TIDAL INFLUENCE ON LAGOONAL TEMPERATURE IN LITTLE CAYMAN, CENTRAL CARIBBEAN, USING HIGH-RESOLUTION IN-SITU TEMPERATURE MEASUREMENTS

Massive corals record environmental conditions of ambient seawater during their growth, including temperature. Sclerochronological data, information derived from the coral’s carbonate skeleton, can be used to reconstruct changes in past water conditions. Living massive corals from around Little Cayman, located in the central Caribbean, have been used to gain information on the past sea surface temperature variability for the past several decades. When plotted with the tidal cycle, there appears to be a correlation between the tidal variability and the temperature variability over the past forty years. To further investigate this relationship, modern temperature and tidal data were collected in the lagoon environment in Little Cayman, where the massive corals had been analyzed.

The lagoon in Grape Tree Bay in Little Cayman is protected by a healthy reef crest, and it was observed that the diurnal temperature cycle in the lagoon varied significantly over the period of a month. In-situ high-resolution data on the temperature and tidal height in three different locations were collected for a full lunar cycle. Analysis of the change in temperature with respect to the tidal cycle revealed that the tide had a significant impact on the timing and magnitude of the daily temperature minimums and maximums. More specifically, there was a positive correlation between low tide and the daily temperature maximum. High tide did not contribute to the variation in temperature as much as low tide. Not only does this support the hypothesis that the tidal cycle plays a significant role in both long-term and short-term temperature variation in the lagoon, it also shows that the tidal cycle must be taken into account when analyzing the paleo-climate record derived from sclerochronology.