Estrutura trófica da ictiofauna estuarina e marinha do complexo Itapissuma/Itamaracá, norte de Pernambuco, Brasil

Abstract

The estuarine and coastal environments of the Itapissuma/Itamaracá Complex (IIC), Pernambuco, Brazil, are areas of relevant biological, fishing and social importance. This work has the objective of investigating the trophic structure of the ichthyofauna and the connectivity between the estuarine and coastal environments through the environmental and trophic guilds, the stable isotopes of carbon (δ13C) and nitrogen (δ15N) and the Ecopath model. Data were collected between 2013 and 2015 in the estuarine and coastal environments of IIC. A total of 140 species from 34 families were collected, 65 species (47%) were exclusive in the estuary, 50 species (35%) in the coast and 25 (18%) in both environments. In the estuary, marine species were dominant in richness and biomass and estuarine species in abundance. Marine migrants presented greater richness, abundance and biomass in coastal waters. Zoobentívores dominated in richness and detritivores in abundance and biomass in the estuary. In the coast, zoobentívores presented greater richness and abundance and the piscivores had greater biomass. δ13C and δ15N were obtained from 9 basal sources, 8 invertebrates and 16 fish. In the estuary, δ13C of fish and δ15N of invertebrates and in the coast, δ13C of POM, SOM and δ15N of POM, SOM and fish were more enriched (p < 0.05). Species of fish caught in the estuary and coast indicated a low overlap of isotope niche (20.36%) between environments. Ecopath was based on 32 functional groups (3 primary producers, 6 invertebrates, 22 fish and 1 detritus). Invertebrates, Lutjanus spp. and Gobionelus oceanicus were highly consumed or exported in the IIC. Most fish biomass dominated at low trophic levels and primary consumers were the major sources of detritus. Predators feed predominantly on prey of low trophic levels, mainly benthic groups. Centropomus spp., Caranx spp. and Sphyraena spp. had a high impact on the trophic web and the increase of fishery negatively impacts Centropomus spp. and, positively, Sphyraena spp. The trophic level estimated by Ecopath and δ15N in IIC were highly correlated (R = 0.77). The IIC has high resilience capacity and complex trophic network dependent on the estuarine and coastal areas formed mainly by migrant and zoobentivorous species.