Shared Uses and Functions and the Potential for Conflicts
Aquatic Plant Management Programs
Most Florida public lakes and rivers are shallow and capable of supporting submersed as well as floating plants across most or all of their surfaces. Couple this topography with a nearly year-round growing season. Add the phenomenal growth of invasive plants, and it becomes clear that plants must be managed to conserve the uses and functions of Florida public waters. When developing aquatic plant management programs, managers must consider multiple perspectives, needs, desires, and impacts upon all user groups. The best means to resolve user conflicts is to involve stakeholders in the development of management plans. By understanding the many demands on Florida’s waters, the stresses from invasive plants, and the management options available, informed citizens can better assist in developing comprehensive management plans that consider all uses of a waterbody. Plant managers can then develop integrated plant management approaches that minimize user conflicts, while accomplishing the statutory requirements of aquatic plant management.
For information on being involved in the development of invasive plant management programs, contact your Florida Fish and Wildlife Conservation Commission (FWC) Regional Biologist in your area of the state.
Florida's unique and plentiful aquatic environments entice millions of residents and tourists alike to spend their time in or on the water.
Swimming, Tubing and Paddling
Swimmers, kayakers, and canoers generally prefer clear water with little or no vegetation. Clear water improves visibility and helps calm fears about what lurks beneath the surface; it also instills a feeling of cleanliness. Although aquatic vegetation promotes water clarity, plants can be annoying obstructions for swimmers and provide camouflage for dangerous animals such as alligators. At high levels, swimmers can become entangled in weeds, and even drown.
Boating and jet-skiing
Like swimmers, power boaters, especially jet-skiers and water skiers, prefer waterbodies to be open with little to no offshore vegetation. Hydrilla and other submersed weeds can become entangled in boat propellers and damage engines. Weeds can also hide dangerous obstructions such as snags, stumps, fence posts, old pilings, and rocks. Power boaters also include recreational anglers and people who just want to motor around the waterbody to enjoy the view or tranquility provided by being on the water.
The popularity of power boats in public waterways is a source of conflict for other users. Fast-moving watercraft can provide hours of pleasure for boaters, but they can also create dangerous conditions for swimmers and wildlife. Powerboats can also promote the spread of invasive plants when fragments shredded by propellers drift to uninfested areas or are carried to another waterbody by the boat or trailer.
See Protect Your Waters and Stop Aquatic Hitchhikers, a site that focuses on how recreational enthusiasts can help stop the spread of invasive plants.
Fishing and Hunting
Aquatic plants provide food, shelter, and habitat for fish, birds and other wildlife, and good fishing and duck-hunting habitat for sportsmen. Unlike the vegetation-free waters preferred by swimmers and boaters, moderate, and sometimes extensive, amounts of aquatic vegetation are preferred by freshwater fishing and duck-hunting enthusiasts. Even invasive species such as hydrilla and water hyacinth can provide conditions for successful fishing and hunting. Therefore, plant removal can cause concern among fishing and hunting advocates. This can be further complicated in that the most cost-effective and environmentally responsible time to control invasive aquatic plants is long before they reach problem levels – often a time when they are supplying maximum benefit for fish, waterfowl, and other wildlife. Learn more about fishing and hunting in Florida.
Scuba Diving and Snorkeling
Florida's freshwater environments offer exceptional scuba diving opportunities. The clear waters of Florida's springs beckon enthusiasts from all over the world. Excessive vegetation poses dangers of entanglement, while inadequate vegetation can increase the abundance of algae. However, scuba and snorkeling activity can impact aquatic plant communities by contributing to bank erosion, bottom disruption, and fragmentation of submersed plants. Divers can inadvertently transport invasive plants from one site to another on their gear. Some state parks in Florida limit recreational activities to specific seasons to protect these resources.
Aquatic plants and management have significant impacts on the availability and quality of freshwater required by a variety of Florida industries.
Agriculture and Aquaculture
Florida agriculture is highly dependent upon large amounts of fresh water for irrigation, watering livestock, and fish ponds and hatcheries. Crop industries include citrus, sugarcane, ornamental plants, vegetables and sod. These user groups are important for their economic contributions to the state. Aquatic plant managers must consider their needs for water and protection from flooding. Water demand for agricultural use usually peaks during the drier months from November through April. This coincides with the optimum times for conducting large-scale hydrilla control using herbicides or for dewatering lakes or reservoirs to thin dense growths of native plants. Consequently, aquatic plant management strategies and timing are greatly influenced by the type and amount of irrigation water use. In addition, pesticides and fertilizers used during cultivation can leach into waterbodies and affect water quality and plant growth. Although agriculture generates billions of dollars for Florida, water consumption and water quality issues often conflict with the desires of conservationists, swimmers, anglers, and homeowners.
Commercial freshwater fishing is a relatively small but important activity sharing Florida freshwaters. Examples include netting species like tilapia or catfish for human consumption and wild shiner harvest for sportfish bait. An abundance of invasive plants like water hyacinth and hydrilla can interfere with fishermen’s ability to net fish while too little vegetation may reduce the numbers or size of catchable fish. Drawdowns for aquatic plant control and habitat enhancement may eliminate commercial fishing altogether for a period of time.
Ecotourism is an expanding industry on Florida lakes and rivers, taking on a diversity of forms from jet-ski to houseboat rentals, guided kayak to airboat tours, to fishing and hunting guides, camps, and lodges. Each of these businesses is affected by different levels of vegetated or open water, and associated activities peak at different times of year. The magnitude and timing of an aquatic plant management program to accommodate one use may detract from another, imparting some level of impact on local economies.
An abundant supply of freshwater is needed to accommodate power plants in Florida. Water is needed to operate cooling systems in thermal power plants (combustion or nuclear-generated heat). These uses can increase water temperature, which can alter habitat and change behaviors of important species such as the endangered manatee. Additionally, two hydroelectric power plants are present on Florida public waters. The aquatic region surrounding these structures must be clear of vegetation that could clog water intakes and other structures. The mechanical requirements of an industrial facility sometimes contradict the needs and desires of other users who prefer an unaltered natural environment.
As the lead agency for aquatic plant management in Florida, FWC is also responsible for controlling aquatic plants to protect human safety and health.
Flooding has caused tragic casualties and devastating economic losses throughout Florida's history. To facilitate drainage and to protect lives and property, environmental engineers continue to refine a complex system of levees, canals, dams and other water control structures as a means to manage excess surface water in Florida. Water transport in Florida waters is inextricably tied to aquatic plant management. Aquatic plants can thrive in all Florida public lakes, rivers and reservoirs. Water control devices and conveyances must be clear of vegetation in order to function properly, especially during hurricane season. The need to consistently control vegetation in reservoirs and canals can conflict with the desires of anglers and waterfront property owners who may prefer the aesthetic and habitat value of plant communities.
See Flood Control for more detailed information.
One of the earliest and important reasons for controlling water hyacinth and water lettuce in Florida waters is mosquito control. Larvae of Mansonia mosquito species have a specialized air tube that can be inserted into the roots of aquatic plants, especially water lettuce, to breathe underwater. Stagnant water associated with vast stands of hydrilla matted at the water surface creates conditions for other mosquito species to thrive. Similarly, masses of duckweed growing in nutrient rich waters support mosquito species capable of spreading disease. Mosquito control and aquatic plant management are closely associated and the larger mosquito control districts in Florida also have associated aquatic plant management programs. Certainly, all aquatic plants cannot be controlled in the name of mosquito control, but managers must be aware of the connection when developing resource management programs for Florida freshwaters, especially with growing concern with mosquito-transmitted diseases like West Nile virus and dengue fever.
Potable Water Supply
There are about 15 functioning drinking water intakes in Florida public waters that can affect aquatic plant management. On one hand, invasive plants like water hyacinth and water lettuce as well as hydrilla may need to be kept at low levels to prevent plants from clogging intake pipes. On the other hand, the presence of a functioning drinking water intake may necessitate implementing plant management strategies that are not as cost-effective or selective in order to comply with Florida’s drinking water standards.
Strategies for managing, restoring, or conserving aquatic plant ecosystems are not always agreed upon by water managers, biologists and conservationists, except that most agree that invasive non-native plants are an unacceptable alternative to a diverse community of native plants. Restoring an ecosystem to its original state may have secondary impacts on the wildlife that have adjusted to the altered conditions. Wildlife advocates and those who are charged with managing an ecosystem may have divergent ideas on the best management practices for a particular area. For example, some individuals may oppose the removal of hydrilla from a waterbody because it is a food source for the endangered manatee, snail kite, or for overwintering waterfowl. Others may recognize how a single non-native plant crowds out many native plant species, and insist that it be controlled to the lowest desired level (maintenance control).
The trampling and uprooting of plants by swimmers, scuba divers, and others can be perceived as a problem by conservationists.
Some waters, such as the St Johns River, Lake Okeechobee, and the Kissimmee Chain of Lakes are Designated Federal Navigation Projects and the U.S. Army Corps of Engineers is mandated by Congress to keep them free from obstructions. These obstructions include water hyacinth. While anglers have learned to fish under bands of water hyacinth lining river and lake shores, plant managers know from more than 100 years of experience that these plants can double populations in as little as two weeks, or coalesce at bridges or river bends during wind or rainfall events and block navigation and access. Similarly, large masses of hydrilla can be uprooted during storms and jam against bridges or clog navigation channels or boat ramps, driven by wind and waves or water currents.
As residential populations in Florida increase, so does the number of people desiring lake and riverfront homes. Public waterbodies are a shared resource and inevitably there are conflicts regarding water uses and management. Use and management of waterbodies directly affects people living on the shores, and people living on the shores directly affect the waterbody. FWC permits waterfront homeowners to remove ample shoreline vegetation to gain access and recreation to Florida lakes and rivers while maintaining sufficient plants to support essential fish and wildlife habitat. FWC also understands that while hundreds or thousands of acres of invasive hydrilla may improve fishing and waterfowl hunting success, it may also drastically impair the access from properties surrounding the waterbody; and the level of access may significantly affect the value of each waterfront property.
Whether a plant is a beneficial native or an invasive non-native, weedy or sparse, the presence of a lush plant community can be aesthetically pleasing. While dense plant growth may be viewed as the sign of a healthy environment, excessive vegetation may be accelerating muck deposition or nutrient enrichment or displacing more desirable plant populations. The sudden removal of a patch of blooming water hyacinth can elicit anger from waterfront property owners who appreciate the purple blossoms or anglers who seek the fish that forage below it. On the other hand, some neighbors may be pleased to see the non-native hyacinths gone and the native plants returned, or no vegetation at all.