Increased and variable particle fluxes were recorded by the sediment traps during the disturbance period. The increase observed was 0.5 to 4 times more than the background predisturbance fluxes. The increases in particle fluxes (∼4 times) recorded by the sediment trap located in the southwestern direction (DMS-1) were the greatest, which could be the result of preferential movement of resuspended particles generated during the deep-sea benthic disturbance along the general current direction prevailing in this area during the experimental period. Also, the traps located closer to the disturbance area recorded greater fluxes than did the traps far away, across the Deep Sea Sediment Resuspension System path. This variability in recorded particle fluxes by the traps around the disturbance area clearly indicates that physical characteristics such as grain size and density of the resuspended particles produced during the disturbance had an important effect on particle movement. The postdisturbance measurements during ∼5 days showed a reduction in particle fluxes of ∼50%, indicating rapid particle settlement.
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  • 73
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    In:  Marine Georesources & Geotechnology, 18 (3). pp. 237-250.
    Publication Date: 2020-07-09
    Description: Observations on seafloor features from subbottom profiling and seabed photography data show that the undisturbed and natural conditions before the benthic disturbance undergo a substantial change after operation of the disturber. The effects can be seen in the form of deep trenches and grooves, formed by the action of the sleds and the pumping of the sediment along its path, as well as sediment piles on either side of the track. Biological traces such as fecal coils, casts, tubes, burrows, and trails get obliterated in the areas of disturbance and resedimentation. The smooth, uniform nature of the seafloor observed in pre-disturbance phase shows microtopographic changes in and around the disturbed area as a result of sediment excavation and resettlement. Vertical mixing as well as lateral transport of sediment alter the geological, biological, physical, and chemical conditions on the seafloor, which need to be monitored over time to assess the process and the time taken for restoration of environmental conditions.
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  • 74
    Publication Date: 2019-03-27
    Description: Antarctic sponges are commonly fouled by diatoms, sometimes so heavily as to occlude pores employed in filter feeding and respiration. This fouling becomes heavier during the annual summer microalgal bloom. Polar and non‐polar extracts of eight species of marine sponges from McMurdo Sound, Antarctica were assayed for cytotoxicity against sympatric fouling diatoms. To identify compounds potentially released by sponges as defenses against diatom biofouling, only fractions of crude extracts that were soluble in seawater or 2% methanol in seawater were assayed. Significant bioactivity was present in seven of the eight species. Both Mycale acerata and Homaxinella balfourensis displayed moderate levels of defense against diatoms even though they are not or are only weakly chemically defended against bacteria and predators. Calyx acuarius extracts, which do have antipredator and antibacterial effects, had no effect on diatoms except at levels many fold higher than present in the intact animal. These results strongly suggest some level of specificity for chemical defenses against diatom fouling in antarctic sponges.
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  • 75
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    In:  Journal of Geoscience Education, 48 (3). pp. 342-361.
    Publication Date: 2021-03-30
    Description: Measurements from a dinosaur trackway are used to estimate how fast the dinosaur track makers were moving. The exercise, which is appropriate for any introductory earth-science course at the secondary-school or college level, introduces students to dimensional analysis by having them construct an empirical graph of dimensionless stride length versus dimensionless velocity. The students then estimate the dimensionless stride length from the trackway data and use the dimensionless graph to determine the speeds of the dinosaurs. Experience with the exercise indicates that even students with little quantitative background are motivated by the challenge of determining whether they could outrun the dinosaurs and often begin to appreciate the power of dimensional analysis, a concept not usually presented in introductory courses.
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  • 76
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    In:  International Geology Review, 42 (6). pp. 481-490.
    Publication Date: 2018-09-03
    Description: A reassessment of the abundance of dolomite in carbonate sediments has confirmed that carbonates deposited during the past 150 Ma contain, on average, less dolomite than Proterozoic and Paleozoic carbonates. The lower dolomite content of the more recent carbonate sediments results from the increase in the deposition of CaCO3 in deep-sea sediments, and to the difficulty of dolomitizing deep-sea CaCO3 by reaction with cold, unevaporated seawater. The decrease in the rate of dolomite formation during the past 150 Ma has led to an increase in the output of oceanic Mg+2 by the reaction of seawater with clay minerals and with ocean-floor basalts. The increase in the output of marine Mg+2 into these reservoirs has been brought about by an increase in the Mg+2 concentration of seawater. During the past 40 Ma, the concentration of Mg+2 in seawater has probably increased by ∼18 mmol/kg, and probably has been accompanied by an equimolar increase in the concentration of SO4−2.
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  • 77
    Publication Date: 2023-11-15
    Description: The morphological features associated with Co-rich manganese deposits, the size variations of nodules, and the occurrence of different substrates have been analyzed, to evaluate the influence of various seabed slope angles on the distribution of these features. The coverage and size of the crusts depend on their surface morphology and seabed topography, resulting in cobble-type, lineated, or step-like outcrops. Small nodules (1–4 cm in diameter) dominate all seabed slopes, with a few locations having nodules ranging from 1 to 8 or 1 to 10 cm. Sediments invariably occur as substrates for nodules and as cover for crusts, their coverage being inversely proportional to that of the nodules and crust outcrops. Steeper seafloor areas have large crust outcrops exposed with no or few nodules and sediments associated with them. The intermediate slopes have a combination of nodules, sediments, and crusts in various proportions, depending on topography and gradient. Large-scale nodule occurrences, followed by sediment fields and crust outcrops on seabed slopes of 〈 3°, 3–7°, and 〉 15°, respectively, represent typical morphological distribution zones of the Co-rich manganese deposits on a seamount in the central Pacific Ocean. A transition zone between nodule-dominated fields and large crust outcrops occurs for slopes from 7° to 15°. This detailed study on distribution of Co-rich deposits gives a better understanding for purposes of their exploitation.
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  • 78
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    In:  Sarsia, 79 (3). pp. 207-283.
    Publication Date: 2018-04-19
    Description: The holoplanktonic family Miraciidae (Copepoda, Harpacticoida) is revised and a key to the four monotypic genera presented. Amended diagnoses are given for Miracia Dana, Oculosetella Dahl and Macrosetella A. Scott, based on complete redescriptions of their respective type species M. efferata Dana, 1849, O. gracilis (Dana, 1849) and M. gracilis (Dana, 1847). A fourth genus Distioculus gen. nov. is proposed to accommodate Miracia minor T. Scott, 1894. The occurrence of two size-morphs of M. gracilis in the Red Sea is discussed, and reliable distribution records of the problematic O. gracilis are compiled. The first nauplius of M. gracilis is described in detail and changes in the structure of the antennule, P2 endopod and caudal ramus during copepodid development are illustrated. Phylogenetic analysis revealed that Miracia is closest to the miraciid ancestor and placed Oculosetella-Macrosetella at the terminal branch of the cladogram. Various aspects of miraciid biology are reviewed, including reproduction, postembryonic development, vertical and geographical distribution, bioluminescence, photoreception and their association with filamentous Cyanobacteria (Trichodesmium).
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  • 79
    Publication Date: 2020-05-28
    Description: The stomach contents of 723 Loligo vulgaris and 440 Loligo forbesi caught in the northwestern Spanish Atlantic waters have been examined. The diets of both species are described and compared. Loligo vulgaris shows 28 different types of prey belonging to four groups (Teleostei, Crustacea, Cephalopoda and Polychaeta) and Loligo forbesi 27 different types of prey belonging to three groups (Teleostei, Crustacea and Cephalopoda). Both species catch similar prey species but in different proportions. Cannibalism was observed in both species. Estimated prey sizes were smaller than squid sizes. No differences in feeding habits of males and females of both species were observed, but females seem to increase food intake during maturation. No significant changes were found in the diet of Loligo vulgaris within the size (DML) range studied (65–465 mm). Importance of cephalopods increased and importance of fish decreased in the diet of Loligo forbesi with growth (65–685 mm). Diet and food intake varied with seasons in both species. Diets of both squids were significantly different. Los contenidos estomacales de 723 Loligo vulgaris y 440 Loligo forbesi capturados en aguas de Galicia (Noroeste de España) fueron examinados. Se describe y compara la dieta de ambas especies. Se identificaron 28 tipos de presa diferentes en Loligo vulgaris que pertenecen a cuatro grupos (Teleostei, Crustacea, Cephalopoda y Polychaeta); y 27 tipos de presa en Loligo forbesi, pertenecientes a tres grupos (Teleostei, Crustacea y Cephalopoda). Ambas especies comen pres as similares, pero en proporciones diferentes. En ambas especies se observó canibalismo. La talla de las presas fue menor que la de los calamares. No se encontraron diferencias en la dieta entre machos y hembras en ambas especies, pero se observó que las hembras incrementan su tasa de ingestión durante la maduración. No se hallaron cambios significativos en la dieta de Loligo vulgaris en función de la talla (DML) dentro del rango de tamanos estudiado (65–465 mm). En Loligo forbesi, los cefalópodos aumentaron y los peces disminuyeron en importancia con la talla (65–685 mm DML). La dieta y la tasta de ingestión de ambas especies varió con la época del ano. Las dietas de ambas especies fueron significativemente diferentes entre sí.
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  • 80
    Publication Date: 2018-08-17
    Description: Individual polychlorinated biphenyl (CB) congeners in adipose and whole blood tissues of a capacitor manufacture worker (occupational/accidental exposure) and of the general population were determined. Nondestructive sample cleanup and multidimensional gas chromatography-electron capture detection (MDGC-ECD) techniques were applied. Special attention was given to the toxicologically relevant congeners CB-77, CB-126, CB-169, CB-105, CB-114, CB-118, CB-156, CB-167, and CB-189 (IUPAC). Lipid-based tissue contents of sigma CBs were higher in the occupationally/accidentally exposed worker (adipose = 7,000 ng/g; whole blood = 11 ng/g) than in the general population (adipose = 300 ng/g; whole blood = 1.9 ng/g). Among the non-ortho Cl CBs, CB-77 was below detection limit (〈 1.0 pg/g). The contents of CB-126 for the capacitor manufacture worker were 2,000 and 3 pg/g, and in the general population were 100 and 2 pg/g for adipose and whole blood, respectively. The corresponding data for CB-169 were 3,500 and 4 for adipose and whole blood, respectively, in the exposed worker, and 40 and 2 for adipose and whole blood, respectively, in the general population. Congeners with highest contents were CB-153, CB-138, CB-180, CB-170, and CB-187. These congeners possess chlorine substitution patterns, making them resistant to metabolism. X/153 ratios suggest that both PB and 3-MC type cytochrome P-450 enzymes were induced in the exposed worker, as well as in the general population.
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  • 81
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    In:  Tellus A: Dynamic meteorology and oceanography, 46 (4). pp. 367-380.
    Publication Date: 2016-06-15
    Description: A coupled ocean-atmosphere GCM is being developed for use in seasonal forecasting. As part of the development work, a number of experiments have been made to explore some of the sensitivities of the coupled model system. The overall heat balance of the tropics is found to be very sensitive to convective cloud cover. Adjusting the cloud parameterization to produce stable behaviour of the coupled model also leads to better agreement between model radiative fluxes and satellite data. A further sensitivity is seen to changes in low-level marine stratus, which is under-represented in the initial model experiments. An increase in this cloud in the coupled model produces a small improvement in both the global mean state and the phase of the east Pacific annual cycle. The computational expense of investigating such small changes is emphasized. An indication of model sensitivity to surface albedo is also presented. The sensitivity of the coupled GCM to initial conditions is investigated. The model is very sensitive, with tiny perturbations able to determine El Niño or non-El Niño conditions just six months later. This large sensitivity may be related to the relatively weak amplitude of the model ENSO cycle.
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  • 82
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    In:  Tellus A: Dynamic meteorology and oceanography, 46 (4). pp. 351-366.
    Publication Date: 2016-06-15
    Description: ECHO is a new global coupled ocean-atmosphere general circulation model (GCM), consisting of the Hamburg version of the European Centre atmospheric GCM (ECHAM) and the Hamburg Primitive Equation ocean GCM (HOPE). We performed a 20-year integration with ECHO. Climate drift is significant, but typical annual mean errors in sea surface temperature (SST) do not exceed 2° in the open oceans. Near the boundaries, however, SST errors are considerably larger. The coupled model simulates an irregular ENSO cycle in the tropical Pacific, with spatial patterns similar to those observed. The variability, however, is somewhat weaker relative to observations. ECHO also simulates significant interannual variability in mid-latitudes. Consistent with observations, variability over the North Pacific can be partly attributed to remote forcing from the tropics. In contrast, the interannual variability over the North Atlantic appears to be generated locally.
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  • 83
    Publication Date: 2019-02-12
    Description: This paper describes the evolution of the former Tethys ocean in terms of successive positions of the involved plates, their boundaries, and the oceanic and continental elements they bore. Most of the past positions for the major continents are obtained from published data on the kinematics of the Atlantic and Indian oceans. As they do not cover the complete time span and area under study, additional solutions for the missing parts are proposed on the basis of paleomagnetic and geologic data. A revised reconstruction of Eastern Gondwana and a reappraisal of the early history of the Indian ocean is presented, as well as a discussion of the Pangea megashear concept which applies to the relations between Gondawa and Laurussia during latest Palaeozoic to Mid-Triassic times. Past positions of continental blocks, basins and associated plate boundaries within the now disappeared Tethys ocean, are determined through the kinematic inversion of the Alpine chains interpreted in terms of break-up, oceanic spreading and drift, subduction and collision. A quantitative solution is obtained by associating Eulerian rotation parameters to any relative displacement, computing their combination, then adjusting until a complete coherency through time and space is obtained. Our method puts emphasis on the former positions of the plate boundaries in the Tethys, and stresses the drastically different organisation of Tethys west and east of a fundamental triple junction located in its Mediterranean part. A symmetric Atlantic part of Tethys, governed by a mid-ocean diverging boundary, was thus linked eastwards to an asymmetric “Transit” part of Tethys where southern diverging boundaries and northern converging boundaries defined a Transit plate (or group of plates). Besides several reorganisations through southward shift of these boundaries, the successive (or coeval) transit plates systematically exhibited the same north-south asymmetry responsible for the northward migration of the various continental blocks they carried, which were successively detached from Gondwana to become accreted to Eurasia. The transit process, while an essential element of the Tethyan tectonic pattern, was not restricted to lifetime of Tethys, as it is still active nowadays and was already active during the Palaeozoic. Nevertheless, its association with the Atlantic Tethys diverging boundary is typical for the lifetime of Tethys, both constituting a “Tethys plate pattern”, in opposition to the present-day and to Hercynian “Anti-Tethys plate pattern” where a converging boundary is and was associated with the transit plate system. Two pre-eminent tectonic events, the Late Triassic switchover from the Anti-Tethys pattern to the Tethys pattern, and the Late Cretaceous switchover back to the Anti-Tethys pattern, decided birth and death of the Tethys ocean.
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  • 84
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    In:  Ostrich, 65 (2). pp. 218-224.
    Publication Date: 2021-06-14
    Description: Site fidelity and dispersal of juvenile and sexually mature adults was investigated at the largest southern African gannetry on Bird Island, Algoa Bay, where a minimum of 65000 airs occupy approximatel 2 ha at a mean density of 2,85 nests per m2. Based on 512 ring recoveries and live retraps of known-aged birds of this colony, immature and non-breeding adult gannets dispersed widely along the coasts o Africa, reaching Maputo Bay (southern Mozambique) on the eastern side of the continent and the Namibian Skeleton Coast on the western side. Very few birds flew farther. There were conspicuously few ring recoveries at 400–500 km straight-line distance east from Bird Island, corresponding with the Pondoland coast in Transkei. A similar drop was observed in the west for the Tsitsikamma coast and the stretch of coast from Cape St. Blaize to Cape Infanta. In these regions reporting by members of the public is presumed to be low. either because the rocky coast is inaccessible or because of socioeconomic reasons. The geographical spread of the ring recoveries suggested a possible range contraction of the species between the 1950's and the period 1978–1993 but the nature of the data prevented a test of this hypothesis. No evidence was found that gannets from Bird Island breed or roost at other southern African colonies as a matter of habit. On the contrary, all survivors of post-fledgling dispersal eventually returned to their native colony, where they exhibited pronounced fidelity to the site where they hatched from the egg. Based on multiple retraps of 862 known-age individuals, 71.7 % of young adults took over vacant sites in the immediate vicinity of their original nest, 8,1% moved once but were faithful to their new site and in 20,2% of all cases faithfulness to the original site could not be shown. Moreover, in subsequent years edge birds did not vacate their sites to move towards the center, refuting the hypothesis that fringes are physically inferior breeding sites.
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  • 85
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    In:  Journal of the American Statistical Association, 89 (428). pp. 1303-1313.
    Publication Date: 2020-08-21
    Description: This article introduces a resampling procedure called the stationary bootstrap as a means of calculating standard errors of estimators and constructing confidence regions for parameters based on weakly dependent stationary observations. Previously, a technique based on resampling blocks of consecutive observations was introduced to construct confidence intervals for a parameter of the m-dimensional joint distribution of m consecutive observations, where m is fixed. This procedure has been generalized by constructing a “blocks of blocks” resampling scheme that yields asymptotically valid procedures even for a multivariate parameter of the whole (i.e., infinite-dimensional) joint distribution of the stationary sequence of observations. These methods share the construction of resampling blocks of observations to form a pseudo-time series, so that the statistic of interest may be recalculated based on the resampled data set. But in the context of applying this method to stationary data, it is natural to require the resampled pseudo-time series to be stationary (conditional on the original data) as well. Although the aforementioned procedures lack this property, the stationary procedure developed here is indeed stationary and possesses other desirable properties. The stationary procedure is based on resampling blocks of random length, where the length of each block has a geometric distribution. In this article, fundamental consistency and weak convergence properties of the stationary resampling scheme are developed.
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  • 86
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    In:  South African Journal of Marine Science, 14 . pp. 281-286.
    Publication Date: 2020-11-09
    Description: A large, discrete aggregation of squid was sampled at short intervals by means of jigging, midwater trawling and purse-seining. Differences among basic parameters of the population (e.g. length frequency) indicate that jigging is a more selective, and therefore biased, method of sampling than midwater trwaling or purse-seining. This has important consequences for stock assessments that take commercial catches into account. The selectivity curve indicates that squid of mantle lenghts (ML) 28-33cm are over-represented (in terms of the situation in the population) in fisheries conducted by jigging and that squid 〈26 and 〉34cm ML are under-represented if purse-seine results are considered to be representative of the population.
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  • 87
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    In:  Ophelia, 39 (2). pp. 137-158.
    Publication Date: 2018-08-10
    Description: The occurrence and distribution of dinoflagellate resting cysts in Recent sediments was investigated at 9 locations in Kiel Bight, Baltic Sea. The assemblage comprised 25 known cyst species and 4 unknown cyst types and is characterized by the dominance of Protoperidinium cf. divergens with a maximal abundance of 1695 living cysts/cm3 in the upper half centimeter. Cysts of the potentially toxic dinoflagellates of the Alexandrium excavatum/tamarense group and A. minutum were scarce. Micro-reticulate resting cysts of the toxic, unarmoured Gymnodinium catenatum, whose motile cell has not been recorded in Northern European waters, are reported for the first time from Recent sediments of the Baltic Sea. In the top 2-cm of sediment up to 1200 living dinoflagellate cysts/cm3 were found and the following trends were noted: Cysts were primarily associated with sediments dominated by mud, sandy stations exhibited the lowest cyst abundance. Highest cyst concentrations were found at the deepest stations and the small-scale vertical distribution ofcysts usually exhibited maximum concentrations below the sediment surface. Empty cysts constituted 16.5–64.0% of total cyst abundance. These results suggest that the spatial distribution of several cyst species is controlled by water circulation patterns. The wide distribution ofliving and empty cysts of Peridinium dalei, Protoperidinium denticulatum and P. punctulatum and corresponding germination experiments suggest that the motile forms, which have not previously been recorded in the area, are common members of the plankton community in the western Baltic Sea. The cysts of Gonyaulax polyedra, P. dalei and Protoceratium reticulatum exhibited a reduced length of processes compared to individuals from marine habitats.
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  • 88
    Publication Date: 2018-08-14
    Description: In situ caging experiments showed that both littorinid snails and gammarid amphipods exerted minimal effects on the suite of algae comprising the canopy of littoral fringe tide pools dominated by Fucus distichus. In the absence of grazers, the Fucus canopy was dramatically reduced by fatal endophyte infections. Among the 10dependent variables making up the algal species and forms at the substratum level below the canopy, 3 were highly affected by grazing. The germlings of F. distiehus were greatly reduced by littorinids. Gamrnarids also reduced germling cover, but were less effective. In addition, the two grazer guilds interactively reduced the cover of algae belonging to the Uniseriate functional form at the substratum level. Sheet/Tube form algae were reduced in cover only by littorinids. Other forms, including calcareous crusts, thalli of Chondrus crispus and 3 Cladophora species were unaffected by grazing. There was no indication of food resource partitioning between littorinids and gammarids.
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  • 89
    Publication Date: 2016-06-15
    Description: Long-range global climate forecasts have been made by use of a model for predicting a tropical Pacific sea surface temperature (SST) in tandem with an atmospheric general circulation model. The SST is predicted first at long lead times into the future. These ocean forecasts are then used to force the atmospheric model and so produce climate forecasts at lead times of the SST forecasts. Prediction of the wintertime 500mb height, surface air temperature and precipitation for seven large climatic events of the 1970 1990s by this two-tiered technique agree well in general with observations over many regions of the globe. The levels of agreement are high enough in some regions to have practical utility.
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  • 90
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    In:  Journal of Natural History, 27 (1). pp. 15-46.
    Publication Date: 2020-07-21
    Description: The present study contributes new information on the cephalopods off Namibia, contains the first record of Ornithoteuthis volatilis (Sasaki, 1915) in the Atlantic, and adds records of six species in the Benguela Current and three species in Namibian waters. The presence of certain species seldom encountered in the Benguela Current has been confirmed. A compilation of the cephalopod fauna off Namibia had also been included, listing 65 species. Additional morphological data on Stoloteuthis leucoptera, Lycoteuthis lorigera, Architeuthis sp., Pholidoteuthis boschmai, Ornithoteuthis volatilis, Eledone nigra, and Graneledone sp. have been provided. The status of the genus Lycoteuthis has been reviewed in the light of the first collection of Lycoteuthis lorigera (Steenstrup, 1875) males in the Atlantic, and Lycoteuthis diadema (Chun, 1900) has been considered to be a synonym for Lycoteuthis lorigera
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  • 91
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    In:  Israel Journal of Zoology, 39 (4). pp. 299-336.
    Publication Date: 2017-08-10
    Description: During the years 1989–1993 an intensive collection of fishes from the aphotic zone (below 150 m) of the northern part of the Gulf of Aqaba was conducted. This survey recorded 69 fish species, 8 elasmobranchs, and 61 teleosts, belonging to 45 families. Fifteen species are endemic to the Red Sea: Mustelus mosis, Narcine bentuviai, Rhinobatos punctifer, Ophichthus echeloides, Rhynchoconger sp., Physiculus marisrubri, Ostichthys hypsipterygion sufensis, Pterygotrigla sp., Uranoscopus marisrubri, Parascolopsis sp.1 and sp. 2, Atrobucca geniae, Chromis pelloura, Samariscus sp., Thamnaconus modestoides erythraeensis. Eleven species are new records for the Red Sea: Gymnothorax johnsoni, Rhynchoconger sp., Synodus doaki, Pterygotrigla sp., Chelidoperca pleurospilus, Carangoides equula, Parascolopsis sp. 1 and sp. 2, Bodianus leucostictus, Paracaesio sordidus, and Samariscus sp. Two species, Cociella crocodilo and Parascolopsis eriomma, are first substantiated records for the Red Sea. None of the species recorded in this list is considered conventional deep-sea fishes. The ichthyofauna of the aphotic zone of the Gulf of Aqaba is composed of species of shallower origin.
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  • 92
    Publication Date: 2018-03-22
    Description: Tests on the effects of two herbivore groups (littorinid snails and gammarid amphipods), on algal succession in high intertidal tidepools dominated by Fucus distichus showed that the grazer groups exert different grazing pressures on the algae. The differences can be related to the feeding morphologies ofthe two grazer guilds. The scraping, microphagous littorinid snails prevent the establishment of both micro- and rnacroalgae at the microscopic level. The biting, macrophagous gammarid amphipods are ineffective at grazing microalgae and prostrate macroalgae from the substratum, but exert a considerable influence on the erect macroalgae which escape littorinid grazing. Despite differences in feeding mechanisms, the magnitude of the effect of the two grazer groups on the canopy cover of macroalgae is similar.
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  • 93
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    In:  Sarsia, 78 (3-4). pp. 255-264.
    Publication Date: 2018-03-05
    Description: A new species of Siboglinum is reported from off the Tejo mouth, Portugal. It was dredged from c. 1100 m. It resembles S. atlanticum and certain other species, in having paired white glandular stripes on the forepart. In the posterior trunk region we found small gram-negative internal symbiotic bacteria. All described species of the genus Siboglinum are equipped with a single tentacle, but one of our specimens bears two tentacles.
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  • 94
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    In:  International Journal of Remote Sensing, 14 (8). pp. 1447-1461.
    Publication Date: 2018-03-22
    Description: Most atmospheric parameters relevant to microbe dissemination into the atmosphere, including aerial transport and deposition, can be monitored by temperature and humidity, aerosols, clouds, precipitation, and wind through current meteorological and other satellite systems. A wide range of these parameters are already extracted and distributed operationally on a regional or global basis like cloudiness, cloud height, cloud motion, winds, surface temperature and atmospheric temperature profiles, and precipitation estimates, Some of these products like cloud motion, winds, and temperature profiles enter weather forecast models for initialization purposes. These models predict the global state of the atmosphere (some include precipitation and cloudiness) quite reliably for several days. Thus, an important part of the necessary technical framework for global disease spread and transmission monitoring exists.
    Type: Article , PeerReviewed
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  • 95
    Publication Date: 2018-03-05
    Description: During the ‘Meteor’ Expedition 13 in July and August 1990 to the northern part of the Norwegian Sea off west Spitsbergen, 7 stations with a depth of 2000 m or more were sampled with Agassiz trawl or hyperbenthos sledge, 14 more with a large box corer. Sponges were found at 6 of the trawl stations and in 2 box cores. A total of 19 species occurred, most of which were new to the area. Eight of the species were encountered more often than the other 11. Literature review and check of unpublished samples showed that by distribution, frequency of occurrence or abundance these species can be defined as the typical sponge association of the Norwegian and Greenland abyssal sea. This sponge association has a wide occurrence over the deep Norwegian-Greenland seas and parts of the Arctic basins. The analysis of substrate utilization of the 8 core species shows that all of them are able to colonize soft bottom, even some that previously had been considered to be dependent on hard substrate exclusively. Alternative substrate utilization and, in some species, the adoption of an infaunallife style are judged to be major reasons for the success of these species in the deep sea. The infaunal life style of the species Thenea abyssorum, Trichostemma sol and Tentorium semisuberites is documented and population structure data are given for the first time.
    Type: Article , PeerReviewed
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  • 96
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    Taylor & Francis
    In:  Tellus A: Dynamic meteorology and oceanography, 45 (1). pp. 72-79.
    Publication Date: 2018-03-22
    Description: Climatological data sets are used to estimate the amount of water changing temperature and salinity at the sea-surface owing to air-sea exchanges. Considering this conversion as a function of sea-surface temperature and salinity leads to the definition of a conversion vector, which represents mass sources and sinks for each water type. The vector representation shows graphically the way the shape of the temperature-salinity relation is driven at the surface by the air-sea heat and fresh water fluxes.
    Type: Article , PeerReviewed
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  • 97
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    Taylor & Francis
    In:  Israel Journal of Zoology, 39 . pp. 255-261.
    Publication Date: 2021-01-11
    Description: The cephalopod fauna of the Sea of Marmara was investigated during the years 1991-1992. Three species, Sepia orbignyana Ferussac, 1826; Rondeletiola minor Naef, 1912; and Todaropsis eblanae (Ball, 1841), are hereby recorded for the first time from the Sea of Marmara.
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  • 98
    Publication Date: 2021-04-30
    Description: Fertilizing capacity of spermatozoa collected from various storage sites in the male and female squids were examined by inseminated eggs in the presence or absence of gelatinous substances of the oviducal gland origin. Over 90% of the eggs were fertilized by the spermatozoa collected from the female's seminal receptacle regardless of the presence or absence of the gelatinous substance. Elevation of the chorion and the formation of perivitelline space was observed only in the jellied eggs. All jellyless eggs without perivitelline space died in 4 days after insemination. Spermatozoa collected from the spermatophore in the male's accessory gland could fertilize the majority of the eggs. On the other hand, those from the male's vas deferens could fertilize only 30–50% of both the jellied and jellyless eggs. It may be concluded from these experiments that the gelatinous substance of the oviducal gland origin has nothing to do with fertilization. However, it is essential for the elevation of the chorion and the formation of the perivitelline space. It may also be concluded that squid spermatozoa become fertile before they are transferred to the female's seminal receptacle.
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  • 99
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    Taylor & Francis
    In:  South African Journal of Marine Science, 13 (1). pp. 51-62.
    Publication Date: 2021-09-06
    Description: Mature males of Histioteuthis atlantica are described. They differ from immature animals mainly in the unique photophore pattern of the distal portion of the mantle, i.e. in the presence of densely set, lensless photophores. These photophores resemble those on H. elongata, but they are smaller and much more dense on male H. atlantica. The occurrence of the photophore pattern in approximately the same dense concentration on the dorsum as well as the ventrum is unique in the family Histioteuthidae.
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  • 100
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    Taylor & Francis
    In:  Journal of the Royal Society of New Zealand, 22 (4). pp. 243-263.
    Publication Date: 2020-07-16
    Description: The beaks of 9,994 cephalopods of 61 species, obtained mainly from chick regurgitations of wandering albatrosses (Diomedea exulans L.) at Gough, Auckland, Antipodes, Prince Edward and Macquarie Islands and South Georgia, were used to specify and calculate the biomass of cephalopods consumed. Histioteuthidae were most important by numbers and biomass at Gough Island (in warmest seas), but Onycboteuthidae increasingly superseded them southwards; Kondakovia longimana formed 59 to 75% of biomass eaten at the three localities nearest the Antarctic Polar Front. Other important families were Octopoteuthidae, Cranchiidae, Architeuthidae (juveniles) and Ommastrephidae (South Georgia only). Most frequently eaten were Histioteuthis atlantica 13.7%, Galiteuthis glacialis 12.4%, H. eltaninae 12.0% and Kondakovia longimana 11.6%. Wandering albatrosses rearing chicks can forage at least to 3,000 km in a single foray, and may exploit an important food source about 1200 km from the nest (as in the probable commensalism of South Georgian birds with the Falkland Islands fishery). They feed, sometimes opportunistically, on cephalopods active or moribund at the surface, or discarded or lost by trawlers, cetaceans or seals. Vertically migrating cephalopods, especially bioluminescent species, are disproportionately frequent in their non-commensal diet, suggesting that they often feed at night.
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