Impacts from Mosquito Control-induced Sulphur Mobilization in a Cape Cod Estuary

Insect control programmes sometimes include environmental modification techniques such as diking and drainage. The impacts of such techniques are not often known or assessed. As a telling example having wide implications, we present an analysis of impacts in a small estuary which has been subjected to both diking and ditching—primarily for mosquito control. The major impacts stem from katteklei formation. Desiccated salt-marsh sediments produce acidified leachates which result from oxidation of pyrites. Lowered pH and high (acid-mobilized) aluminium concentrations both surpass levels that are known to be toxic to aquatic fauna. Fish and invertebrate communities in the basin are impoverished, and important commercial species such as American Eels and Alewives are heavily decimated. The acid-tolerant mosquito Aedes cantator thrives, however. Thus a natural system of substantial economic and aesthetic value has been inadvertently devastated through application of unnecessarily harsh as well as, in this case, ineffective mosquito control methods. Their use should be re-evaluated for similar impacts wherever such application has been carried out or is being contemplated.