PARENT SESSION
Contributed Oral Session 17: Reptiles and Amphibians: Habitat; and Communities
Monday, August 8, 8:00 AM - 11:30 AM, Meeting Room 524 B, Level 5, Palais des congrès de Montréal
Biotic and abiotic influences on pond and forest subsidies associated with ambystomatid salamanders in southern Illinois.
Regester, Kurt*,1, Whiles, Matt1, Lips, Karen1, 1 Southern Illinois University, Carbondale
ABSTRACT- Breeding adults and metamorphosing larval amphibians transfer materials between freshwater and terrestrial ecosystems during seasonal migrations and emergences, although rarely have energy flow and nutrient cycling associated with different life stages been quantified. During 2002-2004, we intensively sampled ambystomatid salamander assemblages in five forested ponds in southern Illinois to quantify energy and nutrients associated with egg deposition, larval production, and emergence of metamorphosed larvae. Adult breeding salamanders represented standing stocks ranging from 1.9-417.7 g C ha-1 (0.5-110.0 g N ha-1) for assemblages and 1.9-406.9 g C ha-1 (0.5-107.1 g N ha-1) for populations, and was highest for Ambystoma maculatum. Oviposition by female salamanders added 3.8-554.8 g C yr-1 (0.7-105.7 g N yr-1) to ponds. Carbon cycling associated with larval production ranged from 0.1-3.8 g m-2 yr-1 (0.1-1.0 g N m-2 yr-1) in three ponds that did not dry during development (annual production to biomass ratio: range=3-14), with as much as 4.0 g m-2 yr-1 (1.1 g N m-2 yr-1) produced by an entire assemblage. Emergence production averaged 21% (range=2-99%) of larval production; larval mortality within ponds accounted for the difference. Hydroperiod and intraguild predation limited larval production in some ponds, but emerging metamorphs exported an average of 35.6±10.0 g C yr-1 (range=10.0-91.7 g C yr-1) and 9.4±2.6 g N yr-1 (range=2.7-24.2 g N yr-1) from ponds to surrounding forest. For the three ponds where larvae survived to metamorphosis, salamander assemblages provided an average net flux of 212.0±60.4 g C yr-1 and 37.6±11.0 g N yr-1 into pond habitats. Our study is one of the first to quantify the contribution of salamanders to energy and nutrient budgets of ponds and demonstrates the influence of hydroperiod and species composition on fluxes between aquatic and terrestrial habitats. These results are particularly important in light of declines among many amphibian populations.
Key words: emergence production, secondary production, subsidy, aquatic-terrestrial link