Effects of stream acidification and habitat on fish populations of a North American river

Abstract

Water quality, physical habitat, and fisheries at sixteen reaches in the Neversink River Basin were studied during 1991 -95 to identify the effects of acidic precipitation on stream-water chemistry and on selected fish-species populations, and to test the hypothesis that the degree of stream acidification affected the spatial distribution of each fish-species population. Most sites on the East Branch Neversink were strongly to severely acidified, whereas most sites on the West Branch were minimally to moderately acidified. Mean density of fish populations ranged from 0 to 2.15 fish/m 2 ; biomass ranged from 0 to 17.5 g/m 2 . Where brook trout were present, their population density ranged from 0.04 to 1.09 fish/m 2 , biomass ranged from 0.76 to 12.2 g/m 2 , and condition (K) ranged from 0.94 to 1.07. Regression analyses revealed strong relations (r 2 ± 0.41 to 0.99; p ≤ 0.05) between characteristics of the two most common species (brook trout and slimy sculpin) populations and mean concentrations of inorganic monomeric aluminum (Al im ), pH, Si, K + , NO 3 -, NH + 4 , DOC, Ca 2+ , and Na + ; acid neutralizing capacity (ANC); and water temperature. Stream acidification may have adversely affected fish populations at most East Branch sites, but in other parts of the Neversink River Basin these effects were masked or mitigated by other physical habitat, geochemical, and biological factors.

Effects of Air Pollution on Ecosystems and Biological Diversity in the Eastern United States

“…For instance, many streams increase in pH as water moves downstream and the area of the contributing watershed increases (Schofield and Driscoll 1987). Even in headwater streams, some sections may be influenced by seepage from well-buffered groundwater and may represent a refuge for fish in an otherwise acidified stream (Baldigo and Lawrence 2001). Similarly, some invertebrates in a lake may escape from acidified water by sheltering in the well-buffered sediments on the bottom of the lake.…”

Effects of recreational flow releases on natural resources of the Indian and Hudson Rivers in the Central Adirondack Mountains, New York, 2004-06

“…Biomass of Fish Populations-Biomass may be a better gage (of the effects of releases on fish communities) than density because biomass tends to fluctuate less widely than density (it is more conservative) when fish react to biotic, habitat, and water-quality stresses (Baldigo and Lawrence, 2001). Biomass data for species populations in this study were, in fact, much less variable among sites (total biomass varied 16-fold) than density (total density varied 103-fold) (tables 18, 19).…”

Relating fish biomass to habitat and chemistry in headwater streams of the northeastern United States

“…Similarly, under natural conditions, bioassay studies have demonstrated that low pH and high aluminum levels are the factors most closely associated with fish mortality during episodic acidification events (Simonin et al 1993;Van Sickle et al 1996;Baldigo and Murdoch 1997). Baldigo and Lawrence (2001) evaluated a large suite of stream characteristics and found that pH and aluminum concentrations during episodic acidification in streams of the Catskill Mountains explained a substantial proportion of the variability in fish abundance. In that study, habitat alone was rarely as important as chemistry alone, and the greatest proportion of the variation in Brook Trout abundance was accounted for when both chemical and physical factors were evaluated together (Baldigo and Lawrence 2001).…”

“…Alternatively, in well buffered streams, physical habitat features such as pools are more closely associated with fish biomass (Stichert et al 2001). In environments that are affected by both acid deposition and habitat modifications such as the streams in eastern North America and northern Europe, measurements of acidification in conjunction with measurements of habitat may be the most effective overall method to account for variability in the biomass of fish in headwater systems (Baldigo and Lawrence 2001). In this study we develop a simple empirical model to estimate fish biomass in headwater streams in the northeastern US from a few easily measured metrics that reflect both stream habitat and stream buffering capacity.…”

“…In that study, habitat alone was rarely as important as chemistry alone, and the greatest proportion of the variation in Brook Trout abundance was accounted for when both chemical and physical factors were evaluated together (Baldigo and Lawrence 2001). In contrast to Baldigo and Lawrence (2001), who evaluated numerous aspects of stream habitat and water chemistry, we confine ourselves in this study to a few easily measured stream habitat features and a single measurement of stream chemistry (low-flow pH) that we use as a proxy for stream buffering capacity.…”