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Effects of acidification on carbon and nitrogen stable isotopes of benthic macrofauna from a tropical coral reef
Author(s) -
Kolasinski Joanna,
Rogers Karyne,
Frouin Patrick
Publication year - 2008
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.3694
Subject(s) - trophic level , benthic zone , carbonate , coral reef , ocean acidification , invertebrate , coral , ecology , chemistry , reef , environmental chemistry , oceanography , biology , geology , seawater , organic chemistry
Stable isotope analyses are widely used to determine trophic levels in ecological studies. We have investigated the effects of carbonate removal via acidification on the stable carbon and nitrogen isotopic composition of 33 species of tropical benthic macrofauna, and we report guidelines for standardizing this procedure for higher taxa in tropical coral reef ecosystems. Many tropical benthic invertebrates are small in size, and therefore body tissue isolation (separating organic carbon from inorganic structures) is difficult and time‐consuming. Literature reviews of invertebrate studies show a lack of consistent procedures and guidelines for preparation techniques, especially for carbonate removal via acidification of whole individuals. We find that acidification decreases the δ 13 C values of samples containing carbonate, with shifts ranging from 0.21 to 3.20‰, which can be related to CaCO 3 content (assessed by a carbonate proxy), justifying acid pre‐treatment. Carbonate‐containing taxa benefiting from acidification included Amphinomida, Terebellida (Annelida), Anomura, Brachyura, Caridea, Amphipoda, Tanaidacea (Arthropoda) and Edwardsiida (Cnidaria). The δ 13 C shifts of samples containing no carbonate varied up to 0.02 ± 0.20‰. As this induced δ 13 C shift was lower than the range of an average trophic level shift (0.5 to 1‰), we conclude that acid pre‐treatment is unnecessary. Carbonate‐free taxa consisted of Eunicida, Phyllodocida (Annelida) and Mollusca. We note minimal impact of acidification on δ 15 N values except for Brachyura, which showed a shift of 0.83 ± 0.46‰, which is still lower than a single trophic level shift (2.9–3.8‰). We conclude that for trophic level studies, both the δ 13 C and the δ 15 N of carbonate‐rich macrofauna can be determined from the same acidified sample. Copyright © 2008 John Wiley & Sons, Ltd.