Evaluating benthic feeding activity of reef fish using remote video in São Vicente Is. (Cape Verde)

The Cape Verde Islands are located in the central Eastern Atlantic, ca. 750 km west of Senegal in West Africa. Due to the strong influence of the Canary Current, the North Equatorial Current and the North Equatorial Counter Current the establishment of coral reefs in the tropical Capeverdien archipelago is limited. Therefore, this tropical coral environment is characterized by rich fauna/flora like reef fish and macroalgae assemblages, encrusting calcareous algae, epilithic algal matrix, invertebrates, some Scleractinia hard coral and hydrocoral species. Remote underwater video method is being a growing trend as an alternative to traditional direct diver observations due to the bias associated whit the diver presence. The main objectives of this study were: (1) to use a remote video method to quantify and compare feeding rates of reef fish community in order to identify the main contributing species or functional groups, with higher interaction with the coralline substrate across depth and exposure; (2) evaluate the relations between benthic cover and feeding activity and the abiotic factors; (3) analyse the effect of the abiotic factors in the benthic percentage cover; (4) evaluate the performance of the potential functional contribution (PFC) index (Longo, 2011). Fixed HD underwater remote cameras at 2 m2 stationary plots for 5 min sampling intervals were deployed. The results of video analyses such as: fish sizes, fish species, individual number of bites were combined with abundance and biomass data obtained trough visual census transects (PFC). During the visual census, a second diver took substratum photo-quadrats and posterior percentage cover analyses were carried. It was clear that depth and exposure shaped the benthic communities. Hence, this study confirmed and reinforce that the variability of trophic groups across depth and exposure exists and the correlation between specific benthic coverage’s and species to. Moreover, the PFC has proven to be a precious tool for this type of herbivory quantifications studies.

ISCED Categories

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0511 - Biology", "0521 - Ecology