ALBERT

Description: The present study analyses the distribution of cephalopod paralarvae off the Portuguese coast. The effects of temporal and physical variables on Loligo vulgaris, Octopus vulgaris, sepiolid and ommastrephid abundances are analysed with generalized linear models. Their distribution patterns are discussed in relation to mesoscale features, including currents, thermal fronts and coastal upwelling cross-shelf transport, prevailing in the western Iberia upwelling system. Paralarvae of the neritic species occur during a considerably extended period of the year with two or three abundance peaks within the highly productive upwelling system of the western Portuguese coast and contrasting with the Gulf of Cadiz area. Temperature and upwelling were shown to be the most important variables in modulating seasonality and distribution of these paralarvae. The influence of the physical environment is particularly pronounced for the paralarvae of O. vulgaris, following distinct patterns according to the oceanography of the western Iberia and the Gulf of Cadiz systems. The paralarvae of oceanic species, which in many cases have their northern limit of distribution at these latitudes, were mainly found in the southern part of the sampling area. The distribution of these species indicates that the prevailing oceanographic features of the Gulf of Cadiz system, especially fronts, together with temperature act as boundaries to geographic dispersal, contributing to an area of high cephalopod biodiversity in the southern Portuguese waters.

Description: The sudden occurrence of the ctenophore Mnemiopsis leidyi has been reported recently from different regions of the Baltic Sea and it has been suggested that the species has invaded the whole basin. Here we provide the first set of quantitative data of seasonal diet composition and life history traits of M. leidyi and its predatory role in the pelagic ecosystem of the Western Baltic Sea. The size structure of the species appeared to be dominated by small size classes and only a few adults were as large as those reported in the native region of the species and in other invaded areas. We show that the species has a high preference for small-sized and slow swimming prey, mainly during the winter low temperature period. Barnacle nauplii appeared to be the main source of carbon for the over-wintering population of M. leidyi. A preference for copepods was only found during August when these prey contributed up to 20% of the gut composition. In summer, planula larvae of the jellyfish Aurelia aurita were the most abundant prey in the gut content (feeding rate of 621 ind. ctenophore−1day−1). We further found that at highest densities of the species, in summer, a significant predation on its larvae occurs, this being the major carbon source of adults. Overall, these results are discussed in the context of trade-offs M. leidyi faces in the new environment and adverse environmental conditions, which are likely forcing the species toward reduced sizes and also probably reducing its potential predatory impact in the Baltic Sea.

Description: Knowledge of the spatial and temporal distribution of juvenile cod is essential to closing the life cycle in population dynamic models, and it is a prerequisite for the design of Marine Protected Areas (MPAs) aiming at the protection of juveniles. In this study, we use a hydrodynamic model to examine the spatial distribution of eastern Baltic cod larvae and early juveniles. The transport patterns of the larvae spawned at the three major spawning grounds in the central Baltic Sea were investigated by drift model simulations for the period 1979–2004. We analysed potential habitats for their suitability for juvenile settlement, i.e. the change from pelagic to demersal life. The results revealed a clear dependence of the probability for successful settling on wind-induced drift of larval cod, which is controlled by the local atmospheric conditions over the Baltic Sea. Furthermore, we found evidence that the final destinations of juvenile cod drift routes are affected by decadal climate variability. Application of the methodology to MPA design is discussed, e.g. identifying the overlap of areas with a high probability of successful juvenile cod settlement and regions of high fishing effort in small-meshed fisheries targeting sprat and herring.

Description: Dynamics of prokaryotic and eukaryotic picophytoplankton were investigated over a 2-year time period using flow cytometry and combined with an in situ experiment in Lake Tahoe, USA to better characterize to which extent environmental factors control these communities. Pronounced seasonal patterns and clear temporal and spatial partitioning were observed between picocyanobacteria and picoeukaryotes. Picocyanobacteria dominated in the nutrient deficient upper water column during the stratified season, while picoeukaryotes reached maximum abundance during isothermal conditions and maintained high numbers in deep-water layers during the stratified season. Picocyanobacteria were more sensitive to high solar and UV radiation compared with picoeukaryotes, which were not affected by high solar radiation and nutrient enrichment stimulated their growth. The opposing response of these two populations is consistent with their vertical distribution: picocyanobacteria dominate below the 30% isolume and above the nitrocline depth, whereas picoeukaryotes increase in the vicinity of the nitrocline and thus increased nutrient concentration. This spatial separation of picophytoplankton groups along environmental gradients in Lake Tahoe is consistent with other deep-oligotrophic lakes and the marine environment, suggesting that these marine and freshwater organisms have similar ecophysiological requirements. These results highlight that the smallest photosynthetic communities show taxon-specific responses to mixing and resource availability, which affect the structure and dynamics of picophytoplankton.

Description: Intraplate volcanism was widespread and occurred continuously throughout the Cenozoic on the New Zealand micro-continent, Zealandia, forming two volcanic endmembers: (1) monogenetic volcanic fields; (2) composite shield volcanoes. The most prominent volcanic landforms on the South Island of New Zealand are the two composite shield volcanoes (Lyttelton and Akaroa) forming the Banks Peninsula. We present new Ar-40/Ar-39 age and geochemical (major and trace element and Sr-Nd-Pb-Hf-O isotope) data for these Miocene endmembers of intraplate volcanism. Although volcanism persisted for similar to 7 Myr on Banks Peninsula, both shield volcanoes primarily formed over an similar to 1 Myr interval with small volumes of late-stage volcanism continuing for similar to 1 center dot 5 Myr after formation of the shields. Compared with normal Pacific mid-ocean ridge basalts (P-MORB), the low-silica (picritic to basanitic to alkali basaltic) Akaroa mafic volcanic rocks (9 center dot 4-6 center dot 8 Ma) have higher incompatible trace element concentrations and Sr and Pb isotope ratios but lower delta O-18 (4 center dot 6-4 center dot 9) and Nd and Hf isotope ratios than ocean island basalts (OIB) or high time-integrated U/Pb HIMU-type signatures, consistent with the presence of a hydrothermally altered recycled oceanic crustal component in their source. Elevated CaO, MnO and Cr contents in the HIMU-type low-silica lavas, however, point to a peridotitic rather than a pyroxenitic or eclogitic source. To explain the decoupling between major elements on the one hand and incompatible elements and isotopic compositions on the other, we propose that the upwelling asthenospheric source consists of carbonated eclogite in a peridotite matrix. Melts from carbonated eclogite generated at the base of the melt column metasomatized the surrounding peridotite before it crossed its solidus. Higher in the melt column the metasomatized peridotite melted to form the Akaroa low-silica melts. The older (12 center dot 3-10 center dot 4 Ma), high-silica (tholeiitic to alkali basaltic) Lyttelton mafic volcanic rocks have low CaO, MnO and Cr abundances suggesting that they were at least partially derived from a source with residual pyroxenite. They also have lower incompatible element abundances, higher fluid-mobile to fluid-immobile trace element ratios, higher delta O-18, and more radiogenic Sr but less radiogenic Pb-Nd-Hf isotopic compositions than the Akaroa volcanic rocks and display enriched (EMII-type) trace element and isotopic compositions. Mixing of asthenospheric (Akaroa-type) melts with lithospheric melts from pyroxenite formed during Mesozoic subduction along the Gondwana margin and crustal melts can explain the composition of the Lyttelton volcano basalts. Two successive lithospheric detachment/delamination events in the form of Rayleigh-Taylor instabilities could have triggered the upwelling and related decompression melting leading to the formation of the Lyttelton (first, smaller detachment event) and Akaroa (second, more extensive detachment event) volcanoes.

Description: The oncaeid genus Epicalymma comprises small copepod species usually living at meso- and bathypelagic depth layers in oceanic areas. The genus had previously been assumed to be absent from the Red Sea, due to the unusually high deep-sea temperatures and salinities in this area. In the present account a new species, Epicalymma bulbosa, is described from the Red Sea, which appears to be the only representative of the genus in the region. The new species is the smallest Epicalymma species so far recorded, with a total body length of ∼0.32 and ∼0.29 mm in the female and male, respectively. Apart from its small size, it differs from all known Epicalymma species by an extremely long exopodal seta on P5 in both sexes, and by a free exopod segment of P5 and a very long and basally swollen spinule on the syncoxa of the maxilliped in the female. In contrast to other Epicalymma species, which are distributed between 500 and 〉2500 m depth, the new species occurred much shallower (100–750 m) in the Red Sea, which may be interpretated as an avoidance mechanism of the unfavourable environmental conditions in the deep Red Sea. The taxonomic status of the new species within the genus Epicalymma is discussed and the few available ecological data on Epicalymma species in the world ocean are summarized.

Description: One of the mysteries regarding Earth’s climate system response to variations in solar output is how the relatively small fluctuations of the 11-year solar cycle can produce the magnitude of the observed climate signals in the tropical Pacific associated with such solar variability. Two mechanisms, the top-down stratospheric response of ozone to fluctuations of shortwave solar forcing and the bottom-up coupled ocean-atmosphere surface response, are included in versions of three global climate models, with either mechanism acting alone or both acting together. We show that the two mechanisms act together to enhance the climatological off-equatorial tropical precipitation maxima in the Pacific, lower the eastern equatorial Pacific sea surface temperatures during peaks in the 11-year solar cycle, and reduce low-latitude clouds to amplify the solar forcing at the surface.

Description: The oceans are a major sink for atmospheric carbon dioxide (CO2). Historically, observations have been too sparse to allow accurate tracking of changes in rates of CO2 uptake over ocean basins, so little is known about how these vary. Here, we show observations indicating substantial variability in the CO2 uptake by the North Atlantic on time scales of a few years. Further, we use measurements from a coordinated network of instrumented commercial ships to define the annual flux into the North Atlantic, for the year 2005, to a precision of about 10%. This approach offers the prospect of accurately monitoring the changing ocean CO2 sink for those ocean basins that are well covered by shipping routes.

Description: Environmentally induced change appears to be impacting the recruitment of North Sea herring (Clupea harengus). Despite simultaneously having a large adult population, historically low exploitation, and Marine Stewardship Council accreditation (implying sustainability), there have been an unprecedented 6 sequential years of poor juvenile production (recruitment). Analysis suggests that the poor recruitment arises during the larval overwintering phase, with recent survival rates greatly reduced. Contemporary warming of the North Sea has caused significant changes in the plankton community, and a recently identified regime shift around 2000 shows close temporal agreement with the reduced larval survival. It is, therefore, possible that we are observing the first consequences of this planktonic change for higher trophic levels. There is no indication of a recovery in recruitment in the short term. Fishing mortality is currently outside the agreed management plan, and forecasts show a high risk of the stock moving outside safe biological limits soon, potentially precipitating another collapse of the stock. However, bringing the realized fishing mortality back in line with the management plan would likely alleviate the problem. This illustrates again that recruitment is influenced by more than just spawning-stock biomass, and that changes in other factors can be of equal, or even greater, importance. In such dynamically changing environments, recent management success does not necessarily guarantee future sustainability.

Description: We propose that the exploitation of the bioactive properties of secondary metabolites (SMs) by animals can provide a “treatment” against various challenges that perturb homeostasis in animals. The unified theoretical framework for the exploitation of SMs by animals is based on a synthesis of research from a wide range of fields and although it is focused on providing generalized predictions for herbivores that exploit SMs of plants, predictions can be applied to understand the exploitation of SMs by many animals. In this review, we argue that the probability of SM exploitation is determined by the relative difference between the cost of a homeostatic challenge and the toxicity of the SM and we provide various predictions that can be made when considering behavior under a homeostatic perspective. The notion that animals experience and respond to costly challenges by exploiting therapeutic SMs provides a relatively novel perspective to explain foraging behavior in herbivores, specifically, and behavior of animals in general. We provide evidence that animals can exploit the biological activity of SMs to mitigate the costs of infection by parasites, enhance reproduction, moderate thermoregulation, avoid predation, and increase alertness. We stress that a better understanding of animal behavior requires that ecologists look beyond their biases that SMs elicit punishment and consider a broader view of avoidance or selection of SMs relative to the homeostatic state. Finally, we explain how understanding exploitation of SMs by animals could be applied to advance practices of animal management and lead to discovery of new drugs.

Description: The abundance and depth distribution of metazoans 〉20 μm were investigated at seven stations across the Southern Indian Ocean (SIO), October–November 2006. Copepod nauplii, copepodites and larvaceans dominated the metazooplankton community. Copepodites were most abundant within Agulhas Current and Southern Ocean waters, decreasing toward subtropical/tropical areas, whereas larvaceans showed the inverse pattern. The fraction 〈200 μm contained the majority of the zooplankton enumerated, including 81, 23 and 93% of the larvacean, copepodite and nauplii abundances, respectively. The relative abundance of larvaceans compared with copepodites increased from 7 to 44% from South Africa towards Australia. Peak copepodite biomass was observed off South Africa, while larvacean biomass was 〈1% of the copepodite biomass there, increasing to 6% in tropical waters. Both copepodite and nauplii biomass were positively correlated to total Chl a (P 〈 0.0001), larvacean biomass was only significantly related to temperature (P = 0.0213). Despite their low biomass, larvacean production was estimated to exceed the copepod production up to five times. It appears that the abundance and role of larvaceans in the SIO has been severely underestimated in previous studies; thus future investigations into the fate of organic matter will remain incomplete if this group is not adequately considered.

Description: Picoeukaryotes are a taxonomically diverse group of organism less than 2 micrometers in diameter. Photosynthetic marine picoeukaryotes in the genus Micromonas thrive in ecosystems ranging from tropical to polar and could serve as sentinel organisms for biogeochemical fluxes of modern oceans during climate change. These broadly distributed primary producers belong to an anciently diverged sister clade to land plants. Although Micromonas isolates have high 18S ribosomal RNA gene identity, we found that genomes from two isolates shared only 90 of their predicted genes. Their independent evolutionary paths were emphasized by distinct riboswitch arrangements as well as the discovery of intronic repeat elements in one isolate, and in metagenomic data, but not in other genomes. Divergence appears to have been facilitated by selection and acquisition processes that actively shape the repertoire of genes that are mutually exclusive between the two isolates differently than the core genes. Analyses of the Micromonas genomes offer valuable insights into ecological differentiation and the dynamic nature of early plant evolution.

Description: The eastern Baltic cod stock collapsed as a consequence of climate-driven adverse hydrographic conditions and overfishing and has remained at historically low levels. Spatio-temporal fishing closures [Marine Protected Areas (MPAs)] have been implemented since 1995, to protect and restore the spawning stock. However, no signs of recovery have been observed yet, either suggesting that MPAs are an inappropriate management measure or pointing towards suboptimal closure design. We used the spatially explicit fishery simulation model ISIS-Fish to evaluate proposed and implemented fishery closures, combining an age-structured population module with a multifleet exploitation module and a management module in a single model environment. The model is parameterized based on (i) the large amount of biological knowledge available for cod and (ii) an analysis of existing spatially disaggregated fishery data. As the population dynamics of eastern Baltic cod depend strongly on the climate-driven hydrographic regime, we considered two production regimes of the stock. MPAs were only effective for stock recovery when they reduced overall fishing effort. The performance of MPAs needs to be evaluated relative to environmental regimes, especially for stocks facing strong environmental variability.

Description: The aim of the study was to examine metazoan parasite communities of European eels (Anguilla anguilla) in fresh-water, brackish water and marine localities in northern Germany. In all, 29 parasite species/taxa were found in 170 eels: eight digeneans, one monogenean, five cestodes, ten nematodes, two acanthocephalans, and three crustaceans. Measures of diversity characteristics of the helminth communities included species richness, Shannon's diversity index and its evenness, and the Berger–Parker dominance index. The highest species diversity and lowest dominance values were calculated for the helminth communities of eels from the two Baltic Sea localities. Parasite communities of European eels clearly exhibit the habitat preferences of their hosts, salinity-dependent specificities, and a clustering into fresh-water, brackish, and marine groups. The highly pathogenic parasite species Anguillicola crassus and Pseudodactylogyrus spp. were found at all sampling sites in fresh water and brackish water, with high prevalence. Basic information is provided on the risks of restocking programmes solely focusing on fresh-water sites.

Description: Abundance and stable isotope composition of large and small mesozooplankton were analyzed in samples taken with 333 and 100 μm nets, respectively, at four sites in the eastern Mediterranean down to 4200 m depth in October 2001. Large mesozooplankton (333 μm nets) was sieved into five size fractions, and the δ13C and δ15N values of the fractions were measured as well as the δ15N values of total small mesozooplankton (100 μm nets) and specific mesozooplankton taxa. These measurements allow insights into the source of the diet and the trophic level relative to sinking and suspended particulate organic matter. Overall, biomass and abundance of zooplankton was low, reflecting the oligotrophic character of the eastern Mediterranean. Stable nitrogen isotope values of mesozooplankton were low (1–4‰) and close to zero in suspended particles at the surface. This indicates that the fixation of atmospheric nitrogen probably contributes to the N-pool in the eastern Mediterranean. Such low values were also found in sinking particles in deep waters and in most zooplankton size classes. However, suspended particles and mesozooplankton in the size class 0.5–1 mm, which was primarily composed of the deep-sea species Lucicutia longiserrata, showed higher values at depths below 1000 m. There is some indication that L. longiserrata was able to utilize the suspended particle pool in the deep eastern Mediterranean.

Description: The igneous forearc basement along the Pacific coast of northern Central America (between southern Mexico and Costa Rica) comprises a highly tectonized accretionary assemblage of igneous and ultramafic rocks. Volcanic and gabbroic rocks with primitive arc geochemical signatures formed between ∼100 and ≥180 Ma and are interpreted to have originated by arc magmatism resulting from subduction of the Pacific–Farallon plate. Geochemically enriched ocean island basalt (OIB)-like units are interpreted as accreted seamounts and islands of a hotspot track, which was active between ≥220 and 100 Ma and originated from a hotspot located in the central Pacific. Based on their combined Pb, Nd and Hf isotopic compositions an affiliation of these rocks with the Caribbean Large Igneous Province or the present-day Galápagos hotspot appears unlikely. Rocks of similar age and geochemistry are exposed on the Santa Elena Peninsula in Costa Rica, suggesting that a similar forearc basement is accreted to the continental Chortis Block from southern Mexico to Costa Rica.

Description: The community composition of pelagic copepods near Australia’s North West Cape (21° 49′S, 114° 14′E) was studied during the austral summers of 1997/98 and 1998/99. Most sampling occurred at a shallow (20 m) shelf station and a deeper (90 m) shelf-break station, though on four occasions a set of eight stations were occupied on a 36 km cross-shelf transect. During the El Niño conditions prevalent during the austral summer of 1997/98, episodic upwelling occurred causing intermittent high primary production. During the El Niño conditions of 1997/98, there was a little difference between stations in the spring (October–November), but communities differentiated later in the sampling season (December–February) with a more characteristic inshore community developing at the shelf station. In the La Niña conditions of 1998/99, the community at the shelf break was invariant, but the shelf community was mainly offshore copepods as a result of seasonal downwelling during the spring that was later replaced by an inshore community of more widely distributed species. Over 120 species of copepods were identified, of which the most speciose families were the Corycaeidae (22 spp.), Oncaeidae (〉20 spp.), Paracalanidae (15 spp.) and the Oithonidae (11 spp.). Cross-shelf transects confirmed the existence of a distinct inshore community of copepods, dominated by small species of Paracalanidae and Oithonidae, and which was at least twice as abundant as those at the shelf break. In both summers, there was an onshore–offshore gradient in community composition, with the inshore stations characterized by small paracalanid and oithonid species.

Description: Abundance, distribution, population structure, lipid content, lipid composition and reproductive and feeding activity of Rhincalanus nasutus were studied in the Gulf of Aqaba and in the northern Red Sea during RV “Meteor”-cruise M 44-2 in February/March 1999. Rhincalanus nasutus occurred in higher numbers in the Gulf of Aqaba (585 ind m−2) than in the northern Red Sea (254 ind m−2). Young developmental stages (nauplii, copepodite stages CI and CII) were absent. In the southern Gulf of Aqaba, the bulk of the population developed from stage CV to adult in the course of the 3-week study period. In contrast, immature CV stages dominated at the adjacent stations in the northern Gulf of Aqaba and in the northern Red Sea. Development was associated with the seasonal vertical migration from wintering mid-water layers and initiation of feeding starting as early as beginning of March in the southern Gulf of Aqaba. No upward migration was observed in the northern parts of the Gulf and in the northern Red Sea, where more than 90% of the females remained immature during our study. Lipids were dominated by wax esters in females and CV. The fatty acid and fatty alcohol compositions of females were very similar throughout the study region and period. Major fatty acids were 18:1(n−9), 16:1(n−7), 16:2(n−4) and 20:5(n−3). Our results support the previous reports of a seasonal dormancy of R. nasutus in the Gulf of Aqaba and suggest that the timing of vertical migration, feeding and maturation is closely coupled to the development of the spring bloom in oligotrophic subtropical waters.

Description: Cephalopod paralarvae and juveniles were sampled with light traps deployed at the surface and deeper in the southern NW Shelf and on Ningaloo Reef off Western Australia during two consecutive summers. One cross shelf transect (Exmouth) was sampled in the late spring and summers of 1997/1998 (summer 1) and 1998/1999 (summer 2), and a second cross shelf transect (Thevenard) and a longshore transect (Ningaloo) along the Ningaloo Reef were sampled in summer 2. Species captured in the order of abundance were octopods, Photololigo sp., Sepioteuthis lessoniana, and Sthenoteuthis oualaniensis. Most were captured in shallow traps except for Photololigo sp., which was common in both shallow and deep traps with larger animals found in deeper water. The presence of Idiosepius pygmaeus in deep water off Ningaloo Reef revealed the species to be eurytopic, inhabiting a wider range of habitats than previously known. Photololigo sp. and S. lessoniana were more abundant inshore, and octopods were especially abundant on mid-depth stations of the Exmouth transect, probably because of the turbulent mixing and increased productivity there. Fewer S. oualaniensis were caught during the first summer on the Ningaloo transect (n = 5) than during the second summer (n = 79).

Description: Zooplankton trade-offs to maximize fitness in highly dynamic environments such as estuaries have long been a question of central importance for understanding the ecology and evolution of estuarine populations. We present here the first comprehensive data set on the population dynamics of the copepod Eurytemmora affinis obtained from 50 h high-frequency sampling in the Seine estuary during spring. Maximum densities of E. affinis were associated with low salinities (0.5–10) and recorded during the ebb in the bottom layer. Vertical variations in population structure were observed between ebb and flood, as well as the spatial distribution of developmental stages. Nauplii were concentrated in the low salinity zone just above salinity 5, and copepodids and adults distributed more widely relative to salinity than nauplii in bottom waters, whereas the opposite pattern was observed in surface waters. The sex-ratio and the proportion “ovigerous females:non-ovigerous females” appeared to be related to tidal cycle and depth, with higher relative densities of non-ovigerous females in bottom waters and around low tide. The vertical variations noticed during the tidal cycle suggest a strategy by the species to avoid flushing by surface currents, although it may incur a cost due to the greater presence of predators in bottom waters.

Description: Phase equilibria simulations were performed on naturally quenched basaltic glasses to determine crystallization conditions prior to eruption of magmas at the Mid-Atlantic Ridge (MAR) east of Ascension Island (7–11°S). The results indicate that mid-ocean ridge basalt (MORB) magmas beneath different segments of the MAR have crystallized over a wide range of pressures (100–900 MPa). However, each segment seems to have a specific crystallization history. Nearly isobaric crystallization conditions (100–300 MPa) were obtained for the geochemically enriched MORB magmas of the central segments, whereas normal (N)-MORB magmas of the bounding segments are characterized by polybaric crystallization conditions (200–900 MPa). In addition, our results demonstrate close to anhydrous crystallization conditions of N-MORBs, whereas geochemically enriched MORBs were successfully modeled in the presence of 0·4–1 wt% H2O in the parental melts. These estimates are in agreement with direct (Fourier transform IR) measurements of H2O abundances in basaltic glasses and melt inclusions for selected samples. Water contents determined in the parental melts are in the range 0·04–0·09 and 0·30–0·55 wt% H2O for depleted and enriched MORBs, respectively. Our results are in general agreement (within ±200 MPa) with previous approaches used to evaluate pressure estimates in MORB. However, the determination of pre-eruptive conditions of MORBs, including temperature and water content in addition to pressure, requires the improvement of magma crystallization models to simulate liquid lines of descent in the presence of small amounts of water.

Description: The abundance and vertical distribution of microcopepods sampled by nets with 55 μm mesh size was compared for two neighbouring but hydrographically different areas, the Gulf of Aqaba and the northernmost Red Sea, during spring 1999. The vertical structure of the total microcopepod communities differed considerably between the two regimes: In the stratified waters of the Red Sea, calanoids outnumbered oncaeids as well as oithonids at 0–100 m, whereas oncaeids dominated in all meso- and bathypelagic layers below 100 m deep. In the unusually deep vertically mixed waters of the Gulf of Aqaba, calanoids outnumbered each of the non-calanoid taxa as deep as 250 or 350 m, whereas the oncaeid dominated deep water community was restricted to depth ranges below 400 m. Dominant non-calanoid species in both areas were Oncaea bispinosa, Paroithona pacifica, Oithona simplex, Spinoncaea ivlevi, O. tregoubovi and O. cristata. O. scottodicarloi occurred in exceptionally high numbers in the northern Gulf. Pronounced differences between the two areas were found in the vertical distribution of poecilostomatoid species. By comparing the present results with published data from the central and southern Red Sea and other tropical and warm-temperate oceanic areas, intra- and inter-oceanic differences in the structure of microcopepod communities in oligotrophic areas are discussed. The high abundance and vertically extended range of calanoid copepods during spring appears to be a specific feature of the Gulf of Aqaba, indicating an unusual vertical succession in the trophodynamic structure of the copepod fauna in this area.

Description: Sponges (phylum Porifera) are among the most ancient of the multicellular animals, or Metazoa, with a fossil record dating back at least 580 million years (1). Found both in marine and freshwater environments, they filter-feed by pumping water through their bodies, which can contain a remarkable number of microbial symbionts. Sponges lack many of the characteristics typical of animals, but recent genomic studies—including the report by Jackson et al. on page 1893 of this issue (2)—have shown that they possess many major metazoan gene families. Sponges are thus invaluable systems for studying the evolution of metazoans and their interactions with microorganisms. Furthermore, their highly stable skeletons are of interest to materials scientists. Biomineralization is an important feature of metazoan life. Animals including vertebrates, insects, mollusks, and sponges use minerals [such as calcium carbonate, iron, and silica] to form skeletal structures such as bones, seashells, and coral reefs (3). Biocalcification arose among many metazoan lineages during the “Cambrian explosion,” between 530 and 520 million years ago, when the ancestors of today's animals first appeared in the fossil record. Did these lineages share the same gene(s) for biocalcification, or did multiple independent evolutionary events give rise to the ability to biocalcify? Recent studies, including that by Jackson et al., are beginning to provide an answer to this question. Jackson et al. use the Indo- Pacific sponge Astrosclera willeyana to show that the last common ancestor of the metazoans possessed a precursor to the α-carbonic anhydrases. This gene family is used by animals today in a range of processes including ion transport, pH regulation, and biomineralization (4). By integrating molecular techniques ranging from protein sequencing to gene expression, the authors identified a group of closely related α-carbonic anhydrase sequences in A. willeyana. These sequences are similar to those recovered from a whole-genome project on another sponge, Amphimedon queenslandica (5). Together, the sponge α-carbonic anhydrases form a sister group to those of all other metazoans.

Description: The Atlantic meridional overturning circulation (MOC), which provides one-quarter of the global meridional heat transport, is composed of a number of separate flow components. How changes in the strength of each of those components may affect that of the others has been unclear because of a lack of adequate data. We continuously observed the MOC at 26.5°N for 1 year using end-point measurements of density, bottom pressure, and ocean currents; cable measurements across the Straits of Florida; and wind stress. The different transport components largely compensate for each other, thus confirming the validity of our monitoring approach. The MOC varied over the period of observation by ±5.7 × 106 cubic meters per second, with density-inferred and wind-driven transports contributing equally to it. We find evidence for depth-independent compensation for the wind-driven surface flow.

Description: The related red seaweeds Gracilaria sp. from the eastern Mediterranean and Gracilaria chilensis from Chile were similar in their enzymatic inventory for halogenation. In both species, halogenation was dependent upon H(2)O(2) and thus driven by haloperoxidases. These could be inhibited with phosphate and reversibly inhibited with azide and were therefore apparently dependent upon vanadate. Both species generated in the first line bromoform and other brominated halocarbons. Gel electrophoresis under non-denaturating conditions demonstrated that both species expressed halogenating peroxidases. Elicitation of Gracilaria sp. with agar oligosaccharides resulted in marked increases in bromination, iodination, and chlorination. Production rates of volatile halocarbons and phenol red bromination both increased by a factor of eight, presumably due to increased availability for haloperoxidases of H(2)O(2) during the oxidative burst response. Elicitation of Gracilaria sp. also triggered a release of bromide ions through DIDS-sensitive anion channels, which allowed for some bromination in bromide-free medium. However, this effect was relatively limited. By contrast, agar oligosaccharide oxidation in G. chilensis did not increase halogenation. Obviously, agar oligosaccharide oxidation does not provide sufficient amounts of hypohalous acids for such increases, because it does not deliver H(2)O(2) at the active site of vanadium-dependent haloperoxidases. These results correlate with earlier findings that the agar oligosaccharide-elicited oxidative burst controls microorganisms while agar oligosaccharide oxidation does not.

Description: A simple and sensitive reversed-phase high-performance liquid chromatography method with UV detection is developed and validated for the determination of 6,7-dimethoxycoumarin in rat plasma and comparative analysis of its pharmacokinetics after intragastric administration of 6,7-dimethoxycoumarin and three different decoctions of yinchenhao tang. The plasma samples are deproteinated with acetonitrile. The components are separated on a Kromasil C18 column (250 x 4.6 mm, 5 microm,) with methanol-1% acetic acid solution-tetrahydrofuran (30:63:7, v/v/v) as the mobile phase, and the UV detector is set at 340 nm. Coumarin is used as an internal standard. The linear calibration curve is obtained in the concentration range of 25-2500 ng/mL. The lower limit of quantitation of the method is 25 ng/mL. The intra- and inter-day precision are less than 12%, and the accuracy determined with relative error ranges from -2.9% to 1.7%. The data obtained from rat plasma are analyzed with Topfit 2.0 Pharmacokinetic Software. With pharmacokinetic analysis, the main parameters after intragastric administration of 6,7-dimethoxycoumarin, Herba Artemisiae Scopariae decoction, Artemisiae Scopariae decoction plus Radix et Rhizoma Rhei and Fructus Gardeniae decoction, yinchenhao tang are as follows: T(1/2) is 0.29, 1.30, 1.07, and 1.75 h, AUC(--〉t) is 919.1, 1215.0, 2035.3, and 2537.9 ng-h/mL, AU(0--〉) is 928.5, 1325.9, 2094.4, and 2612.6 ng x h/ mL, respectively.

Description: The vigor of Atlantic meridional overturning circulation (MOC) is thought to be vulnerable to global warming, but its short-term temporal variability is unknown so changes inferred from sparse observations on the decadal time scale of recent climate change are uncertain. We combine continuous measurements of the MOC (beginning in 2004) using the purposefully designed transatlantic Rapid Climate Change array of moored instruments deployed along 26.5°N, with time series of Gulf Stream transport and surface-layer Ekman transport to quantify its intra-annual variability. The year-long average overturning is 18.7 ± 5.6 sverdrups (Sv) (range: 4.0 to 34.9 Sv, where 1 Sv = a flow of ocean water of 106 cubic meters per second).

Description: Atmospheric carbon dioxide concentration is expected to exceed 500 parts per million and global temperatures to rise by at least 2°C by 2050 to 2100, values that significantly exceed those of at least the past 420,000 years during which most extant marine organisms evolved. Under conditions expected in the 21st century, global warming and ocean acidification will compromise carbonate accretion, with corals becoming increasingly rare on reef systems. The result will be less diverse reef communities and carbonate reef structures that fail to be maintained. Climate change also exacerbates local stresses from declining water quality and overexploitation of key species, driving reefs increasingly toward the tipping point for functional collapse. This review presents future scenarios for coral reefs that predict increasingly serious consequences for reef-associated fisheries, tourism, coastal protection, and people. As the International Year of the Reef 2008 begins, scaled-up management intervention and decisive action on global emissions are required if the loss of coral-dominated ecosystems is to be avoided.

Description: Paralarvae of the family Gonatidae were sampled in the Gulf of Alaska during spring 2001–2003. Taxonomic characters were determined to allow identification of the specimens to species. The dorsal head chromatophore pattern (DHCP) was the most robust character and allowed identification to species for the first time without requiring the removal and examination of the radula. Six different DHCPs were found among the six species in the study area. The 1140 specimens collected consisted of the following six species: Berryteuthis anonychus (759), Berryteuthis magister (71), Gonatopsis borealis (155), Gonatus kamtschaticus (1), Gonatus madokai (4) and Gonatus onyx (143). The specimens had a size range of 3.0–20.63 mm dorsal mantle length with the majority of specimens smaller than 10 mm. All species showed an increasing trend in abundance from the shelf (0–200 m) to the slope (200–1000 m) to the basin (〉1000 m) except G. onyx in 2001 and 2002. Wide variation in distribution and abundance was found for the four most abundant species; however, in general, B. anonychus was most abundant and widely distributed, followed by Gonatopis borealis, Gonatus onyx and B. magister.

Description: Ontogenetic and diurnal vertical migration patterns of Baltic sprat larvae were investigated for the periods 1989–1990 and 1998–2002. Comparison of the results led to the hypothesis that the diel vertical migration behaviour of sprat larvae 〉10 mm has changed. In 1989 and 1990, sprat larvae migrated to the surface at night, whereas they stayed 30–50 m deep by day. From 1998 to 2002, sprat larvae showed no signs of diel vertical migration, remaining in warmer, near-surface water by day and night. This behavioural change coincided with a more general change in the Baltic ecosystem, i.e. an increase in near-surface temperature and a general increase in abundance of the major prey organism (Acartia spp.) of Baltic sprat larvae, with more pronounced aggregation in surface waters.

Description: Lake Geneva is a deep, peri-alpine lake where there has been a continuous monitoring program since the 1970s. The lake has long suffered from eutrophication. In the early 1980s, a restoration plan resulted in a progressive reduction in the phosphorus concentration. During the same period, the lake responded to large-scale climate changes by overall warming of the water, and changes in the timing of stratification. Both the composition and the phenology of the plankton have been affected. This paper focuses on the long-term changes observed in the copepod community. Our findings highlight a switch towards a copepod community dominated by calanoids. In addition we have detected a period (1986 to 1991, 1988 excluded) characterized by an unusual seasonal pattern of species succession. It is suggested that these changes have been induced by qualitative changes in the phytoplankton community, and underline fluctuations in trophic interactions between planktonic species. Re-oligotrophication and warming, therefore, emerge as indirect forcing factors, and these findings contribute to the debate about whether copepods can be used as indicators of environmental changes.

Description: A detailed reconstruction of West African monsoon hydrology over the past 155,000 years suggests a close linkage to northern high-latitude climate oscillations. Ba/Ca ratio and oxygen isotope composition of planktonic foraminifera in a marine sediment core from the Gulf of Guinea, in the eastern equatorial Atlantic (EEA), reveal centennial-scale variations of riverine freshwater input that are synchronous with northern high-latitude stadials and interstadials of the penultimate interglacial and the last deglaciation. EEA Mg/Ca-based sea surface temperatures (SSTs) were decoupled from northern high-latitude millennial-scale fluctuation and primarily responded to changes in atmospheric greenhouse gases and low-latitude solar insolation. The onset of enhanced monsoon precipitation lags behind the changes in EEA SSTs by up to 7000 years during glacial-interglacial transitions. This study demonstrates that the stadial-interstadial and deglacial climate instability of the northern high latitudes exerts dominant control on the West African monsoon dynamics through an atmospheric linkage.

Description: Sampling an intact sequence of oceanic crust through lavas, dikes, and gabbros is necessary to advance the understanding of the formation and evolution of crust formed at mid-ocean ridges, but it has been an elusive goal of scientific ocean drilling for decades. Recent drilling in the eastern Pacific Ocean in Hole 1256D reached gabbro within seismic layer 2, 1157 meters into crust formed at a superfast spreading rate. The gabbros are the crystallized melt lenses that formed beneath a mid-ocean ridge. The depth at which gabbro was reached confirms predictions extrapolated from seismic experiments at modern mid-ocean ridges: Melt lenses occur at shallower depths at faster spreading rates. The gabbros intrude metamorphosed sheeted dikes and have compositions similar to the overlying lavas, precluding formation of the cumulate lower oceanic crust from melt lenses so far penetrated by Hole 1256D.

Description: By amplifying the melanocortin type 1 receptor from the woolly mammoth, we can report the complete nucleotide sequence of a nuclear-encoded gene from an extinct species. We found two alleles and show that one allele produces a functional protein whereas the other one encodes a protein with strongly reduced activity. This finding suggests that mammoths may have been polymorphic in coat color, with both dark- and light-haired individuals co-occurring.

Description: Draining of a huge lake into the Northern Atlantic may have triggered a cold period ~12,900 years ago. The route taken by the flood waters remains unknown.

Description: Gametes from five male and three female haddock ( Melanogrammus aeglefinus ) were crossed to produce 15 half-sibling families that were used to evaluate potential parental contributions to early life history variability. Larval morphology at 0 and 5 days post-hatch (dph) and time to starvation in the absence of food were examined. Maternal influences on larval standard length and yolk area were significant at 0 and 5 dph. Paternal effects on larval standard length were significant at 0 and 5 dph, whereas paternal effects on yolk area were only significant at 5 dph. Larval eye diameter was influenced by maternity at day 0 post-hatch and by both maternity and paternity at 5 dph. Myotome height of larvae was subject to maternal and paternal influences at 0 and 5 dph. Growth rate was significantly influenced by both paternity and maternity. Yolk utilization efficiency was significantly influenced by parental interaction, while the time taken for larvae to die in the absence of food was affected only by maternity. Results of this study not only confirm the importance of female contributions to larval development but also indicate a paternal influence on the development and the early life history success of marine fish.

Description: Post-collisional magmatism in the southern Iberian and northwestern African continental margins contains important clues for the understanding of a possible causal connection between movements in the Earth's upper mantle, the uplift of continental lithosphere and the origin of circum-Mediterranean igneous activity. Systematic geochemical and geochronological studies (major and trace element, Sr–Nd–Pb-isotope analysis and laser 40Ar/39Ar-age dating) on igneous rocks provide constraints for understanding the post-collisional history of the southern Iberian and northwestern African continental margins. Two groups of magmatic rocks can be distinguished: (1) an Upper Miocene to Lower Pliocene (8·2–4·8 Ma), Si–K-rich group including high-K (calc-alkaline) and shoshonitic series rocks; (2) an Upper Miocene to Pleistocene (6·3–0·65 Ma), Si-poor, Na-rich group including basanites and alkali basalts to hawaiites and tephrites. Mafic samples from the Si–K-rich group generally show geochemical affinities with volcanic rocks from active subduction zones (e.g. Izu–Bonin and Aeolian island arcs), whereas mafic samples from the Si-poor, Na-rich group are geochemically similar to lavas found in intraplate volcanic settings derived from sub-lithospheric mantle sources (e.g. Canary Islands). The transition from Si-rich (subduction-related) to Si-poor (intraplate-type) magmatism between 6·3 Ma (first alkali basalt) and 4·8 Ma (latest shoshonite) can be observed both on a regional scale and in individual volcanic systems. Si–K-rich and Si-poor igneous rocks from the continental margins of southern Iberia and northwestern Africa are, respectively, proposed to have been derived from metasomatized subcontinental lithosphere and sub-lithospheric mantle that was contaminated with plume material. A three-dimensional geodynamic model for the westernmost Mediterranean is presented in which subduction of oceanic lithosphere is inferred to have caused continental-edge delamination of subcontinental lithosphere associated with upwelling of plume-contaminated sub-lithospheric mantle and lithospheric uplift. This process may operate worldwide in areas where subduction-related and intraplate-type magmatism are spatially and temporally associated.

Description: Oceanographic conditions in the brackish central Baltic Sea are strongly linked to atmospheric forcing and the unusual period of persistently strong westerlies that, since the late 1980s, have resulted in an increase in average water temperatures and decreasing salinity. These changes in temperature and salinity resulted in a change in the dominance of the mesozooplankton community from Pseudocalanus sp. to Temora longicornis and Acartia spp. Similar to the copepod community, the central Baltic fish community shifted from cod ( Gadus morhua ), dominant during the 1980s, to sprat ( Sprattus sprattus ), dominant during the 1990s. Further, the commercially important pelagic fish species herring ( Clupea harengus ) and sprat exhibited reductions in growth. Using Principal Component and Correlation Analyses we investigated the temporal variability in the importance of the food supply as well as competition on condition of central Baltic pelagic fish species. Our results indicate that herring condition results from a combined effect of changes in the food environment and increased competition with sprat, while sprat condition appeared to be primarily determined by intra-specific competition.

Description: Analysis of the demographic structure of Calanus species in the North Atlantic presents particular difficulties due to the overlapping spatial distributions of four main congeneric species (Calanus finmarchicus, Calanus helgolandicus, Calanus glacialis and Calanus hyperboreus). These species have similar morphologies, making microscopic discrimination only possible between some of the species at late copepodite or adult stages. However, molecular techniques now offer the possibility of screening significant numbers of specimens and unambiguously identifying them to species, regardless of developmental stage. Unfortunately, the processing rate of specimens by molecular methods is still too low to offer a realistic alternative to microscopy for analysis of samples from large field surveys. Here, we outline and test an approach involving the use of molecular methodology in conjunction with conventional microscopy to assess the species assignment of developmental stage abundances of Calanus congeners. Our study has highlighted many important methodological issues. First, it cannot be assumed that the species composition is homogeneous across the development stages; applying proportional species composition of adults to morphologically undistinguishable earlier development stages can result in error. The second important conclusion is that prosome length may be a highly unreliable discriminator of C. finmarchicus and C. glacialis.

Description: Analysis of the demographic structure of Calanus species in the North Atlantic presents particular difficulties due to the overlapping spatial distributions of four main congeneric species (Calanus finmarchicus, Calanus helgolandicus, Calanus glacialis and Calanus hyperboreus). These species have similar morphologies, making microscopic discrimination only possible between some of the species at late copepodite or adult stages. However, molecular techniques now offer the possibility of screening significant numbers of specimens and unambiguously identifying them to species, regardless of developmental stage. Unfortunately, the processing rate of specimens by molecular methods is still too low to offer a realistic alternative to microscopy for analysis of samples from large field surveys. Here, we outline and test an approach involving the use of molecular methodology in conjunction with conventional microscopy to assess the species assignment of developmental stage abundances of Calanus congeners. Our study has highlighted many important methodological issues. First, it cannot be assumed that the species composition is homogeneous across the development stages; applying proportional species composition of adults to morphologically undistinguishable earlier development stages can result in error. The second important conclusion is that prosome length may be a highly unreliable discriminator of C. finmarchicus and C. glacialis

Description: The open oceans comprise most of the biosphere, yet patterns and trends of species diversity there are enigmatic. Here, we derive worldwide patterns of tuna and billfish diversity over the past 50 years, revealing distinct subtropical "hotspots" that appeared to hold generally for other predators and zooplankton. Diversity was positively correlated with thermal fronts and dissolved oxygen and a nonlinear function of temperature (~25°C optimum). Diversity declined between 10 and 50% in all oceans, a trend that coincided with increased fishing pressure, superimposed on strong El Niño–Southern Oscillation–driven variability across the Pacific. We conclude that predator diversity shows a predictable yet eroding pattern signaling ecosystem-wide changes linked to climate and fishing.

Description: Gametophytes of the marine alga Chondrus crispus are more resistant than tetrasporophytes to infection by the filamentous endophytic alga Acrochaete operculata. It has been shown recently that carrageenan oligosaccharides from the resistant gametophytic generation of C. crispus stimulate the secretion of L-asparagine (L-Asn) by the endophyte and that the host generates hydrogen peroxide and 2-oxo-succinamic acid after contact with this amino acid. Here the response of C. crispus to L-Asn and its effect on the pathogen is investigated. Chondrus crispus released hydrogen peroxide, ammonium ions, and a carbonyl compound into the medium when exposed to L-Asn. This response was correlated with an increase in oxygen consumption. Inhibitor studies indicated the involvement of a flavoenzyme in the reaction, which was sensitive to high concentrations of the reaction product, ammonium, and to chlorpromazine, quinacrine, and cyanide, inhibitors of L-amino acid oxidase. Cell wall macerate of C. crispus also responded to L-Asn, while protoplasts were inactive. Uptake of L-Asn into the cell was not necessary for the response, suggesting that the involved L-amino acid oxidase is apoplastic. Acrochaete operculata was more sensitive to hydrogen peroxide than C. crispus and settlement of A. operculata zoospores on C. crispus was reduced by 86% in the presence of L-Asn. This reduced settlement could be prevented with catalase. Chondrus crispus thus features an apoplastic amino acid oxidase, which is involved in the control of its endophytic pathogen. The modulation of the amino acid secretion in A. operculata by carrageenan oligosaccharides is therefore a key issue in the etiology of the association.

Description: Temporal mismatch between the occurrence of larvae and their prey potentially affects the spatial overlap and thus the contact rates between predator and prey. This might have important consequences for growth and survival. We performed a case study investigating the influence of circulation patterns on the overlap of Baltic cod larvae with their prey. A three-dimensional hydrodynamic model was used to analyse spatio-temporally resolved drift patterns of larval Baltic cod. A coefficient of overlap between modelled larval and idealized prey distributions indicated the probability of predator–prey overlap, dependent on the hatching time of cod larvae. By performing model runs for the years 1979–1998 investigated the intra- and interannual variability of potential spatial overlap between predator and prey. Assuming uniform prey distributions, we generally found the overlap to have decreased since the mid-1980s, but with the highest variability during the 1990s. Seasonally, predator–prey overlap on the Baltic cod spawning grounds was highest in summer and lowest at the end of the cod spawning season. Horizontally variable prey distributions generally resulted in decreased overlap coefficients. Finally, we related variations in overlap patterns to the variability of Baltic cod recruitment success.

Description: Large-scale climatic conditions prevailing over the central Baltic Sea resulted in declining salinity and oxygen concentrations in spawning areas of the eastern Baltic cod stock. These changes in hydrography reduced the reproductive success and, combined with high fishing pressure, caused a decline of the stock to the lowest level on record in the early 1990s. The present study aims at disentangling the interactions between reproductive effort and hydrographic forcing leading to variable recruitment. Based on identified key processes, stock dynamics is explained using updated environmental and life stage-specific abundance and production time-series. Declining salinities and oxygen concentrations caused high egg mortalities and indirectly increased egg predation by clupeid fish. Low recruitment, despite enhanced hydrographic conditions for egg survival in the mid-1990s, was due to food limitation for larvae, caused by the decline in the abundance of the copepod Pseudocalanus sp. The case of the eastern Baltic cod stock exemplifies the multitude effects climatic variability may have on a fish stock and underscores the importance of knowledge of these processes for understanding stock dynamics.

Description: Here we report bipedal movement with a hydrostatic skeleton. Two species of octopus walk on two alternating arms using a rolling gait and appear to use the remaining six arms for camouflage. Octopus marginatus resembles a coconut, and Octopus (Abdopus) aculeatus, a clump of floating algae. Using underwater video, we analyzed the kinematics of their strides. Each arm was on the sand for more than half of the stride, qualifying this behavior as a form of walking.

Description: The ECM of astrocytic tumors promotes and modulates a variety of cell functions, such as cell attachment, migration, proliferation, survival, and signaling. Recent studies indicate that there are extensive and complex interactions among ECM molecules and that these can modify the function of the participating molecules, interactions between the proteoglycan, phosphacan, and the ECM protein, tenascin, being an example (63). In addition, on nonastrocytic cell types it has been shown that an integrin receptor and the cell surface proteoglycan CD44 recognize the same ECM ligand osteopontin, and thus modulate each others function (77, 86). Thus, interacting components in the ECM and cell surface receptors likely cooperate in regulating cell function and tumor invasion (59, 77, 80, 85-87, 95). As tumor cells are capable of remodeling their ECM through synthesis of ECM proteins and proteoglycans, as well as upregulating integrin receptors and proteoglycans on their cell surface, tumor cells are capable of controlling their own destiny. ECM molecules which are concentrated in blood vessels of malignant astrocytomas, such as tenascin-C and the 250-kDa CSPG (NG2), are potentially therapeutic targets.

Description: A total of 103 cephalopod paralarvae were sampled during June 1995 in Galician waters (NW Spain). Samples were taken with Bongo nets of 300 and 500 〈IMG SRC="/math/mu.gif"〉m mesh size at 48 sampling stations along 10 transverse transects ranging from 80 to 600 m water depth. Paralarvae of loliginid squid were most abundant (40%). The〈it〉Rhynchoteuthion〈/it〉 paralarvae of ommastrephid squid accounted for 25%, whereas sepiolids comprised 23% of the total sample. Octopods were scarce, at only 6.6%. Other cephalopod families accounted for 5%. Sizes of paralarvae ranged from 1.0 to 7.1 mm mantle length. Temperature and salinity distribution showed the presence of an intense upwelling during the survey period. The sampling data obtained before and during the presence of upwelled water off Rias of Pontevedra and Vigo (southern zone) showed that paralarval cephalopod abundance and distribution were closely related to the upwelled Eastern North-Atlantic Central Water (ENACW).

Description: Chlorofluorocarbon-11 inventories for the deep Southern Ocean appear to confirm physical oceanographic and geochemical studies in the Southern Ocean, which suggest that no more than 5 × 106 cubic meters per second of ventilated deep water is currently being produced. This result conflicts with conclusions based on the distributions of the carbon-14/carbon ratio and a quasi-conservative property, PO4 *, in the deep sea, which seem to require an average of about 15 × 106cubic meters per second of Southern Ocean deep ventilation over about the past 800 years. A major reduction in Southern Ocean deep water production during the 20th century (from high rates during the Little Ice Age) may explain this apparent discordance. If this is true, a seesawing of deep water production between the northern Atlantic and Southern oceans may lie at the heart of the 1500-year ice-rafting cycle.

Description: The seasonal development of oxygen concentrations in the deep water of a nearly permanently stratified station in Kiel Eight, which originates from inflows through the Great Belt and the Kattegat, was investigated. The bottom-water oxygen situation of an individual year was characterized by the apparent oxygen consumption rate from day 80 to day 260. The estimated consumption is poorly correlated with pelagic variables measured during the same year (winter-nutrient concentrations, DON, primary productivity, etc.). For the period 1979-1996, a significant correlation was found between oxygen consumption and average precipitation during the preceding 8 months (June-January). It is suggested that a considerable part of the production is transferred into the next year as particulate organic pool accumulated in, or on top of, the sediment rather than being immediately recycled.

Description: Osmium concentrations and isotopic signatures were measured in 28 primarily Holocene basalts (22 of which have been analyzed for Sr–Nd–Pb isotope composition), two carbonatites and two mantle xenoliths from the Canary Islands, Selvagen Grande and Madeira in the eastern North Atlantic. 187Os/188Os ratios in the basalts range from 0.129 to 0.183. The Os isotope systematics indicate that the basalts fall into three petrogenetic groups: (1) a ‘radiogenic’ group with high 187Os/188Os from 0.152 to 0.183; (2) an ‘unradiogenic’ group with low 187Os/188Os from 0.129 to 0.138; (3) an ‘intermediate’ group with 187Os/188Os between 0.139 and 0.151. The Os isotope systematics of the radiogenic group samples are consistent with minor contamination of the basalts by marine sediment. All samples in the unradiogenic group contain mantle xenoliths, and the unradiogenic Os can be explained by bulk assimilation of ≤ 5% mantle peridotite in the form of disaggregated xenoliths. The radiogenic and unradiogenic groups are also characterized by higher 87Sr/86Sr and 208Pb/204Pb but lower 143Nd/144Nd than samples with similar 206Pb/204Pb from the intermediate group, which is interpreted to reflect interaction of plume magmas with the lithospheric mantle. The intermediate group samples are believed to represent the isotopic signature of the mantle plume. The Os isotopic composition of the Canary plume is among the most radiogenic found in ocean island basalts, comparable with the endmember HIMU islands Mangaia and Tubuaii, but at significantly lower 206Pb/204Pb. The radiogenic Os and moderate 206Pb/204Pb signature of the Canary plume is consistent with a plume which contains 25–35% of relatively young (∼1.2 Ga) recycled oceanic crust. Variable degree of mixing of the Canary Island plume source with shallow depleted asthenosphere containing a component of Paleozoic oceanic crust produces the limited range in Os isotopic signatures observed in the Madeira and Canary Island basalts despite a large range in 206Pb/204Pb isotopic composition.

Description: A coral reef represents the net accumulation of calcium carbonate (CaCO3) produced by corals and other calcifying organisms. If calcification declines, then reef-building capacity also declines. Coral reef calcification depends on the saturation state of the carbonate mineral aragonite of surface waters. By the middle of the next century, an increased concentration of carbon dioxide will decrease the aragonite saturation state in the tropics by 30 percent and biogenic aragonite precipitation by 14 to 30 percent. Coral reefs are particularly threatened, because reef-building organisms secrete metastable forms of CaCO3, but the biogeochemical consequences on other calcifying marine ecosystems may be equally severe.

Description: Statolith microstructure was studied in hatchlings of deepwater-spawned gonatid squid Gonatus onyx, caught between 1350 and 1420 m over a bottom depth of 2100 m in the San Clemente Basin off San Diego, California. It was found that the shape and size of the hatchling statolith were similar to those of the first-check statolith observed in paralarvae and small juveniles of G.onyx. The inner part of the bipartite postnuclear zone (= first-check statolith) is formed during late embryo-genesis, and the first check within the statolith microstructure must be considered as a starting point of increment counting for age estimation of Gonatus

Description: Length–frequency analysis was employed to resolve multiple cohorts in the Loligo forbesi population from coastal waters to the west of Scotland. In both male and female squid two principal cohorts were identified, recruiting to the fished population in April and November. Both cohorts spawned during the winter months (November to April), producing a single extended spawning season, with the April recruits of larger size at spawning than the November recruits. In the males the April recruits appeared to separate into two cohorts of different growth rates, thus producing three rather than two sizes at maturity. The abundance of L. forbesi was low during the summer months, indicating that the squid had moved outside the range of the fishery, perhaps into deeper water. Abundance declined during the spawning season, which is interpreted as post-spawning mortality. Abundance declined earlier in the males than females, producing a female biased sex ratio during most of the spawning season. The two periods of recruitment are not compatible with a 1 year life cycle and single extended spawning season and explanations of this are discussed.

Description: Trace elements and Sr–Nd–Pb isotopes have been analyzed on sedimentary and igneous (metabasalt, metadiorite and metagabbro) samples from the Jurassic oceanic crust beneath Gran Canaria (Canary Islands). The igneous crust exhibits extreme heterogeneity in 87Sr/86Sr (0.7029–0.7052), 206Pb/204Pb (18.2–20.8) and 208Pb/204Pb (38.1–41.3). Leaching experiments indicate that seawater alteration has elevated the 87Sr/86Sr ratio but has not appreciably affected 143Nd/144Nd (0.51295–0.51306). An Sm–Nd isochron gives an age of 178 ± 17 Ma, which agrees with the age predicted from paleomagnetic data. Hydrothermal alteration near the ridge axis has increased 207Pb/204Pb (15.59−15.73), 208Pb/204Pb (as well as Δ7/4Pb and Δ8/4Pb), 238U/204Pb (μ) and Ce/Pb but has not appreciably changed 206Pb/204Pb. The large range in 206Pb/204Pb and 208Pb/204Pb reflects radiogenic ingrowth with μ being as high as 107. Portions of the Jurassic ocean crust have trace element and isotope characteristics within the range found at St Helena, the Atlantic type locality for the HIMU (high μ) mantle end-member. Evaluation of the published isotopic data for Gran Canaria volcanic rocks indicates that the isotopic composition of these melts primarily represents the composition of their mantle sources rather than crustal assimilation.

Description: The impact of nutrient supply ratios on the functional geometry of phytoplankton has been studied by means of competition experiments with phytoplankton communities from the Arabian Sea. Cell length and deviation from spherical shape of dominant competitors increased with Si:N ratios.Surface:volume ratios were minimal at intermediate Si:N ratios. Grazing by the rotifer Brachionus plicatilis did not lead to a qualitative shift in the response of geometric properties to Si:N ratios; however, mean cell lengths increased while surface:volume ratios decreased.

Description: Findings from experiments showed that the web-feeding euthecosomatous pteropod, Limacina retroversa, can produce rapidly sinking, mucous aggregates. It is suggested that, by adhesion, these aggregates scavenged picoplankton-sized particles, which were thus effectively cleared from the medium. In contrast, Calanus finmarchicusw as not able to clear these particles in our experiments. Sedimentation velocities of 10 aggregates measured in vivo were up to 1000 m day1, with an average of —300 m day-1 (not including two aggegates with neutral buoyancy). Mean velocities measured for feces of C.finmarchicus, Calanus hyperboreus and Thysanoessa sp. were considerably lower. We suggest that the sedimentation of L.retroversa aggregates was the source of mucous floes collected in sediment traps (Bathmann et al., Deep-Sea Res., 38,1341-1360,1991) and at the sea floor at 1200 m depth in the southern Norwegian Sea. This process may be an important mediator of sedimentation to the deep sea, when these pteropods are present in surface waters in large abundance.

Description: Statolith morphology and microstructure were studied in two common species of panktonic cranchiid squids, Belonella borealis [four juveniles with mantle length (ML) 375–450 mm] and Galiteuthis phyllura (13 paralarvae and juveniles, ML 9–235mm), caught near the bottom and in pelagic layers over the continental slope of Siberia in the northwest Bering Sea. The total number of growth increments within the statoliths ranged from 277 to 294 in B.borealis and from 10 to 209 in G.phyllura. Assuming that these increments were produced daily, both species grow rapidly in length (daily growth rate = 1.13mm day−1 during the first 8–10 months of their juvenile phase in the mesopelagic layers, prior to migration into deeper waters for maturation.

Description: This paper discusses an observing system simulation experiment which reveals the difference in primary production of (i) phytoplankton moving freely in the turbulent mixed layer of the upper ocean and (ii) a sample of the same population held in a bottle at fixed depths. The results indicate the tendency of incubation measurements to overestimate phytoplankton production rates by up to 40%. Differences in primary production depend to a first approximation on the vertical extent of mixing and on water turbidity. A simple model was constructed leading to a non-linear calibration function which relates the difference in primary production to surface irradiance, mixing depth and to the depth of the euphotic zone. This function has been applied to calibrate the production rates simulated at fixed depths, and the corrected values were verified by comparisons with productivities in the turbulent environment. The calibration function was found to be capable of reducing the differences significantly.

Description: The potentially toxic diatom Pseudonitzschia pungens f. multiseries was grown on different sources of nitrogen in batch cultures. Ammonium did not support growth at concentrations 〉200 μM, and even lowered the growth rate, when it was supplied in addition to growth-saturating nitrate concentrations. This seemed to be a combined effect of inhibition of nitrate uptake and direct ammonia toxicity. Urea, glutamine and nitrite were used readily by P.pungens.

Description: During glacial cycles, different parts of the Earth cool by different amounts. A growing collection of evidence has begun to show that cooling in the tropical oceans was greater than previously thought. In his Perspective, Broecker discusses the oxygen isotope evidence reported by Schrag et al. (p. 1930) that indicates that the cooling in deep tropical water was close to the freezing point.

Description: A number of reproductive indices were compared with a subjective maturity scale for assessment of Loligo forbesi maturity. The ratio between nidamental gland length and mantle length corresponded well with female maturation, as did the ovary mass-soma mass and nidamental gland mass-soma mass ratios. For males, the ratio between spermatophoric complex mass and somatic mass was found to be the most suitable for maturity assessment. The timing of recruitment and maturation of L. forbesi in Irish waters was described from the size and maturity of squid in commercial landings in the south of Ireland during the years 1991–1993. Immature squid first appeared in commercial catches in July and August, and this represented the main period of recruitment. A second period of recruitment was apparent in December 1991, but was not identified in the 1992–1993 season. Mature females were present in the commercially exploited population between November and April, with a small number also found in the summer. The abundance of egg masses was used to indicate timing of spawning. Egg masses recovered from the Cork coast indicated that peak spawning occurred during the winter months, but continued on a small scale for much of the year.

Description: One of the critical issues in large-scale physical/biological coupled models is the survival of zooplankton in a water column circulating an anticyclonic gyre. Survival is most at risk in regions where the phytoplankton food supply is low due to environmental stress by light-limitation (deep mixing in winter) or nutrient limitation (oligotrophy). To investigate this problem we simulated the ecosystem in a 1 m2 cross-section water column, using the Lagrangian Ensemble method in which plankton are treated as particles following independent trajectories through the changing environment. In this first part of a two-part article we report the results of simulating the ecosystem in a water column located off the Azores, where winter mixing reaches 200 m and there is seasonal, but not permanent oligotrophy. The model features diatoms and herbivorous copepods subject to carnivorous predation, with remineralization of carbon and nitrogen by bacteria attached to detritus and faecal pellets. The copepods become extinct after failing to reproduce in years of low food supply. We show that the risk of extinction can be reduced by allowing cannibalism or by reducing carnivorous predation; we discuss other possibilities: enhancing the food supply by adding new guilds of phytoplankton, and relaxing oligotrophy by allowing other sources of nitrogen injection into the euphotic zone.

Description: Greenland ice-core data have revealed large decadal climate variations over the North Atlantic that can be related to a major source of low-frequency variability, the North Atlantic Oscillation. Over the past decade, the Oscillation has remained in one extreme phase during the winters, contributing significantly to the recent wintertime warmth across Europe and to cold conditions in the northwest Atlantic. An evaluation of the atmospheric moisture budget reveals coherent large-scale changes since 1980 that are linked to recent dry conditions over southern Europe and the Mediterranean, whereas northern Europe and parts of Scandinavia have generally experienced wetter than normal conditions.