Wekiva River Aquatic Preserve

The Wekiva River Aquatic Preserve and the designated reach of the Middle St. Johns River consist primarily of nine different communities. Communities associated with the aquatic preserve are all considered to be in good condition, especially considering the extent of urban development adjacent to the aquatic preserve and within the basin.

Aquatic and terrestrial caves are characterized as cavities below the surface of the ground in karst areas of the state. The limestone aquifers that underlie the entire state of Florida could be considered vast aquatic cave communities. Troglobites (also called phreatobites) are organisms specially evolved to survive in deep cave habitats. The occasional observation of various species of troglobites in deep water wells from several regions in the state suggests that this community could be widespread. However, the dependence of troglobites on detrital inputs and other nutrients imported from the surface generally limits the distribution of well-developed aquatic cave communities to karst areas with surface connections. Cave waters are generally clear, with deep water appearing bluish.

The unique environment within spring boils (such as very low oxygen or high chloride content) provides habitat for animals generally not found elsewhere. Several endemic snails and crayfish have specific adaptations allowing them to survive under these unique conditions - Wekiwa hydrobe, Wekiwa siltsnail, Blue Spring hydrobe, pygmy siltsnail and Orlando cave crayfish. Other species occasionally use the boils as refuge, and Florida softshell turtles are occasionally found in the crevices running into the boils.

Blackwater streams are characterized as perennial or intermittent seasonal watercourses originating deep in sandy lowlands where extensive wetlands with organic soils function as reservoirs, collecting rainfall and discharging it slowly to the stream. The tea-colored waters are laden with tannins, particulates, and dissolved organic matter and iron derived from drainage through swamps and marshes. They generally are acidic (pH = 4.0 - 6.0) but may become circumneutral or slightly alkaline during low-flow stages when influenced by alkaline groundwater.

Relict marine sediment deposits and high chloride concentrations from springs result in a relative "saltiness" of water in the aquatic preserve, and several saltwater fish species, including white mullet, American shad and striped bass, have breeding populations in the region.

• Mullet are frequently observed jumping as they travel in the Wekiva River.
• The Atlantic needlefish has been caught on numerous occasions, especially near Katie’s Landing north of State Road 46.
• Blue crab are occasionally observed on the Wekiva River by members of the public and during fisheries research.
• The southern stingray also occurs in the St. Johns River.

Due to its remote location, most of the upstream reaches of Black Water Creek are near pristine and are difficult to traverse due to numerous fallen trees and submerged obstacles. The lower reach of Black Water Creek, within Seminole State Forest and Lower Wekiva River Preserve State Park, is more easily and more frequently navigated.

Bottomland forests are deciduous, or mixed, closed-canopy forest on terraces and levees within riverine floodplains and in shallow depressions. Found in situations intermediate between swamps (which are flooded most of the time) and uplands, the canopy can be quite diverse with both deciduous and evergreen trees.

Dominant species include sweetgum, loblolly pine, sweetbay, swamp laurel oak, water oak, live oak and sugarberry. More flood-tolerant species that are often present include American elm and red maple. Wood storks and limpkins have been observed nesting in bottomland forests in the aquatic preserve.

Floodplain marshes are wetlands occurring in river floodplains and dominated by herbaceous vegetation and/or shrubs. Floodplain marshes are found along rivers and streams from just below the headwaters to the freshwater portions of tidally influenced river mouths. They also occur in river overflow channels and lakes with both input and output of river flow. Woody vegetation is generally sparse. Several wading birds forage within floodplain marshes, including limpkin, little blue heron, snowy egret, tricolored heron and white ibis.

Floodplain marsh may burn periodically depending on dominant vegetation.

Floodplain swamps are closed-canopy forests of water-loving trees occurring on frequently or permanently flooded hydric soils adjacent to stream and river channels and in depressions and oxbows within floodplains. It ranges from narrow strips of cypress along primary and secondary streams to expansive stands along large rivers to tidally influenced freshwater swamps near river mouths. Often, floodplain swamps immediately border the stream or river channel. In many cases, however, floodplain swamps are isolated from the main channel by riverbank levees and restricted to oxbows, overflow channels, old stream beds and expansive flats commonly called backswamps.

The floodplain swamps of the Wekiva and St. Johns rivers can be extensive, ranging up to 3 miles in width. Trees are often buttressed, and the understory and groundcover are sparse. The canopy is commonly bald cypress and swamp tupelo. The “knees” arising from the root systems of both cypress and tupelo are common features in floodplain swamp. Other canopy trees capable of withstanding frequent inundation may be present but rarely dominant, including water hickory, red maple, green ash, American elm and swamp laurel oak.

Along the Wekiva River, however, these other floodplain hardwoods have dominated as second growth, likely because most of the cypress trees were logged out during in the late 1800s and early 1900s. The faster growing hickory, maple and ash out-competed the slower growing cypress, although a few large remnant cypress trees can be found along the Wekiva and Rock Springs Run, and within the interior portions of the state parks and forest, preserves and reserve. The wood stork and limpkin nest in floodplain swamp trees of the aquatic preserve.

Hydric hammocks are evergreen hardwood and/or palm forest with a variable understory typically dominated by palms and ferns occurring on moist soils. Hydric hammock occurs on low, flat, wet sites where limestone may be near the surface and soil moisture is kept high mainly by rainfall accumulation on poorly drained soils. Periodic flooding from rivers, seepage and spring discharge may also contribute to hydric conditions. Fire may be rare or occasional, depending on several factors including how often the surrounding community burns and hammock size.

While species composition varies, the community generally has a closed canopy of oaks and palms, an open understory, and a sparse to a moderate groundcover of grasses and ferns. The canopy is dominated by swamp laurel oak, live oak and/or cabbage palm. Wekiwa Springs State Park contains Florida's largest known population of star anise, a state endangered species. Star anise occurs throughout the hydric hammock/floodplain swamp communities along Rock Springs Run.

River floodplain lakes and swamp lakes are shallow open water areas - with or without floating and submerged aquatic plants - that are surrounded by basin swamp or floodplain swamp. They are generally permanent water bodies, although water levels often fluctuate substantially and they may become completely dry during extreme droughts. Except for the fringe of water-loving trees, shrubs and scattered emergents, plants may be absent altogether or they may almost completely cover the water surface.

Several swamp lakes and floodplain lakes occur near the western banks of the St. Johns River. The state-listed least tern is occasionally observed foraging on Lake Beresford and was also observed in the St. Johns River near its confluence with the Wekiva River.

Slough marshes are primarily herbaceous communities growing in a narrow to broad shallow channel with intermittently flowing water in flat sandy landscapes. Grasses, sedges and emergent herbs dominate the mainly treeless landscape. Patches of coastalplain willow, common buttonbush and wax myrtle are often scattered in deeper pockets of peat. Florida sandhill cranes often nest in the sloughs formed by oxbows within the St. Johns River portion of the aquatic preserve.

Drought conditions can entirely dry out the marsh and associated sloughs.

Spring-run streams are perennial water courses that derive most, if not all, of their water from artesian openings in the underground aquifer. There are 35 identified spring groups within the aquatic preserve (including the first-magnitude Volusia Blue Spring) and its watershed. Waters issuing from the aquifer are generally clear, circumneutral to slightly alkaline (pH=7.0-8.2), and perennially cool (66-75 degrees F). These conditions saturate the water with minerals, allow light to penetrate deeply and reduce the limiting effects of environmental fluctuations, all of which are conducive for plant growth. Thus, spring-run streams are among the most productive aquatic habitats.

Volusia Blue Spring and its run are widely recognized as an important winter ground for the Florida manatee due to the constant temperature of the spring water and proximity to the St. Johns River.

Spring-run streams generally have sand bottoms or exposed limestone along their central channel. Calcareous silts may form thick deposits in quiet shallow zones, while leaf drift and other debris collect around fallen trees and quiet basins. The latter, along with limestone outcrops and rock debris, form important aquatic habitats for many small aquatic organisms. When undisturbed, submerged aquatic vegetation covers most of the spring-run stream bottom and provides shelter and an abundant food source.

Human activity also can substantially affect the quality of spring waters. Agricultural, residential and industrial pollutants may readily leach through soils, especially when they are improperly applied or disposed. If polluted groundwater infiltrates the deep aquifer feeding a spring-run stream, recovery may not be possible. Excessive applications of herbicides to control aquatic plant growth are also detrimental because their use often induces eutrophication of the stream.

Other human-related impacts to spring-run streams include the trampling and destruction of aquatic vegetation by overuse or misuse, and the introduction and proliferation of non-native plants and animals. Both of these impacts have proved very difficult to control. In most spring-fed swimming areas, native vegetation is absent and new vegetation is not likely to recruit due to high use.

Lack of vegetation in swimming areas is likely to persist because of the limited number of publicly owned springs and the continued desire of the population to enjoy the clean, cool, aesthetic qualities and unique recreational opportunities that springs provide. Non-native species are often severely detrimental to native species, and they may also disrupt recreational activities. Maintaining the delicate balance between recreation and preservation is an ongoing challenge for resource managers.