In April of 1990 the Sebastian Inlet Tax District received a long-term (25 year) permit to conduct maintenance dredging of the navigation channel at Sebastian Inlet, Florida. Approximately 105,150 cubic meters of sediment will be removed every two years and pumped to a feeder beach immediately south of the inlet. The renourished beach, a high density nesting beach for loggerhead (Caretta caretta) and green (Chelonia mydas) sea turtles, is within the proposed Archie Carr National Wildlife Refuge and will play a critical role in the long-term maintenance of Sebastian Inlet as a navigable waterway. A turtle monitoring program was implemented by the District at the request of the U.S. Fish and Wildlife Service. The monitoring program was designed to investigate nesting behavior, reproductive success and physical characteristics of the nesting habitat on the renourished beach at Sebastian Inlet and on a control beach (Wabasso Beach).
Daily nesting surveys were conducted to record all sea turtle nests and non-nesting emergences in each study area. All nests were marked, monitored throughout incubation and inventoried to determine hatching and emergence success. Data on physical parameters were collected in monthly profiles of each beach. Compaction values were recorded with a cone penetrometer along transects from the dune to mean high water line. Temperature of the ambient beach was recorded at 30 and 60-cm depths along two transects from the dune to mean high water line. Moisture and sand grain analysis were conducted monthly in 1991. Sea turtle nesting and hatching success were similar on the renourished and control beaches in 1990 and 1991, suggesting that renourishment had no adverse effect on sea turtle reproductive success. Nesting success on the renourished and control beaches, respectively, was 42.0% (N = 104) and 45.0% (N = 65) in 1990, and 62.9% (N = 165) and 62.4% (N = 118) in 1991. Hatching success on the renourished and control beaches, respectively, was 80.7% (N = 85) and 79.3% (N = 59) in 1990, and 69.1% (N = 118) and 66.7% (N = 102) in 1991. Compaction values averaged 500 PSI on the renourished beach, while values on the control were approximately 250 PSI. The higher level of compaction on the renourished beach resulted in a lack of complete nest covering, and aberrant nest chamber configurations on the renourished beach. Grain size and moisture content were similar on the renourished and control beaches. Compaction levels were not related to incompatible fill, implying that the manner in which the material was deposited resulted in the increased compaction. Beach temperatures measured at 30-cm and 60-cm depths indicated that the renourished beach was consistently 0.5°C warmer than the control beach.
If the physical parameters of a subsequent renourishment project are within the findings of 1990 and 1991, there should be no adverse effect on sea turtle nesting and hatching success. The results of this project cannot be applied to other beach renourishment projects however, but should be restricted to future dredging projects at Sebastian Inlet. Although the results are not applicable to other locations, the methodologies developed to study the effects of renourishment on sea turtles could be applied to other beach renourishment situations. Future research should focus on how the physical parameters of a renourished beach affect the micro-environment within the actual nest chamber and embryonic development. / Master of Science
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/44882 |
| Date | 19 September 2009 |
| Creators | Ryder, Cheryl E. |
| Contributors | Fisheries and Wildlife Sciences |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis, Text |
| Format | xii, 109 leaves, BTD, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
| Relation | OCLC# 29741615, LD5655.V855_1993.R923.pdf |
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