EFFECTS OF MULTI‐SCALE ENVIRONMENTAL CHARACTERISTICS ON AGRICULTURAL STREAM BIOTA IN EASTERN WISCONSIN¹

Abstract

The U.S. Geological Survey examined 25 agricultural streams in eastern Wisconsin the determine relations between fish, invertebrate, and algal metrics and multiple spatial scales of land cover, geologic setting, hydrologic, aquatic habitat, and water chemistry data. Spearman correlation and redundancy analyses were used to examine relations among biotic metrics and environmental characteristics. Riparian vegetation, geologic, and hydrologic conditions affected the response of biotic metrics to watershed agricultural land cover but the relations were aquatic assemblage dependent. It was difficult to separate the interrelated effects of geologic setting, watershed and buffer land cover, and base flow. Watershed and buffer land cover, geologic setting, reach riparian vegetation width, and stream size affected the fish IBI, invertebrate diversity, diatom IBI, and number of algal taxa; however, the invertebrate FBI, percentage of EPT, and the diatom pollution index were more influenced by nutrient concentrations and flow variability. Fish IBI scores seemed most sensitive to land cover in the entire stream network buffer, more so than watershed‐scale land cover and segment or reach riparian vegetation width. All but one stream with more than approximately 10 percent buffer agriculture had fish IBI scores of fair or poor. In general, the invertebrate and algal metrics used in this study were not as sensitive to land cover effects as fish metrics. Some of the reach‐scale characteristics, such as width/depth ratios, velocity, and bank stability, could be related to watershed influences of both land cover and geologic setting. The Wisconsin habitat index was related to watershed geologic setting, watershed and buffer land cover, riparian vegetation width, and base flow, and appeared to be a good indicator of stream quality Results from this study emphasize the value of using more than one or two biotic metrics to assess water quality and the importance of environmental characteristics at multiple scales.

Relationship between the riverine nitrate–nitrogen concentration and the land use in the Teshio River watershed, North Japan

“…On the other hand, Fitzpatrick (2001) cited by Allan (2004) described that a decline in fish IBI occurs at >30% agriculture in the catchment and only 10 %-20 % for the riparian buffer area. In the Teshio River basin most of the land use profiles at the riparian buffer scale had much higher percentage of agriculture than the designated by…”

Quantifying the effect of catchment land use and water nutrient concentrations on freshwater river and stream biodiversity

“…Fitzpatrick et al (2001) found that increasing forest cover had a negative effect on fish taxon diversity and increasing nutrient concentrations had a positive effect. Wang et al (2001) also found that an increasing percentage of agricultural land use increased fish taxon diversity, while Harding (2003) and Mensing et al (1998) found that increasing non-natural catchment land use led to a reduction in taxon diversity.…”

Predicting assemblages and species richness of endemic fish in the upper Yangtze River

“…The endemic fish distribution pattern was also correlated with land-cover features of the catchment area. However, several studies have shown that a mixed model containing both fish habitat and landcover variables may be more effective than any individual model in explaining some of the complex fish distribution patterns (Fitzpatrick et al, 2001;Singkran and Meixler, 2008). Therefore, in order to have a better understanding of endemic fish distribution pattern in the upper Yangtze River, both land cover and characteristic river variables were integrated into the modeling in the present study.…”