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Indian River Lagoon Aquatic Preserves - Wildlife and Plants Quick Topics

The IRL contains one of the richest and most productive estuarine faunas in the continental United States (Gilmore, 1985). The IRLAP System straddles the boundary between two biotic provinces, the temperate Carolinian Province and the tropical/subtropical Caribbean Province. As a result, the IRLAP System represents a latitudinal ecotone where flora and fauna from each province overlap. Many tropical and temperate species reach their north/south distribution limit within the IRLAP System. Due to the geographic location, tidal connectivity through inlets, and freshwater tributaries, the IRLAP System is teeming with a unique combination of temperate and tropical species that tolerate a wide salinity range (fresh to estuarine). To date, more than 1,000 native species, including fish, amphibians, reptiles, birds, mammals, invertebrates and plants, have been located and identified within the IRLAP System and adjacent floodplain.

Wood stork bird rookeryBird Rookeries

The IRLAP System supports seven significant wading bird rookeries. Five of these are located in Indian River-Malabar to Vero Beach Aquatic Preserve; two of which are rookeries for the threatened (federal and state) wood stork (Mycteria americana) in the IRLAP System. The sixth rookery is located in IR-Vero Beach to Ft. Pierce Aquatic Preserve. The seventh rookery is located near the St. Lucie Inlet in Jensen Beach to Jupiter Inlet Aquatic Preserve, which also serves as a rookery for wood storks. In addition to wood storks, rookeries support nesting activity for snowy egret (Egretta thula), tricolored heron (E. tricolor), little blue heron (E. caerulea), anhinga (Anhinga anhinga), brown pelican (Pelecanus occidentalis), yellow-crowned night-heron (Nyctanassa violacea), black-crowned night-heron (Nycticorax nycticorax), glossy ibis (Plegadis falcinellus), white ibis (Eudocimus albus), double crested cormorant (Phalacrocorax auritus), great blue heron (Ardea herodias), great egret (A. alba), and green heron (Butorides virescens), American oystercatcher (Haematopus palliatus), and roseate spoonbill (Platalea ajaja). Wading bird nesting occurs to a lesser degree on many of the spoil islands throughout the IRLAP System. Nesting surveys conducted by IRLAP staff from January 2006 to March 2013 documented nesting activity on twenty-two spoil islands in Indian River-Malabar to Vero Beach Aquatic Preserve and nine spoil islands in IR-Vero Beach to Ft. Pierce Aquatic Preserve. These surveys do not include all of the spoil islands and may not include some rookery islands, such as MC2 which is monitored by Martin County.

Diamondback terrapinDiamondback Terrapin

Named for the diamond-shaped growth rings on its carapace, the diamondback terrapin (Malaclemys terrapin) is a small turtle that is restricted to the mangrove and salt marsh habitats of the United States from Cape Cod south to the Keys, and along the Gulf Coast to Texas. The diamondback terrapin is believed to be the only turtle in the world that lives exclusively in brackish water habitats. Although there is only one species of diamondback terrapin in the world, there are seven described sub-species in the United States. The Florida East Coast terrapin (M. t. tequesta) occurs from St. Augustine to Miami, including the IRL.

Although diamondback terrapins live in tidal marshes, estuaries and lagoons, their preferred nesting sites are sandy beaches. Terrapins are carnivorous and are well adapted for eating hard-shelled prey including aquatic snails, crabs, and small bivalves. They also eat carrion, fish, marine worms, and insects. Exhibiting extreme sexual dimorphism, adult males are significantly smaller than females in weight and carapace length. Males can reach a maximum shell length of 5.5 inches, and females can grow up to 11 inches.

The two most significant limiting factors for terrapin populations in the nation today are by-catch in the blue crab fishery and predation of adults and nests by raccoons. Other factors causing declines in terrapin populations include the loss of salt marsh habitat and destruction of nesting beaches due to waterfront development, road mortalities of nesting females, and boat strikes. Survival rates of nests and hatchlings are very low due to high predation and flooding.

The subspecies is currently considered a non-listed imperiled species by FWC. Diamondback terrapins have been identified as associated species of greatest conservation for critical components of the lagoon ecosystem such as saltmarsh, mangrove, oyster reef, and seagrass habitats. Since 2013, Brevard Zoo and IRLAP staff have conducted a multifaceted research and outreach initiative focused on diamondback terrapins in the IRL. The Florida Atlantic Coast Terrapin Team consists of local and state agencies, researchers, nature centers, and engaged members of the community. The team has grown to encompass representatives and organizations throughout the IRL area with a mission to bring diamondback terrapin research and conservation in Florida to the forefront. This program combines community outreach, research, and citizen science including citizen reports of diamondback terrapin sightings in the IRL to focus research and conservation efforts. Program goals include expanding upon existing outreach and research to incorporate habitat restoration to increase nesting success of diamondback terrapins and to address threats to diamondback terrapins in the IRL.

Bottlenose Dolphin

A large number of Atlantic bottlenose dolphins (Tursiops truncatus) inhabit the IRL. Aerial surveys conducted from 2002 to 2004 estimated seasonal abundance of dolphins in the IRL ranged from 362 in summer to 1,316 in winter. Bottlenose dolphins are recognized as marine mammal sentinels in coastal environments and are apex predators in the IRL. Research suggests that at least three different dolphin communities exist within the IRL: Mosquito Lagoon, north IRL and south IRL. The north IRL includes Banana River Aquatic Preserve and the northern half of IR-Malabar to Vero Beach Aquatic Preserve. The south IRL includes the southern half of IR-Malabar to Vero Beach, IR-Vero Beach to Ft. Pierce and Jensen Beach to Jupiter Inlet aquatic preserves. Dolphins residing in the IRL are exposed to an increasing variety of persistent pollutants from anthropogenic sources that degrade their habitat, limit their food resources, and increase their susceptibility to diseases.

Florida Manatee

The Florida manatee (Trichechus manatus latirostris) is the only listed mammal (Endangered at both the federal and state level) found within the aquatic preserves. The manatee experiences low natural adult mortality. However, it is listed as endangered because its population is impacted by man-made alterations to estuarine and freshwater systems and by fast moving boat traffic in the waters where the species breeds, sleeps, and feeds. The IRL serves as a travel corridor and supports a resident population during all seasons. Although survival and reproduction rates are adequate in a small portion of its range, survivability studies indicate a cause for concern for the species population in the Atlantic region of Florida. Declining water clarity and seagrass beds, and increased boat traffic in the IRL are of concern when considering support of the manatee population. Within the IRL, manatee mortality rates are highest in Brevard County, typically exceeding the combined total of all other counties in the IRL. This is due, in part, to the fact that Brevard County contains much more of the IRL than the other counties. Boat collisions account for the largest known cause of manatee deaths. Between 1976 and 2000, watercraft-related deaths accounted for 24 percent of the total mortality and increased at an average of 7.2 percent per year. Maps of manatee protection zones in the IRL can be accessed at http://myfwc.com/wildlifehabitats/managed/manatee/protection-zones.

In winter, Florida manatees migrate to warm-water habitats such as natural springs and discharge canals of industrial power plants. The largest winter aggregations (maximum count of 100 or more animals) are at refuges in central and southern Florida. These include the Reliant Energy Plant in Titusville and the Florida Power and Light Canaveral Power Plant north of the IR-Malabar to Vero Beach Aquatic Preserve and the Florida Power and Light Riviera Beach Power Plant south of the Jensen Beach to Jupiter Inlet Aquatic Preserve. During mild winter periods, manatees at thermal refuges move to nearby sea grass beds to feed, or even return to a more distant warm season range. For example, manatees using the Riviera Power Plant feed in adjacent Lake Worth and in Jupiter and Hobe sounds in Jensen Beach to Jupiter Inlet Aquatic Preserve, 12 to 15 miles to the north. Other important warm water refuges in the IRLAP System include the St. Sebastian River, the Vero Beach Power Plant and Treasure Coast Energy Center in Ft. Pierce. Winter aggregations at these sites typically number between 25 and 100 manatees.

The most important spring habitat along the east coast of Florida has been the northern Banana River Lagoon and IRL and their associated waters in Brevard County; more than 300 to 500 manatees have been counted in this area shortly before dispersing in late spring. Shallow grass beds with ready access to deep channels are preferred feeding areas in coastal and riverine habitats. Manatees often use secluded canals, creeks, embayments, and lagoons, particularly near the mouths of coastal rivers and sloughs, for feeding, resting, cavorting, mating, and calving. In estuarine and brackish areas, natural and artificial fresh water sources are sought by manatees. As in winter, manatees often use the same summer habitats year after year.

Indian River Lagoon Aquatic Preserves


Last updated: November 03, 2016

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