Feeding in Syntopy: Diet of Hydromedusa tectifera and Phrynops hilarii (Chelidae)

Abstract

Stomach contents were obtained from 25 Hydromedusa tectifera and 47 Phrynops hilarii that live in syntopy in a pampasic stream in Buenos Aires province, Argentina. Both species are arthropod consumers. Copepods, ostracods, and hemipterans are the preferred items for P. hilarii, and H. tectifera prefers copepods, ostracods, immature dipterans (mainly chironomids), and ephemeropteran larvae. Items that most contribute to the diet of both species are immature chironomids, corixids, and belostomatids. Available food varies little among seasons, being slightly lower in winter months and part of the summer. Diet diversity changes by seasonal variation of prey item abundance in the diet of both species. Diet diversity is higher for P. hilarii (more generalist and broader trophic niche) than in H. tectifera, but there is no niche overlap between them. No significant correlation between the size of turtles and length of prey items was found. There is no evidence that the long neck of H. tectifera relates to piscivorous habits, because fish are a small fraction of its diet and arthropods constitute the bulk of the ingested items.

Seasonal activity and basking of the southernmost population of the freshwater turtle Phrynops hilarii (Chelidae)

“…In this case, turtles would reduce food intake and basking activities as a response instead of as a cause. In fact, our data on captures of P. hilarii throughout a whole year, together with data on prey availability and feeding information on the species from Alcalde, Derocco and Rosset (2010), demonstrate that neither activity nor food intake cease in the coldest months.…”

“…However, prey availability seems not to constrain the activity level or basking behaviour in the studied population of P. hilarii. Prey items are available throughout the year in the Buñirigo stream with variations in prey composition but not in prey abundance (see Alcalde, Derocco and Rosset, 2010). It is possible that turtles decrease their metabolism gradually as both photoperiod and temperature decrease.…”

New records of helminths in Chelidae freshwater turtles (Testudines) in South America

“…Molluscs, fish, and anurans act as intermediate hosts of digeneans belonging to Cryptogonimidae (Cribb et al, 2003;Miller & Cribb, 2008). The host species of the present study were considered generalist and/or opportunistic, with the diet composed of invertebrates (Insecta, Gastropoda, Crustacea, Hirudinea, Arachnida, Malacostraca, and Oligochaeta), anurans, fish and plant fragments (Huckembeck et al, 2007;Bonino et al, 2009;Alcade et al, 2010;Brasil et al, 2011;Assman et al, 2013). In this context, helminth infections may be related to the diet of the freshwater turtles, since these infections may be influenced by the habitat and eating habits of their hosts (Ferguson & Smales, 2006).…”

Carnian (Late Triassic) ostracods from the Sorgun Ophiolitic Mélange (Southern Turkey): Taxonomy, palaeoenvironment, and evidence of predation

“…Ostracods constitute a minor component of the diet of diverse organisms, such as bivalves, gastropods, echinoids, turtles, amphibians, fishes, annelids and other crustaceans including other ostracods (e.g., Lowndes, 1930;Harding, 1962;Reyment, 1966;Robertson, 1988;Penchaszadeh et al, 2004;Costa et al, 2006;Ghioca-Robrecht and Smith, 2008;Leal, 2008;Alcalde et al, 2010;Rossi et al, 2011;Vandekerkhove et al, 2012). Identifiable evidence for the predatory pressure imposed on ostracods in the fossil record is associated with drilling gastropods of the families Naticidae and Muricidae (e.g., Maddocks, 1988;Reyment and Elewa, 2002).…”