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  • 1
    Electronic Resource
    Electronic Resource
    Variability of particulate organic carbon and nitrogen in the Namibian upwelling system (1991)
    Springer
    Marine biology 110 (1991), S. 409-418 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Particulate organic carbon (POC) and nitrogen (PON) were analyzed during cruises undertaken in September 1985 and April 1986 along the Namibian upwelling system. The main objectives were to provide estimates of standing stocks of particulate organic matter (POM) and analyze its temporal and spatial variability. Average estimates of total carbon standing stock (0 to 100 m depth) accounted for 1.2 g-at C m−2 during active and 1.32 g-at C m−2 during abated upwelling. Zooplankton carbon was estimated as 0.22 and 0.27 g-at C m−2, respectively, for both periods. POM was generally concentrated near the surface, especially during abated upwelling. During abated upwelling, POM was not only abundant inshore but also over the shelf, as a response of a more diffuse frontal system and a more strongly stratified water column. Cross-shelf gradients were more significant during active upwelling, while alongshore gradients accounted for most of the variance of particulate organic matter during abated periods. This result was a consequence of the seasonal intrusion of warm, Angolan water from the north during the period of minimum upwelling, and resulted in poorer POM concentrations and higher consumer: producer ratios (24.4%). Nevertheless, this last conclusion should be regarded with caution due to the lack of comparative interannual variability. A 48 h study at a fixed station permitted analysis of the daily variability in POM during the intrusion process. Changes in the thickness of the surface mixed layer due to irregular time-spaced pulses of non-homogeneous water masses resulted in sudden enrichments and renewals of phytoplankton and zooplankton populations in a matter of hours.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01344360
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  • 2
    Electronic Resource
    Electronic Resource
    Distribution patterns, abundance and population dynamics of the euphausiidsNyctiphanes capensis andEuphausia hanseni in the northern Benguela upwelling system (1991)
    Springer
    Marine biology 109 (1991), S. 93-101 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Distribution patterns, population structure and biomass of the euphausiidsNyctiphanes capensis andEuphausia hanseni were examined off the coast of Namibia, southwest Africa, in relation to temperature, depth and season, from data collected on nine surveys from September 1982 to March 1984. High densities ofN. capensis were found in the shallow coastal waters (〈200 m), with the biomass of adults ranging from 675 to 5 706 mg dry wt m−2. For adultE. hanseni, the biomass was an order of magnitude lower, ranging from 65 to 505 mg dry wt m−2, with most specimens occurring over the shelf break at depths of 200 to 1000 m. These distribution patterns remained relatively constant throughout the year, despite seasonal differences in upwelling events. Both species displayed continuous breeding, with 43 to 82% of the adult femaleE. hanseni being fertilized, while a much lower proportion ofN. capensis females were reproductively active (0.5 to 26%). Different breeding strategies were adopted by these two euphausiid species, withE. hanseni producing frequent broods (14.8 broods in 6 mo) consisting of relatively large eggs which are released into the sea, andN. capensis exhibiting a lower frequency of spawning, with broods consisting of large numbers of relatively small eggs, protected by a brood pouch. These strategies enable both species to maintain high densities throughout the year in a fluctuating physical environment. Growth rate estimated from size-frequency distributions were 0.003 to 0.063 mm d−1 forN. capensis and 0.077 to 0.083 mm d−1 forE. hanseni, suggesting an adult lifespan of approximately 6 mo for both species. Maximum sizes were attained in September, withN. capensis reaching a total length of 21 mm (in contrast to all previous studies onN. capensis, where the maximum size recorded was only 13 mm total length) andE. hanseni a total length of 33 mm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01320235
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  • 3
    Electronic Resource
    Electronic Resource
    Antarctic krill aggregation characteristics from acoustic observations in the Southwest Atlantic Ocean (1993)
    Springer
    Marine biology 117 (1993), S. 171-183 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The distributional features and physical characteristics of 4830 krill (Euphausia superba Dana) aggregations detected acoustically in the Southwest Atlantic between 26 January and 21 February 1981 are described. Results are compared with aggregations detected in the Indian Ocean. Aggregations in the Atlantic were larger, closer to the surface and to each other than in the Indian Ocean. Similar patterns in the distribution of aggregation spacing along survey transects were found in the two areas, although the pattern of spacings in the Atlantic indicates differences in the scale of aggregation. Serial interdependence of aggregation variables was minimal in the Atlantic, with aggregation thickness, length and spacing showing weak inter-relationships. Weak functional association, between water depth and aggregation thickness was evident. Investigation of variability in aggregation structure in relation to prevailing environmental conditions gave equivocal results and no clear association between any aggregation variable and prevailing hydrography was observed. The implications of these results for future studies on krill aggregation are discussed in relation to a conceptual framework which was developed from the present results and aimed at linking krill aggregation characteristics to environmental features.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00346440
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  • 4
    Electronic Resource
    Electronic Resource
    Zoogeography and diversity of euphausiids around southern Africa (1995)
    Springer
    Marine biology 123 (1995), S. 257-268 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Published and unpublished records of euphausiid distributions around southern Africa are examined for zoogeographic pattern and the results compared with patterns generated from intertidal data sets. Two basic groups of euphausiids are discerned from cluster analysis, corresponding to neritic and oceanic assemblages. Superimposed upon these are Indian Ocean (Agulhas Current) and Atlantic Ocean (Benguela Current) groups. Patterns of diversity and zoogeography generally conform to the large-scale hydrological features in the area. Diversity is higher in the oceanic than in neritic regions. Maximum diversity is recorded off Cape Point, where Indian, Atlantic and southern Ocean waters interact. Diversity is otherwise higher along the east coast, and particularly low in the nearshore waters of the Benguela Current. While particular species of euphausiids can be associated with Agulhas Current and Angola Current waters, westcoast communities lack any distinctive species, and this is discussed. Although the patterns of zoogeography observed for euphausiids are generally similar to those observed for rocky shore communities, there are clear differences between them that reflect their respective habitats and the influence that large-scale water movement has on each.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00353617
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  • 5
    Electronic Resource
    Electronic Resource
    Diel feeding periodicity, daily ration and vertical migration of juvenile Cape hake off the west coast of South Africa (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 47 (1995), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Feeding periodicity, daily ration and vertical migration of juvenile Cape hake Merluccius capensis are investigated from midwater and bottom trawl collections taken during a 42-h period between 29 February and 2 March 1992 at a fixed position off the west coast of South Africa. Feeding of 10-20 cm hake intensified during the night when they ascended into subsurface layers to prey on recruits of anchovy Engraulis capensis. Larger hake remained close to the bottom, were partially cannibalistic and exhibited no diel feeding periodicity. M. capensis appear to migrate vertically and feed asynchronously in midwater, as individuals, and not as a population, returning to the bottom when satiated. Based upon the exponential rate of decline in stomach fullness throughout the day, the evacuation rate by hake 〈20 cm was estimated as 0.054 h−1; 90% evacuation of anchovy prey required an estimated 43 h. Using the Elliott & Persson and Eggers methods, the daily ration was estimated as 5.51 and 4.15% of wet body weight respectively. The effect of the foraging behaviour of M. capensis on the appropriateness of acoustic sampling for estimates of their abundance is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1995.tb06000.x
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  • 6
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    Projecting marine fish production and catch potential in Bangladesh in the 21st century under long-term environmental change and management scenarios (2016)
    Oxford University Press
    Details
    Publication Date: 2016-06-24
    Description: The fisheries sector is crucial to the Bangladeshi economy and wellbeing, accounting for 4.4% of national gross domestic product and 22.8% of agriculture sector production, and supplying ca. 60% of the national animal protein intake. Fish is vital to the 16 million Bangladeshis living near the coast, a number that has doubled since the 1980s. Here, we develop and apply tools to project the long-term productive capacity of Bangladesh marine fisheries under climate and fisheries management scenarios, based on downscaling a global climate model, using associated river flow and nutrient loading estimates, projecting high-resolution changes in physical and biochemical ocean properties, and eventually projecting fish production and catch potential under different fishing mortality targets. We place particular interest on Hilsa shad ( Tenualosa ilisha ), which accounts for ca. 11% of total catches, and Bombay duck ( Harpadon nehereus ), a low price fish that is the second highest catch in Bangladesh and is highly consumed by low-income communities. It is concluded that the impacts of climate change, under greenhouse emissions scenario A1B, are likely to reduce the potential fish production in the Bangladesh exclusive economic zone by 〈10%. However, these impacts are larger for the two target species. Under sustainable management practices, we expect Hilsa shad catches to show a minor decline in potential catch by 2030 but a significant (25%) decline by 2060. However, if overexploitation is allowed, catches are projected to fall much further, by almost 95% by 2060, compared with the Business as Usual scenario for the start of the 21st century. For Bombay duck, potential catches by 2060 under sustainable scenarios will produce a decline of 〈20% compared with current catches. The results demonstrate that management can mitigate or exacerbate the effects of climate change on ecosystem productivity.
    Print ISSN: 1054-3139
    Electronic ISSN: 1095-9289
    Topics: Biology , Geosciences , Physics
    Published by Oxford University Press
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  • 7
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    The evolving and increasing need for climate change research on the oceans (2016)
    Oxford University Press
    Details
    Publication Date: 2016-06-24
    Description: The 3rd International Symposium on the Effects of Climate Change on the World's Oceans was held in Santos, Brazil, in March 2015, convened by the International Council for the Exploration of the Sea (ICES), the North Pacific Marine Science Organization (PICES), and the Intergovernmental Oceanographic Commission of UNESCO (IOC), and organized locally by the Oceanographic Institute, University of Sao Paulo (IO-USP). The symposium was designed to do two things. First, to get updates on new scientific developments that would address recognized uncertainties that remained from Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report and to contribute to building bridges between research in the natural and social sciences in respect to the human dimensions of climate change, with a focus on coastal communities, management objectives, governance and adaptation measures. The choice of the venue in Santos, Brazil, was aimed to stimulate and widen this thematic discussion in Latin America and southern Atlantic regions, where there still are important knowledge gaps and scientific, politic and societal challenges to be overcome. The meeting was attended by 280 participants from 38 countries, contributing 336 oral and poster presentations. This paper summarizes the main outcomes of the symposium and introduces a number of papers submitted to this special issue.
    Print ISSN: 1054-3139
    Electronic ISSN: 1095-9289
    Topics: Biology , Geosciences , Physics
    Published by Oxford University Press
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  • 8
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    Uncertainties in projecting climate-change impacts in marine ecosystems (2016)
    Oxford University Press
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    Publication Date: 2016-06-24
    Description: Projections of the impacts of climate change on marine ecosystems are a key prerequisite for the planning of adaptation strategies, yet they are inevitably associated with uncertainty. Identifying, quantifying, and communicating this uncertainty is key to both evaluating the risk associated with a projection and building confidence in its robustness. We review how uncertainties in such projections are handled in marine science. We employ an approach developed in climate modelling by breaking uncertainty down into (i) structural (model) uncertainty, (ii) initialization and internal variability uncertainty, (iii) parametric uncertainty, and (iv) scenario uncertainty. For each uncertainty type, we then examine the current state-of-the-art in assessing and quantifying its relative importance. We consider whether the marine scientific community has addressed these types of uncertainty sufficiently and highlight the opportunities and challenges associated with doing a better job. We find that even within a relatively small field such as marine science, there are substantial differences between subdisciplines in the degree of attention given to each type of uncertainty. We find that initialization uncertainty is rarely treated explicitly and reducing this type of uncertainty may deliver gains on the seasonal-to-decadal time-scale. We conclude that all parts of marine science could benefit from a greater exchange of ideas, particularly concerning such a universal problem such as the treatment of uncertainty. Finally, marine science should strive to reach the point where scenario uncertainty is the dominant uncertainty in our projections.
    Print ISSN: 1054-3139
    Electronic ISSN: 1095-9289
    Topics: Biology , Geosciences , Physics
    Published by Oxford University Press
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  • 9
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    Introduction to the BASIN Special Issue: State of art, past present a view to the future (2014)
    Elsevier
    Details
    Publication Date: 2014-12-01
    Print ISSN: 0079-6611
    Electronic ISSN: 1873-4472
    Topics: Geosciences , Physics
    Published by Elsevier
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  • 10
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    Distribution patterns, abundance and population dynamics of the euphausiidsNyctiphanes capensis andEuphausia hanseni in the northern Benguela upwelling system (1991)
    Springer
    Details
    Publication Date: 1991-02-01
    Print ISSN: 0025-3162
    Electronic ISSN: 1432-1793
    Topics: Biology
    Published by Springer
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