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Aquatic Preserves

St. Martins Marsh Aquatic Preserve

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St. Martins Marsh Aquatic Preserve is situated along the coast of Citrus County between Crystal River to the north and Homosassa to the south. It extends southward to the northern boundary of the Chassahowitzka National Wildlife Refuge. The eastern boundary follows the Citrus County shoreline. The preserve extends westward, encompassing a chain of islands including the St. Martins Keys. 

History

The St. Martins Marsh Aquatic Preserve was officially designated in 1969 to protect its rich coastal ecosystems. Located near the Crystal River, this area is known for its extensive seagrass beds, salt marshes, hardbottom habitat and mangrove islands, which provide critical habitat for various species, including manatees, fish and migratory birds.

Scientific Information

St. Martins Marsh Aquatic Preserve is recognized as a significant center of Indigenous activity in Florida, with numerous archaeological sites that include shell mounds, pottery fragments and tools. These artifacts, some dating back thousands of years, highlight the area as a hub for Indigenous communities who thrived off the rich resources of the marshes and coastal ecosystems. St. Martins Marsh lies in the broader Springs Coast region, known for its limestone formations and the warm waters that attracted early Indigenous people. The mix of estuarine and upland environments provided ample food resources, like fish and shellfish and access to raw materials. 

The St. Martins Marsh Aquatic Preserve’s geological history traces back millions of years to when it was submerged under shallow seas, forming limestone bedrock from ancient marine sediments. Over time, fluctuating sea levels exposed and eroded this bedrock, creating Florida’s karst landscape, with sinkholes, springs and caverns that characterize the area today. This porous limestone allows for nutrient and water exchange between surface waters and the aquifer, supporting the preserve’s unique habitats like seagrass beds, salt marshes and mangrove forests. These ecosystems, shaped by the geological structure, are crucial for diverse marine life and migratory bird populations.

St. Martins Marsh Aquatic Preserve is home to diverse habitats, including seagrass beds, salt marshes, mangrove islands and tidal creeks, all crucial for supporting a variety of wildlife. These ecosystems provide food and shelter for species like fish, shellfish, manatees and migratory birds, making the area a vital nursery for marine life. The seagrass beds, in particular, are rich in nutrients and offer habitat for juvenile fish and invertebrates, while the mangroves and marshes protect the coastline and support shorebirds. Collectively, these habitats play essential roles in maintaining biodiversity and promoting the health of coastal ecosystems in the region.

Nesting and Migrating Birds
Purple martin, brown pelican, white pelican, great blue heron, peregrine falcon, roseate spoonbill, Scott’s seaside sparrow, snowy egret, white ibis, and the wood stork

Mammals
Florida manatee, bottlenose dolphin

Reptiles
American alligator, ornate diamondback terrapin, loggerhead sea turtle (threatened species), green sea turtle (threatened species), Kemp’s ridley sea turtle (endangered species) 

Fish
Notable species include grouper, snappers, red drum, sheepshead, sand tiger shark 

Other Species
Eastern oyster, pink shrimp, stone crab, bay scallop, blue crabs 

A full list of species can be found in the management plan.

Conservation Efforts

  • Water Quality Monitoring: The preserve staff monitors water quality throughout St. Martins Marsh through long-term, continuous water quality monitoring. Off of the Homosassa River, they use YSI EXO 3 Sondes to continuously monitor water quality, gathering data on temperature, salinity/conductivity, pH, dissolved oxygen, depth and turbidity. This monitoring provides valuable insights into the overall health of the ecosystem.
  • Seagrass Monitoring: The preserve staff monitors seagrass and macroalgae at 25 fixed locations each summer, tracking changes in species, coverage and overall health.

        A full list of data and reports can be found on SEACAR.

  • Hardbottom Monitoring: The preserve staff is in the initial stages of implementing a hardbottom monitoring program to identify and monitor the sponges and corals throughout St. Martins Marsh.
  • Boater Education: The "Scars Hurt: Be Seagrass Safe" campaign educates boaters about safe boating practices in shallow seagrass areas to prevent damage from propellers.
  • Marine Debris Cleanup: Preserve staff participate in multiple marine debris removal events each year. Removing marine debris like derelict crab traps, which can shade out seagrass, allows for submerged aquatic vegetation such as seagrass and algae to recover.

Ongoing Research

  • University of Florida: partner on SECAR MAPS project is a project. Also, the University of Florida conducts COAST water quality monitoring and is partnering with the Florida Department of Environmental Protection on a hardbottom monitoring program.
  • University of South Florida: is conducting research on bull sharks in St. Martins Marsh Aquatic Preserve.
  • Florida State University: is conducting sea turtle population monitoring.
  • InWater Research Group: conducts sea turtle monitoring Southwest Florida Water Management District conducts seagrass mapping.
  • Florida Wildlife Research Institute: conducts project SIMMs in the St. Martins Marsh Aquatic Preserve.
Frequently Asked Questions

Spring is great for kayaking and paddling due to mild weather and calm water. Migratory birds start to return to the area in late spring. Summer offers scalloping and snorkeling. Fall weather makes fishing more comfortable while species are still active. Winter offers great viewing of wildlife, specifically manatees.

Yes. Aquatic preserves often are adjacent to other conservation areas that may have nesting birds or other easily disturbed wildlife. Please do not let your pet run free in areas not designated for pets, and please pick up after your pet to avoid hazardous pathogens in our coastal waters. 

Follow current FWC saltwater fishing regulations.

Follow current FWC boating regulations.

Seagrass is protected within aquatic preserves; avoid shallow waters and raise motor if over seagrass. Damage to seagrass can result in a fine up to $1,000. 

Call Florida Fish and Wildlife Conservation Commission at 1-888-404-FWCC (3922).

ADA accommodations are specific to each access point and the managing entity for that site. 

There are no fees required by the preserve, but specific access points may charge access fees to those sites.  

Partner Groups

  • University of Florida
  • University of Florida's Institute of Agricultural Sciences (UF/IFAS)
  • Florida Sea Grant