Big Bend Coast
Most of the coast remains undeveloped, with extensive salt marshes, mangrove forests, seagrass meadows, and oyster reefs offshore, and coastal hammocks onshore.
The Big Bend Coast is a drowned karst region, covered with salt marsh and mangrove forests.
[8] Sediment of Holocene origin is generally limited to salt marshes and the nearshore zone, and is redistributed by tidal action and storm events.
[9] The Big Bend Coast is on the Gulf Coastal Lowlands of Florida, which has recently exposed ocean-smoothed terraces with Tertiary limestone at or just below the surface.
The flatness of the Big Bend Coast is interrupted by an area of relic sand dunes just inland from the Cedar Keys.
At the southern end of the Springs Coast, the Pithlachascotee and Anclote rivers arise further inland, but are almost entirely spring-fed.
[11][12] The many rivers and smaller streams flowing to the Big Bend Coast lower the salinity of the nearshore water.
Tropical species may be killed by cold weather, or may migrate southward or to deeper water less subject to cooling in winter.
The close proximity of the Florida aquifer to the surface with only a shallow soil layer over the porous limestone bedrock means that groundwater can emerge in many locations.
The thermal images revealed 874 "hot spots" along the coast which were at least 6 °F (3.3 °C) warmer than Gulf waters in the study area.
The authors estimated that the discharge from the identified inland sources is equivalent to that of one 1st-magnitude spring for every 2 miles (3.2 km) of coast.
[14] The streams and springs flowing to the Big Bend Coast contribute approximately 1,000,000 US gallons (3,800,000 L; 830,000 imp gal) of freshwater to the Gulf of Mexico each day.
[16] In the mid-20th century the intertidal zone of the Big Bend Coast consisted of salt marshes up to 10 kilometres (6 mi) wide, dominated by herbaceous (non-woody) plants, including Juncus roemerianus, Distichlis spicata, Sporobolus pumilus (formerly Spartina patens), and Salicornia species.
The marshes grow on sediment that is usually no more than 2 metres (6.6 ft) thick, although some depressions in the karst bedrock may have thicker deposits.
[30] The nearshore or littoral zone of the Big Bend Coast was estimated to have 3,000 square kilometres (1,200 sq mi) of seagrass meadows in 1999, consisting primarily of the seagrasses Thalassia testudinum (turtlegrass), Syringodium filiforme (manatee grass), and Halodule wrightii (shoal grass).
Atlantic Spanish mackerel, bluefish, crevalle jack, pigfish, and spot enter the seagrass meadows to forage.
[34] The seagrasses of the Big Bend Coast are typically found in tropical waters, and are at or near the northern limit of their ranges.
The lowest tides of the year generally occur in the winter, and expose the seagrasses to freezing air temperatures for significant periods on the coldest mornings.
Such climate stress may reduce the ability of the seagrass to recover from the impacts of pollution and other disturbances caused by human activities.
One study estimated that 23 square kilometres (9 sq mi) of seagrass beds had been lost off the mouth of the Fenholloway River because of pollution from pulp mill discharge.
[36] Extensive seagrass beds around Anclote Key, at the southern end of the Big Bend Coast, disappeared in the early 1960s.
[37] Water from the Caribbean Sea flows northward between Cuba and the Yucatán peninsula into the southeastern Gulf of Mexico.
[50] A comparison of Landsat images and United States Coast and Geodetic Survey charts from between 1852 and 1886 showed a loss over 120 years of 43 square kilometres (17 sq mi) of salt marsh to open water along the shoreline with the Gulf of Mexico, while 82 square kilometres (32 sq mi) of coastal hammocks had been replaced by new salt marsh.
[52] Evidence of human presence in what is now the Big Bend Coast goes back more than 14,000 years, when Paleoindians butchered or scavenged mastodons at the Page-Ladson site on the Aucilla River.
[55] Surveys of the submerged bottom of Apalachee Bay, concentrating on the PaleoAucilla River channel[b] have found 30 sites yielding pre-historic human artifacts.
The Bird Hammock site, near Wakulla Beach, Florida, was apparently a ceremonial center during the Swift Creek and Weeden Island periods.
At around the same time, the northern variety of the Safety Harbor culture appeared along the Big Bend Coast south of the mouth of the Withlacoochee River.
The Narváez expedition traveled close to the coast from Tampa Bay to the Withlacoochee River in 1528 without finding any signs of occupation.
After crossing the Withlacoochee, the Spaniards encountered inhabitants of the area and thereafter travelled towards Apalachee Province, passing through lands with villages and agricultural fields.
As they approached Apalachee Province the natives that had been pressed into service as guides apparently led the Spaniards through difficult country.
