Projeto de pesquisa

Study area
This study will be conducted along the SSC, located in the northern coast of São Paulo State. Sampling sites will be defined after preliminary diving at several locations along the channel, at both the coasts of llhabela and São Sebastião. Three sites of each habitat type (unvegetated, Halodule and Halophila) will be sampled assuring interspersion, avoiding pseudorreplication, and generality to a spatial scale of tens of km. Depth will range from 1 to 3 m, where seagrass meadows are more frequently found in the area.
Task 1: Comparison of invertebrate assemblages and environmental parameters at vegetated and unvegetated habitats
Replicate corer samples will be obtained at each site of each habitat type, and at two different seasons allowing a test for temporal consistency of any trends. Corer sampling will be carried out by SCUBA divers, aiming sample volumes of ca. 3 l restricted to the top 15 cm sand layer. Temperature and salinity readings will be obtained in the field before obtaining each sample. In the laboratory, individuals retained in 500 microm sieves will be identified and counted under a dissecting microscope. Sediment subsamples will be separated to estimate grain size distributions and organic matter contents. In the case of vegetated habitats, seagrass materials will be sorted out and dry weighed.
Task 2: Estimates of predation pressure and consumer exclusion experiments
Two sites o each habitat type will be selected for further experimental work. Fish predation pressure will be tentatively assessed by a combination of field procedures, including haul seining (estimates of fish assemblage structure and density), baiting (consumption rate on a prey common to all habitat types) and Go-Pro video sampling (bite frequency on natural prey). Consumer exclusion will be achieved by caging 40 X 40 replicate square plots, using a 3 cm plastic mesh, at each site. Control (marked units, ot