Influence of water salinity on the strontium:calcium ratios in otoliths of the giant mottled eel, Anguilla marmorata
The otolith strontium (Sr):calcium (Ca) ratios have been widely used to reconstruct the migratory history of anguillid eels. However, factors affecting the Sr:Ca ratios in otoliths are incompletely understood in tropical anguillid species. To determine the salinity effect on the otolith Sr:Ca ratios, the Sr and Ca contents of otoliths of the giant mottled eel, Anguilla marmorata, reared for 60 days in four salinities (0 psu, 10 psu, 20 psu, 28 psu) were examined. The Ca and Sr contents and the resultant Sr:Ca ratios in the rearing water significantly increased with salinity. The otolith Sr:Ca ratios were also positively correlated with salinity. These results indicated that the Sr:Ca ratios in otoliths of a tropical eel could be used to reconstruct the migratory history of the fish as well as those of temperate species by differentiating when the fish migrated between fresh water and seawater.
KeywordsAnguilla marmorata Otolith Sr:Ca ratios Salinity Migration
We are grateful to Dr. Dung Quang Le for the assistance with the laboratory experiments and the members of the Atmosphere and Ocean Research Institute, The University of Tokyo for assistance with the chemical analysis of the water. This work was supported in part by the Ministry of Higher Education Malaysia under the Fundamental Research Grant Scheme (Vot No. 59406) and by Universiti Brunei Darussalam under the Competitive Research Grant Scheme (Vot No. UBD/OVACRI/CRGWG(003)). This work was conducted under permits from the Institute of Marine Environment and Resources, Vietnam and with the ethical standards of Universiti Brunei Darussalam Animal Welfare and Care Committee.
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