A Unique Mangrove Arthropod Community in the Jobos Bay National Estuarine Research Reserve, Puerto Rico

Mangroves provide important ecosystem services and products, and are also habitat for many endemic and endangered species. In Puerto Rico, mangroves are threatened by urban development and sea level rise that reduce the available area for mangrove growth. Terrestrial arthropods are a key component in various ecological processes such as organic matter decomposition, herbivory and pollination. Currently there is little known about arthropod biodiversity in mangroves, as a consequence we aim to establish whether mangrove arthropods are a subset of surrounding communities or a unique community.  We addressed these hypotheses: 1- litter mass and arthropod abundance and richness is higher in dry forest than in mangroves, 2- arthropod species composition is different between mangroves and dry forests.  To test these hypotheses we studied terrestrial arthropods in mangroves and surrounding dry forest, by collecting litter samples and extracting arthropods with modified Berlese-Tullgren funnels. We recorded litter mass, and abundance and richness of arthropod species per sample.  Collected arthropods were sorted into adult and immature individuals.  Adults were identified to the lowest possible taxonomic category and assigned to morphotypes. Litter mass was 840(±624) g m^-2 in mangroves and 587(±204) g m^-2 in dry forest.  We obtained an average of 2650(±1735) ind m^-2 in mangroves and 9031(±4985) ind m^-2 in dry forest.  Arthropod species composition varied between mangrove and dry forest as well as the trophic composition. These data suggest that the mangrove arthropod community is unique, and contribute to the ecosystem services that mangroves provide, highlighting the importance of protecting mangrove ecosystems.