Characteristics of the Unionid Community and Habitat in a Power Plant Thermal Plume in Western Lake Erie

Native unionids are endangered in the Laurentian Great Lakes due to habitat degradation and biofouling by dreissenids. However, a robust community was discovered living within the thermal discharge of a power plant at Oregon, Ohio, on the south shore of Lake Erie. Chapter 1 describes comparisons of the characteristics of this community to nearby communities outside the thermal plume, and examines habitat characteristics that may affect unionids. Unionids were sampled from the exposed lake bed at three sites during a seiche in 2011: (1) within the thermal plume, (2) at Bayshore Park (2.0km east of the plant), and (3) at the University of Toledo’s Lake Erie Center (4.0km east). In 2010, sediment samples were collected along a 2km transect extending east from the plant discharge roughly parallel to the south shore of Lake Erie. Data from other studies done in proximity to the power plant were also analyzed. Results indicated that the community within the thermal plume had higher densities, higher diversity (H’), more small individuals, and overall larger sizes than communities outside the plume (all p<0.05). Both the rate and intensity of fouling by dreissenids were lower within the plume (p<0.05). Both dry mass of coarse surface sediment and lakebed sediment organic matter content were negatively correlated with distance from the plant (both p<0.05; R2 = 0.497, and 0.479, respectively). An unexpected discovery was that the bulk of the coarse sediment was comprised of shell material from Asian clams and dreissenid mussels, suggesting a contribution of these exotic species to sediment accumulation. In total, these results suggest that several habitat characteristics close to the power plant are favorable to unionids. Chapter 2 outlines work completed in the summer of 2012, examining habitat characteristics within the thermal plume for insights to why it is favorable to unionids: I expected warmer water temperatures, higher POM concentrations, higher organic matter in sediments, and greater coarse sediment mass in the plume. Water temperature averaged 3.8±1.5°C warmer (N=8) at the plant’s outflow than at the intake and decreased by 3.6±1.5°C by 2.0km from the outflow (N=4). The decline in temperature over distance was negatively correlated with wind speed and positively correlated with wind direction (N=4; R2=100%; p=0.003 and 0.005 respectively). Particulate organic matter (POM) was not consistently greater at either the intake or outflow but the difference in POM between the intake and outflow was positively correlated with wind speed (N=5; R2=98.3% p=0.0006). Wind speed was also positively correlated with the change in POM concentration over distance (N=5; R2=86.9%; p=0.01); concentration also increased when the Maumee River discharge was increasing and decreased when discharge was falling. Differences in dreissenid veliger density between the intake and outflow were positively correlated to wind direction (N=5; R2=94.9%; p=0.0003). The ratio of live:dead veligers was significantly higher at the intake than at the outflow on most dates. A laboratory experiment showed that heating to levels experienced by passing through the power plant caused significant mortality in veligers (N=20; p<0.0001). These findings show that water temperatures were higher in the plume, POM was higher in the plume on most dates, and that heating during passage through the power plant likely increases dreissenid veliger mortality. We found no significant relationships between sediment characteristics and distance from the power plant. Thus not all factors considered favorable for unionids were enhanced by proximity to the power plant.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Biology (Ecology)

Grantor dc:publisher

University of Toledo

Year dc:date

2013

Author dc:creator

• Bryan, Nicholas Joseph

Contributors dc:contributor

• Moorhead, Daryl
• Crail , Todd

• Conservation
• Ecology
• Environmental Science
• Natural Resource Management
• Organismal Biology
• Wildlife Conservation
• Wildlife Management
• Unionidae
• Dreissena
• Veligers
• Corbiculidae
• Refugia
• Thermal Plume
• Lake Erie

Statement dc:rights

• unrestricted
• This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.

Language dc:language

English

Repository record dc:identifier

http://rave.ohiolink.edu/etdc/view?acc_num=toledo1369403135

OAI identifier oai:identifier

oai:etd.ohiolink.edu:toledo1369403135