Ecología trófica en larvas de <i>Rhinella arenarum</i> (Anura: Bufonidae) en agroecosistemas y sus posibles implicaciones para la conservación

Abstract

Trophic ecology in tadpoles of Rhinella arenarum (Anura: Bufonidae) in agroecosystems and their possible implications for conservation. The progress of the agriculture border has led an important loss of natural habitats, with significant consequences for biodiversity. In this sense, the studies in anuran amphibian tadpoles inhabiting these environments are relevant, because the larval stage is a phase of population regulation. The aim of this study was to analyze the body condition and diet in Rhinella arenarum, tadpoles, an anuran species widely distributed in South America and that inhabit agroecosystems. Three sites were sampled, two agroecosystems with different alteration degrees (C1 and C2) and an uncultured (SM) third place. The captured tadpoles were anesthetized, fixed and preserved in formaldehyde (10%). Subsequently, body measurements were made and the complete intestine was removed and analyzed for food items under a binocular microscope. The diet in R. arenarum tadpoles has a dominance of algae Bacillariophyceae, followed by Cyanophyceae. In particular, the class Bacillariophyceae, due to the presence of the genus Navicula, Nitzschia, Gomphonema and Hantzschia, was important in the diet of the anurans in those agroecosystems. Class Cyanophyceae, mainly represented by genus Oscillatoria and Euglenophyceae represented by Euglena and Strombomonas, were predominant in the diet of the anurans in SM. Some differences in the total items consumed by tadpole were observed between the studied sites. Tadpoles that inhabit the modified sites (C1 and C2) recorded a significantly smaller amount of food. Moreover, the tadpoles that inhabit these sites showed a lower body condition. The presence of certain algae associated with eutrophic environments, could indicate some pollution in agroecosystems (C1 and C2). Food resources would be lesser in places with strong agricultural activity, possibly with a greater degree of eutrophication. A smaller food amount could have consequences at population level for the short and long time terms, because of its impact on individual growth. Larval diet is suggested as a potential bioindicator of environmental health for these areas.

Trophic ecology of syntopic anuran larvae, Rhinella arenarum (Anura: Bufonidae) and Hypsiboas cordobae (Anura: Hylidae): its relation to the structure of periphyton

“…Under a stereoscopic microscope complete intestine of 12 larvas was removed and their contents were analyzed (only first third) according to Bionda et al (2012). For species identification, a Zeiss optic microscope was used.…”

“…Consequently, studies on amphibian larvae diet may represent a general measure of the offer and trophic availability of different habitats and be a tool for characterization and monitoring as bioindicator of environmental quality (Ju¨ttner et al, 1996;Blanco et al, 2004;Dı´az Quiros and Rivera Rondo´n, 2004;Bionda et al, 2012Bionda et al, , 2013.…”

“…Several studies have been performed about the diet of larval amphibians in central Argentina (Arana et al, 2003(Arana et al, , 2005Bionda et al, 2012Bionda et al, , 2013. But neither of these studies has focused on analyzing dietary overlap between species and the structure and architecture of the consumed algal community, thus becoming the first reference to Argentina, contributing significantly to the theoretical framework of the ecology of neotropical tadpoles.…”

Anuran larvae diet from agroecosystem’s ponds: environmental quality and implications for their populations

“…In addition, may reduce survival and increase predation pressure (Carey and Bryant, 1995;Altig et al, 2007). Recent evidence has revealed that the deterioration of agricultural ponds might modify the trophic availability, affecting the development and growth of tadpoles that are sustained by such environments (Bionda et al, 2012;2013). Impacts on the early stages of development negatively affect the recruitment of metamorphs (Schmutzer et al, 2008;Burton et al, 2009) and the populations' size (Heyer, 1974;Wilbur, 1980).…”

“…However, most tadpoles are primarily herbivorous, consuming a wide variety of algal taxa (Kupferberg, 1997;Altig et al, 2007). Diatoms are one of the most common taxa of algae in the diet of tadpoles (Bionda et al, 2012). Diatoms are widely used to monitor river organic pollution and eutrophication because they are sensitive to water chemistry, especially ionic content, pH, dissolved organic matter, and nutrients (Potapova and Charles 2007;Gómez and Licursi, 2001).…”