Preliminary data on the feeding habits of the freshwater stingrays Potamotrygon falkneri and Potamotrygon motoro (Potamotrygonidae) from the Upper Paraná River basin, Brazil

Abstract

Stingrays of the Potamotrygonidae family are a singular group of Neotropical ichthyofauna. Although ancient reports exist about the group, there are still many questions that need to be clarified, such as the biology of the species that occur in the Paraná-Paraguay River system. In the present work, the diet of Potamotrygon falkneri and Potamotrygon motoro, captured in the Upper Paraná River, downstream from the Engenheiro Souza Dias Hydroelectric Power Station (UHE Jupiá), was analyzed. Both species showed a diversified diet, consisting of 14 food items, including Mollusca, Crustacea, Insecta and fish, with the predominance in diversity and abundance of aquatic insects. Only one individual of each species ingested fish. Potamotrygon motoro consumed mainly Ephemeroptera, while P. falkneri consumed mainly Mollusca, Hemiptera and Trichoptera. The data apparently indicate a more specialized diet for P. motoro, consuming more Ephemeroptera (Baetidae), and a more generalized diet for P. falkneri. The analysis of individuals captured in three microhabitats that differ in function of the substrate type and presence of marginal vegetation, suggests differences in the food items consumed.

Insectivory in Potamotrygon signata (Chondrichthyes: Potamotrygonidae), an endemic freshwater stingray from the Parnaíba River basin, northeastern Brazil

“…Ontogenetic differences in dietary habits and between immature and mature individuals have been reported for freshwater stingrays by Charvet- Almeida (2006) and Silva and Uieda (2007), as well as for marine batoids (Muto et al, 2001;Moura et al, 2008).…”

“…An essentially insectivorous diet was also reported for the congeners P. orbignyi (Lasso et al, 1996;Rincon, The numbers in bold correspond to the highest values. 2006; Charvet- Almeida, 2006) and P. motoro from the upper Paraná River (Silva and Uieda, 2007). On the Marajó Island, at the lower Amazon drainage, P. motoro also consumed insects, but decapod crustaceans and fish were the dominant items .…”

“…A recent literature review on feeding studies of Brazilian elasmobranchs (Aguiar and Valentin, 2010) pointed out only three published papers on the diet and/or feeding behavior of potamotrygonids (Lonardoni et al, 2006;Garrone-Neto andSazima, 2009a, 2009b). Overlooked papers in this review were those by Shibuya et al (2009), analyzing stomach contents of freshwater stingrays from the middle Negro River, and by Silva and Uieda (2007) and Lonardoni et al (2009), on the feeding behavior of Potamotrygon falkneri Castex and Maciel, 1963 and Potamotrygon motoro (Natterer in Müller and Henle, 1841). After this review, two additional papers were published Moro et al, 2011), focusing on the diet of P. motoro and P. orbignyi, respectively.…”

Catfishes as prey items of Potamotrygonid stingrays in the Solimões and Negro rivers, Brazilian Amazon

“…Potamotrygonidae stingrays consume a wide variety of prey, feeding on insects, mollusks, crustaceans, and teleosteans (Lasso et al 1996, Lonardoni et al 2006, Rincon-Filho 2006, Silva & Uieda 2007, Shibuya et al 2009). Their diets may be directly related to the availability of any given prey, and some species display specific dietary habits [e.g.…”

“…Specimens of Potamotrygon motoro (Müller & Henle 1841) from the Middle Negro River in the Brazilian Amazon is known to consume principally crustaceans, although teleosteans also appear to be an important element in its diet (Lasso et al 1996, Shibuya et al 2009). Silva & Uieda (2007) reported that the two potamotrygonid species found in the Paraná River (Potamotrygon falkneri Castex & Maciel 1963 and P. motoro) have diversified diets, and teleosteans were found in the stomach contents of just one specimen of each species. In addition to these observations, Garrone-Neto & Uieda (2009) pointed out that the rare occurrences of catfishes (Siluriformes) in stingray diets may be considered occasional, as a consequence of inexperience and/or an accidental predation, since one of the analyzed specimens (a young individual of P. falkneri) had a dead catfish stuck in its oral chamber.…”