In situ Bioassays of Brook Trout ('Salvelinus fontinalis') and Blacknose Dace ('Rhinichthys atratulus') in Adirondack Streams Affected by Episodic Acidification

摘要

In situ bioassays were conducted using native Adirondack brook trout and blacknose dace in four headwater streams. Conductivity, pH, temperature, and stage height were monitored continuously, and water samples for laboratory analysis were collected during hydrologic episodes. Fish survived well during baseflow conditions, but during periods of spring snowmelt or large precipitation events, survival was poor. Bioassay fish that had been in the stream 15-24 d survived episodes better than fish that had either not become acclimatized or recovered from handling. Duration of exposure to acidic episodes was critical. Extended periods of poor water quality resulted in fish mortality and may be more important to native populations than short acidic episodes.