Literaturdatenbank
Literaturdatenbank |
|
 |
|
DeCatanzaro, R. (2008). The impact of anthropogenic disturbance on aquatic turtle assemblages of great lakes coastal marshes. Unpublished thesis , McMaster University, Hamilton, ON.
Added by: Sarina Wunderlich (18 Nov 2012 17:43:19 UTC) |
| Resource type: Thesis/Dissertation BibTeX citation key: DeCatanzaro2008 View all bibliographic details  |
Categories: General Keywords: Chelydra, Chelydra serpentina, Chelydridae, Chrysemys, Chrysemys picta, Emydidae, Emydoidea, Emydoidea blandingii, Graptemys, Graptemys geographica, Habitat = habitat, invasive Arten = invasive species, Kinosternidae, Nordamerika = North America, Schildkröten = turtles + tortoises, Sternotherus, Sternotherus odoratus, Trachemys, Trachemys scripta Creators: DeCatanzaro Publisher: McMaster University (Hamilton, ON) |
Views: 3/694
Views index: 16% Popularity index: 4% |
| Abstract |
|
Chrysemys picta Sternotherus odoratus Emydoidea blandingii Graptemys geographica Chelydra serpentina Trachemys scripta elegans An emerging issue in conservation biology is the striking decline in many freshwater turtle species in areas with high anthropogenic activity. Agricultural, urban, and recreational development that alter terrestrial and wetland habitat are believed to have caused many regional extirpations, particularly in the lower Great Lakes. In chapter 1, we use a 7-year database containing 83 wetland-years spanning three Great Lakes to evaluate the impact of anthropogenic wetland degradation on the occurrence and abundance of aquatic turtles. Abundances of five species were obtained from turtle bycatch records from fish surveying in coastal marshes of Lakes Erie, Ontario, and Huron (primarily Georgian Bay). Painted turtles were found disproportionately in degraded wetlands and abundance was negatively correlated with wetland quality (P<0.001), while common snapping turtles were most abundant in sites of intermediate quality. The common musk turtle was absent from degraded wetlands and increased in abundance as wetland condition improved. A comparison of turtles caught in a highly urbanized area of western Lake Ontario and a relatively less developed area of southern Georgian Bay revealed less diverse turtle assemblages in the urbanized wetlands that were more heavily dominated by painted turtles. Painted turtles of the urban wetlands had a highly male-biased sex ratio, most likely as a result of high road mortality of nesting females. Georgian Bay is a part of Lake Huron that has experienced relatively low human impact and continues to support the common musk turtle in high abundance. In chapter 2, we examine the overall distribution of the common musk turtle in Georgian Bay, and use a combination of GIS and field data to evaluate the impact of near-shore cottage development and other wetland habitat features, including size, exposure and sediment organic content on common musk turtle abundance along a stretch of the eastern Georgian Bay coast. Overall, abundance was negatively correlated with latitude throughout Georgian Bay (P=0.012). Wetlands with a high density of cottage docks supported higher abundances of the common musk turtle and also had elevated levels of phosphorus and nitrogen. Of the other habitat features examined, only sediment organic content was positively correlated with common musk turtle abundance (P=0.016). Our findings suggest that while the common musk turtle is intolerant of extensive alteration of habitat, low levels of human activity in a relatively pristine area may benefit this species, possibly by increasing nutrient concentrations that can enhance wetland productivity and food availability. However, the impact of cottage development on the occurrence of other rare turtle species in Georgian Bay remains unknown.
Added by: Sarina Wunderlich |