부산대학교 도서관

Bioassay studies were conducted to determine if leachate from a coal ash depository was a potential factor in reducing abundance of yellow perch spawning stocks in Zekiah Swamp Run, a tributary of the Wicomico River, Maryland. In situ bioassays conducted in Zekiah Swamp Run in 1989 and 1990 using yellow perch yolk-sac larvae resulted in higher mortality upstream and downstream of the ash storage facility relative to reference stations in both years. Similar high mortality was observed at the upstream unaffected site and the downstream potentially affected site, suggesting that poor larval survival in these locations is a system-wide phenomenon. Analysis of water samples for metals, inorganic monomeric-aluminum, volatile organics, pH and measurements of physical parameters did not identify a specific cause for the high mortality observed. Surveys of the abundance and distribution of yellow perch egg strands during spring 1990 revealed that over 1,500 females spawned in a relatively restricted area in the vicinity of the fall line. In contrast to poor larval survival observed at upstream locations above the fall line, good survival was observed in bioassays conducted at a location below the fall line. Results to date are insufficient to establish the specific factors causing high mortality of larval yellow perch above the fall line. However, the ash storage site does not appear to be a contributing factor at the present time.