Use of Reference-Site Fish Assemblages to Assess Aquatic Degradation in Pinelands Streams

Zampella, Robert; Bunnell, John

We compared species composition, relative abundances, and species richness of reference-site fish assemblages to fish samples collected from Pinelands streams that displayed a range of water quality and watershed land-use characteristics. We used detrended correspondence analysis (DCA) and principal component analysis (PCA) to relate community gradients to a complex watershed disturbance gradient characterized by increasing pH, specific conductance, and the percentage of developed and agricultural land in a drainage basin. Native species occurred across a range of conditions and dominated all sites. The major difference between reference-site assemblages and those found in degraded streams was the occurrence of nonnative species at the degraded sites. Species whose occurrence within New Jersey is generally limited to the Pinelands were more frequently found at reference sites compared with disturbed sites, but these differences were not statistically significant. Based on relative abundance, only two native species displayed a clear affinity to either the disturbed or undisturbed end of the watershed gradient. Species richness did not clearly distinguish reference sites from degraded sites. Neither species composition nor species richness was related to stream size. Species composition based on presence/absence provided as good an estimate of Pinelands watershed disturbance as did relative abundance. The study demonstrates that ordination of presence/absence or relative abundance data using DCA provides a good measure of Pinelands watershed conditions. When evaluating assemblages found at both reference sites and degraded sites, our approach can provide at least part of the basis for developing regional metrics to assess the status of species-poor fish communities or ranking biological samples based on inherent community attributes.

Use of Reference-Site Fish Assemblages to Assess Aquatic Degradation in Pinelands Streams

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