12/08/2020 - Laserfiche WebLink

Home Browse Search

Attachment B: Supporting Research November 24, 2020 Research Review Phase of the IRC Lagoon Management Plan: Update 2 1. Ecosystem Functions and Habitat Use (Part 2) The ecosystems, habitats, and organisms that make up the Indian River Lagoon all play a unique and important role in the health and sustainability of the Lagoon. All of these elements interconnect to create the biodiverse environment of the Lagoon. As human populations continue to grow and expand, this unique environment faces numerous challenges to its long-term sustainability. This update will focus on mangroves, spoil islands and their importance to bird populations, and species of concern within the County's portion of the Lagoon. Mangrove fringes along the Lagoon's shoreline are common throughout the County. Studies have shown that mangrove communities support the protection of barrier islands against tidal and wave forces. There are three main types of mangroves: red mangroves, black mangroves, and white mangroves. Red mangroves are typically found growing at or a little above mean sea level, black mangroves are found growing in the upper portions of the intertidal zone, and white mangroves are found growing on higher ground where the soil is seldom flooded. Buttonwood trees are commonly associated as mangroves, but they are not true mangroves. They are often found adjacent to mangroves, and have become the unofficial fourth type of mangrove. Mangroves act as one of the most productive plant communities, supporting high level of animal diversity in a monoculture community. This is due to the complex structures and microhabitats that makeup mangroves. Root structures create nursery and shelter for most of the commercial and recreational fish species in the state. High quality seagrass beds are often found adjacent to mangrove fringes along the shoreline. Mangroves also act as important nutrient sinks in estuaries by removing nutrients from the water, such as nitrogen and phosphorus. Mangroves are susceptible to natural and human -induced impacts. Since the beginning of the 1900's, Florida has lost approximately 125,000 acres of mangrove forest to waterfront development and mosquito impoundments. Cutting mangroves and dredge and fill projects for development severely damage mangrove forests. Another factor is the manipulation of water management practices. Mangroves rely on a mixture of saltwater and freshwater to grow, and alterations in natural freshwater flow regimes affects the salinity balance and encourages exotic vegetation growth. Florida Fish and Wildlife Conservation Commission estimated the Lagoon as a whole has lost 85% of its mangrove forest. However, most of the mangroves that do remain are located within Indian River County. Agencies in the County actively work to purchase Lagoon -front land in order to keep it natural and prevent it from being developed. Unfortunately, due to human waste, mangroves act as traps for trash, monofilament, and other marine debris that can harm wildlife. Education, enforced regulation, and biodegradable options need to occurto placate the impacts of human actions on the success and growth of mangroves. Sea level rise and warming temperatures are other obstacles mangroves must face. Mangroves will shift inland as their habitat changes and depending on the location of development and/or seawalls, may not have room to retreat inland. Major hurricanes also damage mangroves. Mangroves act as a buffer between the water and land and during hurricanes may be sheared by the storm and/or smothered by accumulation of soil or organic matter over the roots. 102