Beach nourishment has become common in Florida and it occurs on beaches that are major loggerhead (Caretta caretta) nesting grounds. Despite efforts to use beach-quality sand, nourishment sand may be different in grain size, moisture content, shear resistance and temperature when compared to native sand. Two main aspects of loggerhead nesting may be affected by nourishment. First, nourishment may reduce nesting success [(female nesting emergences/ female total emergences) X 100] due to physical barriers (i.e., scarps or steep cliffs) that can impede gravid females. Second, nourishment may reduce reproductive success {i.e., hatching success) by altering the nestsand environment. The objective of this study was to compare loggerhead nesting success, nest placement, slopes at nest sites, nest depths, incubation periods, reproductive success and egg fates among an old renourished beach {"south"), a recently nourished beach ("treatment") and a natural beach ("control") at Sebastian Inlet, Florida in 1996, 1997 and 1998. In all three years, nesting success was significantly different among study sites. After nourishment (1997), nesting success was reduced at the treatment site due to a seaward scarp. A year later (1998), the scarp was leveled and nesting success improved. Nest placement was not significantly different between study sites prior to nourishm_ent of the treatment study site (1996), but it was after nourishment (1997) and one-year post-nourishment (1998). After nourishment, most nests at the treatment beach were placed too close to the water or too close to the dune. There were no significant differences in the slope at nest sites in 1997; suggesting females may have selected similar increases in slope, but at varied cross-shore locations. Nest depths were significantly shallower at the treatment beach after nourishment, probably due to higher compaction of the nourishment sand. In addition, incubation periods were significantly longer on the nourished beaches one year post-nourishment. Loggerhead hatching success was significantly reduced on the nourished beaches in 1996 and 1997. The reduction was seen primarily in a larger proportion of eggs that were arrested early in development. The higher moisture in the nourishment sand may have impeded gas exchange, which resulted in decreased hatching success. One year post-nourishment (1998), there were no significant differences in hatching success. The lack of rainfall in 1998 may have introduced better incubation conditions on the nourished beaches. Researchers at the Florida Institute of Technology continued to show that the nourishment sand exhibited significantly smaller grain size, higher moisture content, lower temperature and higher shear resistance. These attributes were probably responsible for many of the results reported herein. However, other variables such as non-random nest depredation, inlet influences and water table levels may have also contributed to the results.
| Identifer | oai:union.ndltd.org:ucf.edu/oai:stars.library.ucf.edu:rtd-3146 |
| Date | 01 January 1999 |
| Creators | Herren, Richard Michael |
| Publisher | University of Central Florida |
| Source Sets | University of Central Florida |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Retrospective Theses and Dissertations |
| Rights | Written permission granted by copyright holder to the University of Central Florida Libraries to digitize and distribute for nonprofit, educational purposes. |
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