Doctor of Philosophy, University of Toledo, 2009, Biology (Ecology)

The growing numbers of species introductions, with many having significant ecological and economic impacts, constitute one of the greatest challenges facing our native ecosystems today. To make correct ecological comparisons among native and introduced populations and minimize their further spread, we must (1) identify the introduced species/taxon/population correctly and (2) determine its source population(s) and its transmission pathways. This dissertation study analyzes and compares the population genetic and phylogeographic structure of three successful invasions by Ponto-Caspian species into the North American Great Lakes and beyond: the round goby Neogobius melanostomus and the dreissenid mussels Dreissena polymorpha and Dreissena rostriformis bugensis. In Chapters 2 and 3 we describe evidence for two subspecies of round goby, both of which have expanded their range. From this background information, likely sources are identified for invasive populations in Eurasia and North America. In Chapter 4, the genetic structure of zebra and quagga mussels in North America is analyzed in comparison with sites in Eurasia. Zebra mussel populations have appreciable genetic diversity, whereas quagga mussel populations from the Colorado River and California show some founder effects. The population genetic composition of both species changed over time at given sites; with some adding alleles from adjacent populations, some losing them, and all retaining closest similarity to their original composition. Zebra and quagga mussels from the western United States assign to possible origins from the St. Lawrence River and Lake Ontario, respectively. These assignments suggest that overland colonization pathways via recreational boats do not necessarily reflect the most proximate connections. The results show that all three species likely experienced multiple introductions into the Great Lakes, which brought a large proportion of the native genetic diversity to North America. This cr (open full item for complete abstract)

Committee: Carol Stepien PhD (Advisor); Jonathan Bossenbroek PhD (Committee Member); Lynda Corkum PhD (Committee Member); Christine Mayer PhD (Committee Member); Jeffrey Miner PhD (Committee Member) Subjects: Ecology

Master of Science, University of Toledo, 2007, Biology (Ecology)

Stream flow is a major vector for zebra mussel spread among inland lakes. I hypothesized that vegetated waterways, i.e. wetland streams, would hinder downstream dispersal of zebra mussels in connected inland lake systems. To test this hypothesis, veliger (larva) abundance, recruitment, and adult mussels were surveyed in four lake-wetland systems in southeastern Michigan, USA from May through August 2006. Sampling was conducted downstream of the zebra mussel invaded lakes, beginning at the upstream edge of aquatic vegetation and continuing downstream through the wetland streams. Results showed that veliger abundance decreased rapidly in vegetated waterways compared to their previously reported rates of decrease in non-vegetated streams. Veligers were rarely found more than 1 km downstream from where vegetation began. Newly recruited individuals and adults were extremely rare beyond open water in the study systems. These results suggest that densely vegetated aquatic ecosystems limit the dispersal of zebra mussels downstream from invaded sources. Natural, remediated and constructed wetlands may therefore serve as a protective barrier to help prevent the spread of zebra mussels and other aquatic invasive species to other lakes and ecosystems.

Committee: Jonathan Bossenbroek (Advisor) Subjects:

Master of Science (MS), Ohio University, 1997, Civil Engineering (Engineering)

Experimental investigation of a vacuum apparatus for zebra mussel control in closed conduits

Committee: Tiao Chang (Advisor) Subjects: Engineering, Civil

Master of Science (MS), Ohio University, 1997, Civil Engineering (Engineering)

Analysis of water quality in Lake Erie using GIS methods

Committee: Tiao Chang (Advisor) Subjects: Engineering, Civil

Master of Science (MS), Bowling Green State University, 2011, Biological Sciences

Dreissena bugensis, a freshwater mussel from the Ponto-Caspian region, was discovered in Lake Erie in 1989. Though similar to Dreissena polymorpha, a previous invader to the Great Lakes, it was initially thought that Dreissena bugensis is regulated to colder, deeper portions of the lake were they were thought to be competitively dominant. However, recent evidence indicates that quagga mussels (Dreissena bugensis) have replaced zebra mussels (Dreissena polymorpha) throughout the shallow warm water of Lake Erie's western basin. Many studies have looked at the physiological and biochemical differences between the two dreissenid species, but no definitive explanation has been given for the slow but overwhelming displacement of Dreissena polymorpha by Dreissena bugensis. In this study, I look specifically at the hypoxia tolerance of post-veliger dreissenids, and determine if mortality rates vary between species over a range of dissolved oxygen concentrations (0.0 – 2.0 mg/l) in a 12-hour period. From August 2007 to September 2007 over 900 dreissenids were collected and tested in 48 trials. Based on a binary logistic regression analysis there was a direct correlation between dreissenid survivorship and dissolved oxygen concentrations (p<0.001), but there was no difference between D. polymorpha and D. bugensis mortality over the dissolved oxygen levels tested (z=-0.069, p=0.484). For the size class tested, visual identification was not possible and some D. polymorpha may have been present in the D. bugensis trials. In order to determine the effect of misclassifying our dreissenids from Lake Erie, I reanalyzed the data assuming that as many as 10% of the D. bugensis were actually D. polymorpha and found a significant species iii effect (z=-2.40, p=0.016). My hypothesis that D. bugensis are more tolerant of lower dissolved oxygen than D. polymorpha as settling post-veligers was not supported by the data I was able to generate. However, the data is limited because it is possi (open full item for complete abstract)

Committee: Jeffrey G. Miner PhD (Advisor); Christine Mayer PhD (Committee Member); R. Michael McKay PhD (Other) Subjects: Biology; Ecology; Freshwater Ecology

Doctor of Philosophy (Ph.D.), Bowling Green State University, 2009, Biological Sciences

The ability of established populations of the non-native zebra mussel (Dreissena polymorpha) to influence phytoplankton communities and promote Microcystis aeruginosa, a potentially toxic cyanobacterium, has been reported by Fahnenstiel et al. (1995), Vanderploeg et al. (2002) and others, in the Great Lakes region. This study documents changes following zebra mussel establishment in six low-nutrient inland lake basins in northwest lower Michigan (Leelanau County). Shifts in phytoplankton communities that occurred only in basins with zebra mussels included declines in spring diatoms and chrysophytes prior to blooms of cyanobacteria. Decreases in these taxa support a competitive release hypothesis for M. aeruginosa dominance. It should also be noted that study basins did not experience increases in phosphorus or summer temperatures. M. aeruginosa proliferation may be related to zebra mussel filtering behavior, a combination of total zebra mussels and lake morphology. Zebra mussel populations were estimated using underwater video, M. aeruginosa densities were quantified from surface water and lake bathymetry and basin-wide zebra mussel densities were estimated using ArcGIS. Underwater video ground-truthed using SCUBA was an effective, yet labor intensive method to estimate zebra mussel populations, and kernel interpolation provided acceptable zebra mussel density estimates basin-wide. The relationship between M. aeruginosa density and zebra mussel filtering capacity was not significant, however the sample size may have been an issue. Microcystin (MC), the hepatotoxin produced by M. aeruginosa and other cyanobacteria, was measured before and after blooms of M. aeruginosa over depths and across seasons in whole water, sediment, macroinvertebrates, bivalves and fishes, using enzyme linked immunosorbent assay. A subset of sediment and Hexagenia spp. samples were analyzed using high performance liquid chromatography and mass spectrometry for microcystin-LR. MC was presen (open full item for complete abstract)

Committee: Rex L. Lowe PhD (Advisor); Karen V. Root PhD (Committee Member); Dan M. Pavuk PhD (Committee Member); George S. Bullerjahn PhD (Committee Member); Dawn L. Anderson PhD (Committee Member) Subjects: Biology