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What we wish we knew then - Impacts of Mosquito Ditching and Seeing into the Future of Restoration
Introduction
Sea level rise is occurring in multiple areas along our coast. Maryland, marshlands are being impacted, taking with them vital services- such as protection from storm surges and placing surrounding communities at risk. The vulnerability of these communities is intensified by the impacts of historic land use practices. For example, wetland ditching, called “mosquito ditching,” used from the 1930's to the 1950's to try and control mosquito-borne disease, may limit the ability of marshes to grow in response to sea-level rise. Researchers at the Chesapeake Bay National Estuarine Research Reserve in Maryland and from the University of Maryland have partnered to try and identify:
which ecosystem services provided by marshlands are highly valued by local communities,
understand how current management practices impact the marshes’ ability to provide these services, and
develop a process for stakeholders to work together to conserve and restore marshes for the future.
In Delaware, New Jersey, New York, and other coastal areas marsh restoration techniques are creatively using silt and mud dredge from waterways (to open up channels for barges and other water vessels) to manually build marshes more rapidly than nature.
Investigation Overview
Students will be presented with two scenarios:
depicting historic perceptions of mosquito control and
demonstrating restoration practices to create more resilient salt marshes.
They will read a few paragraphs on the practice of mosquito ditching and its known impacts on ecosystem services, and watch a video on historic threats to values of the time (explaining why we ditched for mosquito control). Students will be asked to share their reflections on the change in values (what was important in the video, based on what was known at the time) in comparison to our current practices in trying to restore and support (and basically undo, or heal) salt marshes today to try to regain the ecosystem services lost through past practices.
Impacts from Mosquito Ditching
Coastal wetlands and salt marshes are among the most biologically productive natural ecosystems on Earth. Unfortunately, the activities of people have diminished or eliminated these important tidal areas over the past century.
Wetland habitats are transitional regions between land and sea that provide an array of ecosystem functions. Wetlands filter pollutants from surface waters; store water from storms; prevent flood damage; recharge groundwater; serve as nurseries for saltwater and freshwater fish and shellfish that have commercial, recreational and ecological value; and provide habitat for a variety of fish, wildlife and plants. In the early to mid 20th century ditches were used cut through historical coastal wetland habitat, altering the hydrology of the remaining wetland and providing access for mosquito-eating fish. The ditches were cut to interrupt the life cycle of saltmarsh mosquitoes (Aedes sollicitans), which lay their eggs on moist soils so that the eggs hatch when the marsh is flooded by tides or rain.
While ditching effectively reduced the mosquito population in coastal wetland areas, an unintended result was a greatly altered and reduced wetland ecosystem. This reduced ecological productivity, resulting in reduced fish and wildlife, and the protection from storms that wetlands provide.
To understand why marshes were ditched to control mosquitoes students will watch this 1930's video on Malaria. http://youtu.be/kTGAn2hEdZQ
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