Geographic Features

Text Box: The Indian River Lagoon is located on the east coast of Florida, stretching from Ponce de Leon Inlet near Daytona Beach to Jupiter Inlet north of West Palm Beach. It extends approximately 156 miles through six coastal counties  (Volusia, Brevard, Indian River, St. Lucie Martin, Palm Beach) and includes a portion of a seventh (Okeechobee) within its watershed. It is the location of such well known institutions as Kennedy Space Center, Cape Canaveral, the Indian River citrus industry and Pelican Island National Wildlife Refuge.

The Indian River Lagoon is composed of three major waterbodies: Mosquito Lagoon, Banana River and the Indian River. The Lagoon varies in width from one-half mile near Vero Beach to more than five miles near Titusville and has an average depth of three feet. Several tributaries drain the lands surrounding the Lagoon. Major tributaries include Eau Gallie River, Crane Creek, Turkey Creek, Sebastian River, Taylor Creek and the St. Lucie River. The Indian River is connected to the Atlantic Ocean at seven points. These are Ponce de Leon Inlet near Daytona Beach, Sebastian Inlet, Fort Pierce Inlet, St. Lucie Inlet near Stuart and Jupiter Inlet. In addition there is a limited connection at Port Canaveral where navigation locks allow boaters to travel between oceanic waters in the port and the Banana River.

More than 1 million people work and play in the Indian River Lagoon region, attracted here by the mild climate and the resources of the Lagoon. The Indian River Lagoon region produces more than $300 million each year in fishery revenues, includes a $2.1 billion citrus industry and generates more than $300 million in boat and marine sales annually. The region contains five state parks and recreation areas, four national wildlife refuges and a national seashore.

Physical Features

Although the word “river” appears in its name, the Indian River Lagoon is not a river in any sense of the term. A river, by definition, has headwaters and flows to a mouth. The Indian River Lagoon has no headwaters, has no mouth and when it does “flow,” it often flows in many directions. The direction of this flow is dependent on winds, tides, and several other factors.

The Indian River Lagoon is an estuary – a body of water where freshwater draining from the land meets and mixes with the ocean’s salt water. The main freshwater sources for the Indian River Lagoon are direct rainfall onto the Lagoon and runoff from lands within the watershed of the Lagoon. Runoff is carried by creeks, rivers, canals and ditches to the Lagoon. Ocean water enters the Lagoon through the six ocean inlets and the navigation locks at Port Canaveral.

The Indian River Lagoon is special type of estuary called a lagoon - a body of water separated from the ocean by a barrier island with a limited exchange of waters through inlets. The shape and location of the Lagoon, its shallowness, variations in the amounts of freshwater discharged to the system and the few, widely-spaced ocean inlets combine to reduce exchange with the ocean. The Indian River Lagoon is unique among Florida estuaries because of this limited exchange of water with the ocean. As the result of this limited exchange with the ocean, the Indian River Lagoon is sensitive to the amount and timing of freshwater discharges and pollutant loadings associated with these discharges.

The Indian River Lagoon is a complex, dynamic and variable system. This system is composed of several smaller segments, each of which is slightly different from other segments. The various segments that compose the Indian River Lagoon system are influenced by the locations of inlets that connect the Indian River Lagoon to the ocean as well as by the location, size and volume of freshwater tributaries. As a result, each segment has individual characteristics that contribute to the unique nature of the Indian River Lagoon.

Watersheds

Text Box: Indian River Lagoon Watershed The watershed (or drainage basin) is the area of land that drains to a receiving surface water body. Historically, the Indian River Lagoon had a long, narrow watershed. Most of the drainage basin (with a few exceptions such as the St. Lucie River) was limited to the area east of the Atlantic Coastal Ridge. This area, which is roughly east of present-day US Highway 1, totaled approximately 572,000 acres.

For more than a century, projects have been undertaken to in Florida to develop or reclaim lands for urban or agricultural development. Development or reclamation in many areas involved projects designed to control floodwaters or lower the water table by draining these waters to waterbodies that ultimately flowed to the ocean. In the portion of the Indian River Lagoon basin from Melbourne south, several large drainage systems associated with water control districts or federal flood control projects were constructed which extended the drainage basin of the Lagoon westward to include extensive areas that historically drained to the St. Johns River or Lake Okeechobee. The extended, present-day watershed of the Indian River Lagoon now includes more than 1.4 million acres, an increase of 146 percent over the historic drainage basin acreage. As a result of this extended and enlarged drainage basin substantially more fresh water flows into the Indian River Lagoon.

Changes to the watershed and increased freshwater discharges have meant the Lagoon’s ecosystems and their inhabitants have had to adapt to change. These adaptations have had a price: over time seagrass acreage and distribution has changed, resulting in losses in several areas, and certain fish populations have declined. Discharges of large quantities of freshwater may cause rapid and dramatic changes resulting in algae blooms, fish kills, or shellfish area closures.

Circulation and Mixing

Circulation and mixing in the Indian River Lagoon are quite complex. While the tidal currents which drive circulation and mixing in a typical estuary are important in the Indian River Lagoon, there are several additional factors which are unique to this system.

Within a given segment of the Indian River Lagoon, circulation and mixing are primarily influenced by the distance from the segment to an ocean inlet. Other influences include freshwater discharges, wind-generated currents and evaporation processes. With increased distance from an ocean inlet, these other factors increase in importance.

Text Box: Sebastian Inlet In the vicinity of ocean inlets, tidal currents dominate and control mixing and circulation. Where the larger tributaries discharge to the Lagoon, freshwater flows drive these processes. In those portions of the Lagoon that are not near an inlet or a larger tributary, wind-driven currents provide the primary energy for circulation or mixing.

Evaporation also plays a role in circulation in the Indian River Lagoon system. When evaporation exceeds the amount of fresh water entering the Lagoon from rainfall or runoff, more salt water will enter the Lagoon from the ocean. In addition to raising the salinity through evaporation, this process also contributes to mixing and circulation in certain areas of the Lagoon.

During the warmer months of the year, evaporation in the Banana River, southern Mosquito Lagoon and the northern Indian River normally exceed the inflow of fresh water. These areas have a relatively small watershed with few streams or other drainage flowing to the Lagoon.

In contrast, evaporation never exceeds freshwater inflows in the southern portion of the Indian River Lagoon during a normal year. The large, extended watershed and extensive drainage systems in this area deliver more than adequate amounts of fresh water to the Lagoon even in times of drought.

Circulation and mixing processes in the Indian River Lagoon are further complicated by factors such as seasonal influences, structures such as causeways and alterations to the Lagoon’s shoreline and bottom, all of which may affect water movement.

Salinity

The distribution of salinity in the Indian River Lagoon is another example of the complexity of the Lagoon system. In general, high salinity ocean water is carried into the Lagoon by tides and currents through ocean inlets. This saline ocean water mixes with fresh water entering the Lagoon from runoff and rainfall. The result is a distribution of salinities, which range from fresh water to high-salinty ocean water. 

Previously it was mentioned that the Banana River, southern Mosquito lagoon and the northern Indian River Lagoon have a limited inflow of fresh water. Combining this limited inflow of fresh water with the evaporative losses results in higher salinities in the northern portion of the Lagoon system. Even in theses areas salinity is highly dependent on rainfall and runoff. In drought years salinities may approach (and may occasionally exceed) oceanic levels. In rainy years, salinities may approach fresh water.

In contrast, fresher waters are found in the portion of the Indian River Lagoon from Melbourne to Vero Beach. This is the result of large volumes of fresh water entering the Lagoon from the Eau Gallie River, Crane Creek, Turkey Creek and Indian River Farms Water Control District canals in the Vero Beach area, particularly in the wet season.  Another contributing factor may be the fact that Sebastian Inlet, the only connection to the ocean in the central part of the Lagoon system, is relatively small. The smaller size of this inlet limits the volume of water exchanged between the Lagoon and the ocean. The resulting lower, but highly variable, salinities in this area may be a factor in determining the type and extent of certain biological resources such as seagrasses, clams, and oysters.

In the southern portion of the Lagoon, mixing of fresh water and ocean water is controlled by slightly different factors. Because this area has more ocean inlets, it is more directly interconnected with the ocean, and tidal currents dominate in driving circulation. Similar to the central and northern portions of the Indian River Lagoon, tidal effects and circulation diminish with distance from an ocean inlet. The southern portion of the Lagoon shows high salinities and demonstrates a greater influence by ocean water, even though the area’s extensive drainage system transports and discharges a much larger quantity of fresh water than any other portion of Lagoon system.

As can be seen from the distribution of salinities, mixing differs significantly in the various segments of the Indian River Lagoon system. These differences can be important to the ecosystems established in each part of the Lagoon. Although tolerant of seasonal changes that alter patterns of salinity distribution, long-term changes in salinity can result in ecosystem changes.

Water and Sediment Quality

Water and sediment quality in the Indian River Lagoon has changed over the years. Much of this change has occurred in the last 50 years. Long-term residents of the Lagoon region tell of clear waters, extensive wetlands and seagrass beds, as well as an abundance of fish and wildlife. Reminders of these conditions can be found today, but only in the less developed portions of the Indian River Lagoon.

Most of the Lagoon meets the minimum water quality standards set by state and federal agencies. In fact, much of the Lagoon has been designated as Aquatic Preserves and/or Outstanding Florida Waters. However, water quality in many areas of the Lagoon is not sufficient to support healthy seagrass beds or permit the unrestricted harvest of shellfish. Reduced water quality, as the result of increased discharges of nutrients, suspended matter, fresh water and other pollutants, has contributed to the reduced abundance of fish and wildlife throughout the Lagoon. Many of the Lagoon’s tributaries and deeper areas contain significant deposits of muck or ooze which, in turn, often contain elevated levels of metals or other contaminants.

Water and sediment quality of any waterbody is directly related to activities that occur within their watershed. In estuaries, water and sediment quality is also affected by their connection to the ocean. Water and sediment quality may also be affected by the physical configuration of the waterbody and watershed, as well as alterations to this caused by natural phenomena or man’s activities. All these factors combine to affect water and sediment quality in the Indian River Lagoon.

The geographic setting and shape of the Indian River Lagoon affect the water and sediment quality of the Lagoon. They also cause the Lagoon to be different from most of the bays and estuaries in Florida. The long, narrow shape and the shallow waters result in a sluggish circulation pattern in many areas. The circulation that does occur is primarily wind-driven since the tidal exchange with the ocean is through six widely separated inlets with restricted tidal flushing. As the result of limited circulation and tidal flushing, the Indian River Lagoon is particularly sensitive to influxes of pollutants or other materials resulting from activities in the watershed.

The primary types of pollutants affecting the Indian River Lagoon and their impact on water quality are as follows:

Point Source/Non-Point Source Pollutant Loadings

Text Box: Summer thunderstorm On the average, the Indian River Lagoon region receives approximately 50 inches of rainfall each year. Roofs, roads, parking lots, and other impervious surfaces now cover areas that once were covered with native vegetation. These impenetrable surfaces prevent water from soaking into the ground as it once did. Now, large volumes of stormwater run off into creeks, streams canals and ditches which ultimately discharge to the Indian River Lagoon. Uses of the land from which the runoff originates and flows through determine the pollutant load picked up in the runoff and carried to the receiving surface water. Pollutant loads include sediments, decomposed organic matter, nutrients, heavy metals, viruses and bacteria as well as many other pollutants.

Text Box:

Stormwater is considered a non-point source of pollution. Non-point source pollution is generated over a wide area with no single identifiable source of pollution. Although stormwater may be discharged through a single pipe or canal, it is still considered a non-point source of pollution.

Point source pollution, on the other hand, is generally the product of a process such as manufacturing or treatment. Until recently, almost all the point sources in the Indian River Lagoon region were domestic wastewater plants. The effluent from domestic wastewater treatment plants contains significant amounts of nutrients and may contain other pollutants. In addition to the domestic wastewater plants there are Text Box: Wastewater discharge to Crane Creek in the 1980s about 30 point source discharges that are classified as industrial. These are primarily cooling water discharges from power generation plants or brine from reverse osmosis drinking water treatment plants.

Recognizing the impacts of discharges from the domestic wastewater treatment plants on the Lagoon, the Florida Legislature passed the Indian River Lagoon Act (Chapter 90-262, Laws of Florida) in 1990, requiring these facilities to cease discharging their effluent to the Lagoon. Presently, all domestic wastewater plants are in compliance with this act. 

While implementation of the Indian River Lagoon Act has significantly reduced the amount of pollutants discharged to the Lagoon, non-point sources contribute significant pollutant loadings to the Lagoon. In the early 1990s, it was estimated that non-point source pollution contributed more than 60 percent of the pollutant loadings to the Indian River Lagoon. With the elimination of domestic wastewater treatment plant discharges, the importance of non-point source loadings increases even further. Even with current laws and regulations, it is estimated that in the future increased non-point source pollutant loadings resulting from anticipated development in the watershed will nearly equal the reductions from eliminating wastewater plant discharges should no action be taken to address existing non-point source pollutant loadings as well as future loadings.

Sediment Quality

Most sediments in the Indian River Lagoon are sands, silts and shell fragments. However, about 10 percent of the bottom is covered with a loose, black organic–rich mud commonly referred to as “muck” or “ooze.” This muck may affect fish, shellfish, and seagrasses by affecting respiration, light penetration or simply smothering these resources. Not only does muck cover important bottom habitat it also can easily be stirred up by storms and boats, creating large areas of turbid water with decreased water clarity. Elevated concentrations of copper, lead, zinc and other pollutants have been found in muck deposits in several locations in the Lagoon.

Text Box: Indian River Lagoon Muck

Major muck deposits are generally found in deeper areas of the Lagoon, especially in areas that have been dredged. These areas include the Intracoastal Waterway and other channels as well as borrow pits where fill for causeways and other development was mined from the bottom of the Lagoon. Muck deposits are also found at or near the mouths of most of the Lagoon’s tributaries. The mouths of these tributaries act as traps, often capturing large portions of the muck before it reaches the Lagoon. In the event of a hurricane or major storm, these deposits could be flushed into the Lagoon.

LIVING RESOURCES

Within the Indian River Lagoon a broad variety of natural community types, watershed and drainage features, connections to the Atlantic Ocean and complex hydrodynamics have combined to create a complex landscape unique among Florida’s estuaries. The overlapping boundaries of two biotic provinces, the temperate Carolinian and the sub-tropical Caribbean province also occur within the region. Biological diversity is high as a variety of species associated with both these provinces as well as species unique to the area are found in the Indian River Lagoon region. More than 75 of the species found in the region are listed as rare, threatened, endangered or species of special concern by state or federal agencies or private organizations. This has resulted in the Indian River Lagoon being labeled as the m,ost diverse estuary in North America.

BIODIVERSITY

Text Box: IRL Species Inventory http://www.sms.si.edu/irlspec/index.htm Maintaining biological diversity (the existence of many types of plants and animals) is a key part of maintaining the health of the earth’s ecological systems and its future resources. The same could be said for the Indian River Lagoon.

Besides the 2,100 species of plants, the Lagoon is home to more than 2,200 species of animals – the most in any North American estuary. All seven species of seagrass found in Florida are found in the Lagoon including Johnson’s seagrass (Halophila johnsonii), which is found nowhere else in the world.

Text Box: Why does such biological diversity occur in the Indian River Lagoon? There are several reasons but perhaps the primary causes are the unique combination of its north-south orientation along the Atlantic coast and  the Lagoon’s long, narrow configuration.

The Lagoon is located in the zone where tropical and temperate climates meet. As a result, tropical species of plants and animals that cannot tolerate much cold weather, along with species that thrive in cooler climates are found in the Lagoon region. The mean annual temperature differs as much between the northern and southern ends of the Lagoon region as much as it does between the northern end of the Indian River Lagoon and North Carolina, 500 miles to the north.

The Lagoon region’s habitats range from ocean inlets, which are like the open ocean, to the dry upland oak scrub ridges. Many of these habitats are so specialized and unique that they have limited tolerance to change. Many of the plant and animal communities found within these habitats are equally specialized and also have little tolerance for change. As a result, changes in the Lagoon region have resulted in the loss of a great deal of these specialized habitats as well as the species that depend on them.

Many of these areas are critical habitats for the 36 species of animals classified by state or federal agencies as threatened or endangered that are found within the Lagoon’s watershed. The Merritt Island National Wildlife Refuge, located in the northern section of the Lagoon, contains more species of threatened and endangered wildlife than any other national wildlife refuge in the continental U.S.

HABITATS & COMMUNITIES

Habitats (the environments in which plants and animals live) result from physical conditions as well as the effects of he plants and animals themselves. Communities are assemblages of plants or animals that live in these habitats.

Complex interactions occur between habitats and the surrounding environment so that the actions that affect one habitat can affect other, even distant, habitats. When we affect one part of his complex system, we may be affecting all parts of the system.

The major habitats of the Indian River Lagoon system and its associated tidal zone can be described as:

Text Box: Seagrass Seagrass Habitats

Seagrasses are a particularly valuable component of an estuarine ecosystem, providing important habitat for many species. These include threatened and endangered species; species of recreational or commercial value as well as many other species that, while not having great individual value, are vital components of the Indian River Lagoon ecosystem. All these species are part of a complex food web whose common and perhaps most important element is seagrass.

Text Box: Seagrass structures Seagrasses are plants that grow and complete their life cycles entirely underwater. Seagrasses are higher plants that have roots, leaves, flowers, pollen and seeds. In comparison, algae are simpler plants that have none of these characteristics. Approximately 52 species of seagrass have been identified worldwide of which seven are found in Florida. Of all the estuarine areas in Florida, the only estuary where all seven species are present is the Indian River Lagoon. One species, Halophila johnsonii, is found nowhere else in the world.

The seven species of seagrass found in the Indian River Lagoon include:

·        Shoal grass Halodule wrightii;

·        Turtle grass, Thalassia testudinum;

·        Manatee grass, Syringodium filiforme;

·        Johnson’s seagrass, Halophila johnsonii;

·        Star grass, Halophila engelmanii;

·        Paddle grass, Halophila decipiens; and,

·        Widgeon grass, Ruppia maritima.

Line drawings of these plants may be found in the appendix.

Of these seven species the first four represent the predominant species found in the Indian River Lagoon. Shoal grass is the most commonly found species in the Lagoon.

Seagrasses, along with the microscopic algae that often cover their leaves, convert soar energy into plant tissue. In terms of biomass production, the seagrass community is one of the most productive ecosystems on earth. The complexity of the structure of the seagrass community, its biodiversity and productivity have been compared to rain forests.

The plant tissue produced by seagrass forms the basis of the food webs for many animals in the Indian River Lagoon. The Lagoon is known as a “seagrass-based ecosystem rather than a “phytoplankton based ecosystem,” meaning that these rooted plants rather than free-floating algae provide most of the food for animals in the system.

Seagrasses are sensitive to water quality conditions, particularly those parameters that affect water clarity. Waters that are turbid or cloudy as the result of high amounts of suspended solids or algae do not allow needed sunlight to reach bottom-growing seagrasses.  As a result, seagrasses are a good “barometer” or indicator od f the condition of a watern body. In areas of good water quality with low concentrations of suspended solids or algae-producing nutrients, seagrasses can form dense “meadows” or “beds.”

In many Florida estuaries and coastal areas the acreage of seagrasses has declined. These losses have been primarily attributed to development within the watershed and resulting impacts to water quality. These impacts are generally the result of discharges of stormwater or fresh water drainage from urban, industrial or agricultural areas and discharges of wastewater from domestic and industrial sources. In addition, there have been direct losses of seagrass acreage to dredge and fill projects.

Open Water Habitats

Open water habitats include all of the submerged portions of the Indian River Lagoon that are not covered by seagrasses, encompassing both the water column and bottom of the Lagoon.

Bottom types may be rocky, sandy or muddy. Most animals that live on the bottom or in the sediments are invertebrates (having no backbone). The animals include mollusks, tiny polychaete worms, crustaceans, sponges, bt ryozoans, oysters and blue crabs.

Open water habitats comprise about 65% of the area of the Lagoon. Although most of the productivity of the Lagoon is based on seagrasses and other plants, smaller free-floating microscopic plants known as phytoplankton also play an important role. Phytoplankton forms one of the key bases of the food web. Small, free-floating animal species of plankton known as zooplankton feed on these algae. The phytoplankton and zooplankton are, in turn, eaten by larval forms of important species such as the spotted seatrout or by other fish species such as bay anchovy or black mullet. The anchovy and mullet, in turn, are primary food sources for significant species such as the red drum (redfish) and tarpon, along with a number of other species important to to the ecology and economy of the Indian River Lagoon region.

In this delicate environment, too many phytoplankton can kill both seagrasses (due to shading) and fish (due to a lack of oxygen consumed by dying or decaying phytoplankton). When high levels of nutrients, such as those associated with stormwater runoff and other pollution are combined with high summer temperatures and light, an overabundance or “blooms” of algae may occur. Algae blooms can upset the delicate balance of the Lagoon causing fish kills, of dors, decreased water clarity and other problems.

Text Box: Mangrove forest Mangrove Forests & Salt Marshes

Two important habitats adjacent to the open waters of the Indian River Lagoon are mangrove forests and salt marshes. The sediments supporting these habitats are often covered by water at high tide but are exposed at low tide. Mangrove forests and salt marshes are home to a large number of plants and animals, several of which could not survive elsewhere. For example, the salt marshes of Mosquito Lagoon are the only habitat of the threatened Atlantic Salt Marsh snake. The salt marshes of Merritt Island were once the prime habitat of the Dusky Seaside Sparrow prior to their impoundment for mosquito control. Losses of this prime habitat contributed to the extinction of this species.

Large numbers of wading birds forage for small fish and insects in these wetlands. The mangrove forest s also provide roosting and nesting areas for many of these v birds, and 80 percent or more of the recreational and sport fish species spend at least part of their lives in tidal wetlands.

Mangrove forests and salt marshes also play an important role in the protection of water quality. The tidal wetlands along the shore serve as a filter, removing sediments, nutrients and other pollutants from runoff before it reaches the open waters of the Lagoon. These same wetlands buffer the impacts of waves from storms or boats, helping protect the shoreline from erosion.

Mangroves are a tropical species that have adapted to a saltwater environment. Worldwide, there are 50 species of mangrove. Three mangrove species are found in Florida, all of which are found in the Indian River Lagoon. These are:

·        Red mangrove, Rhizophora mangle;

·        Black mangrove, Avicienna germinans; and,

·        White mangrove Laguncularia racemosa.

Line drawings of these species may be found in the appendix.

Red mangroves which are often found in water or adjacent to the waters edge can be readily identified by their tangled, reddish support roots called “prop roots.” Black mangroves are typically found at a slightly higher elevation and can be identified by numerous finger-like projections from the root system known as pneumatophores. The white mangrove normally occupies the highest elevations further upland than either the red or black mangroves. The white mangrove has visible aerial root structures such as prop roots or pnematophores.

Salt marshes are dominated by non-woody plant species such as grasses or rushes. Common species found in Indian River Lagoon salt marshes include:

·        Smooth cordgarss, Spartina alterniflora;

·        Saltmeadow cordgrass (or salt hay), Spartina patens;

·        Black rush (or needle rush), Juncus roemerianus;

·        Saltwort, Batis maritima;

·        Text Box: Salt Marsh Glasswort (or pickleweed), Salicornia sp.;

·        Saltgrass, Distichlis spicata; and ,

·        Sea-oxeye daisy, Borrichia futescens.

Most salt marshes in the Indian River Lagoon occur from Merritt Island north, where periodic winter freezes limit the spread of mangroves. Many of the salt marshes of the Indian River Lagoon differ from those elsewhere in Florida because a natural berm restricts flooding to only the highest tides, limiting vegetation to those species capable of tolerating high salinities as the result of evaporation.

Mosquito Control Impoundments

Text Box: Mosquito Control Impoundment Since 1950, more than 75 percent of the Lagoon’s mangrove forests and salt marshes bordering the Lagoon have been destroyed, altered or functionally isolated. More than 40,000 acres of these wetlands have been impounded for mosquito control.

Salt marsh mosquitoes that breed in these marshes need alternating wet and dry soils to reproduce. Building an impoundment and flooding the wetlands during mosquito breeding season interrupts this reproductive cycle. Many mosquito control impoundments were constructed in the 1940s, 1950s and 1960s. An impoundment is created by digging a ditch around the edge of a wetland and using the dredged material to create a dike along the ditch. The impoundment is then flooded, which prevents mosquitoes from laying their eggs. Artesian wells or pumps are used to maintain water levels in the impoundment, replacing water lost to seepage or evaporation.

Flooding for mosquito control has resulted in the loss of much of the original wetland vegetation and a change to a different vegetative community. This, in turn, changed the habitat so that many species that were adapted to the pre-impoundment conditions could no longer survive in the impoundments. On the other hand, some species (particularly waterfowl) have benefited from impoundment and flooding of the marshes that created sheltered, shallow-water habitat for these species. Construction of mosquito control impoundments had several detrimental impacts on the Indian River Lagoon including:

·        Cutting off exchange of waters between the Lagoon and the wetlands, losing the wetland benefits of water quality improvement,

·        Blocking the export of detritus and food materials from the wetlands to the Lagoon, matter which forms the basis of the food chain, and,

·        Restricting the movement of fish, crabs and other aquatic species between the Lagoon and the wetlands, which are vital habitat to many species in certain portions of their life cycle.

Text Box: Impoundment Reconnection In recent years, agencies have begun to implement improved impoundment management strategies to increase the hydrologic connection between impoundments and the Lagoon, restoring the vital link between the wetlands and the Lagoon. As the result of these efforts approximately 70 percent of the impoundments in the Lagoon now have at least some type of open connection to the Lagoon.

While additional impoundment reconnection projects are scheduled for coming years but many of the impoundments are private land, limiting the ability to use public funds. To address this problem many privately owned impoundments are targeted for purchase through various environmental land acquisition programs.

Spoil Island & Shoal Habitats

Text Box: Spoil Islands These little-appreciated habitats in the Indian River Lagoon are man-made islands created by deposition of dredged material in the open waters of the Lagoon. Most of the 200-plus spoil islands were created in the 1950s during the dredging of the Intracoastal Waterway.

When the islands were constructed, many environmental impacts resulted. One impact was the destruction of seagrass beds by filling and the large areas of turbid waters generated as the islands were constructed.

Over the years, many of the islands have stabilized and seagrasses  have colonized portions of the shallow submerged areas of these islands. Mangroves have often become established in the intertidal areas along with some native trees and shrubs on the upland portions of many islands, providing roosting and nesting sites for a variety of birds. Typically, spoil islands have a mangrove fringe with the interior comprised primarily of exotic plants such as Brazilian pepper or Australian pine. Bare, sandy areas and sand spits provide alternative nesting sites for terns and several other shorebirds who have been displaced from their natural nesting sites on the ocean beaches.

FISH & WILDLIFE

Fisheries

Text Box: The fisheries of the Indian River Lagoon have played an important role in the human use and development of the region throughout recorded history. The remains of fish and shellfish in Ais and Timucuan indian shell mounds and camp sites show that these early settlers depended heavily on the bountiful fishery resources of the Indian River Lagoon for food.

The commercial fishing industry in the Indian River Lagoon began in the mid 1860s. Many commercial fishermen took advantage of he long docks at places such as Cobb’s store and landing in Fort Pierce. At many of these locations, large racks were used to dry miles of nets. Mule-drawn carts hauled the catch from the piers on a rail lines running to shore, where he the catch was processed and shipped to market.

 Today, fisheries-related employment represents only a fraction of the regional total, but the value of the fishery resource is measured in other terms as well.  Sport fishing and abundant fresh fish in local restaurants and markets attract visitors and residents alike, contributing millions of dollars to local economies. Many people are employed in related fields such as boat construction and sales, bait and tackle, and restaurants, all of which depend on a healthy fishery.

Fishery resources were extremely abundant in the 1800s and early 1900s, as can be seen in photographs from that era showing large catches of snook, redfish, spotted seatrout and even sawfish. Today, with exception of the sawfish, these species are still present but many fishermen will tell you that today’s fish are fewer and smaller.

Catch data collected over the last thirty years show that catches of some species such as snook snd spotted seatrout have declined severely. In recent years, the snook has been declared a gamefish and has been listed as a species of special concern by the state, so it is no longer sold commercially. Reports of more and bigger snook caught by anglers have appeared in recent magazines and newspapers, which may indicate that this species is responding to improved management techniques.

The spotted seatrout is one of the most popular species of gamefish in the Indian River Lagoon. It is also an important commercial species. Declines of important species such as the spotted seatrout hurt both recreational and commercial fisherman. Since 1953 the recorded seatrout commercial catch has declined more than 50 percent in the region. Creel surveys have found that sport fishermen have also caught fewer seatrout. According to the National Marine Fisheries Service, the average time to catch a seatrout has increased from two hours to four hours since 1980. Because the seatrout depends on the Lagoon exclusively throughout its life, factors within the Lagoon are apparently related to its decline.

Overfishing has been cited by some as a cause of declining fish populations. Another major factor is the loss of productive habitat. Seatrout use seagrass beds during significant portions of their lives. In some portions of the Lagoon, seagrass beds have decreased by more than 90 percent. Other changes in habitat include the isolation of productive mangrove and salt marsh habitats for mosquito control and filling of productive areas for coastal development.

Wildlife

The Indian River Lagoon contains more than 2,200 species of animals. This number includes more than 700 species of fish, 68 species of reptiles and amphibians, 370 bird species and 29 mammal species. Among the birds more than 125 species breed in the Lagoon region, while another 175 species winter here.

The estuary is located along the Atlantic flyway, the route used by millions of birds that migrate between eastern North America and the Caribbean. Some get as far as the Lagoon and decide to forgo the rest of the trip south. More than 20,000 ducks and other waterfowl have been counted at the Merritt Island National Wildlife Refuge alone. Wading birds and shore birds are also abundant year-round in the region as well. The Lagoon is also home to more than 50 communal nesting areas (rookeries); most of them located on spoil islands or in mangrove forests.

Text Box: Pelican Island One of the major rookeries is the Pelican Island National Wildlife Refuge. The nation’s first wildlife refuge, Pelican Island National Wildlife Refuge was established in 1903 by President Theodore Roosevelt in response to a severe decline in brown pelicans (particularly in central and southern Florida) in the early 1900s. Many of the breeding birds were located at Pelican Island, which was virtually the only remaining nesting site of any significance in southern or eastern Florida.

When brown pelican populations dipped again in the 1960s and 1970s reportedly as the result of DDT use, the Lagoon’s brown pelican population was affected only slightly because less DDT was used for mosquito control here. Mangrove forests and salt marshes were either ditched and drained or impounded and flooded to control mosquito breeding. This approach to mosquito control was developed as a less expensive yet highly effective alternative to pesticides such as DDT.

Although ditching, draining and impounding marshes instead of using DDT may have aided the brown pelican, it disturbed the fragile ecology of the Indian River Lagoon system. Changes in salt marsh habitat helped make the dusky seaside sparrow extinct and caused the Smyrna seaside sparrow to disappear from Indian River Lagoon marshes. These changes also affected feeding and nesting patterns for many species and restricted access or use of wetlands by other species.

Among marine mammals, the manatee (also known as the sea cow) and the Atlantic bottlenose dolphin are found in the Lagoon year-round. Some use the Lagoon seasonally or as a migratory route to other feeding grounds or refuge areas.

Text Box: Manatee The manatee is a large plant-eating mammal, which swims slowly through shallow water, grazing on seagrasses and other plant life. The Indian River Lagoon is used by at least one-third of the U.S. manatee population, of which some are permanent residents while others are migratory. As an example of manatee use of the India River Lagoon system, as many as 300 manatees have been counted in surveys in the northern end of the Banana River alone.

Manatees are quite susceptible to injury from watercraft using the Lagoon. Much of the manatee population has prop scars or other evidence of encounters with watercraft. Collisions with watercraft are the leading human-related cause of manatee mortality.

Text Box: Dolphin

The fish-eating Atlantic bottlenose dolphin is found most commonly in the central and southern portions of the Lagoon system. As many as 300 dolphins live permanently in the Lagoon with others moving between the Lagoon and the Atlantic Ocean.

Many other species of wildlife depend on the Lagoon at various times in their life cycle. All of these species contribute to the biodiversity of the Lagoon but their continued existence requires adequate amounts of suitable habitats. Many species have become endangered or threatened and will require special attention if they are to remain part of the Indian River Lagoon system.