Ecological review of hydroelectric reservoirs in Puerto Rico

A review of published literature and available data on the ecology of hydroelectric reservoirs and other lakes in Puerto Rico yielded various studies on unrelated elements in the aquatic ecology, but very few comprehensive investigations. The majority of the island-wide studies pertained to surveys on snails related to the parasitic disease bilharzia. A survey of 28 major lakes in 1976 showed that Biomphalaria glabrata had gradually been displaced from most of the lakes by Marisa cornuarietis and Tarebia granifera, two foreign snails which do not transmit bilharzia. Of the 17 lakes containing B. glabrata in 1956, only 8 remained infested in 1966 and only 5 in 1976, twenty years after the introduction of Marisa cornuarietis. Although the trend indicates that the lakes may be safe from transmission a monitoring system is necessary before the lakes could be used for recreation.