Turnover of trophic markers and lipid carbon in Arctic marine food webs -- The contribution of key zooplankton species


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Martin.Graeve [ at ] awi.de

Abstract

The Arctic pelagic food web is characterized by a high seasonality in terms of light and therefore primary production. To cope with the long winter periods of low food availability, many species have developed the ability to store large amounts of lipid reserves. These high-energy compounds are of major importance in different processes such as somatic growth, survival, development, reproduction and metabolism independently on ambient food levels. In the Arctic pelagic food web, zooplankton plays a crucial role linking primary production and higher trophic levels. The effciency of zooplankton species to transfer lipids and fatty acids in the food web depends on a combination of ecological and physiological aspects such as distribution, life cycle strategies, lipid content and lipid assimilation rapidity. In the context of climate warming, severe shifts in the phyto- and zooplankton communities, and thus changes in trophic interactions, are expected. It is therefore essential to better understand the lipid and fatty acid turnover in the in the lipid-driven Arctic food web. This study aims at evaluating the role of zooplankton in the transfer of lipids from primary producers to higher trophic levels. It combines field observations and experimental work to fill the gaps of knowledge in the ecology and lipid biochemistry of Arctic zooplankton key species, i.e. the copepods Calanus glacialis, Pseudocalanus minutus and Oithona similis, the thecosome pteropods Limacina helicina and L. retroversa and the gymnosome pteropod Clione limacina. The life cycle and the distribution of thecosome pteropods were investigated by field observations that were conducted year-round in 2012 and 2013 in Svalbard waters. These studies aimed at relating the distribution of L. helicina and L. retroversa to environmental parameters and examining the growth of veligers and juveniles. To study the metabolic capacities of key zooplankton species in terms of lipid and fatty acid turnover, feeding experiments were conducted with animals that were collected in Svalbard waters during the late productive season (summer/early autumn) in 2014 and 2015. Consumers of the first trophic level were fed a 13C labeled diatom-flagellate mixed diet for one week (thecosome pteropods) and for three weeks (copepods). The consumer representing the second trophic level, i.e. C. limacina, was fed 13C labeled Limacina spp. for 3 weeks. The 13C incorporation into fatty acids and alcohols was monitored by compound specific isotope analyses (CSIA). The use of CSIA in combination with labeling experiments allowed for a precise evaluation of the lipid and fatty acid turnover in zooplankton organisms.



Item Type
Thesis (PhD)
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Not peer-reviewed
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Published
Eprint ID
52691
Cite as
Boissonnot, L. (2017): Turnover of trophic markers and lipid carbon in Arctic marine food webs -- The contribution of key zooplankton species , PhD thesis,


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