거제 연안에서 채집된 자연산 감성돔(Acanthopagrus schlegelii) 치어의 현장 출현과 저염분 노출 반응에 대한 예비 연구

초록

The black sea bream (Acanthopagrus schlegelii) is a euryhaline species with broad salinity tolerance, but little is known about the responses of wild juveniles to low-salinity exposure. In this study, we investigated the occurrence of wild juveniles in estuarine and sandy coastal habitats along the coast of Geoje, Korea, and conducted a preliminary laboratory exposure experiment at low salinities (0, 5, and 12 psu). Juveniles were collected at an estuarine station (St. 1; 5.7–14.5 psu) and a sandy coastal station (St. 2; 31.8–33.5 psu). After 186.5 h of exposure, survival was low in both the 12 psu and 5 psu treatments (5.56±3.85% and 7.78±5.09%, respectively; P=0.751), whereas all fish at 0 psu died within approximately 84.5 h. Pathological signs, including exophthalmos and globe rupture, were observed only at 0 psu, suggesting that freshwater exposure may cause physiological damage in juvenile A. schlegelii. However, because mortality was also high at 12 and 5 psu, the lower salinity tolerance limit could not be reliably determined, and the confounding effects of capture and handling stress cannot be excluded. These results provide baseline data on the field occurrence of wild juveniles and their early-life responses to low-salinity exposure.

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