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  • 1
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Two species of the echinoid genus Sterechinus were documented from 92 trawl stations and 55 photographic stations in the eastern and southern Weddell Sea between 100 and 1200 m water depth. We found two species occuring along the whole shelf and slope, S. neumayeri being more abundant above 450 m water depth and S. antarcticus dominating the deeper regions. The size-frequency distributions of both species indicate differences in growth, mortality and longevity. First estimates of abundance and biomass of S. neumayeri and S. antarcticus are 0.085 ind/m2 & 0.005 gAFDW/m2 and 0.022 ind/m2 & 0.005 gAFDW/m2, respectively.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Population dynamics of the epizoic bivalve Lissarca notorcadensis living on spines of cidaroid sea urchins in the Weddell Sea were investigated. Total production (somatic & gonad) of the suspension feeding bivalve ranged between 16.5 and 487.4 mg AFDM y−1 per sea urchin. Annual sedimentation rates are not sufficient to maintain the production of the Lissarca sub-populations carried by the sea urchins, and resuspension of organic matter is most likely to be an important food source. The ratio of the number of freshly settled juveniles to the number of embryos brooded is between 0.054 and 0.207 and seems negatively related to the biomass already present, indicating intraspecific competition for space. Interspecific competition for space is caused by the strong preference of L. notorcadensis as well as other epizoa (colonial anthozoans and bryozoans) for the spines located on the aboral hemispere of the sea urchins.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Growth marks in calcareous shells or skeleton parts of benthic invertebrates are often assumed to be formed annually and hence are used for ageing purposes. For some Antarctic species this assumption has been validated by tagging experiments or direct monitoring of growth throughout the year. Here we use the record of stable isotope ratios (δ18O and δ13C) deposited in shell carbonate of Laternula elliptica from King George Island to demonstrate that shell growth bands are formed annually in this species.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1438-3888
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The surface deposit feeding speciesPygospio elegans andMacoma balthica are dominant members of many sandy bottom communities of northern boreal regions. The feeding mode of both species and the tube-building ofP. elegans are assumed to affect community structure by interactions with other species. The weight of tubes ofP. elegans varied between 2 and 13 g DW/100 cm2 at the two stations investigated and during the year, which is equivalent to 230–1500 cm of tubes per 100 cm2 of sediment surface. Sediment stability may be affected directly or indirectly by the amount of tubes present.M. balthica shows a linear relation between the maximum size of particles which can be inhaled and animal length. In Kiel Bay, particles〉0.5 mm are out of the range of this species. In summer, the potential feeding area (PFA) of aP. elegans population at one station in Kiel Bay was 1.8 times the available surface area. The PFA of three different populations ofM. balthica in Kiel Bay exceeded the available surface area by factors of 2.6, 2.7, and 3.2. These findings indicate strong intra- and interspecific competition for food. Additionally, the feeding of both species may strongly affect the recruitment of benthic species via pelagic larvae. Experiments are proposed to evaluate the significance of the investigated behavioural aspects for community structure.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-5125
    Keywords: Population dynamics ; mudskipper ; Periophthalmus papilio ; Cross River ; Nigeria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A seminal study was conducted in which the population dynamics (growth, mortality and recruitment) of the mudskipper (Periophthalmus papilio) in the Cross River, Nigeria, was elucidated for the first time using length frequency data and the ELEFAN software. The allometric relationship was: Weight=0.012(Length)2.940, n=415, r2=0.939, P 〈0.0005. The seasonalized Von Bertalanffy growth parameters were L∞=19.39 cm, K=0.51 y−1, C=0.3, and WP=0.4. The instantaneous total mortality coefficient Z was 2.208 y−1 while the instantaneous natural mortality coefficient was 1.341 y−1. The instantaneous fishing mortality coefficient of 0.867 y−1 yielded the expectedly low exploitation rate E of 0.393. Our estimate shows that the species could reach an average maximum life span of about 6 years in the Cross River system. These results are used in quantitative elucidation of the state of exploitation of the population and will serve as input for the proper and scientific management of the fish resource.
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  • 6
    Publication Date: 2014-09-01
    Description: The ongoing process of ocean acidification already affects marine life, and according to the concept of oxygen and capacity limitation of thermal tolerance, these effects may be intensified at the borders of the thermal tolerance window. We studied the effects of elevated CO2 concentrations on clapping performance and energy metabolism of the commercially important scallop Pecten maximus. Individuals were exposed for at least 30 days to 4 °C (winter) or to 10 °C (spring/summer) at either ambient (0.04 kPa, normocapnia) or predicted future PCO2 levels (0.11 kPa, hypercapnia). Cold-exposed (4 °C) groups revealed thermal stress exacerbated by PCO2 indicated by a high mortality overall and its increase from 55 % under normocapnia to 90 % under hypercapnia. We therefore excluded the 4 °C groups from further experimentation. Scallops at 10 °C showed impaired clapping performance following hypercapnic exposure. Force production was significantly reduced although the number of claps was unchanged between normocapnia- and hypercapnia-exposed scallops. The difference between maximal and resting metabolic rate (aerobic scope) of the hypercapnic scallops was significantly reduced compared with normocapnic animals, indicating a reduction in net aerobic scope. Our data confirm that ocean acidification narrows the thermal tolerance range of scallops resulting in elevated vulnerability to temperature extremes and impairs the animal’s performance capacity with potentially detrimental consequences for its fitness and survival in the ocean of tomorrow.
    Type: Article , PeerReviewed
    Format: text
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  • 7
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    Springer
    In:  EPIC3Handbook on Marine Environment Protection, Cham, Switzerland, Springer, 21 p., pp. 353-373, ISBN: 978-3-319-60156-4
    Publication Date: 2018-02-09
    Description: In this chapter, the effects of temperature change—as a main aspect of climate change—on marine biodiversity are assessed. Starting from a general discussion of species responses to temperature, the chapter presents how species respond to warming. These responses comprise adaptation and phenotypic plasticity as well as range shifts. The observed range shifts show more rapid shifts at the poleward range edge than at the equator-near edge, which probably reflects more rapid immigration than extinction in a warming world. A third avenue of changing biodiversity is change in species interactions, which can be altered by temporal and spatial shifts in interacting species. We then compare the potential changes in biodiversity to actual trends recently addressed in empirical synthesis work on local marine biodiversity, which lead to conceptual issues in quantifying the degree of biodiversity change. Finally we assess how climate change impacts the protection of marine environments.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Inbook , peerRev
    Format: application/pdf
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  • 8
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    Springer
    In:  EPIC3Towards an Interdisciplinary Approach in Earth System Science, (Springer Earth System Sciences), Heidelberg [u.a.], Springer, 251 p., pp. 173-182, ISBN: 978-3-319-13864-0
    Publication Date: 2015-02-11
    Description: Understanding the climate of the past is essential for anticipating future climate change. Palaeoclimatic archives are the key to the past, but few marine archives (including tropical corals) combine long recording times (decades to centuries) with high temporal resolution (decadal to intra-annual). In temperate and polar regions carbonate shells can perform the equivalent function as a proxy archive as corals do in the tropics. The bivalve Arctica islandica is a particularly unique bio-archive owing to its wide distribution throughout the North Atlantic and its extreme longevity (up to 500 years). This paper exemplifies how information at intra-annual and decadal scales is derived from A. islandica shells and combined into a detailed picture of past conditions. Oxygen isotope analysis (δ18O) provides information on the intra-annual temperature cycle while frequency analysis of shell growth records identifies decadal variability such as a distinct 5-year signal, which might be linked to the North Atlantic Oscillation.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Inbook , peerRev
    Format: application/pdf
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  • 9
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    Springer
    In:  EPIC3Earth system science: bridging the gap between disciplines, Earth system science: bridging the gap between disciplines, Heidelberg, Springer, 7 p., pp. 97-103, ISBN: 978-3-642-32234-1
    Publication Date: 2023-06-21
    Description: Information about past environmental conditions is preserved in the elemental signature of biogenic marine carbonates. Thus, trace element to calcium ratios (Me/Ca) of biogenic calcium carbonates, such as bivalve shells, are often used to reconstruct past environmental conditions at the time of carbonate formation (Foster et al., 2008). In this study, we examine the suitability of the long-lived (〉 400 years) bivalve Arctica islandica as a high-resolution bioarchive by measuring Me/Ca ratios in the shell carbonate. Pb/Ca concentrations in A. islandica shells reflect anthropogenic gasoline lead consumption and further provide a centennial record of lead pollution for the collection site off the coast of Virginia, USA. With A. islandica shells from the North Sea we test the hypothesis that Ba/Ca and Mn/Ca ratios are indicators of the diatom abundance. Our results indicate that statistically both ratios correlate well with the diatom abundance, and yet, on a year-to-year base, there is no consistent reflection of diatom abundance patterns in the Ba/Ca and Mn/Ca annual profiles. These findings indicate that primary production affects Ba/Ca and Mn/Ca shell ratios, though we suggest that both elements are coupled to primary production through different processes and are affected by further, yet unknown processes.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Inbook , peerRev
    Format: application/pdf
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