Seasonal Diet Shifts and Overlap Between Two Sympatric Catfishes in an Estuarine Nursery

Abstract

This study describes the seasonal feeding habits of different size classes of Cathorops spixii and Cathorops agassizii along an estuarine ecocline and the food overlap when different size classes occur together. These species were essentially zoobenthivorous, feeding mainly on Polychaeta Nereis sp., Copepoda Pseudodiaptomus acutus, Ostracoda Asterope sp., Gastropoda: Littorinidae, and Bivalvia Mytilus sp. and Anomalocardia brasiliana. However, during their life cycle and between different habitats and seasons, their trophic guild can change to zooplanktivore. The competition for resources was observed among C. spixii and C. agassizii, but was significantly reduced due to the seasonal diference in habitat use by different ontogenetic phases in the main channel of the estuary. The food niche separation was strongly influenced by environmental fluctuations, principally of salinity, resulting from rainfall and river inflow. High abundance of some preys, such as P. acutus (all estuary), Asterope sp. (upper and middle estuary), and Littorinidae (upper and lower estuary), could influence the significant diet overlap, principally during the rainy season, and call for more detailed studies of the benthic community structure. Moreover, dietary overlap was observed mainly between smaller sizes (intraspecific and/or interspecific) or between corresponding ontogenetic phases (interspecific), suggesting some differentiation in the diet in relation to the size class. Differences in prey type and size between the different ontogenetic phases of these ariids, principally among juveniles and adults, could be related to the size of the mouth, since adults are able to successfully capture larger preys or larger quantities of particular items.

Trophic relationships among fish assemblages on a mudflat within a Brazilian Marine protected area

“…In general, the results of the present study were similar to those of other studies of estuarine environments, corroborating the hypothesis that, although fish species composition may differ considerably among estuaries, the basic trophic structure within an estuary is usually very similar (ELLIOTT; DEWAILLY, 1995;BARLETTA;. Studies of South African estuarine ichthyofauna (HARRINSON; WHITFIELD, 2012) indicate that Zooplanktivore species were a dominant component in subtropical estuaries, probably due to river flow and nutrient supply within this region, whereas another study at that tropical bay also found Calanoida as the primary food resource for dominant fishes species (HAJISAME; IBRAHIM, 2008).…”

“…Although the number of guilds was constant, their compositions changed, as observed in the Zooplanktivore and Zoobenthivore-epifaune guilds. The increase, decrease, or replacement of species within a guild is a result to be expected in tropical regions (BARLETTA;. For example, BALDÓ and DRAKE (2002) suggested that the mysids (hyperbenthic) replace copepods (zooplanktonic) progressively in the diet of juvenile fish (2006) found that the grazing fish, which kept a roughly balanced diet between microphytobenthos and detritus, changed their exclusively herbivorous diet during summer to prey on nematofauna during winter on a mudflat.…”

“…The structures of fish assemblages that use the shallow areas of estuaries are strongly influenced by trophic relationships. Knowledge of the trophic web allows one to describe energy flows in ecosystems and ecological relationships among organisms (PAIVA et al, 2008;DANTAS et al, 2013). Thus, it is important to understand the trophic relationships between fish and their potential prey to understand the relationships among fish in a community.…”

Diet and trophic organization of the fish assemblage from the Mamanguape River Estuary, Brazil

“…This information may also aid ecosystem management, as it can be used to construct trophic models (Elliott et al, 2002;Dantas et al, 2013) or be ____________________ Corresponding editor: Andrés Abitia applied to studies of trophic ecology that include spatial, seasonal and ontogenetic changes in the diet of species (Guedes et al, 2015).…”

Dietary overlap and food resource partitioning among fish species of a tropical estuary in Northeastern Brazil

“…Overall, fish species exhibit different diets and feeding behaviors that help them to minimize niche overlap and interspecific competition for food estuarine resources (Alanara et al 2001;Dantas et al 2012). In estuaries, in particular, prior studies have shown that fish species commonly explore distinct food resources (Kanou et al 2004;Dolbeth et al 2008).…”