It is well known that large waves associated with hurricanes can have a devastating effect on shallow water coral communities (Woodley et al., 1981 Rogers et al., 1982 Edmunds and Witman, 1991 Hubbard et al., 1991 Rogers et al., 1991 Bythell et al., 1993). Direct mortality due to dislodgment by large swells was documented.
Mortality of coral colonies on Caret Bay reef could have resulted from dislodgment by large waves during winter months, smothering due to excess sedimentation or death due to pigment loss. The third major finding of this study was that the percent cover of living coral decreased from 4.55 to 3.91% across Caret Bay reef, representing a 14% decline over 18 mo. Unpaved roads and lack of vegetative cover are the primary sources of sedimentation in the Virgin Islands (MacDonald et al., 1997 Sladek Nowlis et al., 1997 Anderson and MacDonald, 1998), therefore changes in these parameters (i.e., area of exposed soil) will greatly influence erosion rates. The intensity of tropical rain showers on bare soils promotes suspension and movement of soil particles, and road cuts concentrate and accelerate storm water runoff further increasing erosion. Reduced sedimentation rates could be attributed to the progress of construction where 90% of the dirt roads accessing the site were paved by July 1998 and a majority of the site was landscaped by February 1999. During the same time period of the following year rainfall greatly exceeded 1997 levels but sedimentation rates were considerably lower relative to rainfall (Fig. The magnitude of sediment runoff during these periods corresponded roughly with the construction schedule in that the largest area of exposed soil occurred between October 1997 and April 1998. Sedimentation rates tracked monthly rainfall during the first four months (August to November 1997), exceeded rainfall during the next 6 mo (December 1997 to May 1998), and then were lower relative to rainfall during the last 8 mo (June to January 1999). The second major finding of this study was that patterns of sedimentation, relative to monthly rainfall, were related to the progress of construction. More distant control sites would have minimized the effect of lo- calized currents and eddies and would have provided greater resolving power to the ex- perimental design. Placing transects too close to the source of sedimentation was one of the primary limitations of this monitoring study. Thus, transect E2, which was expected to be a low-impact site, actually received some of the highest amounts of sediment. Since large swells were typically associated with heavy rainfall, any sediment entering the sea would be carried eastward with the reversed current and, as the sediment-laden water moved into the lee of the Brass Islands, the suspended sediments would have a greater chance of settling onto the reef.
Moreover, the eastern end of the study site was sheltered from large swells by Inner and Outer Brass Islands located less than 2 km northeast (Fig. When seas were large the typical east-to-west current reversed (R.S.N. Two hydrodynamic features of the Caret Bay site may have contributed to this result. On the contrary, the most easterly transect (East 2) received a greater amount of sediment than predicted while transects West 2 and Central received the least ( Table 1, Fig. Thomas (Dammann, 1969), the predicted sediment distribution path was westward. Commercial reproduction, distribution or transmission of any part or parts of this website or any information contained therein by any means whatsoever without the prior written permission of the Club is not permitted.
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