Evaluation of Impact of Land Use, Habitat, and Water Quality Parameters on Macroinvertebrate Index Metrics by Redundancy Polynomial Regression Analysis

Habitat parameters, land use characteristics, and water chemistry data from sample locations within watersheds of Massachusetts were analyzed to assess their influences on macroinvertebrate metrics. The habitat parameters and macroinvertebrate metrics were obtained from the Massachusetts Department of Environmental Protection - Division of Watershed Management (MA-DEP-DWM). The water quality data was obtained from a different database also obtained from MA-DEP-DWM. The sample locations and macroinvertebrate locations were placed in ArcGIS 9.1, where it was determined whether they were close enough to each other and whether there were any obstructions between locations. Some valid reasons for eliminating locations from being related to each other included fork in streams, dams, location of discharge facilities, distance between points greater than 1- kilometer (stream length), and sample date. The disparity in the sample date for the water quality and the macroinvertebrate data was not greater than 30 days but was primarily within one week of each other. Land use characteristics for the watershed and 100-ft riparian buffer were calculated using ArcGIS 9.1. A 100-ft riparian buffer was used because of the Wetland Protection Act of Massachusetts which prohibits development within 100-ft of the water body. Once all of the data was combined into one database, redundancy analysis was performed to evaluate the relationships between explanatory (environmental) and response (species) variables. Polynomial regression equations were developed to calculate species metrics and assemblages. The results show a good agreement (R2 ranging between 0.4 and 0.7) between the measured macroinvertebrate index metrics and those predicted by the model