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Freshwater Fish Communities
Citation:
Rashleigh, B. AND E. Monroy. Freshwater Fish Communities. Chapter 20, Narragansett Bay Estuary Program: State of the Watershed. Narragansett Bay Estuary Program, PROVIDENCE, RI, , 376-391, (2017).
Impact/Purpose:
Freshwater fish are ecologically important in southern New England streams, yet are affected by environmental change and land development, can alter flow patterns and warm the water, thus reducing the abundance of fish species that need cold or cool water and/or flowing water for some or all of their life cycle. Consequently, the relative abundance of these cold-coolwater and fluvial fish serves as an indicator of ecosystem condition. In the Narragansett Bay watershed, cool-coldwater and fluvial fish % relative abundance ranged from 67% & 65% (Upper Blackstone) to 11% & 9% (Palmer River). This study contributes to the overall assessment of freshwater ecosystems for the Narragansett Bay Estuary Program, identifies data gaps and research needs, and provides a baseline to assess future trends.
Description:
Freshwater fish are ecologically important in stream ecosystems, and they provide people with significant food, recreation, and conservation value as biological indicator of freshwater streams. Historically, the streams and rivers of southern New England supported moderately diverse and abundant assemblages of native fishes. Climate change and land development are strongly affecting freshwater habitats by altering flow patterns and warming the water, which can reduce the abundance of fish species that need cold or cool (referred through this chapter as cold-coolwater fish species) and/or flowing water for some or all of their life cycle. Consequently, the relative abundance of these cold-coolwater and fluvial fish serves as an indicator of ecosystem condition. For example, brook trout (Salvelinus fontinalis) is a cold-water, fluvial species that is highly valued for conservation and recreation. Data on freshwater fish species composition and abundance within the Narragansett Bay watershed have been collected for over two decades by Rhode Island and Massachusetts environmental agencies. The presence of brook trout and other cold-coolwater, fluvial species is indicative of good environmental health, and their distribution within the watershed provides a benchmark for the development of a robust indicator such as an index of biological integrity. In the Narragansett Bay watershed, the Palmer River had the lowest percent relative abundance of cold-coolwater (11 percent) and fluvial (9 percent) fish species. The Upper Blackstone River had the highest at 69 percent (cold-coolwater) and 67 percent (fluvial). In the Little Narragansett Bay watershed, the percent relative abundances were lowest in the Wood River, which had 30 percent cold-coolwater and 18 percent fluvial, and highest in the Lower Pawcatuck River (60 percent, 57 percent). The Southwest Coastal Ponds watershed had 21 percent cold-coolwater fish and 15 percent fluvial fish. Brook trout habitat is largely concentrated in the Lower Blackstone River and the Pawtuxet River, along catchment areas covering over 25 percent of those two watersheds.
