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Effects of formalin preservation on stable carbon and nitrogen isotope signatures in Calanoid copepods: implications for the use of Continuous Plankton Recorder Survey samples in stable isotope analyses
Author(s) -
Bicknell Anthony W. J.,
Campbell Maria,
Knight Mairi E.,
Bilton David T.,
Newton Jason,
Votier Stephen C.
Publication year - 2011
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.5049
Subject(s) - zooplankton , plankton , copepod , stable isotope ratio , gelatinous zooplankton , chemistry , isotope analysis , isotope , isotopes of nitrogen , calanus , isotopes of carbon , oceanography , environmental chemistry , ecology , nitrogen , total organic carbon , crustacean , biology , geology , organic chemistry , quantum mechanics , physics
Preserved and archived organic material offers huge potential for the conduct of retrospective and long‐term historical ecosystem reconstructions using stable isotope analyses, but because of isotopic exchange with preservatives the obtained values require validation. The Continuous Plankton Recorder (CPR) Survey is the most extensive long‐term monitoring program for plankton communities worldwide and has utilised ships of opportunity to collect samples since 1931. To keep the samples intact for subsequent analysis, they are collected and preserved in formalin; however, previous studies have found that this may alter stable carbon and nitrogen isotope ratios in zooplankton. A maximum ~0.9‰ increase of δ 15 N and a time dependent maximum ~1.0‰ decrease of δ 13 C were observed when the copepod, Calanus helgolandicus , was experimentally exposed to two formalin preservatives for 12 months. Applying specific correction factors to δ 15 N and δ 13 C values for similarly preserved Calanoid species collected by the CPR Survey within 12 months of analysis may be appropriate to enable their use in stable isotope studies. The isotope values of samples stored frozen did not differ significantly from those of controls. Although the impact of formalin preservation was relatively small in this and other studies of marine zooplankton, changes in isotope signatures are not consistent across taxa, especially for δ 15 N, indicating that species‐specific studies may be required. Copyright © 2011 John Wiley & Sons, Ltd.