Possible environmental factors underlying amphibian decline in eastern Puerto Rico: Analysis of US government data archives

The past three decades have seen major declines in populations of several s pecies of amphibians at high elevations in eastern Puerto Rico, a region un ique in the humid tropics because of the degree of environmental monitoring that bets taken place through the efforts of U.S. government agencies. I e xamined changes in environmental conditions by examining time-series data s ets that extend back at least into the 1980s, a period when frog population s were declining. The data include forest cover; annual mean, minimum, and maximum daily temperature; annual rainfall; rain and stream chemistry; and atmospheric-dust transport. I examined satellite imagery and air-chemistry samples from a single National Aeronautics and Space Administration aircraf t flight across the Caribbean showing patches of pollutants, described as t hin sheets or lenses, in the lower troposphere. The main source of these po llutants appeared to be fires from land clearing and deforestation, primari ly in Africa. Some pollutant concentrations were high and, in the case of o zone, approached health limits set for urban air. Urban pollution impinging on Puerto Rico, dust generation from Africa (potential soil pathogens), an d tropical forest burning (gaseous pollutants) have all increased during th e last three decades, overlapping the timing of amphibian declines in easte rn Puerto Rico. None of the data sets pointed directly to changes so extrem e that they might be considered a direct lethal cause of amphibian declines in Puerto Rico. More experimental research is required to link any of thes e environmental factors to this problem.