DONNELLY, M J*; WALTERS, L J; University of Central Florida; University of Central Florida: Effects of the exotic Brazilian pepper in a Florida mangrove ecosystem

Disturbances to mangrove ecosystems in Florida potentially leave them vulnerable to exotic plants, such as Brazilian pepper (Schinus terebinthifolius). Although mangrove forests are difficult to invade by terrestrial species, observations in New Smyrna Beach, FL have found Brazilian pepper growing beside native mangroves. The purpose of this study is to examine two possible negative impacts of Brazilian pepper in the mangrove ecosystem: 1) inhibition by Brazilian pepper fruits on mangrove survival and growth and 2) the effect of Brazilian pepper on biodiversity of the invaded area. To test for inhibition effects, native mangrove seeds were grown in 15 or 30 ppt saltwater for one year. Brazilian pepper fruits were then added to the pots in three densities, 0, 25 or 50 intact fruits/ pot. Growth of mangroves was monitored before and after the addition of fruits to determine changes in growth rate. To estimate species richness, three line transects (30 meters) perpendicular to the lagoon shoreline were surveyed at fourteen sites, 7 with Brazilian pepper and 7 without. I hypothesized sites with Brazilian pepper would have lower species richness than areas without the exotic, because this exotic tends to form monotypic stands. However, results showed higher species richness where Brazilian pepper was present compared to sites without the exotic, 7.9 � 0.3 (mean � SE) and 3.8 � 0.2 (mean � SE), respectively. Sites without Brazilian pepper were dominated by mangroves and other halophytic plants, while sites with Brazilian pepper supported halophytic species as well as upland plants, resulting in the higher diversity. Although the presence of Brazilian pepper in the mangrove system did not decrease biodiversity in our study, long term impacts of this exotic on mangrove systems is still uncertain.