Impacts of Land Use on the Habitat and Macroinvertebrate Assemblage of the Tributaries of the Lower Brazos River




Lash, Frances P.

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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.



Macroinvertebrate communities, Land use, Brazos river tributaries, Habitat structure


Lash, F. P. (2011). <i>Impacts of land use on the habitat and macroinvertebrate assemblage of the tributaries of the lower Brazos River</i> (Unpublished thesis). Texas State University-San Marcos, San Marcos, Texas.


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