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  • 2000-2004  (11)
  • 2002  (11)
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  • 2000-2004  (11)
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  • 1
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    Oxygen microoptodes: a new tool for oxygen measurements in aquatic animal ecology (2002)
    In:  EPIC3Marine biology, 140(6), pp. 1075-1085, ISBN: 0025-3162 (Paper) 14
    Details
    Publication Date: 2019-07-16
    Description: We describe two applications of a recently introduced system for very precise, continuous measurement of water oxygen saturation. Oxygen microoptodes (based on the dynamic fluorescence quenching principle) with a tip diameter of ~50µm, an 8-channel optode array, an intermittent flow system, and online data registration were used to perform two types of experiments. The metabolic activity of Antarctic invertebrates (sponges and scallops) was estimated in respiration experiments and, secondly, oxygen saturation inside living sponge tissue was determined in different flow regimes. Even in long-term experiments (several days) no drift was detectable in between calibrations. Data obtained were in excellent correspondence with control measurements performed with a modified Winkler method. Antarctic invertebrates in our study showed low oxygen consumption rates ranging from 0.03 - 0.19 cm3O2oh-1oind-1. Oxygen saturation inside living sponge specimens was affected by flow regime and culturing conditions of sponges. Our results suggest that oxygen optodes are a reliable tool for oxygen measurements beyond the methodological limits of traditional methods.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 2
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    Growth, production and respiration in scallops (2002)
    In:  EPIC3Comparative biochemistry and physiology a-molecular and integrative physiology, 132, 20 p.
    Details
    Publication Date: 2019-07-16
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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  • 3
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    Individual age and connective tissue lipofuscin in the hard clam Eurhomalea exalbida (2002)
    In:  EPIC3Journal of experimental marine biology and ecology, 276, pp. 83-94, ISSN: 0022-0981
    Details
    Publication Date: 2019-07-16
    Description: In the hard clam Eurhomalea exalbida autofluorescent granules were detected in high concentrations in the connective tissue around the intestine and in other tissues. Autofluorescence combined with Sudan Black B and PAS positive reactions suggested that these granules were lipofuscin-like. The concentration of this material in the connective tissue (CT) around the intestine was quantified by image analysis and expressed as total area fraction occupied by lipofuscin granules. Lipofuscin concentration was distinctly better related with individual age as determined from stable isotope validated shell growth bands, than with any morphometric parameter. This relationship was described best by a Gompertz model: Lipofuscint = 24.79 * e -e 0.029 * (Age t 58.578) (N = 38; r2nl = 0.882). Age was predicted from lipofuscinCT concentration by a von Bertalanffy model: Age t = 68.00 * (1 - e -0.146 * (Lipofuscint + 0.028))0.664 (N = 38; r2nl = 0.933). Our findings suggest that lipofuscinCT concentration in E. exalbida is a function of individual age. If this holds true for bivalves in general, lipofuscin may be a suitable proxy for age in species with less clear shell growth band patterns.
    Repository Name: EPIC Alfred Wegener Institut
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  • 4
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    A stable isotope approach to the eastern Weddell Sea trophic web: focus on benthic amphipods (2002)
    In:  EPIC3Polar biology, 25, pp. 280-287
    Details
    Publication Date: 2019-07-16
    Description: Stable isotope (13C/12C and 15N/14N) analyses were performed on 90 species belonging to different benthic communities sampled in the eastern Weddell Sea. The study focused on eight amphipod species whose isotopic composition was compared to their previously described respective gut contents. Amphipod stable isotope ratios correspond fairly accurately to the trophic classification based on gut contents and attest to their wide spectrum of feeding types. Since the fundamental difference between the isotope and the gut content approaches to diet studies is the time scale each method addresses, this coincidence indicates that there would be no significant changes in feeding strategies over time. Three levels of the food web are covered by the eight species and, instead of belonging strictly to one trophic category, amphipods display a continuum of values from the suspension-feeder to scavengers.
    Repository Name: EPIC Alfred Wegener Institut
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  • 5
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    The reproductive cycle of Eurhomalea exalbida (Chemnitz, 1795) (Bivalvia: Veneridae) in Ushuaia Bay (54°50′ S), Beagle Channel (Argentina) (2002)
    In:  EPIC3Invertebrate reproduction & development, 42(1), pp. 61-68
    Details
    Publication Date: 2019-07-16
    Description: The reproductive cycle of Eurhomalea exalbida (Chemnitz, 1795) in Ushuaia Bay, Beagle Channel, was studied from October 1998 to December 1999. Clams were collected monthly by SCUBA diving at 3 to 5 m water depth. The degree of sexual maturity was determined histologically (n=318). The sex ratio was 1:1 (Chi-squared p 〉 0.05). First sexual maturity occurred at 39 mm shell heigth in males and 40 mm in females (i.e. 4 years of age).Five distinct histological stages of sexual maturity could be established in males: (1) Early Active, (2) Late Active, (3) Ripe, (4) Partially Spawned and (5) Spent. Females had oocytes ranging from small and immature to large and developed in their ovaries throughout the year, hence we could not classify reproductive stages based on a qualitative histological scale of sexual maturity. Therefore, quantitative measures using an image analyzer were used. In males a high percentage of ripe individuals were present between January and August. The percentage of early active and partially spawned individuals was highest in November 1998 (70%) and 1999 (60%). In females, the mean number of developed oocytes per gonadal area, the mean diameter (minor axis) of oocytes, and the percentage of gonadal area occupied by oocytes were lowest in November, indicating a spawning peak. These results indicate synchronous gonadal development and spawning in males and females. The more intensive spawning activity in November coincides with the higher biomass and production of phytoplankton in spring.
    Repository Name: EPIC Alfred Wegener Institut
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  • 6
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    Comparing production-biomass ratios of benthos and suprabenthos in macrofaunal marine crustaceans (2002)
    In:  EPIC3Canadian journal of fisheries and aquatic sciences, 59, pp. 1616-1625
    Details
    Publication Date: 2019-07-16
    Description: Using available data from the literature, we compared the productionbiomass ratios (P/B) between the suprabenthic (= hyperbenthic) and the benthic (infaunaepifauna) species within the group of the macrofaunal marine crustaceans. This data set consists of 91 P/B estimates (26 for suprabenthos and 65 for infaunaepifauna) for 49 different species. Suprabenthic crustacean P/B was significantly higher than P/B of benthic crustacean (post-hoc Scheffé test; one-way analysis of covariance, ANCOVA; p 〈 103) and also of other (noncrustacean) benthic invertebrate (p 〈 104). Predictive multilinear regression (MLR) analysis for macrofaunal marine crustaceans showed P/B to depend significantly on mean annual temperature (T) and mean individual weight (W) (R2 = 0.367). Adding the variable swimming capacity increased goodness-of-fit to R2 = 0.528. The higher P/B of suprabenthic (= swimming) macrofauna in comparison with that of the benthic compartment seems to be related to the most apparent feature of the suprabenthos, its swimming capacity. The high P/Bs reported for suprabenthic species indicate how a nontrivial part of benthic production can be ignored if suprabenthos is not well sampled, therefore biasing the models of energy flow generated for trophic webs.
    Repository Name: EPIC Alfred Wegener Institut
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  • 7
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    Survivorship of juvenile surf clams Donax serra (Bivalvia, Donacidae) exposed to severe hypoxia and hydrogen sulphide (2002)
    In:  EPIC3Journal of experimental marine biology and ecology, 271(1), pp. 9-23
    Details
    Publication Date: 2019-07-16
    Description: Toxic "sulphide eruptions" sporadically occur in the highly productive inshore regions of the central Namibian Benguela upwelling system. The surf clam Donax serra (Röding, 1798) dominates the intertidal and upper subtidal of large exposed sandy beaches of southern Africa and its recruitment seems to be affected by sulphide events. The reaction of juvenile surf clams to low oxygen concentrations and sulphide occurrence (0.1 mmol l-1) was examined by in vitro exposure experiments in a gas-tight continuous flow system. After 2 h of hypoxic- and hypoxic-sulphidic conditions clams moved to the sediment surface, aiding their passive transport to areas with more favourable conditions. The clams showed a high sulphide detoxification capacity by oxidising the penetrating hydrogen sulphide to non-toxic thiosulphate. Moreover, juvenile D. serra switched to anaerobic energy production, indicated by the significant accumulation of succinate and, to some extent, alanine. Test animals were not able to reduce their energy requirements enough to withstand long periods of exposure, leading to a median survival time (LT50) of 80 h under hypoxic sulphide incubation. In conclusion, natural "sulphide eruptions", especially those with a large spatial and temporal extension, have to be considered as an important factor for D. serra recruitment failures. Hydrogen sulphide is assumed to be a potential community structuring factor.
    Repository Name: EPIC Alfred Wegener Institut
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  • 8
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    Growth and production of the venerid bivalve Eurhomalea exalbida in the Beagle Channel, Tierra del Fuego (2002)
    ELSEVIER SCIENCE BV
    In:  EPIC3Journal of Sea Research, ELSEVIER SCIENCE BV, 48, pp. 209-216, ISSN: 1385-1101
    Details
    Publication Date: 2019-07-16
    Description: Growth, mortality and productivity of the hard clam E. exalbida from Ushuaia Bay, Beagle Channel were investigated. The parameters of the von Bertalanffy growth function were estimated to be H = 73.98 mm, K = 0.180 y 1, t0 = 0.147 y. Maximum individual production amounted to 2.742 g shell free wet mass (SFWM) at 49.5 mm shell height. Animals between 40 mm and 70 mm shell height contribute most to overall population somatic production P of 133.89 g SFWM m-2 y-1. Mean annual biomass B amounted to 1122.69 g SFWM m-2 y-1. Annual P/B ratio and mortality rate Z were estimated to 0.119 y-1 and 0.141 y-1, respectively. Slow growth and low turnover makes this population less suitable for sustainable commercial exploitation.
    Repository Name: EPIC Alfred Wegener Institut
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  • 9
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    The role of benthic amphipods in Antarctic trophodynamics: a multidisciplinary study (2002)
    In:  EPIC34th European Crustacean Conference, Lodz, Poland.
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    Publication Date: 2019-07-16
    Repository Name: EPIC Alfred Wegener Institut
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  • 10
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    Growth of the hard clam Eurhomalea exalbida in Tierra del Fuego a biogenic archive of climatic events? (2002)
    In:  EPIC3Institut fuer Aquatische Oekologie, University Rostock, Germany.
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    Publication Date: 2019-07-16
    Repository Name: EPIC Alfred Wegener Institut
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