Open marsh water management in Massachusetts: adapting the technique to local conditions and its impact on mosquito larvae during the first season.

In recent years, mosquito abatement techniques known variously as quality ditching, source management, or open marsh water management (OMWM), have shown promise of reducing mosquito numbers on salt marshes while preserving habitats and species diversity (Provost, 1977). Pool habitats are created or maintained rather than destroyed, and the levels of insecticide use greatly reduced. Although these techniques have been successfully used in the Chesapeake Bay region (Ferrigno 1970, Whigham, et al. 1983, Saveikis et al. , 1983), they have not yet been tested in New England. The physical and biological characteristics of New England salt marshes are different from those farther south and the success of OMWM as practiced in the mid-Atlantic states, cannot be readily extrapolated to New England. In Massachusetts, for example, the tidal range on salt marshes is between 7 and I I ft, and icing can be severe in winter. North of Cape Cod, marsh biota tends to be predominantly boreal rather than temperate because the coastal waters are linked to the Gulf of Maine. In 1982, the Essex County (Massachusetts) Mosquito Control Project, in collaboration with the Massachusetts Audubon Society and the Manomet Bird Observatory, began a five-year study to test OMWM on Essex County marshes. In trying to apply the standards and methods proposed by Ferrigno et al. (1975), we found that some were not practical on our local marshes. For example, many of the marshes that breed mosquitoes are small and not suited for construction of large ponds, since this method would eliminate relatively large areas of productive plant habitats. Also, the unavailability of a rotary ditcher to the Mosquito Control Project meant that alterations which