ANALYSIS OF MACROINVERTEBRATE COMMUNITIES IN SEASONAL WETLANDS THROUGH TIME, ACROSS SPACE, AND USING SPECIES TRAITS

Restoration of natural wetlands may be informed by macroinvertebrate community composition. Macroinvertebrate communities of wetlands are influenced by environmental characteristics such as vegetation, soil, hydrology, land use, and isolation. This dissertation explores multiple approaches to the assessment of wetland macroinvertebrate community composition, and demonstrates how these approaches can provide complementary insights into the community ecology of aquatic macroinvertebrates. Specifically, this work focuses on macroinvertebrates of Delmarva Bays, isolated seasonal wetlands found on Maryland’s eastern shore. A comparison of macroinvertebrate community change over a nine years in a restored wetland complex indicated that the macroinvertebrate community of a rehabilitated wetlands more rapidly approximated the community of a reference site than did a newly created wetland. The recovery of a natural macroinvertebrate community in the rehabilitated wetland indicated that wetland rehabilitation should be prioritized over wetland creation and long-term monitoring may be needed to evaluate restoration success. This study also indicated that characteristics of wetland vegetation reflected community composition. The connection between wetland vegetation and macroinvertebrate community composition led to a regional assessment of predaceous diving beetle (Coleoptera: Dytiscidae) community composition in 20 seasonal wetlands, half with and half without sphagnum moss (Sphagnum spp.). Species-level identifications indicated that wetlands with sphagnum support unique and diverse assemblages of beetles. These patterns suggest that sphagnum wetlands provide habitat that supports biodiversity on the Delmarva Peninsula. To compare traits of co-occurring beetles, mandible morphology and temporal and spatial variation were measured between three species of predaceous diving beetles. Based on mandible architecture, all species may consume similarly sized prey, but prey characteristics likely differ in terms of piercing force required for successful capture and consumption. Therefore, different assemblages of aquatic beetles may have different effects on macroinvertebrate community structure. Integrating community-level and species-level data strengthens the association between individual organisms and their ecological role. Effective restoration of imperiled wetlands benefits from this integration, as it informs the management practices that both preserve biodiversity and promote ecosystem services.

PREVALENCE, ISOLATION, AND GENETIC CHARACTERIZATION OF TOXOPLASMA GONDII IN CHICKEN

Toxoplasma gondii (T. gondii) is one of the most successful parasites in the world because of its capability of infecting all warm-blooded animals. It has been reported that up to one third of the world population is infected with this parasite. Chickens are recognized as good indicators of the environmental T. gondii oocysts contamination because they obtain food from the ground. Thus, the prevalence of T. gondii in chicken provides more insight related to public health concern from T. gondii. Previous studies have shown a high isolation rate from free-range chickens raised in the United States. The objectives of this study were to evaluate the microbial safety and infection of T. gondii in free-range chickens available at the grocery stores and farms for the consumers to purchase and genotype T. gondii isolates. Chicken hearts were obtained from the local markets and also from the farms raising free- range chickens. Heart juice was obtained from cavities of each heart. Modified agglutination test (MAT) for detection of IgG antibodies was conducted with those heart juice samples with titer of 1:5, 1:25, and 1: 100. Each seropositive heart was pepsin digested and bioassayed into a group of two mice. Six weeks post inoculation (p.i.) mice were bled and euthanized to examine the infection of T. gondii. In addition, multiplex multilocus nested PCR-RFLP was performed to genetically characterize T. gondii isolates with eleven PCR-RFLP markers including SAG1, SAG2, altSAT2, SAG3, BTUB, GRA6, c22-8, c29-a, L358, PK1, and Apico. One hundred fifty from a total of 997 samples (15.0%) were found seropositive for T. gondii. No viable T. gondii was isolated from chicken hearts that were sampled. A total of four genotypes were identified, including one new genotype and three previously identified genotypes. The results suggest that T. gondii oocysts could present in the environment and infect the food animals. T. gondii prevalence in chicken hearts could reflect the environmental contamination of T. gondii and prevalence information can be used to manage T. gondii infection risk.