Spatio-temporal variability in the winter diet of larval and juvenile Antarctic krill, Euphausia superba, in ice-covered waters

Antarctic krill Euphausia superba is an ecological key species in the Southern Ocean and a major fisheries resource. The winter survival of age class 0 (AC0) krill is susceptible to changes in the sea-ice environment due to their association with sea ice and their need to feed during their first win...

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Bibliographic Details
Published in:Marine Ecology Progress Series
Main Authors: Schaafsma, FL, Kohlbach, D, David, C, Lange, BA, Graeve, M, Flores, H, van Franeker, JA
Format: Article in Journal/Newspaper
Language:unknown
Published: 2017
Subjects:
Antarctic
Southern Ocean
Weddell
Weddell Sea
Antarc*
Antarctic Krill
Euphausia superba
Sea ice
Copepods
ice covered waters
Online Access:https://epic.awi.de/id/eprint/52363/
https://doi.org/10.3354/meps12309
https://hdl.handle.net/10013/epic.db229e6d-288a-4d1f-96a9-97138d9021b1
Description
Summary:Antarctic krill Euphausia superba is an ecological key species in the Southern Ocean and a major fisheries resource. The winter survival of age class 0 (AC0) krill is susceptible to changes in the sea-ice environment due to their association with sea ice and their need to feed during their first winter. However, our understanding of their overwintering diet and its variability is limited. We studied the spatio-temporal variability of the diet in 4 cohorts of AC0 krill in the Northern Weddell Sea during late winter 2013 using stomach contents, fatty acids (FAs) and bulk stable isotope analysis (BSIA). Stomach contents were dominated by diatoms in numbers and occasionally contained large volumes of copepods. Many of the prey species found in the stomachs were sea ice-associated. Our results show that the diet of overwintering AC0 krill varies significantly in space and time. Variability in stomach content composition was related to environmental factors, including chlorophyll a concentration, copepod abundance and sea-ice cover. In contrast, FA composition mainly varied between cohorts, indicating variation in the long-term diet. The condition of the AC0 krill was reflected in FA and BSIA analysis, suggesting that the availability of sea ice-derived food sources over a long period may impact the condition of developing AC0 krill significantly. The spatio-temporal availability of sea-ice resources is a potentially important factor for AC0 krill winter survival.

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