Browsing by Subject "macroinvertebrate"

By concentrating materials and increasing the speed with which rainfall is conveyed off of the landscape, nearly all forms of land use change lead to predictable shifts in the hydrologic, thermal, and chemical regimes of receiving waters that can lead to the local extirpation of sensitive aquatic biota. In Central Appalachian river networks, alkaline mine drainage (AlkMD) derived from mountaintop removal mining for coal (MTM) noticeably simplifies macroinvertebrate communities. In this dissertation, I have used this distinct chemical regime shift as a platform to move beyond current understanding of chemical pollution in river networks. In Chapter Two, I applied a new model, the Hierarchical Diversity Decision Framework (HiDDeF) to a macroinvertebrate dataset along a gradient of AlkMD. By using this new modeling tool, I showed that current AlkMD water quality standards allow one-quarter of regional macroinvertebrates to decline to half of their maximum abundances. In Chapter Three, I conducted a field study in the Mud River, WV to understand how AlkMD influences patterns in aquatic insect production. This work revealed roughly 3-fold declines in annual production of sensitive taxa throughout the year in reaches affected by AlkMD. These declines were more severe during summer base flow when pollutant concentrations were higher, thereby preventing sensitive organisms from completing their life cycles. Finally, in Chapter Four I described the idea of chemical fragmentation in river networks by performing a geospatial analysis of chemical pollution in Central Appalachia. In this work I showed that the ~30% of headwaters that remain after MTM intensification over the last four decades support ~10% of macroinvertebrates not found in mined reaches. Collectively my work moves beyond the simple tools used to understand the static, local consequences of chemical pollution in freshwater ecosystems.

Increasing competition between offstream and instream water uses emphasizes the need for accurate and equitable river management decisions. Minimum instream flow requirements necessary to sustain aquatic diversity can best be determined through habitat classification and modeling. Although previous studies focused on fish communities, the flow needs and responses of other organisms to inevitable flow disturbances vary greatly depending on the trophic level and mobility of the species considered. This research attempts to quantify and describe the available habitats and the suitability of those habitats for macroinvertebrates in the Eno River, as well as highlight management strategies consistent with invertebrate preferences.

Through field sampling two sets of data were collected: macroinvertebrate counts and measurements of the physical habitat parameters of depth, velocity, and substrate. The habitat parameters were subset into utilization and availability data. Utilization data described parameters where macroinvertebrates were collected and availability data described all parameters whether macroinvertebrates were collected or not. Results showed that the habitat used by macroinvertebrates was the same as the available habitat meaning, in theory, that the macroinvertebrates can choose their habitat because it is the most suitable for them not because it is the only habitat available. Suitability indices for several macroinvertebrates revealed that low and mid depths and low and mid-high velocities were the most common optimal habitat types. Substrate suitabilities were greatly varied although many species favored aquatic vegetation, sand-gravel, and cobble-boulder combinations.

The results of this study will be an important element in the formulation of instream flow management plans in the state of North Carolina. Additionally, the suitability curves could be used by professionals interested in stream restoration, water quality, and aquatic resource management to help them preserve macroinvertebrate diversity and in the process the health and functionality of aquatic ecosystems.