Effects of Anuran Larvae on Aquatic Processes Associated with Water Quality

摘要

Laboratory and field experiments and field observations were conducted to assess the role of native anuran larvae in several ecosystem processes associated with water quality. The impacts were investigated of these animals on populations of problem-causing toxic cyanobacteria, on rates of sedimentation and water clearing, on rates of decomposition of sediments and on export of biomass from aquatic to terrestrial systems. Anuran larvae were killed by intraperitoneal injection of the toxic cyanobacteria Aphanizomenon flos-aquae and Anabaena flos-aquae, but were unaffected by injections of Anacystis aeruginosa. All three species of cyanobacteria were effectively ingested by anuran larvae without ill effects; the filimentous forms were quickly exterminated from experimental chambers. Cyanobacteria were not a good ration for the larvae, as they lost weight rapidly on a diet of pure cyanobacteria. Anuran larvae were extremely effective at removing suspended sediments (tripton) from the water column, increasing light transmission through water much more rapidly than would occur through physical settlement. Sediments (tripton) from the water column, increasing light transmission through water much more rapidly than would occur through physical settlement. Sediments processed by anuran larvae and released as feces decomposed much more rapidly than unprocessed sediments. These results suggest that anuran larvae could have major effects on algal blooms, water clarity, and decomposition rates.