Studies on Experimental Harvesting and Regrowth of Plexaura Homomalla in Grand Cayman Waters

Abstract

The prostaglandins are lipid acids which are important metabolic regulators for all animal species including man.1 Some members of this family of compounds have considerable potential as medicinal agents. 2 Weinheimer and Spraggins 3 reported the is flation of the prostaglandins, (15R)-PA2 and its acetate methyl ester, from the sea whip Plexaurahomomalla obtained from the waters of Florida. More recently a new variant of this gorgonian was discovered in certain Caribbean waters from which (15S)-PGA2 and its acetate methyl ester could be isolated. 4 In addition, two new natural prostaglandins, the lS(S) and l5(R)-5,6-trans isomers of PGA2 (and the corresponding 15-acetate methyl esters), were found. 5 Since these compounds can serve as useful intermediates in the preparation of clinically important prostaglandins, 6 studies were undertaken to determine the ecological and economical feasibility of utilizing P.homomalla as a raw material. These studies-included surveys to supplement existing knowledge on distribution and abundance of the species, harvesting methods, regrowth rates and the influence of harvesting on the reef ecology. The most extensive studies have been carried out in the off-shore waters of Grand Cayman Island, B.W.I. with the full cooperation of the Cayman Islands Government. A comprehensive review and evaluation of this work was conducted in May, 1972 at an International Symposium organized by Dr. F.M. Bayer and Dr. G.L. Voss of the Rosenstiel School of Marine and Atmospheric Science of the University of Miami. The proceedings of the symposium are being published in StudiesinTropicalOceanography. In addition similar studies have been carried out in the coastal waters in the Bahamas and other islands in the Caribbean. In this presentation I shall try to summarize the more important aspects of these studies, and indicate the trend we see for this research. Two objectives of this project were as follows:Estimate the quantities of P.homomalla available.Develop methods for harvesting which would be ecologically acceptable and would provide maximum opportunity for replenishing the natural supply. This study was initiated in December, 1970 with the advice, recommendations and active participation of Dr. F. M. Bayer, Dr. Robert A. Kinzie III and Mr. Sid R. Anderson, Jr. Grand Cayman Island was chosen as the study site for the early experiments because of the abundance of P.homomalla, a minimum of logistics problems and because of the interest and splendid cooperation of the Cayman Islands' government. In addition, we were fortunate to enlist the able assistance of Mariculture, Ltd., a research-minded corporation located on Grand Cayman Island. This company is studying the domestication and commercial production of the green sea turtle. They were in a position to provide the boats, divers, pilots, freezer storage, etc. required to make our project feasible.