Photo Credit: P. Lilienthal
A Diverse Ecosystem
The Indian River Lagoon (IRL) is a diverse ecosystem that stretches approximately 156 miles along the east central Florida coast. It comprises three connected water bodies, each unique in its own right:
- The Mosquito Lagoon
- The Banana River Lagoon
- The Indian River Lagoon
Together, these waters create a mix of marine and estuarine environments that support many different lagoon habitats.
In general terms, a habitat is the specific place in an environment where an organism lives. Terrestrial and marine ecosystems have distinct characteristics that determine whether they’re suitable for different animals and plants.
A close look at any area along the IRL reveals a number of different habitat types. These habitats include coastal forests (hammocks), mangroves, salt marshes and submerged habitats like seagrasses. Each habitat supports its own array of species.
Photo Credit: D. Bonosconi
Explore IRL Habitats
The IRLNEP has partnered with the Smithsonian Marine Station at Ft. Pierce to develop and host the Indian River Lagoon Species Inventory. The inventory is the most comprehensive source for information about lagoon ecology, species and habitats. It has its own website, IRLSpecies.org, where you can access species and habitat information, species checklists and a wealth of other information about the lagoon’s animals and plants.
Explore the information below, or use the links to access the IRL Species Inventory website and learn much more about the lagoon’s diverse habitats.
Photo Credit: K. Hill
Overview
Around 1,181 miles of tidal coastline border the Florida peninsula, second only to Alaska. Of this total, approximately 746 miles, primarily along Florida’s east coast, consist of sandy beaches. There, high-energy waves constantly break along the shoreline.
Beaches are home to a medley of plants and animals. While some are too small to see, others (like sea turtles) are iconic to Florida’s coastline. However, they’re all part of the same delicate ecosystem and rely on the habitat as a source of food and shelter.
Threats to Beaches
Florida’s barrier islands are extensively developed and support a large human population, leaving little of the original landscape unaltered. Florida’s beaches rate among the finest in the U.S. and draw tourists from around the globe. As a result, tourism has become the premier industry in Florida, providing more than 845,000 jobs and generating billions in revenue each year.
While development and tourism have been economic boons to Florida, they have also brought associated problems. We must continually address these issues to ensure healthy habitats for the wildlife and plants that depend on Florida’s beaches.
Learn more about the lagoon’s habitats and species at the Indian River Lagoon Species Inventory.
Photo Credit: D. De Freese
Overview
Wind and sand combine to create sand dunes on virtually any barrier island. Dunes play a vital role in protecting coastlines and property. They act as buffers against severe storms, protecting the lands beyond the dune from saltwater intrusion, high wind and storm surges.
Dunes also act as sand reservoirs. These are important for replenishing coastlines after tropical storms, hurricanes, intense wave action or other erosional events.
Threats to Dunes
Despite the stabilizing ability of dune plants, dunes are highly susceptible to human actions.
Vehicles and heavy foot traffic on beaches damage vegetation by shifting sand and roots, destabilizing the dune community.
Coastal development can also affect the natural dune replenishment process by harming natural erosion patterns.
Visit the Smithsonian Marine Station website to learn more.
Photo Credit: K. Hill
Overview
Stable back-dune areas give rise to scrub communities built upon sandy or well-drained soils. The predominant vegetation is usually herbaceous shrubs, evergreen oaks or pines.
Strong winds and flooding from storm events affect coastal scrub communities. However, fires typically maintain most types of scrub.
Frequent fires are beneficial to oak scrub and scrubby flatwoods communities. Meanwhile, less frequent fires are more beneficial to sand pine scrub and other pine-dominated scrub types.
A number of plants and animals specialize in scrub habitats, including prickly pear cactus, scrub oaks and gopher tortoises. Many other species also use scrub areas for feeding and shelter.
Threats to Scrub
Coastal scrub communities, commonly known as coastal strand, are vanishing ecosystems due to developmental pressures in the coastal zone. Most coastal habitats, from Cape Canaveral in Brevard County to Miami in Dade County, are highly fragmented due to development. In Brevard County alone, researchers estimate the natural scrub community shrank by 69% from 1943 to 1991.
Learn more by visiting the Smithsonian Marine Station website.
Photo Credit: K. Hill
Overview
Maritime hammocks are also known as maritime forests, tropical hammocks or coastal hammocks. Narrow bands of forest are their defining characteristic. These bands develop almost exclusively on stabilized barrier island back-dunes, inland of primary dunes and scrub.
With the longest coastline in the contiguous U.S., Florida has approximately 468,000 acres of barrier islands. Maritime forests occupy the highest, most stable island areas.
The canopy is typically closed in maritime forests. This makes these areas shady and cool compared to adjacent scrub, dune and beach areas. A wide variety of plants and animals use hammocks for habitat, including some rare, threatened and endangered species.
Threats to Maritime Hammocks
Because maritime forests occur on the most stable areas of barrier islands, they’re attractive development sites. When developed, the land-clearing process involves disturbing or destroying most, if not all, of the natural vegetative cover to make space for homes, parking areas, drainage fields, septic systems and roads.
Following construction, humans often replace native vegetation with lawns and ornamental shrubs, many of which are exotic.
Learn more by visiting the Smithsonian Marine Station website.
Photo Credit: K. Hill
Overview
Mangrove forests are among the world’s most highly productive ecosystems. We loosely use the term “mangrove” to describe an array of often-unrelated tropical and subtropical trees and shrubs with common characteristics.
Mangroves perform a vital ecological role: providing habitat for hundreds of different species. These include fish, reptiles, mammals and birds that all use mangroves as habitat during some period of life.
Although they’re not permanent mangrove inhabitants, many species use mangrove areas for foraging, roosting and breeding. In addition to providing vital nursery and feeding habitat to fishes, mangroves help protect and stabilize shorelines.
Threats to Mangroves
Researchers estimate that since the 1950s, 75% of the mangrove forests and salt marshes bordering the IRL have been destroyed, altered or functionally isolated. In more recent years, we’ve recognized the importance of coastal wetlands and have devoted significant work to reconnecting wetlands to the lagoon to improve water flow and natural function.
Learn more by visiting the Smithsonian Marine Station website.
Photo Credit: T. Sailor-Tynes
Overview
Salt marshes form in sheltered coastal areas where sediments accumulate. This accumulation allows for the growth of a variety of plants forming the ecosystem’s foundation.
Salt marshes are biologically diverse communities adapted for harsh environmental conditions. Tough conditions include desiccation, flooding and extreme temperature and salinity fluctuations.
Marshes also act as nurseries to many organisms, some of which are notably threatened or important fisheries species.
Rapid marsh vegetation growth and use of incoming nutrients make salt marshes highly productive systems. In fact, they’re on par with tropical rainforests in terms of their productivity.
In addition to providing habitat and food sources for many organisms, salt marshes benefit humans and surrounding ecosystems by sheltering coasts from erosion and flooding. They also act as filters for stormwater runoff, trapping sediments and using nutrients in stormwater flowing across them.
Threats to Salt Marshes
Salt marsh habitats face pressure from shoreline development, altered water flow, sea level rise and invasive species. Nutrient-rich stormwater runoff can also stress marshes. This runoff changes water quality and affects the plants and animals that rely on these ecosystems.
Learn more by visiting the Smithsonian Marine Station website.
Photo Credit: H. McVay
Overview
Tidal flats are highly productive ecosystem components, responsible for recycling organic matter and nutrients from both land and ocean sources. They provide enormous water-carrying capacity, helping protect areas of the IRL from storm surge and stormwater runoff.
In addition, tidal flats help reduce erosion and dissipate wave energy. They also reduce the impacts of storms by forming a buffer zone between deeper lagoon channels and the shoreline.
In combination with mangroves and salt marshes, these intertidal habitats are integral to large numbers of invertebrates and fish. They support a complex estuarine food web and provide resting and feeding areas to many resident and migratory birds.
Threats to Tidal Flats
Water and sediment quality characteristics are important factors in maintaining healthy lagoon habitats. Tidal flats face many serious human and natural threats. These include muck deposit accumulation, rapid salinity fluctuations, nutrient pollution, erosion and invasive species.
Learn more by visiting the Smithsonian Marine Station website.
Photo Credit: A. Arteaga
Overview
Oyster reefs, often known as oyster bars, are common submerged habitats in the southern U.S.
In the IRL, oyster reefs exist in the vicinity of spoil islands and impounded areas. In addition to being commercially valuable, oyster reefs serve important ecological roles in coastal systems:
- Providing important habitat for a large number of species
- Improving water quality by filtering particulates out of the water
- Stabilizing bottom areas to prevent erosion
- Influencing water circulation patterns within estuaries
Threats to Oyster Reefs
Overharvesting, as well as persistent diseases such as MSX and Dermo, has taken a devastating toll on many oyster populations along the east and Gulf coasts. In recent years, oyster reef restoration has been a concern for resource managers along the U.S. east coast.
It’s of special concern in areas like the lagoon, where oyster harvesting has historically been commercially important. Fisheries throughout the lagoon have declined in recent years. Still, we’ve seen renewed interest in reestablishing oyster reefs, primarily due to the water quality benefits they offer the ecosystem.
Learn more by visiting the Smithsonian Marine Station website.
Photo Credit: D. Deis
Overview
Seagrasses are types of submerged aquatic vegetation (SAV) that evolved from terrestrial plants and have become specialized to live in the marine environment. Physiologically, they’re not too different from the grasses that grow on land and produce flowers and seeds.
Within seagrass communities, a single acre of seagrass can produce over 10 tons of leaves per year. This vast biomass provides food, habitat and nursery areas for many adult and juvenile vertebrates and invertebrates.
Because seagrasses support such high biodiversity and are sensitive to water quality changes, scientists have recognized them as key indicator species. In other words, they reflect a coastal ecosystem’s overall health.
When seagrasses do well, other animals and plants do well; when seagrasses decline, other species follow.
Threats to Seagrass Communities
Seagrasses are subject to a number of biotic and abiotic stresses:
- Storms
- Excessive grazing by herbivores
- Disease
- Anthropogenic threats due to point and nonpoint sources of pollution
- Decreasing water clarity
- Excessive nutrients in runoff
- Sedimentation
- Prop scarring (boat propeller damage to seagrass in shallow water)
The effect these stresses have on seagrasses depends on the particular environmental challenge’s nature and severity.
Learn more by visiting the Smithsonian Marine Station website.
No Habitats. No Lagoon Resources.
Habitats don’t just disappear: Stressors nibble away at them acre by acre. As habitats die, so do the resources they provide. Donate to One Lagoon through the IRLNEP to help protect the IRL’s precious habitats.
Protecting lagoon habitats means protecting our wildlife, local communities and future.
Photo Credit: E. Brooks
Habitat Threats
Why Care About Sea Level Rise?
People and organizations have paid much attention to the effects of rising sea levels on global coastal ecosystems. From 1900 until 1990, sea levels rose an average of 1.2 to 1.7 mm per year. By the year 2000, this had become 3.2 mm per year and 3.4 mm per year by 2016.
Today, seas are rising faster than they have at any time over the past 6,000 years, and we expect that figure to only increase. In coming years, sea level rise will affect our coasts the hardest.
How Sea Level Rise Affects the Lagoon
Surrounded by the Atlantic Ocean and Gulf of Mexico and inundated by waters from the Everglades, low-lying Florida is particularly prone to climate change and rising sea levels.
Furthermore, most of Florida sits on porous bedrock that allows for saltwater infiltration. Rising sea levels can do more damage:
- Erode beaches
- Submerge estuaries and low-lying wetlands
- Enhance coastal flooding
- Increase the salinity of estuaries
It may take decades to centuries for some effects to materialize. Nonetheless, Florida is already experiencing coastal flooding issues during normal summer rainstorms and king tides. We’re also seeing increased flooding effects during hurricanes and tropical storms.
What Are We Doing About Sea Level Rise?
Scientists, planners and local partners are monitoring sea level trends. They assess vulnerable habitats and communities, as well as incorporate sea level rise into long-term planning.
Restoration of wetlands, mangroves and other natural buffers can also help the lagoon’s habitats absorb some impacts and increase resilience over time.
Learn more by visiting the Smithsonian Marine Station website.
How Impoundments Affect the Lagoon
Impounding of coastal wetlands has been one of the widest-reaching and most destructive disturbances in coastal Florida ecosystems.
In the 1950s, impounding marshes became a preferable and more environmentally friendly way to control mosquitoes with significantly fewer pesticides. Because salt marsh mosquitoes lay their eggs in moist soils, keeping impoundments flooded disrupted the mosquito’s life cycle.
However, isolating these coastal wetlands was ecologically damaging.
What Are We Doing About Impoundments?
Since the mid-1990s, newer methods of impoundment management have allowed for reconnecting formerly isolated wetlands to the lagoon. This move restores ecological function while continuing to help control mosquito breeding.
While humans have reconnected many impoundments to the lagoon since the late 1980s, many are still closed systems with no natural hydrology. They receive water only from precipitation and stormwater runoff.
In closed impoundments, particularly during drought years, this has resulted in extremely salty (hypersaline) conditions. Hypersalinity has killed vegetation and allowed a limited number of species to survive in the harsh environment.
Learn more by visiting the Smithsonian Marine Station website.
How Shoreline Development Affects the Lagoon
Continuing land use changes from Florida’s growing population and increasing urbanization have permanently altered coastal ecosystems.
Coastal development has filled and altered scrub, maritime hammock, mangrove and salt marsh areas to build commercial properties, housing and roads. These changes eliminate or fragment critical habitats and leave ecosystems more vulnerable to other disturbances, including invasive species.
What Are We Doing About Shoreline Development?
Despite the substantial loss of habitat, large swaths of natural area still remain. The federal government protects much of it through the National Wildlife Refuge system.
The IRL region is home to four national wildlife refuges:
- Merritt Island National Wildlife Refuge
- Archie Carr National Wildlife Refuge
- Pelican Island National Wildlife Refuge
- Nathaniel P. Reed Hobe Sound National Wildlife Refuge
Florida Department of Environmental Protection and the Florida Fish and Wildlife Conservation Commission manage more than 10 million acres of public Florida land, much of it in the lagoon region.
Counties along the IRL have set aside land as conservation areas and public parks. Many have departments to manage environmentally sensitive lands. Cities also maintain a mosaic of lands that they manage for conservation and passive recreation.
The state also has dedicated programs, like the Florida Forever and Rural and Family Lands Protection Program. Their initiatives aim to conserve natural and agricultural lands.
Floridians enjoy year-round access to countless recreational opportunities. Many people are actively involved in ensuring the state’s public lands remain accessible and natural. We all have an array of ways to participate in conservation efforts, land acquisition programs, advocacy and community engagement through environmental nonprofit organizations.
How Muck and Nutrients Affect the Lagoon
Muck is a problem due to the many excess nutrients it carries. Although fine silts, sand and soils compose most of it, muck also contains a variety of formerly living things. These include lawn and yard wastes, pet wastes, dead fish and other animals, and many other materials. These organic materials continually release nutrients into the water, becoming an internal source of pollution.
Stormwater runoff and discharges from canals and other conveyances introduce muck to the lagoon.
Muck generally settles into depressions in the sediment and can be meters deep in some areas of the IRL. It’s easily resuspended and redeposited when something disturbs the water column, which clouds the water, blocking sunlight from reaching seagrasses and other vegetation.
What Are We Doing About Muck and Nutrients?
Muck accumulation in the IRL has been ongoing since the 1950s. Unless we remove it, muck can continue polluting for potentially hundreds of years. Muck deposit removal by dredging is the most effective method but also the most expensive management approach.
Ultimately, source control to prevent muck from accumulating in the lagoon is the best approach.
Learn more by visiting the Smithsonian Marine Station website.
How Invasive Species Affect the Lagoon
Invasive species have become a high-profile issue affecting Florida ecosystems. Nearly 200 non-native or invasive species are currently in the lagoon region. Many are outcompeting native species for food and habitat resources, so they affect how the ecosystem functions.
What Are We Doing About Invasive Species?
Efforts are ongoing to remove invasive plants from terrestrial areas. However, aquatic fish and invertebrate invasions are often difficult or impossible to reverse once a species takes hold and begins reproducing.
We can manage most invasive species only to prevent them from further range expansion. It’s unlikely that we can ever eradicate them.
Visit the Smithsonian Marine Station website to learn more.
How Hurricanes Affect the Lagoon
Salt marshes, mangroves and other coastal ecosystems have adapted to recover quickly from natural disturbances like fires and hurricanes.
However, when disturbance events occur in close succession, they may have more lasting effects on ecosystems. Hurricanes produce storm surges, high winds and waves that can impact coastal systems in several ways.
Hurricanes and tropical storms can cause influxes of seawater that rapidly change salinity. Although adapted for change, many lagoon organisms are sensitive to rapid shifts in either temperature or salinity. As a result, those changes can damage them.
Extreme winds can strip trees and bushes of foliage and damage tree branches and trunks. Lower-elevation areas can also experience extreme rates of either sedimentation or erosion, which can have lasting effects on habitat quality and ecosystem function.
What Are We Doing About Hurricanes?
After major storms, scientists and resource managers assess damage and monitor water quality and habitat changes. They then track how the lagoon recovers.
Local partners also work to strengthen the lagoon’s resilience over time by restoring habitats and supporting nature-based solutions that help buffer future storms.
Learn more by visiting the Smithsonian Marine Station website.