Water Management

Seven different types of habitat are found on Merritt Island NWR:  beaches, coastal dunes, scrub, pine flatwoods, brackish impoundments, hardwood hammocks, and vast open water estuaries all provide food, water, and shelter for more than 500 species of wildlife. 

Active management of both uplands and wetlands ensures high quality habitat is available for wildlife that depend on the refuge for survival.  Water level management in the refuges 70+ impoundments, the use of prescribed fire, and control of invasive exotic plants are all critical components of refuge management.

Impoundment Management
Until the 1950's, natural salt marshes covered much of what today is Merritt Island National Wildlife Refuge.  Wind-driven “tides” often flooded the marshes with brackish water from the Indian River Lagoon.  These fluctuating water levels created ideal breeding habitat for the prolific salt marsh mosquito. When NASA acquired the land for what would be come the Kennedy Space Center, local cities began to grow and a more effective mosquito control program was needed. A network of earthen dikes allowed water to be held (impounded), thereby maintaining flooded conditions during the peak mosquito breeding season (May – September) that significantly reduced the amount of mudflats available for mosquitoes to lay eggs.

This technique proved to be an effective means of controlling mosquito, but it had adverse effects on the marsh.  Working with the Brevard Mosquito Control District, the refuge has focused efforts on managing the impoundments to benefit waterfowl, wading birds, shorebirds, and other wildlife.  Lowering water levels during spring and summer allows vegetation to sprout and grow.  Early fall, the impoundments with their new vegetative growth are re-flooded to depths of 6 to 12 inches. This provides excellent habitat for invertebrates, small fishes, worms, and crabs that are in turn used for food by birds and other wildlife who feed in the impoundments. Beyond controlling mosquitoes, providing food and habitat for migratory birds is the primary goal of impoundment management.  Each impoundment has its own management plan that outlines water and salinity (salt) levels, depending on the specific focus for that area. 

Marsh Habitat - USFWS Photo

Wetlands
In partnership with  Brevard Mosquito Control and the St Johns River Water Management District, the refuge has been able to restore hundreds of acres of salt marsh by reconnecting the marsh to the river through culverts, or eliminating the dike altogether to allow for natural water level fluctuations.  The goal for past and future restoration efforts is to return as much of the habitat as possible to a more natural state while ensuring NASA workers and the local community are not negatively impacted by more mosquitoes.  Only impoundments that are certain to have zero or a nominal effect on the mosquito population will be considered for restoration.

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