Alimentación de Characidium rachovii (Characiformes: Crenuchidae) y Pyrrhulina australis (Characiformes: Lebiasinidae) en lagunas someras de la provincia de Corrientes, Argentina.

Abstract

Feeding of Characidium rachovii (Characiformes: Crenuchidae) and Pyrrhulina australis (Characiformes: Lebiasinidae) in shallow lakes of Corrientes, Argentina. Fishes display diverse feeding strategies that may undergo modifications through ontogeny or seasonally with ecological implications in the food webs. Even though the significance of fishes as top predators is recognized, the diet of many of them is still scarcely known; especially in fish that inhabit shallow lakes densely vegetated. The aim of this study was to investigate the diet of Characidium rachovii and Pyrrhulina australis of different size classes (I, II and III); during winter and summer, and estimate their trophic niche breadth. The field work was carried out in two shallow lakes fed by rain (Soto and Pampin lake, Corrientes province), from July 2011 to August 2012. The stomach contents of 104 individuals of C. rachovii and 91 specimens of P. australis were examined. Accumulation curve showed that the number of analyzed stomachs was representative for both species. Twenty three food items for C. rachovii and twenty eight for P. australis were recognized in the gut contents. According to the index of relative importance (IRI), both species feed preferably on cladocerans and midges (Chironomidae), and both species showed a large overlap in their diets (85 %), according to Morisita index. However the diversity of food items and the trophic niche breadth of P. australis (1 D = 8.86; B = 4.76) were higher than C. rachovii (1 D = 3.37; B = 2.25). Significant differences were observed in the diet of three sizes of P. australis (χ2, p < 0.01) and between the sizes I and III of C. rachovii (χ2, p = 0.03). In both species the diversity of food items increased with increasing their size. Between seasons, the diet differences were significant for both species (χ2, p < 0.0001). The high feeding overlap indicates that both species mostly use the same resources. Notwithstanding this, both the number of food items as the diversity and breadth of the trophic niche, suggest that these species use different feeding strategies, C. rachovii showed a trend towards specialization in microcrustacean consumption; while P. australis exhibited a broader trophic spectrum, incorporating insects from littoral areas and from the terrestrial community. The loss of the trophic dominant resource, by increasing urbanization on the margin of the studied shallow lakes, could lead to increased competition, due to the wide diet overlap in both species. Rev. Biol. Trop. 64 (2): 603-615. Epub 2016 June 01.

Pathology associated with three newClinostomummetacercariae from Argentina with morphological and DNA barcode identification

“…Rachow's Darter Tetra is a freshwater fish that feeds on small invertebrates (Bonetto et al ., 1978; Casciotta et al ., 2005; Teixeira de Mello et al ., 2011; Bastos et al ., 2013; Ibarra-Polesel & Poi, 2016). This species is prey to larger fish, such as Hoplias malabaricus Bloch, 1794 and Crenicichla lepidota Heckel, 1840 (Ibarra-Polesel & Poi, 2016), and birds.…”

Do local environmental factors structure the trophic niche of the splash tetra, Copella arnoldi? A test in an Amazonian stream system

“…Our findings of high detritus/sediment consumption by C. arnoldi contradict previous studies that characterize the diet of lebiasinids as insectivores with a tendency to omnivory. Similarly, Pyrrhulina australis Eigenmann & Kennedy, 1903 had a different trophic composition in lagoons of the middle Paraná River, based primarily on aquatic larvae of dipterans and cladocerans (Arias and Rossi 2005;Ibarra-Polesel and Poi 2016). Therefore, lebiasinids exhibit a larger variation in their trophic niche than usually assumed, varying from diets composed mainly by allochthonous prey to diets composed mainly by autochthonous prey.…”

Sistemática y distribución geográfica de la familia <i>Crenuchidae</i> (Ostariophysi: Characiformes) en la Argentina

“…En cuanto a la alimentación, Characidium rachovii muestra un nicho trófico similar al descripto para otras especies del género. Presenta una dieta carnívora y depreda preferentemente sobre larvas de insectos y microcrustáceos (cladóceros y copépodos) asociados a la vegetación acuática litoral (Oliveros, 1980;Ibarra & Poi, 2016 -.-.-.-.-.-.-.-.-.-.-.-.-…”

“…Por otra parte, la información colectada sobre dieta, estrategia alimentaria y preferencia de hábitat, muestra que entre las distintas especies del género Characidium existen grandes similitudes. Los hábitos de forrajeo sobre la comunidad bentónica y la fauna asociada a la vegetación de arroyos y lagunas, así como el consumo de una amplia gama de recursos en baja cantidad (comportamiento oportunista) parece ser el patrón dentro del género (Bastos et al, 2013;Ibarra Polesel & Poi, 2016). Los estudios sobre dieta (Oliveros, 1980;Sabino & Macedo, 1990;Arias, 1998;Aranha et al, 1998Aranha et al, y 2000da Motta & Sanches Uieda, 2004;Souza Braga, 2005;Barreto & Aranha, 2006;Fernández et al, 2012;Bastos et al, 2013;Ibarra Polesel & Poi, 2016) señalan que las especies de este género consumen preferentemente larvas de insectos y microcrustáceos.…”

“…Los hábitos de forrajeo sobre la comunidad bentónica y la fauna asociada a la vegetación de arroyos y lagunas, así como el consumo de una amplia gama de recursos en baja cantidad (comportamiento oportunista) parece ser el patrón dentro del género (Bastos et al, 2013;Ibarra Polesel & Poi, 2016). Los estudios sobre dieta (Oliveros, 1980;Sabino & Macedo, 1990;Arias, 1998;Aranha et al, 1998Aranha et al, y 2000da Motta & Sanches Uieda, 2004;Souza Braga, 2005;Barreto & Aranha, 2006;Fernández et al, 2012;Bastos et al, 2013;Ibarra Polesel & Poi, 2016) señalan que las especies de este género consumen preferentemente larvas de insectos y microcrustáceos. Este consumo estaría favorecido por la coloración disruptiva y forma corporal que responderían a un ajuste al modo de captura de las presas que es del tipo quieto y al acecho entre las rocas del fondo o la vegetación (Arias, 1998;Bastos et al, 2013;Ibarra Polesel & Poi, 2016).…”