Download Free Land Use Impacts On Benthic Macroinvertebrate Communities In The Central Grand River Basin Book in PDF and EPUB Free Download. You can read online Land Use Impacts On Benthic Macroinvertebrate Communities In The Central Grand River Basin and write the review.

Southern Appalachian watersheds of the United States are negatively affected by pesticides and fertilizers used in row crop agriculture. The objective was to determine if the amount of row crops is connected to changes in aquatic biotic assemblages draining the Nolichucky River watershed in east Tennessee. The hypothesis was the amount of row crops will negatively correlate with indices of biotic integrity (IBI) metrics for fish and benthic macroinvertebrates indicating healthy aquatic communities. For 18 sample sites in 2014 and 2015, IBI metrics were calculated. Water quality and elevation measurements were made before conducting IBIs. To assess changes in and amounts of land use/land cover (LULC), maps from 1999 to 2014 were produced with Landsat satellite imagery. Pollutant estimates (sediment, phosphorus, and nitrogen) were calculated using the Soil & Water Assessment Tool (SWAT) model. The area of row crops increased since 1999 (39 km2 in 1999 to 71 km2 in 2014). A principal component analysis was performed on LULC measurements from different scales (local, reach and catchment), water quality data, and elevation to produce a reduced set of explanatory variables that were uncorrelated but could be associated with IBI metrics. A canonical correspondence analysis associated fish metrics with LULC types: Impervious surfaces, non-row crop fields, and forest (p = 0.04 for axis 1 eigenvalue, p = 0.05 for species-environment correlations). For the benthic macroinvertebrate metrics, nonmetric multidimensional scaling found metrics indicative of poor stream health (percentage of oligochaetes and chironomids, percentage of nutrient tolerant organisms) were strongly positively associated with increasing use of row crops, impervious surfaces (p ≤ 0.01), and pollutant estimates (p ≤ 0.004). A redundancy analysis found increasing pollutant estimates were associated with fish metrics indicative of poor stream health (percentages of hybrids, piscivores, diseased fish, and number of sunfish species) (p = 0.03). When watersheds of tributary streams are converted to impervious and non-row crop field LULC, they function biologically like the larger main stem river. Although fish and benthic macroinvertebrate metrics indicated the tributary and main stem Nolichucky sites were in relatively good condition, increases in land conversion can further degrade stream biotic integrity.
In this study, I examined relationships between land-use patterns and macroinvertebrate communities in 45 first through fourth-order stream reaches in four subwatersheds within a New England watershed. Land-use patterns were quantified in GIS at three spatial scales to determine the effect of scale on the strength of relationships between instream biological conditions and adjacent land-use conditions. A GIS was used to quantify forest, agricultural, and developed land use at three spatial scales, including the entire upstream catchment area and two sub-corridors. Macroinvertebrate communities were analyzed using a multimetric approach and a multivariate approach to relate community composition to land-use variables measured at each spatial scale. Among community metrics, richness, EPT richness, percent affinity, and total metric scores were significantly correlated with quantified land-use variables, including percent forest, percent agriculture, percent developed, and percent agriculture + developed at the upstream catchment scale. Land-use variables also showed significant correlations with community composition as indicated by ordination axes resulting from multivariate analysis. Results of the approaches were in general agreement with each other, each indicating that relationships between instream benthic conditions and adjacent land use were strongest at the entire-upstream-catchment scale. These results suggest that conditions and processes occurring at this scale appear to be more influential than are localized adjacent land-use conditions in shaping community composition and in-stream biological conditions.
Ecological research on stream and river ecosystems aims to gain an understanding of the dynamic and complex impacts of environmental factors on biotic communities within riverine landscape (riverscape). Human activities significantly impact both terrestrial and aquatic ecosystems. Local environmental factors are known to influence the structure and function of stream ecosystems and biodiversity. The patterns of benthic macroinvertebrate distribution are related to the natural and human influenced variation of environmental factors. Ecologists assess stream physical and biological conditions in response to human land use activities using ecological indicators. This study is an assessment of the ecological condition of the Lower Brazos River Watershed. Macroinvertebrate assemblage structure was compared from 33 sites within the 6 subbasins differing in land use type and degree. Land use within the subbasins was measured using data from the National Land Use Database. Benthic macroinvertebrate samples were collected and a variety of physiochemical variables were measured. Multivariate analysis grouped the subbasins using habitat variables and macroinvertebrate assemblages. Decreasing habitat heterogeneity resulted in a decline of diversity and richness of organisms. Differences in the richness and diversity of the macroinvertebrate assemblages are attributed to habitat structure and land use. This study highlights the importance of considering both local habitat and landscape parameters of watersheds in stream biological assessments to understand the response of benthic communities to disturbances.
Farmers have been encouraged to adopt more sustainable farming practices (BMPs) that mitigate adverse agricultural effects on the natural environment. However, the ability of BMPs to protect or restore riverine systems continues to be questioned due to limited evidence directly linking BMP use with improved ecological conditions. The exclusion of hydrological pathways in previous field studies may explain why a direct link has not yet been established. The goal of this study was to assess the association between benthic macroinvertebrate community structure and the number and location of agricultural BMPs. Macroinvertebrates and water chemistry were sampled in 30 headwater catchments in the Grand River Watershed. Catchments exhibited gradients of BMP use and location as measured by the degree of hydrologic connectedness. Stepwise ordination regressions and variance partitioning were used to determine which environmental variables (i.e., BMP metrics, water chemistry parameters, habitat characteristics, and land use variables) were associated with benthic macroinvertebrate community structure. Water chemistry parameters were negatively associated with BMP metrics suggesting BMPs were mitigating losses of nutrients and sediments. However, BMP abundance and location explained minimal variation in benthic macroinvertebrate structure within the 30 sampled catchments. The absence of a strong association between BMPs and benthic macroinvertebrates may indicate a need for greater numbers and targeted siting of BMPS to improve water quality beyond a threshold point that would allow recolonization of intolerant invertebrate taxa. Focusing of conservation goals on ecological conditions and the promotion of BMPs that enhance in-stream habitat may also be required.