Feeding comparisons of four batoids (Elasmobranchii) in coastal waters of southern Brazil

Abstract

Food partitioning between species is a common strategy for avoiding resource competition which allows the coexistence of two or more species in the same place. In order to evaluate the feeding of four species of batoids regularly caught by artisanal fisheries in southern Brazil, the present study aimed to analyse and compare the diet of the four batoid species. The Chola guitarfish, Rhinobatos percellens, had a specialized diet, consisting predominantly of blue crabs Callinectes sp., followed by teleost fish. The Lesser guitarfish Zapteryx brevirostris also had a very specialized diet, consuming mainly on Polychaeta, followed by Caridea shrimp. The Cownose ray, Rhinoptera bonasus, fed mainly on Ophiuroidea, followed by Gastropoda and Bivalvia. Finally, the Rio skate Rioraja agassizi, fed on teleost fish, Gammaridae, Caridea shrimp and Dendrobranchiata shrimp. An analysis of similarity showed significant differences among species in their diet. The trophic levels of the batoids in this study are ,4.0, placing them in intermediate trophic levels. The analysis of the diets indicates that feeding differs substantially among the four species, suggesting a partitioning of food resources available in the environment.

Feeding ecology of elasmobranch species in southeastern Brazil

“…The same behavior was observed for the species in Uruguay and Argentina by Barbini, Lucifora (2012). Bornatowski et al (2014d) found that teleosts were the main item, followed by gammarideans, caridean shrimp and dendobranchiate shrimp.…”

Diet of the chola guitarfish, Rhinobatos percellens (Rhinobatidae), in the Paranaguá Estuarine complex

“…In general, decapod crustaceans tended to be the most important prey of rhinobatid species (e.g. Talent 1982, Kyne and Bennett 2002, White et al 2004, Bornatowski et al 2010, 2014b. The importance of Polychaeta and Amphipoda was reduced in R. percellens feeding, which agreed with the results obtained on the continental shelf for the same species (Bornatowski et al 2010(Bornatowski et al , 2014b.…”

“…On the other hand, R. percellens, has a relatively larger mouth, allowing the consumption of elusive larger prey such as blue crabs and flatfishes (Dean et al 2007). This fact was observed in the continental shelf by Bornatowski et al (2010Bornatowski et al ( , 2014b, but not in the present study. So, we hypothesized that 1) R. percellens feed on the most abundant preys in the environment or, 2) large individuals >75 cm -TL (see Bornatowski et al 2010Bornatowski et al , 2014b) feed on elusive larger preys.…”

“…Talent 1982, Kyne and Bennett 2002, White et al 2004, Bornatowski et al 2010, 2014b. The importance of Polychaeta and Amphipoda was reduced in R. percellens feeding, which agreed with the results obtained on the continental shelf for the same species (Bornatowski et al 2010(Bornatowski et al , 2014b. Other food items, such as the squid Lolliguncula brevis (Blainville, 1823), was one of the food items of R. percellens on the continental shelf of Southern Brazil (Bornatowski et al 2010(Bornatowski et al , 2014b, but it did not appear on this study in estuarine waters.…”

“…Navia et al 2007, Vaudo and Heithaus 2011, Bornatowski et al 2014b. Therefore, batoids can be considered mesopredators that provide an important link between top predators and lower trophic levels in the marine ecosystem, and play an important role in marine ecosystem dynamics (Vaudo and Heithaus 2011).…”