CASTANARO, J.C.; LASKER, H.R.; University at Buffalo; University at Buffalo: Colony Growth Responses of the Carribean Octocoral Pseudopterogorgia elisabethae to Harvesting

Colonies of the Caribbean gorgonian, Pseudopterogorgia elisabethae were subjected to partial mortality at two sites in the Bahamas to study the effects of disturbances such as harvesting, grazing and storm damage on colony growth. Colonies were clipped so that either four or ten branches remained. The growth rates of branches were observed over one year and compared with nearby unclipped colonies. No significant differences were found between branch extension rates among the three treatments. Growth rates of newly formed branches were significantly greater in all treatments than among branches present at the start of the experiment. Per capita branching rates were greater on the more severely clipped colonies and were lowest on unclipped colonies. Per capita branching rates were significantly different because the proportion of unclipped branches that became source branches was greater in colonies with four branches than in the other treatments. However, the absolute number of branches that became source branches did not differ among treatments. Colonies clipped so that 4 and 10 branches remained had the same average number of source branches per colony, and there were no significant differences in the number of new branches formed between the two treatments. Total growth (cumulative growth on all branches) was not significantly different among treatments. Among the surviving colonies, differing levels of partial mortality did not lead to different recovery rates. Many of the unclipped colonies suffered extensive damage, which may have obscured treatment effects. The insignificant treatment effects are relevant to assessing the effects of harvests on the future growth of naturally occurring colonies.