MEPS 500:245-264 (2014)  -  DOI: https://doi.org/10.3354/meps10699

Physiological influences can outweigh environmental signals in otolith microchemistry research

Anna M. Sturrock1,4,*, Clive N. Trueman1, J. Andy Milton1, Colin P. Waring2, Matthew J. Cooper1, Ewan Hunter3

1Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton Waterfront Campus, European Way, Southampton, Hampshire SO14 3ZH, UK
2University of Portsmouth, Institute of Marine Sciences, Ferry Road, Eastney, Hampshire PO4 9LY, UK
3Centre for Environment, Fisheries and Aquaculture Science, Lowestoft Laboratory, Pakefield Road, Lowestoft, Suffolk NR33 0HT, UK
4Present address: Institute of Marine Sciences, A317 Earth & Marine Sciences Building, University of California, Santa Cruz,
1156 High Street, Santa Cruz, California 95064, USA
*Corresponding author:

ABSTRACT: Most studies that infer geographic distributions of fish using otolith microchemistry assume that environmental factors (e.g. temperature, salinity) outweigh intrinsic effects (e.g. size, condition); however, this assumption has not been rigorously tested, particularly in marine fish. Here, we report the results of a long-term experimental study of European plaice Pleuronectes platessa L. and explore relationships between blood plasma and ambient water chemistry over a 12 mo reproductive cycle. Overall, blood plasma was found to be highly regulated, with few elements exhibiting strong, if any, correlation with ambient concentrations. This sets a first order limit on the sensitivity of otolith chemistry to fluctuations in ambient seawater chemistry. The observed temporal, ontogenetic and sex-specific variations in blood plasma elemental concentrations indicated significant physiological influences on elemental uptake and processing mechanisms. Physiological variables exerted relatively strong influences on the uptake and regulation of the softer, more thiophilic elements (Mn, Cu, Zn, Se and Pb), as well as Sr and Ca. By contrast, seasonal and sex-related variations were relatively minor among the hard acid metal ions (Li+, Mg2+, K+, Rb+, Ba2+). Overall, plasma elemental concentrations covaried most strongly and consistently with plasma protein concentrations. For this exclusively marine species, seasonal changes in physiology governed intra-annual variations in blood chemistry and, by implication, also regulate ion availability to the otolith. Based on these observations, we recommend that sex and age should be controlled for in future experimental designs using otolith microchemistry to infer stock structure or migration patterns.


KEY WORDS: Trace metals · Blood plasma · Otolith microchemistry · Plaice · Reproductive cycles


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Cite this article as: Sturrock AM, Trueman CN, Milton JA, Waring CP, Cooper MJ, Hunter E (2014) Physiological influences can outweigh environmental signals in otolith microchemistry research. Mar Ecol Prog Ser 500:245-264. https://doi.org/10.3354/meps10699

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