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An elemental and stable isotope assessment of water strider feeding ecology and lipid dynamics: synthesis of laboratory and field studies
Author(s) -
JARDINE TIMOTHY D.,
KIDD KAREN A.,
POLHEMUS JOHN T.,
CUNJAK RICHARD A.
Publication year - 2008
Publication title -
freshwater biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.297
H-Index - 156
eISSN - 1365-2427
pISSN - 0046-5070
DOI - 10.1111/j.1365-2427.2008.02044.x
Subject(s) - gerridae , biology , ecology , isotope analysis , carbon fibers , isotopes of nitrogen , stable isotope ratio , fractionation , isotopes of carbon , environmental chemistry , nitrogen , chemistry , total organic carbon , hemiptera , materials science , physics , organic chemistry , quantum mechanics , composite number , composite material
Summary 1. Despite the ubiquity and abundance of water striders (Hemiptera: Gerridae) in temperate streams and rivers and their potential usefulness as sentinels in contaminant studies, little is known about their feeding ecology and lipid dynamics. 2. In this study we used stable isotopes of carbon (δ 13 C) and nitrogen (δ 15 N) and elemental carbon to nitrogen ratios (C/N) to assess dietary habits and lipid content, respectively, for water striders. 3. To determine diet‐tissue fractionation factors, nymphs of the most common species in New Brunswick, Canada, Aquarius remigis were reared in the laboratory for 73 days and exhibited rapid isotopic turnover in response to a switch in diet (C half‐life = 1.5 days, N half‐life = 7.8 days). Their lipid content increased towards the end of the growing season and resulted in lower δ 13 C values. Diet‐tissue fractionation factors were established after correction of δ 13 C data for the confounding effect of de novo lipid synthesis (strider δ 13 C adj – diet δ 13 C adj = 0.1‰, strider δ 15 N – diet δ 15 N = 2.7‰). 4. Water striders from the majority of 45 stream sites (83%) in New Brunswick had less than 50% contribution of aquatic carbon to their diets but showed a gradual increase in the contribution of this carbon source to their diet with increasing stream size. 5. These data indicate that striders exhibit a strong connection to terrestrial carbon sources, making them important users of energy subsidies to streams from the surrounding catchment. However, this dependence on terrestrial organic matter may limit their utility as indicators of contamination of aquatic systems by heavy metals and other pollutants.