Predation is an interaction between species in which members of a specie are food source for other species. In seed predation, this can be an advantage for the plant because the consumption of the fruit helps with the dispersion of the seeds, but it can be harmful if seed is consumed in excess. In the Natural Reserve of Punta Tuna, Maunabo, Puerto Rico, a decrease in the population of Annona glabra tree juveniles has been observed. This tree inhabits coastal wetland areas and serve as barrier against storm surge. The objective of this study is to identify the predator of the A. glabra seed. Since Iguana iguana and Cardisoma guanhumi have a dense population in the Natural Reserve, they have been identified as possible predators of seed. The hypothesis states that C. guanhumi is the predator of the A. glabra seed. We collected the feces of I. iguana, dried it and dissect it to collect A. glabra seeds present in the feces. We also collected A. glabra seeds, for a feeding experiment. We put three or five seeds in front of each C. guanhumi burrow and observed them for one or two hours via direct observation or using a video camera.
Results/Conclusions
We collected 243 I. iguana feces in which we found 54 A. glabra seeds (22%), and 13 unidentified seeds (5%), for a total of 67 seeds found. Two hundred and ninety-six seeds were distributed among 91 burrows. Of those, crabs consumed 109 seeds (36.8%). We assume that I. iguana is not a predator, but a probably a disperser of A. glabra seeds since the seeds found were not digested. We found, in one of the feces, 16 A. glabra seeds suggesting that I. iguana is eating the ripe fruit. On the other hand, C. guanhumi could be the possible predator of A. glabra seed because when it was observed eating the seed and breaking it in several pieces. By consuming the seeds, C. guanhumi removes the seed from the seed bank of A. glabra. These are the preliminary results of the study. More observations and feces collection are needed to determine the effects that C. guanhumi might have on the population structure and abundance of A. glabra.