Date of Award


Degree Type


Degree Name

Master of Science


Integrated Environmental Sciences

First Advisor

Timothy W. Stewart, Ph.D.

Second Advisor

Mary E. Lehman, Ph.D.

Third Advisor

Joseph E. Garcia, Ph.D.


This study shows the importance of structurally complex habitat on abundance and diversity of organisms in a benthic macroinvertebrate community in the James River, Nelson County, Virginia. Structural complexity was manipulated by attaching stones to five concrete blocks (12.8 ± 0.97% coverage; mean ± SE) and comparing organism abundance on these blocks and blocks lacking stones (0% coverage). Concrete blocks were randomly placed at a site in the James River on November 14, 1999 and collected on December 12, 1999. Macroinvertebrates and particulate organic and inorganic matter on the blocks were collected. Total invertebrate abundance, abundance of eight individual taxa, taxonomic richness, and particulate organic and inorganic matter mass were greater in the low-coverage treatment then the control treatment. The increase in the particulate organic and inorganic matter in the low-coverage treatment likely provided the major resources for the invertebrates that positively responded. The slight increase in physical structure in the low-coverage treatment provided the organisms with refuge from predators and natural disturbances, as well as increased habitat variety . Physical structural complexity is an important habitat quality that is able to regulate organism distribution, abundance, and diversity.

This study could be an effective model to predict habitat changes and promote efficient management of a variety of natural resources in many ecosystems .



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