Parecer da Comissão Científica

Projeto do CEBIMar

Dados do solicitante

Carla Brunner Pavone

Natureza do projeto

Projeto de formação discente
Augusto Alberto Valero Flores

Pesquisadores ou docentes associados

Daniel Gorman


serviços, materiais consumíveis, equipamento.

Descrição do projeto

Ecosystem functioning of seagrass habitats in the São Sebastião Channel, SP, Brazil: Trophic complexity linked to diversified benthic invertebrate assemblages
Seagrasses often add physical complexity and trophic resources to otherwise bare substrates, potentially enhancing the abundance and diversity of vagile invertebrates, which may, in turn, trigger a sort of ecosystem functions. Two seagrass species are found along the São Sebastião Channel (SSC), SP, Brazil: Halodule emarginata, a long-standing and well established species, and Halophila decipiens, a more tropical species that has recently extended southwards and colonized the area. Compared to most other seagrass habitats worldwide, patches of both species are sparse and plant biomass low, but their presence may still be important to sustain invertebrate mesoherbivore assemblages which may either fuel benthic or pelagic carnivore trophic levels. In this project, we will first compare fish and benthic invertebrate assemblages among bare, Halodule and Halophila habitats along the SSC to better frame hypotheses on the role of these vegetated habitat types. We will then manipulate the access of consumers at all these three habitats in order to tease apart bottom-up and top-down processes led, respectively, by surplus trophic and shelter resources provided by seagrasses, or higher-order indirect predatory effects. We expect that any such effects would be weaker in Halophila compared to Halodule, given that plant-animal interactions in the former more recent habitat may have not developed yet.
seagrasses, invertebrate assemblages, fish, bottom-up processes, top-down control, Halophila, Halodule
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
Field sampling: August - September 2017; August - September 2018
Lab procedures: September - December 2017; September - December 2018
Data analyses: January - April 2018; January - April 2019
Writing August 2017, July 2019


Áreas sob responsabilidade do Prof. Augusto Flores e sala de preparações.
Equipamentos já disponíveis nas áreas laboratoriais acima (equipamento óptico, material de dissecção, peneiras, estufa, mufla).
- Não há necessidade de coleta de organismos -
Habitats não consolidados rasos (1-3 m) ao longo do canal de São Sebastião ainda não definidos.
- Nada a acrescentar -
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