Seagrass Meadows

Seagrass Ecosystem

Sea grasses play an integral role in the health of coastal areas throughout the world, including Florida. The submerged grasses provide food for microscopic organisms and shelter for small fish and other marine life. Sediment pollution is trapped by grasses, which also absorb fertilizer nutrients that wash into rivers, creeks and coastal waters -- helping to stifle outbreaks of harmful algae.

Sea grass beds are important to the places where they exist -- places that should not be destroyed to make way for new marinas and the channel dredging that can come with waterfront development.
Also, it is not clear weather sea grass beds can be effectively moved from one place to another.

Coral reefs, mangroves and marshes are coastal habitats that get attention from the public and media, said an article 18 months ago in the scholarly journal Bioscience. The two marine scientists who wrote the article said sea grasses, which are just as important, are often ignored.

SeagrassesFlowering plants that grow and reproduce under water like eelgrass or a similar grass-like plant that grows near the sea. exist in a complex ecosystema community of organisms, including humans, interacting with one another and the environment in which they live. built up over the ages. They are specialized marinerefers to sea water, to sediments deposited in sea water, or to animals that live in the sea, as opposed to fresh water. flowering plants which have adaptedTo be accustomed to the natural factors that are in a given area and to be able to survive these factors, being either positive or negative. to the environment near the shore. Some speciesA taxonomic category subordinate to a genus (or subgenus) and superior to a subspecies or variety, composed of individuals possessing common characters distinguishing them from other categories of individuals of the same taxonomic level. In taxonomic nomenclature, species are designated by the genus name followed by a Latin or Latinized adjective or noun. need to be exposed at low tide or need some fresh waterWater that is relatively free of salts. inflow in order to thrive, and some can thrive in a range from fresh to salt water conditions.

Several factors affect their ability to thrive. Light for photosynthesisIs the chemical process where plants and some bacteria can capture and organically fix the energy of the sun. This chemical reaction can be described by the following simple equation:
6CO₂ + 6H₂O + light energy >>> C₆H₁₂O₆ + 6O₂
The main product of photosynthesis is a carbohydrate, such as the sugar glucose, and oxygen which is released to the atmosphere. All of the sugar produced in the photosynthetic cells of plants and other organisms is derived from the initial chemical combining of carbon dioxide and water with sunlight. This chemical reaction is catalyzed by chlorophyll acting in concert with other pigment, lipid, sugars, protein, and nucleic acid molecules. Sugars created in photosynthesis can be later converted by the plant to starch for storage, or it can be combined with other sugar molecules to form specialized carbohydrates such as cellulose, or it can be combined with other nutrients such as nitrogen, phosphorus, and sulfur, to build complex molecules such as proteins and nucleic acids. Also see chemosynthesis. It is said that photosynthesis gives rise to three quarters of the world supply of oxygen that we breathe. is critically important, and this is affected by turbidity and by attenuation according to water depth or water color. EpiphytesType of vegetation that gets its physical support from the branches of other plants. Commonly found in the tropical forests. may also shade the leaves from receiving adequate light. Hydrostatic pressurePressure exerted by the weight of water bearing down is a function of water depth and may also affect seagrass growth. The way that water moves is also important, both with respect to tidalRelating to or affected by tides. range and motion patterns which affect depth and turbulenceAn eddying motion of the atmosphere that interrupts the flow of wind., making pollinationFertilization of a flower or plant with pollen more difficult, for example. Tolerance to temperature, as described herein below, can have dramatic effect.

AnthropogenicResulting from human activity influences probably have been responsible for the general decline in seagrass populations observed in recent years, especially in regard to nutrientAny food, chemical element or compound an organism requires to live, grow, or reproduce. enrichment and chemical pollution from urbanizationExpansion of cities into rural regions because of population growth. In most cases, population growth is primarily due to the movement of rural based people to urban areas. This is especially true in Less Developed Countries. of coastal regions. Recreational and professional boating have also damaged seagrass beds. The effects of climate change, if unchecked, may yet cause a complete transformation of seagrasses on a global scale with lasting consequences to us all.

Seagrasses take nutrientsAny food, chemical element or compound an organism requires to live, grow, or reproduce. from the biomassThe total mass of living matter within a given unit of environmental area. in which they root and from the water column through their leaves, using energy from sunlight for photosynthesisIs the chemical process where plants and some bacteria can capture and organically fix the energy of the sun. This chemical reaction can be described by the following simple equation:
6CO₂ + 6H₂O + light energy >>> C₆H₁₂O₆ + 6O₂
The main product of photosynthesis is a carbohydrate, such as the sugar glucose, and oxygen which is released to the atmosphere. All of the sugar produced in the photosynthetic cells of plants and other organisms is derived from the initial chemical combining of carbon dioxide and water with sunlight. This chemical reaction is catalyzed by chlorophyll acting in concert with other pigment, lipid, sugars, protein, and nucleic acid molecules. Sugars created in photosynthesis can be later converted by the plant to starch for storage, or it can be combined with other sugar molecules to form specialized carbohydrates such as cellulose, or it can be combined with other nutrients such as nitrogen, phosphorus, and sulfur, to build complex molecules such as proteins and nucleic acids. Also see chemosynthesis. It is said that photosynthesis gives rise to three quarters of the world supply of oxygen that we breathe.. Restoration of damaged seagrasses needs the entire ecosystema community of organisms, including humans, interacting with one another and the environment in which they live. (below and above ground) to function properly, and usually requires transplanting of functioning entity taken from a donor ecosystemAn ecosystem from which a section has been transported to replenish another ecosystem, damaging it in the process. Enhanced water qualityA term used to describe the chemical, physical, and biological characteristics of water, usually in respect to its suitability for a particular purpose. enables a damaged seagrass bed to attempt self-recovery. Prevention from damage, conservation and management of seagrass meadows are therefore critically important to us all. Seagrasses take in nutrientsAny food, chemical element or compound an organism requires to live, grow, or reproduce. both through their roots in the sediment layers, and through their leaves in the water column, using energy from sunlight to photosynthesize complex transformation of their food sources.

Seagrasses serve as hosts for bacterial, algal and planktonic epiphytes (on leaves) which are food source for grazers, the preyOrganism that is consumed by a predator. for larger invertebrates and fish. Epiphytic growths (and excess chlorophyllGreen pigment found in plants and some bacteria used to capture the energy in light through photosynthesis., stimulated by phosphorous concentrations) also shield seagrass blades from sunlight necessary for their photosynthesisIs the chemical process where plants and some bacteria can capture and organically fix the energy of the sun. This chemical reaction can be described by the following simple equation:
6CO₂ + 6H₂O + light energy >>> C₆H₁₂O₆ + 6O₂
The main product of photosynthesis is a carbohydrate, such as the sugar glucose, and oxygen which is released to the atmosphere. All of the sugar produced in the photosynthetic cells of plants and other organisms is derived from the initial chemical combining of carbon dioxide and water with sunlight. This chemical reaction is catalyzed by chlorophyll acting in concert with other pigment, lipid, sugars, protein, and nucleic acid molecules. Sugars created in photosynthesis can be later converted by the plant to starch for storage, or it can be combined with other sugar molecules to form specialized carbohydrates such as cellulose, or it can be combined with other nutrients such as nitrogen, phosphorus, and sulfur, to build complex molecules such as proteins and nucleic acids. Also see chemosynthesis. It is said that photosynthesis gives rise to three quarters of the world supply of oxygen that we breathe. and health. Animals that live in the ground, together with those living among plants of the seagrass beds transfer nitrogen, phosphorous and organic

1. Relating to an organism.
2. Derived from an organism.

Ecosystem Decline

Both natural and human induced disturbances cause decline of the seagrass meadows. Storms, overgrazing by urchins, competition, disease and bioturbidity constitute examples of natural reasons for decline. Oil spills, thermal pollutionIndustrial discharge of heated water into a river, lake, or other body of water, causing a rise in temperature that endangers aquatic life. by power plants, human originated detritusShed tissues, dead body parts, and waste products of organisms. In most ecosystems, detritus accumulates at the soil surface and other types of surface sediments., thoughtless boating, eutrophication, nutrient run off of excess fertilizers and detergents from urbanizationExpansion of cities into rural regions because of population growth. In most cases, population growth is primarily due to the movement of rural based people to urban areas. This is especially true in Less Developed Countries., and effluents from mining, farming, industry and manufacturing, compounded by inadequate water management (e.g., permitting destruction of wetlands ), constitute the principal human induced reasons for decline.

In addition to periodic and sporadic storms, population explosions in speciesA taxonomic category subordinate to a genus (or subgenus) and superior to a subspecies or variety, composed of individuals possessing common characters distinguishing them from other categories of individuals of the same taxonomic level. In taxonomic nomenclature, species are designated by the genus name followed by a Latin or Latinized adjective or noun. of grazers, such as that of sea urchins in the north east Gulf of Mexico reported in 1973, have caused significant declines from natural causes. Crabs, fish and particularly bottom feeding flatfish disturb seagrasses by digging in it for food or resting upon it, as do manatees which shovel out strips as they feed on the grasses.

It is the impact of human activity that can and must be controlled if seagrass meadowsSeagrass Meadows consist of specialized marine flowering plants which have adapted to the environment near the shore. Some species need to be exposed at low tide or need some fresh water inflow in order to thrive, and some can thrive in a range from fresh to salt water conditions. are to remain the origin of the seafood we enjoy, and the economic and social benefits afforded by recreational boating and fishing are to be retained.

Dredging is a most harmful activity to be avoided whenever possible. When used to create canals and channels to provide waterfront to housing, turbidity is the culprit, especially when using hydraulic dredging which projects a water stream into the bottom leaving deep trenches a meter wide in a meadow. Even when dredging with nets or rakes to harvest oysters, scallops and clams, similar impacts are produced. Oyster dredging in eelgrassA marine plant with long ribbon-like leaves. [Zostera marina.], or, a submerged aquatic plant with narrow, grass-like leaves. [Genus Valisneria.] beds have been reported to cause a 70% reduction in seagrass shoot density. Not only does dredging produce turbidity of particulate matterParticles of dust, soot, salt, sulfate compounds, pollen, or other particles suspended in the atmospher which shades the leaves from sunlight, the sediment layers built up over the ages are destroyed, taking a very long time to recover.

Careless boating in seagrass beds allows propeller damage having a similar effect to that already described.

Heated water effluent of power stations which raise temperatures only 4 deg. C above ambient reportedly has caused die off of 60% of the seagrass leaf growth in some areas. A temperature rise of 5 deg. C above ambient has reportedly caused seagrass death. Such heated waters also disrupt adaptive tolerances of species and their reproductive cycles. A particular pollutantSomething which contaminates (water, the air, etc.) with harmful or poisonous substances. from coal fired power stations is mercurya heavy, silver-white, metallic element, the only metal that is liquid at room temperature; also called quicksilver. A virulent poison, dangerous to handle and work with. in down wind fallout, which as methylmercuryThe form of mercury taken up into tissues, for example fish tissue, making it harmful to eat contaminates fish tissueA group of similar cells that are organized into a structure with a specific purpose. to levels dangerous to humans, a reason for Crystal River to be on the FDEP impaired waters list.

Release of agriculture chemicals, sewage and industrial effluents into waters can cause a severe decline in submerged aquatic vegetation (SAV), including eelgrass in a river run. Reported declines have been registered following the use of atrazineA synthetic compound derived from triazine, used as an agricultural herbicide. on upland cereal cultivation, in 1982, and release by industry of PCB was identified as a direct cause of tumors on flatfish livers, rendering the fish unfit to eat. Chemical additions have also resulted in decline in water clarity, plant density, and biomassThe total mass of living matter within a given unit of environmental area. production. Oil and gas drilling and increased ship traffic related to oil, brings the specter of extensive negative impacts. In these cases seagrass ecosystemsa community of organisms, including humans, interacting with one another and the environment in which they live. may be greatly affected and in no case may these events be termed “natural” any longer. (Meaning, they are to be avoided, or their consequences remedied by the perpetrators at their cost.)

In Crystal River, for example, the application of chemical compounds to reduce concentrationsThe amount of a component in a given area or volume. of certain aquatic vegetation was stopped, when traces of heavy metal used in the compounds were discovered in the stomach of a manatee carcass, and sediment was found to have been contaminated by heavy metal residuesWhat is left over or remains; the part of a molecule that remains after portion of its constituents are removed. Residues of some contaminants may remain after.

The Big Bend Aquatic Seagrass Preserve (945,000 acres) consists mainly of a large, remote, and undeveloped expanse of submerged seagrasses and nearshore marshlands located along some 150 miles of the northeast coast of the Gulf of Mexico where the Florida peninsula joins the panhandle. The preserve boundary encompasses all tidalRelating to or affected by tides. lands, islands, seagrass beds, shallow banks, and submerged bottoms from the mean high water line extending 9 miles into the Gulf of Mexico. Landward, it includes all natural waterways tidally connected to the preserve to the extent of state jurisdiction.

Numerous flora and faunaThe animals of a particular region, habitat, or geological period., are formed at the confluence of the many rivers and streams that flow into the preserve. Open waters and submerged bay bottoms of these estuariesThe wide lower course of a river where the tide flows in, causing fresh and salt water to mix. support numerous speciesA taxonomic category subordinate to a genus (or subgenus) and superior to a subspecies or variety, composed of individuals possessing common characters distinguishing them from other categories of individuals of the same taxonomic level. In taxonomic nomenclature, species are designated by the genus name followed by a Latin or Latinized adjective or noun. of commercially and recreationally important fish. The shoreline is dominated by intertidalOf or denoting the area of a seashore which is covered at high tide and uncovered at low tide. marsh grasslands, a temperate natural community that is replaced in the tropics my mangroves. Some mangroves occur in the southern reaches of the marshes but are stunted and die back in periodic freezes.

Ecological Importance

Mullet, sea trout, redfish, scallops, oysters, clams, shrimp, blue crab, seagrasses, and Juncus are ecologically and economically important species.

The whole of the preserve, with its seagrass beds and saltmarshes, provides a nursery area for finfish and shellfish and a forage area for these same speciesA taxonomic category subordinate to a genus (or subgenus) and superior to a subspecies or variety, composed of individuals possessing common characters distinguishing them from other categories of individuals of the same taxonomic level. In taxonomic nomenclature, species are designated by the genus name followed by a Latin or Latinized adjective or noun. as well as manatee, osprey, bald eagles, sea turtles, sturgeon, and dolphin.

Recreational Importance

Fishing with appropriate license, canoeing/kayaking, swimming, SCUBA and snorkeling, nature study, bird watching, boating.

Commercial Importance

Fisheries for mullet, blue crab, shrimp, oyster, scallop, clams. Ecotourism.

The Big Bend Aquatic Seagrass Preserve is every bit as beautiful and ecologically important (if not more so) than the Everglades and its time we treated it that way.

It is time that we give all of Florida’s unique and dwindling natural resources the respect and protection they deserve. It’s time that state and federal environmental agency employees are given the freedom to express their professional opinions without fear of punishment.

Project Coast

An abstract from the Final Report on Project COAST 1997 - 2005 (Thomas K. Frazer et al. August 2006) is included on this website for the excellent science, clarity and rationale that it portrays, and as it refers to seagrass meadows.

Click here to view the abstract from the final report.