A Reciprocal Inter-habitat Transplant Reveals Changes in the Assemblage Structure of Macroinvertebrates Associated with the Sponge Halichondria melanadocia

Sponges harbor great diversity and an abundance of organisms. Although this community can vary temporally, and between and within sponge species, it is not known how an induced change in habitat-specific environmental conditions might affect the structure of macroinvertebrate assemblages associated with sponges. Here, a reciprocal transplant experiment of individuals of the estuarine sponge Halichondria melanadocia was conducted between two neighboring habitats (seagrass and mangrove prop root habitats) in the Southern Gulf of Mexico. Transplanted sponges experienced different hydrodynamic and light conditions. Multivariate analyses showed differences in community structure of associated assemblages among treatments, which were mainly driven by changes in the abundance of common species. Sponges moved from seagrass to mangrove habitat experienced a significant increase in abundance and taxonomic richness of 88 and 35%, respectively. Given that changes in the volume and aquiferous system (oscula diameter and density) of the hosts and in salinity were also recorded during the study period, it is concluded that the structure of the H. melanadocia-associated assemblages was not only influenced by the habitat change but also by other factors such as host morphology and short-term variations in the population abundance of associated organisms.