Disparities in habitat use and migratory behavior between tropical eel Anguilla marmorata and temperate eel A. japonica in four Taiwanese rivers
Resource
Marine Ecology Progress Series, 261, 233-242
Journal
Marine Ecology Progress Series
Journal Issue
261
Pages
233-242
Date Issued
2003-10
Date
2003-10
Author(s)
Abstract
Strontium (Sr):calcium (Ca) ratios in otoliths of the eels Anguilla japonica and A. marmorata caught in 4 Taiwanese rivers were examined to reconstruct their migratory environmental history. In all sampling locations, each eel species preferred a different environment and all were differently distributed in the river. A. japonica was more abundant than A. marmorata in the lower reach, accounting for 76 to 86% of the eel population. In contrast, A. marmorata was more abundant than A. japonica in the upper reach, accounting for 76 to 100% of the eel population. A. japonica consisted of diversified migratory contingents, including freshwater, brackish-water and seawater eels, but A. marmorata tended to reside in freshwater and seemed to avoid seawater during the yellow eel stage. This disparity in migratory behaviors and habitat use between species may reflect interspecific competition and adaptive radiation. The flexible migratory behavior and adaptation to different salinities of A. japonica may be an advantageous evolutional fitness when facing competition, heavy fishing pressure and environmental stress. The freshwater-restricted A. marmorata is more easily threatened by both fishing pressure and continuous habitat degradation than A. japonica.
Subjects
Anguilla japonica
Anguilla marmorata
Otolith microchemistry
Environmental history
Migratory behaviors
Adaptive radiation
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