The population of the Annona glabra tree (Cayur tree) in the Punta Tuna natural reserve in Maunabo, Puerto Rico, has been under investigation due to the absence of juvenile stages. It is of vital importance to know if the common crab Cardisoma guanhumi can be part of the explanation, because the consumption of leaves that the species prefers can affect the establishment of trees or communities of plants. In this research, we study the dietary preference of C. guanhumi by measuring the amount of leaves consumed. We chose leaves of Calophyllum antillanum (Maria tree) and leaves of A. glabra to compare preference. The hypothesis proposed was that the crab will consume both species as a first option in the same way. The first method used was to place three leaves of Maria and three leaves of Cayur at the entrance of twenty burrows of C. guanhumi. After an hour, the leaves left outside the burrows were counted and collected. A second method used was direct observation of C. guanhumi. Three leaves of Maria and three leaves of Cayur were placed at the entrance of eight burrows and left for one hour. We recorded the leaf that the crab first grasped. Data was analyzed with a chi-square test.
Results/Conclusions
We concluded that the crab does not prefer the leaves of A. glabra nor C. antillanum. Therefore, the hypothesis is accepted. However, we found that the crab prefers A. glabra since this is the first leaf chosen. In seven of eight burrows observed, C. guanhumi selected A. glabra as first option. This preliminary study provides knowledge to encourage future research on the possible effects of C. guanhumi on A. glabra. It is important to consider the effect that herbivores have on the structure, composition and abundance of coastal plant communities when developing strategies for the conservation of coastal wetlands.