Dolphins are found in the Everglades, inhabiting the estuarine and marine boundaries of the South Florida ecosystem. This unique environment, where freshwater from the mainland meets the sea, supports a population of marine mammals adapted to its fluctuating conditions. Their presence highlights the biodiversity, extending beyond the famous “river of grass” into its coastal bays and complex network of mangrove rivers.
Dolphin Presence and Species
The primary species documented in the Everglades coastal regions is the common bottlenose dolphin (Tursiops truncatus). These dolphins belong to a distinct coastal ecotype, which is smaller compared to the larger, darker offshore populations found in deeper ocean waters. This population is a resident stock. Photographic identification studies confirm that many individuals exhibit a high degree of site fidelity, remaining year-round within the protected bays and mangrove areas. The overall density of these dolphins within the estuarine Everglades is considered moderate to high when compared to other coastal populations in the southeastern United States.
Navigating the Everglades Ecosystem
The Everglades system is a vast gradient, transitioning from low-salinity freshwater marshes of the interior to high-salinity marine waters of the coast. Dolphins are exclusively found within the brackish estuaries and saltwater boundaries of the park, avoiding the deep freshwater core. Their habitat primarily encompasses Florida Bay, which forms the southern boundary, and the Ten Thousand Islands area along the Gulf of Mexico coast. This territory includes numerous shallow inland bays, mangrove-lined rivers, and associated coastal oceans.
The boundaries of their habitat are dictated by their physiological need for salt water, preventing them from penetrating far into the freshwater “river of grass.” Specific areas like Whitewater Bay, the Shark River, and the Joe River are known dolphin habitats where salinity fluctuates dramatically with the seasons and rainfall. The Florida Bay Stock is a recognized management unit, confirming these animals are adapted to the unique conditions found between the mainland and the Florida Keys. They prefer areas close to mangrove islands, suggesting a reliance on the shelter and concentrated prey found in these complex coastal habitats.
Life in Brackish, Shallow Waters
Surviving in the Everglades requires specific behavioral and physical adaptations to manage the highly variable salinity of the estuarine environment. The Everglades population regularly tolerates salinities ranging from nearly oceanic to significantly diluted, sometimes as low as five parts per thousand during the wet season. Their kidneys must constantly manage this fluctuating salt-to-water balance, a significant physiological challenge compared to open-ocean counterparts. The smaller body size of the coastal population may also be an adaptation, helping them navigate the shallow, confined waterways of the mangrove estuaries.
The shallow, often turbid waters influence their hunting techniques, leading to specialized foraging behaviors to trap fish near the shorelines. One observed strategy is “mud ring feeding,” where a dolphin swims in a tight circle, using its tail to create a circular plume of mud that drives schooling fish, such as mullet, toward the surface. Another tactic is strand feeding, where dolphins chase fish onto mud banks or shallow shorelines, briefly beaching themselves to capture their prey. These unique strategies demonstrate the high degree of behavioral flexibility required to thrive in this challenging coastal environment.