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  • AMER SOC LIMNOLOGY OCEANOGRAPHY  (1)
  • INST MALACOL  (1)
  • Inter-Research  (1)
  • 2020-2023
  • 2010-2014  (3)
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Years
Year
  • 1
    Publication Date: 2019-07-16
    Description: The population structure, particularly growth, age, mortality and somatic production of the olivid snail Olivancillaria deshayesiana were investigated. Annual formation of internal shell growth marks was confirmed by the record of stable oxygen isotopes in the shell, which reflects seasonal patterns of water temperature. A von Bertalanffy growth model fitted to 81 size-at- age data pairs, indicating that O. deshayesiana may attain 31 mm SL in about 10 years. The estimated total mortality Z and natural mortality M were 0.651 y-1 and 0.361 y-1, respectively. Fishing mortality F was 0.290 y-1, and the exploitation rate E was 0.445, indicating that this population was not overexploited at the time of the study. However, this situation may well change in the future, since the important prawn and shrimp fisheries (in intensity and scale) in the Mar del Plata area (38°20’S, 57°37’W) may indirectly affect the exploitation status of the studied population
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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  • 2
    Publication Date: 2019-07-16
    Description: We compared primary production and respiration of temperate (Helgoland, North Sea) and subtidal Arctic (Kongsfjorden, Svalbard) microphytobenthic communities during summer. The diatom communities were generally characterized as cosmopolitan, displayed no site specificity, and had similar chl a and fucoxanthin concentrations. Their net and gross photosynthesis rates and light adaptation intensities, derived from laboratory microsensor measurements, were also similar, despite differences in water temperature. Daily oxygen fluxes across the sediment− water interface were estimated by combining laboratory microprofile and planar optode measurements with in situ data on oxygen penetration and light dynamics. During the study period, the Svalbard sediments were on average net heterotrophic,while the Helgoland sediments were net autotrophic (−22.4 vs. 9.2 mmol O2 m−2 d−1). This was due to high infaunal abundance in the Svalbard sediments that caused high oxygen uptake rates in the sediments and consumption below the sediment euphotic zone. Additionally, bioirrigation of the sediment due to infaunal burrow ventilation was reduced by light; thus, the sedimentary oxygen inventory was reduced with increasing light. Conversely, light-enhanced the oxygen inventory in the Helgoland sediments. Oxygen dynamics in the Svalbard sediments were therefore dominated by bioirrigation, whereas in the Helgoland sediments they were dominated by photosynthetic oxygen production.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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  • 3
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    AMER SOC LIMNOLOGY OCEANOGRAPHY
    In:  EPIC3Limnology and Oceanography-Methods, AMER SOC LIMNOLOGY OCEANOGRAPHY, ISSN: 1541-5856
    Publication Date: 2019-07-16
    Description: I developed a new model for estimating annual production-to-biomass ratio P/B and production P of macrobenthic populations in marine and freshwater habitats. Self-learning artificial neural networks (ANN) were used to model the relationships between P/B and twenty easy-to-measure abiotic and biotic parameters in 1252 data sets of population production. Based on log-transformed data, the final predictive model estimates log(P/B) with reasonable accuracy and precision (r2 = 0.801; residual mean square RMS = 0.083). Body mass and water temperature contributed most to the explanatory power of the model. However, as with all least squares models using nonlinearly transformed data, back-transformation to natural scale introduces a bias in the model predictions, i.e. an underestimation of P/B (and P). When estimating production of assemblages of populations by adding up population estimates, accuracy decreases but precision increases with the number of populations in the assemblage.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
    Location Call Number Limitation Availability
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