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Factors affecting trophic compositions of offshore benthic invertebrates at a sub‐Antarctic archipelago
Author(s) -
Puccinelli Eleonora,
McQuaid Christopher D.,
Ansorge Isabelle J.
Publication year - 2018
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.1002/lno.10934
Subject(s) - trophic level , benthic zone , oceanography , primary producers , ecology , microbial loop , guild , marine ecosystem , zooplankton , polychaete , food web , environmental science , biology , benthos , phytoplankton , ecosystem , habitat , nutrient , geology
Food availability is a key regulator of the distribution, metabolism, and success of benthic populations. In deep sea ecosystems, hydrodynamics and depth play fundamental roles in determining benthic food resources. Recent studies suggest that the Southern Ocean sub‐Antarctic front is shifting southward, with implications for primary production and food availability around the sub‐Antarctic Islands embedded in the Antarctic Circumpolar Current. We used fatty acid (FA) and stable isotope (SI) analyses to investigate the trophic pattern of benthic invertebrates and suspended particulate matter (SPM) at three Depths (shallow: 100 m, middle: 300 m, and deep: 600 m) in three hydrographic regions with different flow and productivity regimes around the Prince Edward Islands. Both region and depth affected the SI values of SPM, while feeding guild was the key factor influencing consumer trophic values. Depth affected the δ 15 N of all trophic groups and the FA compositions of suspension feeders. Deeper samples had a higher δ 15 N and showed a greater proportion of mono‐ and saturated fatty acids, reflecting greater remineralization of SPM and of food reaching the seafloor. Region affected the δ 13 C and FA values of SPM, suspension feeders and deposit feeder/scavengers, with differences between the interisland and open ocean regions. This was probably linked to the retention of nutrients and phytoplankton between the islands. Critically, the effects of depth and hydrographic region were taxon specific, indicating that long‐term responses to environmental change may have complex consequences for the feeding ecology and viability of benthic populations, with implications for the higher trophic levels that these populations support.