Theses and Dissertations

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Defense Date

2002

Document Type

Thesis - NSU Access Only

Degree Name

M.S. Marine Biology

Second Degree Name

M.S. Coastal Zone Management

Department

Oceanographic Center

First Advisor

Curtis Burney

Second Advisor

Edward O. Keith

Third Advisor

Stephen M. Blair

Abstract

Loggerhead sea turtles (Caretta caretta) deposit eggs on 1250 km of Florida beaches in underground egg chambers. Florida beaches host more than 20,000 loggerhead sea turtles per year, which comprise 90% of the total nesting population of the United States. Coastal erosion has caused depletion of much of the suitable nesting habitat. Beaches in Florida also support various developments, homes, recreational activities, and serves other environmental networks. This erosion can be attributed to coastal development, global warming and the rise in sea level. Due to economic, recreational, safety, and environmental conservation reasons one mechanism, beach preservation has become necessary. Beach renourishment, adding sand to the beach via dredging,accoplishes this. The source of sand, the time of renourishment, and the biological, chemical and geological parameters of the sand must all be considered to minimize ecological disturbances.

The impact of three beach renourishment projects were examined that occurred in Broward County, John U. Lloyd State Park (1989), Hollywood Beach (1990), and Hillsboro Beach (1998). Nesting success, incubation time, and hatching success were analyzed via one-way ANOVA and slope tests. Nest depth and emergence success were analyzed when the data were available. Pre-nourishment data were used to analyze the nesting conditions prior to erosion. The post-nourishment data were compared to test the impacts of renourishment on nesting and hatching parameters.

On all three beaches, the highest nesting success was found before the renourishment. The success dropped the year of the renourishment. The number of adult female emergences did increase the year follwing the renourishment, due to the increased beach width. Incubation times are decreased during the year following the renourishment. However, this data as well as the nest depth data on all three beaches strongly related to the weather data. The hatching success data could not be conclusively linked with the renourishment. The Hillsboro Beach project only indicated a decrease in the hatching success the year after the renourishment. The emergence success was slightly lower the year following renourishment, however not significantly so.

While beach renourishment did affect some aspects loggerhead sea turtles' nesting parameters, the effects were minimal and did not appear to be long term. In most cases, the data had returned to pre-nourishment levels within three years after the renourishment. As renourishment has become beneficial in order to restore nesting habitat, it is important to study ways to protect the sand that is placed on the beaches. According to the three projects in Broward County, Florida, beach renourishment does appear to be a viable solution for the erosion problem. Since this is only a short term solution to a reoccuring problem, designing a complete beach maintainence plan could ensure the continuation of the beaches.

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