PHYSICAL EFFECTS OF REEF RUGOSITY ON THREE DIMENSIONAL HYDRODYNAMICS AND SEDIMENTATION OVER TRANSPLANTED OYSTER REEFS IN A SHALLOW TIDAL CREEK SYSTEM
The study area was sub-divided into three separate sites, all of which received the same treatments. At each site, both higher and lower rugosity reefs were constructed from dead shell material (culch). The constructed reefs have an approximately circular base with a diameter of 2 m, and a height of approximately 0.4 m. Rugosity of the reefs was altered by adjusting the attitude and direction of the shells along the surface of the reef. Sediment traps were placed within the surface of the constructed reefs in order to measure sedimentation rates and to conduct sediment analyses. Sediment traps were deployed three times for approximately one month durations. Preliminary results indicate that sediment retention ranges from 0.094 g day-1 to 1.043 g day-1, with lower rates on the higher rugosity reefs. The Aquadopp® was deployed over the reefs, in a downward looking manner, attached to a portable frame, which will be set on the substrate. Preliminary data show that the shape of the vertical profile and extent of turbulence near the reef surface differs with rugosity. Although both data collection and analyses are ongoing, initial findings indicate that turbulent flow over the reefs is proportional to reef rugosity and that sediment retention rates are inversely proportional to reef rugosity.