Macroinvertebrate communities were examined in conjunction with landuse and water-chemistry variables at 60 sites in the NYC drinking-water-supply watersheds over a 3-y period. The watersheds are in 2 adjacent regions of New York State (east of Hudson River [EOH] and west of Hudson River [WOH]) that are geographically distinct and have unique macroinvertebrate communities. Nonforested land use at EOH sites was mostly urban (4–57%), whereas land use at sites in the rural WOH region was more agricultural (up to 26%) and forested (60–97%). Land use accounted for 47% of among-site variability in macroinvertebrate communities in the EOH region and was largely independent of geological effects. Land use accounted for 40% of among-site variability in macroinvertebrate communities in the WOH region but was correlated with underlying geology. Comparisons among 3 landuse scales emphasized the importance of watershed- and riparian-scale land use to macroinvertebrate communities in both regions. Multivariate and bivariate taxa–environment relationships in the EOH and WOH regions identified specific landuse and water-chemistry gradients and, in general, showed a continuum in conditions across the watersheds. WOH macroinvertebrate communities varied primarily with specific conductance, population density, and agricultural and urban land use, but communities were not classified as impaired along these gradients. EOH macroinvertebrate communities were associated with a wider range of watershed conditions than WOH communities. Conditions ranged from forested to urban, and distinctive communities were associated with point-source discharges, road density, and lake outlets. The severity of the impact gradient in the EOH region resulted in impaired macroinvertebrate communities with decreased total and Ephemeroptera, Plecoptera, and Trichoptera (EPT) taxon richness and increased densities of oligochaetes and chironomids.
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Vol. 25 • No. 4