Diet composition and feeding habits of the eyespot skate, Atlantoraja cyclophora (Elasmobranchii: Arhynchobatidae), off Uruguay and northern Argentina

Abstract

The eyespot skate, Atlantoraja cyclophora, is an endemic species from the southwestern Atlantic, occurring from Rio de Janeiro, Brazil, to northern Patagonia, Argentina. The feeding habits of this species, from off Uruguay and north Argentina, were evaluated using a multiple hypothesis modelling approach. In general, the diet was composed mainly of decapod crustaceans, followed by teleost fishes. Molluscs, mysidaceans, amphipods, isopods, lancelets and elasmobranchs were consumed in lower proportion. The consumption of shrimps drecreased with increasing body size of A. cyclophora. On the other hand, the consumption of teleosts increased with body size. Mature individuals preyed more heavily on crabs than immature individuals. Teleosts were consumed more in the south region (34º -38ºS) and crabs in the north region (38º -41ºS). Shrimps were eaten more in the warm season than in the cold season. Prey size increased with increasing body size of A. cyclophora, but large individuals also consumed small teleosts and crabs. Atlantoraja cyclophora has demersal-benthic feeding habits, shifts its diet with increasing body size and in response to seasonal and regional changes in prey availability and distribution.La raya de círculos, Atlantoraja cyclophora, es una especie endémica del Atlántico Sudoccidental, que se distribuye desde Río de Janeiro, Brasil, hasta el norte de la Patagonia, Argentina. Los hábitos alimentarios de esta especie fueron evaluados frente a la costa de Uruguay y norte de Argentina, utilizando un enfoque de modelado de múltiples hipótesis. En general, la dieta estuvo compuesta principalmente por crustáceos decápodos (71,37 %IRI), seguido de peces teleósteos (28,54 %IRI). En menor proporción fueron consumidos moluscos, misidáceos, anfípodos, isópodos, anfioxos y elasmobranquios. El consumo de decápodos Natantia disminuyó con el incremento del tamaño del cuerpo de A. cyclophora. Por otro lado, el consumo de teleósteos se incrementó con el incremento del tamaño del cuerpo. Individuos maduros consumieron cangrejos en mayor proporción que individuos inmaduros. Los teleósteos fueron consumidos mayormente en la región sur (34º -38ºS) y los cangrejos en la región norte (38º -41ºS). Los decápodos Natantia fueron más consumidos en la estación cálida que en la estación fría. El tamaño de las presas consumidas se incrementó con el aumento del tamaño corporal de A. cyclophora, pero individuos de mayor tamaño no abandonadon el consumo de pequeños cangrejos y teleósteos. Atlantoraja cyclophora presenta hábitos alimentarios demersal-bentónicos, cambia su dieta con el incremento del tamaño corporal y en respuesta a cambios estacionales y regionales en la disponibilidad y distribución de las presas.

Trophic ecology of young‐of‐the‐year elasmobranchs in a critical habitat within the Río de la Plata outer estuarine waters

“…shrimps, crabs, isopods and cumaceans) is also characteristic of young individuals of bignose fanskate S. acuta Garman, 1877 (Barbini & Lucifora 2016a) and from several other skates inhabiting the SWA coast. Some examples include zipper sand skate Psammobatis extenta (Garman, 1913; Braccini & Perez ; Barbini & Lucifora 2012a), Rio skate Rioraja agassizii (Müller & Henle, 1841; Barbini & Lucifora ), spotback skate Atlantoraja castelnaui (Miranda Ribeiro, 1907; Barbini & Lucifora 2012b) and eyespot skate A. cyclophora (Regan, 1903; Barbini & Lucifora 2016b). Therefore, preying on small crustaceans seems to be a wide‐spread adaptation among early‐life stages of these bottom‐dwelling feeders in the region.…”

Reproductive biology of the eyespot skate Atlantoraja cyclophora (Elasmobranchii: Arhynchobatidae) an endemic species of the Southwestern Atlantic Ocean (34ºS - 42ºS)

“…In summary, the results obtained in this work were consistent with those reported for this species in Brazilian populations (Oddone, Vooren, 2005;Oddone et al, 2008) and suggest that the pattern of sexual and morphometric development of A. cyclophora would be similar between regions. Especially, if it is taken into account that this species maintains its feeding habits along its distribution range, using similar food resources and possibly having the same trophic role (Barbini, Lucifora, 2016). Ebert et al (2008) and Frisk, Miller (2009) exposed that for species with a large geographic range, the differences in size at maturity and other vital rates may have profound implications in the way that the species should be managed.…”

Ontogenetic diet shifts of rough scad Trachurus lathami in the North Patagonian shelf (south‐west Atlantic Ocean)

“…Since the mid‐1990s, an increasing number of T. lathami individuals has been captured in the ACS between 35° and 41°S for research purposes (Orlando et al ., 2018). It has been mentioned as a key prey in the diet of many bony fishes of commercial interest ( i.e ., stripped weakfish Cynoscion guatucupa , García & Marí, 2008; Brazilian flathead Percophis braziliensis , Milessi & Marí, 2012; Argentine hake Merluccius hubbsi , Cousseau, 1967), elasmobranch fishes ( i.e ., skates, Barbini & Lucifora, 2011a, 2011b, 2016a, 2016b) and marine mammals ( i.e ., franciscana dolphin Pontoporia blainvillei , Paso‐Viola et al ., 2014; South American sea lion Otaria flavescens , Jarma et al ., 2019). Hence, both as prey and/or as a potential competitor for food items with co‐current E. anchoita and S. colias , the species can be considered an important component of the ACS marine ecosystem.…”