Trophic structure of a nektobenthic community exploited by a multispecific bottom trawling fishery in Northeastern Brazil

Abstract

We used complementary stable isotope (SIA) and stomach content (SCA) analyses to investigate feeding relationships among species of the nektobenthic communities and the potential ecological effects of the bottom trawling of a coastal ecosystem in northeastern Brazil. Carbon (δ13C) and nitrogen (δ15N) compositions were determined for five basal sources and 28 consumers, from zooplankton to shrimp and fish species. Fishes and basal sources showed a broad range of δ15N (fishes: 6.49–14.94‰; sources: 2.58–6.79‰) and δ13C values (fishes: -23.86 to -13.71‰; sources: -24.32 to -13.53‰), while shrimps and crabs exhibited similar nitrogen and carbon ratios. Six trophic consumer groups were determined among zooplankton, crustaceans and fishes by SIA, with trophic pathways associated mostly with benthic sources. SCA results indicated a preference for benthic invertebrates, mainly worms, crabs and shrimps, as prey for the fish fauna, highlighting their importance in the food web. In overall, differences between SCA and the SIA approaches were observed, except for groups composed mainly for shrimps and some species of high δ15N values, mostly piscivorous and zoobenthivores. Given the absence of regulation for bottom trawling activities in the area, the cumulative effects of trawling on population parameters, species composition, potentially decreasing the abundance of benthic preys (e.g., shrimps, worms and crabs) may lead to changes in the trophic structure potentially affect the food web and the sustainability of the fishery.

Ecomorphological relations of sympatric juveniles of Clupeiformes from a Brazilian sandy beach

“…These authors observed distinct feeding preferences between species, A. clupeoides being a piscivorous one, H. clupeola showing a phytoplanktonic preference in its diet, and A. tricolor together with O. oglinum a zooplanktonic preference. These differences in feeding habit between the species corroborate with literature, as they are reported to belong to distinct trophic guilds (Mai & Vieira, 2013;Andrade-Tubino et al, 2019;Favero et al, 2019;Lira et al, 2021) coupled with differences in ecomorphological attributes which possibly contribute to their coexistence.…”

“…To evaluate eventual correlations between morphological similarities, the species and feeding were classified into the following trophic guilds: carnivore first order (Favero et al, 2019): individuals that feed primarily of benthic invertebrates; carnivore second order (Favero et al, 2019): fish with the diet based on invertebrates which may occasionally consume fish; planktivore (Favero et al, 2019): species that feed predominantly on phytoplankton occasionally also feeding on zooplankton; zoobenthivore (Elliott et al, 2007): fish species that feed predominantly on invertebrates associated with the substrate, specially animals that live just above the sediment; and zooplanktivore (Elliott et al, 2007): fish species with diet predominantly composed by zooplankton, such as planktonic crustaceans and fish eggs and larvae. Species feeding guilds classification was based on literature (Mai & Vieira, 2013;Andrade-Tubino et al, 2019;Favero et al, 2019;Lira et al, 2021).…”

Estuarine food web structure and relative importance of organic matter sources for fish in a highly connected Northeastern Brazil ecotone

“…Functional guild: ES, estuarine species; MM, marine migrants; MS, marine stragglers; Trophic guild: HV, herbivore; DV, detritivore; OV, omnivore; PV, piscivore; ZB, zoobenthivore; ZP, zooplanktivore; IR, relative importance based on the abundance and frequency of species: 1, abundant and frequent; 2, abundant and infrequent; 4, less abundant and infrequent. *Ecological role information obtained by (Ferreira et al, 2019); (Lira et al, 2021b); (Gonzalez et al, 2019). **Economic role information obtained by (ESTATPESCA, 2006;Lira et al, 2010…”

“…However, studies characterising the functioning of tropical coastal ecosystems are scarce. Except for the studies published by Lira et al (2021b) and (Pereira et al, 2020), those available are monospecific (Gonzalez et al, 2019;Soares et al 2020, Pelage et al 2021 or only focus on the relative importance of basal food sources to macroconsumers (Claudino et al, 2015).…”