International eel symposium, 2003 - Quebec August 11, 2003
Poster Session

Difference in Salinity Choice and Adaptation between Temperate Eel (Anguilla japonica) and Tropical Eel (A. marmorata) Elvers

Shiao, J.C.* Institute of Zoology, Academia Sinica, Novnkang, Taipei, Taiwan 115, ROC
Tzeng, W.N. Department of Zoology, College of Science, National Taiwan University, Taipei, Taiwan 106, ROC
Hwang, P.P. Institute of Zoology, Academia Sinica, Novnkang, Taipei, Taiwan 115, ROC

Presenter email address: jcshiao AT gate.sinica.edu.tw

Abstract Text: Previous studies have found that A. japonica is predominately found in brackish water while A. marmorata is overwhelmingly found in fresh water (FW). A compartmentalized tank with water of salinity ranging from 0 to 30 ppt was designed to test salinity choice of A. japonica and A. marmorata elvers. Initially, elves of the two species, collected from the river mouth, were stocked in the sea water area (SW, 30 ppt). Most elvers of both species stayed in salinities of 0 to 10 ppt and few elvers stayed in 20 and 30 ppt, indicating that elvers can adapt to a wide range of salinity but prefer lower salinities. Elvers acclimated in FW for two weeks were transferred to 35 ppt SW and FW respectively to understand their response to acute salinity change. All A. japonica elvers survived, but the mortality rate of A. marmorata elvers increased from 4% at hour 10 to 73% at hour 24 in the FW-SW group. No mortalities occurred in the FW-FW group. These results indicate that seawater adaptation capability differed between A. japonica and A. marmorata, which may relate to their habitat use during the freshwater growth stage.