Decomposition Rates of Salamander (Ambystoma Maculatum) Life Stages and Associated Energy and Nutrient Fluxes in Ponds and Adjacent Forest in Southern Illinois

Abstract

Amphibian populations comprise a large fraction of vertebrate biomass in many freshwater and terrestrial ecosystems where they produce organic matter in the form of egg clutches and carcasses. A lack of quantitative information on the decomposition of these materials for any species precludes an accurate assessment of energy and nutrient fluxes from amphibians to detrital food webs and comparisons among taxa and systems. We estimated decay rates (−k) of Spotted Salamander (Ambystoma maculatum) egg clutches and larval and adult carcasses, and then used this information to estimate C and N fluxes associated with ambystomatid assemblages in breeding ponds. We found that all life stages represent a high quality source of organic matter (range C∶N = 3.7∶1–5.3∶1) in aquatic and terrestrial habitats, particularly in ponds where egg clutches and larvae are seasonally abundant. Decay rates for egg clutches (−k = 0.075 d−1), larval carcasses (−k = 0.758 d−1), and adult carcasses (−k = 0.062 d−1) were more rapid compared to published estimates for other types of animal matter in similar habitats and were much more rapid than estimates for detritus of dominant species of vegetation found in breeding ponds and adjacent forest in southern Illinois. For five regional breeding ponds, we estimated that mortality of larval A. maculatum provided a flux to detrital food webs ranging from 34.6–165.1 mg C m−2 d−1 and 6.6–31.5 mg N m−2 d−1 during decomposition; fluxes associated with egg clutches ranged from 38.8–895.0 mg C m−2 d−1 and 10.4–239.3 mg N m−2 d−1. Our study suggests that ambystomatid salamanders seasonally provide appreciable inputs of labile materials to detrital food webs and facilitate the rapid recycling of energy and materials within breeding ponds and between ponds and adjacent forest.