Diet of Hydromedusa tectifera (Testudines-Chelidae) in a mountain stream of Córdoba province, Argentina

Abstract

The diet of Hydromedusa tectifera occurring in two mountain streams in the province of Córdoba is described through a comparative analysis of 154 individuals. Turtles were manually captured between August 2005 and August 2006 from streams at the localities of Tanti and Flor Serrana. Before being released, turtles were stomach-flushed, and sex and carapace length were recorded. The stomach contents were observed under stereomicroscope; prey items were identified and classified according to size and volume. The importance of the different items was quantified using the Index of Relative Importance (IRI). Similarity in the diet between sexes and among size classes and seasons of an annual cycle was evaluated using the simplified Morisita index. Trophic breadth was estimated with the Shannon diversity index. Detrended Correspondence Analysis (DCA) was used to evaluate differences in the diet between categories (sex, size classes). Fortyseven food items belonging to the following taxa were identified: leeches, annelids, gastropods, arachnids, insects, and fishes. According to the IRI value, the most important items in the diet of H. tectifera were larvae of Trichoptera (IRI = 33.5), fishes (IRI = 30), and naiads of Odonata (IRI = 25.2). The relative importance of the items varied with size of turtles but not with sex. Size of prey consumed increased with increasing turtle size. A greater trophic breadth was observed in smaller individuals.

A new pelomedusoid turtle,Sahonachelys mailakavava, from the Late Cretaceous of Madagascar provides evidence for convergent evolution of specialized suction feeding among pleurodires

“…Studies of Chelodina spp. and Hydromedusa spp., however, have established a much wider carnivorous dietary spectrum that includes small aquatic invertebrates (mostly insect larvae) and vertebrates [95][96][97][98]. A similarly broad, opportunistic food palate seems plausible for Sahonachelys mailakavava as well.…”

Nocturnal and diurnal activity of armored suckermouth catfish (Loricariidae: Pterygoplichthys) associated with wintering Florida manatees (Trichechus manatus latirostris)

“…Chi-square (3 x 2 comparison) test indicated no statistical difference between major diel period and the proportion of manatees with armored catfish (χ 2 = 4.634, df = 2, p = 0.0986). Willard, 1985;and Caiman latirostris;Borteiro et al, 2009), aquatic snakes (e.g., Helicops; Aguiar & Di-Beernardo, 2004), freshwater turtles (e.g., Hydromedusa tectifera; Bonino et al, 2009), the large catfishes Phractocephalus hemioliopterus and Pseudoplatystoma fasciatum and certain other predatory fishes (Nico & Taphorn, 1988;Bistoni et al, 1995;BarbarinoDuque & Winemiller, 2003).…”

Estructura poblacional de la tortuga blanca, De r matemys maw ii Gray (Testud i nes , Dermatemydidae), en la Laguna El Perú, Petén, Guatemala

“…Para calcular la abundancia relativa durante los meses de estudio se consideró la captura mensual por unidad de esfuerzo (CPUE), determinada como el número total de los individuos capturados dividido entre el número de trasmallos colocados por las horas diarias que estuvieron abiertos (Lescano, Bonino & Leynaud, 2008;Zenteno, Barba, Bello & Ochoa, 2010). El cambio mensual de la abundancia relativa de la especie se determinó mediante la comparación del número de individuos capturados por el esfuerzo de captura mensual y se multiplicó por 100 (Lescano et al, 2008). Por otro lado para determinar si las variables ambientales tienen relación con el número de individuos capturados en la época seca y lluviosa, se midieron datos de profundidad del agua.…”