PARENT SESSION
PM15 - Field Studies: Causal Relationships Between Exposure & Effect
Monday, 18 November 2002
8:00 AM to 6:30 PM
Exhibit Hall
(P354) Landscape Influences on In-Stream Biotic Integrity: Use of macroinvertebrate metrics to identify landscape stressors in headwater catchments.
Daniel, F.*,1, Griffith, Michael2, Lazorchak, James1, Troyer, Michael2, 1 National Exposure Research Laboratory, USEPA, Cincinnati, OH, USA2 National Center for Environmental Assessment, USEPA, Cincinnati, OH, USA
ABSTRACT- The biotic integrity of streams is profoundly influenced by quantitative and qualitative features in the landscape of the surrounding catchment. In this study, aquatic macroinvertebrate metrics (e.g., relative abundance of Ephemeroptera, Trichoptera, and/or Plecoptera taxa, or the relative abundance of non-insects, oligochaetes, tolerant, intolerant, or facultative taxa, and Hilsenhoff Biotic Index, etc.) were measured over three successive seasons (1999 - 2001) in 35 headwater streams (sub-watersheds) located in the Little Miami River (Ohio) watershed. These sub-watersheds are spread across three Omernik Level IV ecoregions (Darby Plains, Loamy, High Lime Till Plains and Pre-Wisconsinan Drift Plains) and they exhibit variations in the landscape features of their catchments including, land cover (e.g., 23-91% row crop agriculture), geophysical (e.g., drainage density 1.1 - 3.6 km-1), and soil types (e.g., 27-36% soil clay content). Using stepwise multi-regression, relationships between measures of in-stream habitat quality (as dependent variables) and various classes of landscape features (as independent variables), were examined at three spatial scales: the sample reach, the riparian corridor, and the entire catchment. The goal of this effort was to generate models for various in-stream stressor gradients (e.g., substrate embeddedness, canopy cover, and nutrient loads), based on landscape measures. In turn, these stressors influence in-stream water quality and biotic integrity. Accordingly, in these sub-watersheds, several of the macroinvertebrate metrics exhibited significant correlations with the stressor, substrate embeddedness (percent fines and sand). In addition, the landscape features measured at the catchment scale were more significantly correlated to embeddedness than the analogous features measured at the riparian corridor scale.
Key words: Aquatic Invertebrates , Biotic Integrity, Watershed Assessment, Landscape Studies