Trophic ecology and food consumption of fishes in a hypersaline tropical lagoon

Abstract

This study evaluated the trophic ecology (diet composition, trophic strategy, similarities and overlap between species, feeding period and food consumption) of six benthivorous fish species in Araruama Lagoon, the largest hypersaline tropical lagoon on the east coast of South America, with an area of 210 km(2) and an average salinity of 52. The burrfish Chilomycterus spinosus fed on Anomalocardia flexuosa shell deposits, ingesting associated fauna. The caitipa mojarra Diapterus rhombeus differed from all other species, having not only the highest proportions of algae and Nematoda, but also feeding on polychaete tentacles. The two mojarras Eucinostomus spp. showed similar trophic strategies, feeding mostly on Polychaeta. The corocoro grunt Orthopristis ruber also fed mainly on Polychaeta, but differed from Eucinostomus spp. in secondary items. The whitemouth croacker Micropogonias furnieri fed mainly on small Crustacea at night, showing a high number of secondary prey items with low frequencies and high prey-specific abundance. The daily food consumption (g food g(-1) fish mass) for Eucinostomus argenteus was 0·012 and was 0·031 and 0·027 for M. furnieri in two different sampling events. The diet similarities between Araruama Lagoon and other brackish and marine environments indicate that hypersalinity is not a predominant factor shaping the trophic ecology of fishes in this lagoon. The stability of hypersaline conditions, without a pronounced gradient, may explain the presence of several euryhaline fishes and invertebrates well adapted to this condition, resulting in a complex food web.

Do the shallow‐water habitats of a hypersaline tropical estuary act as nursery grounds for fishes?

“…This movement emphasizes the importance of the nursery function of the Tubarão river estuary. Other studies of the Brazilian coast have reported that these species are most abundant as juveniles in estuarine areas of bays (Vilar et al., ), coastal lagoons and mangroves (Almeida‐Silva et al., ; Xavier et al., ) before migration to the coastal zone.…”

“…Baltz, Fleeger, Rakocinski, and McCall () showed that salinity had eco‐physiological effects on the growth rates of juveniles, whilst Almeida‐Silva et al. () reported that competition and predation are reduced in hypersaline conditions. Vega‐Cendejas and Santillana () established that high salinity creates an environment that is unfavorable to predators thus allowing tolerant fish species better access to food and space in the upstream gradient in estuaries.…”

“…There are some hypersaline environments along the Brazilian coast for which there are few records of fish ecology although there have been two studies of the Araruama Lagoon, an important hypersaline lagoon: an analysis of the relationship between length and weight in 25 fish species (Franco, Araújo, & Araújo, ) and an analysis of the trophic ecology of six benthivorous fishes (Almeida‐Silva et al., ). The hypersaline estuaries in Northeastern Brazil have been poorly studied.…”

Dietary composition of black drum Pogonias cromis in a hypersaline estuary reflects water quality and prey availability

“…Similarly, in a hypersaline lagoon in South America, increased food‐web complexity has been related to the stability of hypersaline conditions (Almeida‐Silva et al . , ). Longer‐term research is warranted to better understand the response and recovery of food‐web functioning in hypersaline systems as a result of acute salinity fluctuation.…”

Trophic relationships in fish assemblages of Neotropical floodplain lakes: selectivity and feeding overlap mediated by food availability

“…This condition allows ecologically similar species to coexist, and can reduces competition among them (Schoener, 1974;Correa & Winemiller, 2014;Olson et al, 2015). Habitat structure and the daily activities of the species as important factors in determining interspecific interactions may also be considered (Gelós et al, 2010;Carniatto et al, 2012;Almeida-Silva et al, 2015); these aspects were not evaluated in this study.…”