Florida Bay is the bay located between the southern end of the Florida mainland (the Florida Everglades) and the Florida Keys in the United States. It is a large, shallow estuary that while connected to the Gulf of Mexico, has limited exchange of water due to various shallow mudbanks covered with seagrass. [1] The banks separate the bay into basins, each with its own unique physical characteristics.
Encompassing roughly one-third of Everglades National Park, [2] Florida Bay is variously stated to be 800 square miles (2,100 km2), [3] or 850 square miles (2,200 km2), [4] or 1,000 square miles (2,600 km2). [5] Nearly all of Florida Bay is included in Everglades National Park. The southern edge, along the Florida Keys, is in the Florida Keys National Marine Sanctuary. The bay muds of portions of Florida Bay have been cored to develop insights on the paleontology of previous biota.
While there is no sharp boundary between Florida Bay and the Gulf of Mexico, the westernmost edge of Florida Bay can be approximated by a line drawn from Long Key to Cape Sable on the mainland. [6] The northeastern edge of Florida Bay is at Jewfish Creek in Key Largo. Blackwater Sound, southwest of Jewfish Creek, is generally considered part of Florida Bay; Barnes Sound, on the other side of jewfish Creek, is not. Barnes Sound is generally considered part of the Biscayne Bay system. [7]
The bay consists of more than 50 shallow (one to three meters deep) basins separated by mud banks and mangrove islands. Such basins include: Little Blackwater Sound, Blackwater Sound, Tarpon Basin, Buttonwood Sound, Duck Key Basin, Eagle Key Basin, Madeira Bay, Calusa Key Basin, Crane Key Basin, Rankin Lake, Whipray Basin, Twin Key Basin, Rabbit Key Basin, and Johnson Key Basin. [8] [9]
Water flows between the basins in narrow channels and over the mud banks. The bay is open to the Gulf of Mexico to the west, but connection to the Atlantic Ocean to the east is restricted to narrow channels between the Florida Keys. The average tidal range along the western edge of the bay is 1 to 1.5 meters, but the tidal range diminishes quickly eastward in the bay due to the restricted flow of water between basins. Fresh water flow into the bay is restricted to Taylor Slough and Trout Creek in the northeast corner of the bay, and is only 10% of the freshwater supply to the bay (rainfall provides the rest of the fresh water). Due to the poor circulation of water within the bay, salinity increases rapidly away from the margins of the bay, except for the northeast part of the bay where it receives fresh water from rivers. [10]
The bay receives freshwater from two major drainage basins: Shark River Slough and Taylor Slough. The clean freshwater delivered by these sloughs is essential for maintaining water levels and preventing salinity levels from getting too high. [11] The bay currently receives less than half of the freshwater from the sloughs compared to historic, pre-drainage conditions. [11]
The bay's many basins that are broken up by banks serve as plentiful fishing grounds for snook (Centropomus undecimalis), redfish (Sciaenops ocellatus), spotted seatrout (Cynoscion nebulosus), tarpon (Megaflops atlanticus), bonefish (Albula vulpes), and permit (Trichinous falcatus), among others. [12]
The bay is home to many species of wading birds. Most notably, Roseate spoonbills (Platalea ajaja), Reddish egrets (Egretta rufescens), and Great White Herons (Ardea herodias occidentalis) have unique subpopulations that are largely restricted to Florida Bay. [13] Other bird species include Bald eagles, seagulls, pelicans, sandpipers, cormorants, ospreys, and flamingos. [14]
Bay land animals include raccoons, opossums, bobcats, and fox squirrels. [14]
Florida Bay has undergone a series of ecological changes beginning in the late 1980s that have severely altered the ecosystem. [15] Originally, clean freshwater flowed south through the state into the Florida Bay. To support the state's agricultural water needs, namely for sugar cultivation, the water was rerouted and no longer flows into the Bay, causing numerous and severe environmental issues and loss of native wildlife.
The rerouting of the flow of freshwater to the Bay coupled with periods of drought have caused massive seagrass die-offs. [16] The first major die-off occurred from 1987 to 1991 as thousands of hectares of turtlegrass beds ( Thalassia testudinum ) were devastated by high levels of toxic dissolved sulfide. [17] 10,000 acres died in the central and western bay, and almost 60,000 additional acres suffered reduced productivity and biomass as a result. [18] Then, following the 2015 drought, extreme temperatures and heightened salinity reduced the amount of oxygen that could remain dissolved in the water, causing periods of anoxia during nighttime and thereby damaging the health of the turtlegrass in the bay. During the summer and fall of 2015, approximately 40,000 acres of seagrass died. [19]
The 2015 drought period of low precipitation combined with high temperatures and calm winds that produced rapid evaporation caused salinity to increase in the semi-enclosed basins in north-central Florida Bay. Without the freshwater, the water has become stagnant and salty with excess nitrogen from the fertilizer. [20] This hyper-salinity contributes to the massive seagrass die-offs and algal blooms, and kills submerged aquatic vegetation. [18]
Cyanobacterial harmful algae blooms (also known as blue-green algae) have flourished in the bay due to a variety of environmental stressors: Agricultural fertilizer run-off increases nutrients in the delicately balanced environment and the excess increases the bacteria's rate of growth; The newly hyper-saline environment provides an ideal breeding ground for cyanobacteria; [21] Rafts of dead seagrass floating on the surface of the water as well as decaying on the bay bottom leads to anoxia and in turn, algal blooms. [1]
Blue-green algae causes numerous severe health consequences for the marine ecosystem as well surrounding human populations. Blooms result in reduced dissolved oxygen concentrations, alterations in aquatic food webs, algal scum lining the shores, the production of compounds that cause distasteful drinking water and fish flesh, and the production of toxins severe enough to poison aquatic as well as terrestrial organisms. [22] Blooms have been reported throughout the continental United States, and resulting cyanotoxins have been associated with human and animal illness and death in at least 43 states. [23] Most cyanobacteria produce the neurotoxin beta-N-methylamino-l-alanine (BMAA) that has been implicated as a significant environmental risk in the development of neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis (ALS). [24] The cyanobacteria has also been linked to liver cancer, chronic fatigue illness, skin rashes, abdominal cramps, nausea, diarrhea and vomiting. [25]
The 2002 algal bloom in the central portion of the Florida Bay was associated with high concentrations of dissolved organic nitrogen and organic phosphorus, whereas the eastern bay regions bloom was associated with high concentration of inorganic nutrients. [26]
By the mid 1930s, the three main species of wading birds in the bay (Roseate spoonbills, Reddish egrets, Great herons) were driven to near extinction by human harvesting for food and feathers. [13]
The cyanobacteria create an oxygen-free environment teaming with toxic gases, creating an unsuitable living environment for many marine and terrestrial animal species. [27] As a result, seasons during which algal blooms flourish cause a temporary loss in wildlife.
Spotted seatrout populations in the coasted Everglades are declining. [28] As the second most commonly caught species of fish in the Florida Bay, spotted seatrout comprise a large portion of the fishing industry and are integral to the ecosystem as well as surrounding economy. Water temperature of less than 80 °F (27 °C) and salinity levels below 37.5 parts per thousand (ppt) are ideal for seatrout spawning; however, water management stations in the Everglades and Florida Bay reported salinity levels of 64.4 ppt in July 2015 and recorded water temperatures of up to 92 °F (33 °C). [28] These environmental conditions are far from ideal for the seatrout and add additional difficulties for the survival of juveniles as well as important prey such as larval shrimp and small fish. [28]
The bay is an economic and environmental asset. As of 2017 [update] , the recreational fishing industry in Florida Bay had an estimated value of $7.1 billion, and generated $73 million in federal, state and local taxes annually, while the bay's commercial fishing industry had an estimated value of $400 million, and generated $3 million in taxes. [29]
Various projects are funded by the government in an attempt to manage the hydrology issues present in the Florida Bay, including the C-111 South Dade, Modified Water Deliveries, and C-111 Spreader Canal Western Project from the Comprehensive Everglades Restoration Plan (CERP). [11] These projects seek to distribute more freshwater into the sloughs but do not deliver additional water to the bay.
The U.S. Atlantic Intracoastal Waterway goes through Florida Bay, generally following the southern boundary of the Everglades National Park. [9] Florida Bay is a Marine protected area designated as a "Particularly Sensitive Sea Area" by the International Maritime Organization in 2002. [30] Boating in Florida Bay off the Intracoastal Waterway is considered challenging, because of shallow depths, mud, and seagrass. [31]
An algal bloom or algae bloom is a rapid increase or accumulation in the population of algae in freshwater or marine water systems. It is often recognized by the discoloration in the water from the algae's pigments. The term algae encompasses many types of aquatic photosynthetic organisms, both macroscopic multicellular organisms like seaweed and microscopic unicellular organisms like cyanobacteria. Algal bloom commonly refers to the rapid growth of microscopic unicellular algae, not macroscopic algae. An example of a macroscopic algal bloom is a kelp forest.
Eutrophication is a general term describing a process in which nutrients accumulate in a body of water, resulting in an increased growth of microorganisms that may deplete the water of oxygen. Although eutrophication is a natural process, manmade or cultural eutrophication is far more common and is a rapid process caused by a variety of polluting inputs including poorly treated sewage, industrial wastewater, and fertilizer runoff. Such nutrient pollution usually causes algal blooms and bacterial growth, resulting in the depletion of dissolved oxygen in water and causing substantial environmental degradation.
Cyanobacteria, also called Cyanobacteriota or Cyanophyta, are a phylum of autotrophic gram-negative bacteria that can obtain biological energy via photosynthesis. The name 'cyanobacteria' refers to their color, which similarly forms the basis of cyanobacteria's common name, blue-green algae, although they are not scientifically classified as algae. They appear to have originated in a freshwater or terrestrial environment.
Everglades National Park is an American national park that protects the southern twenty percent of the original Everglades in Florida. The park is the largest tropical wilderness in the United States and the largest wilderness of any kind east of the Mississippi River. An average of one million people visit the park each year. Everglades is the third-largest national park in the contiguous United States after Death Valley and Yellowstone. UNESCO declared the Everglades & Dry Tortugas Biosphere Reserve in 1976 and listed the park as a World Heritage Site in 1979, and the Ramsar Convention included the park on its list of Wetlands of International Importance in 1987. Everglades is one of only three locations in the world to appear on all three lists.
Lake Okeechobee is the largest freshwater lake in the U.S. state of Florida. It is the tenth-largest natural freshwater lake among the 50 states of the United States and the second-largest natural freshwater lake contained entirely within the contiguous 48 states, after Lake Michigan.
Microcystins—or cyanoginosins—are a class of toxins produced by certain freshwater cyanobacteria, commonly known as blue-green algae. Over 250 different microcystins have been discovered so far, of which microcystin-LR is the most common. Chemically they are cyclic heptapeptides produced through nonribosomal peptide synthases.
Dead zones are hypoxic (low-oxygen) areas in the world's oceans and large lakes. Hypoxia occurs when dissolved oxygen (DO) concentration falls to or below 2 mg of O2/liter. When a body of water experiences hypoxic conditions, aquatic flora and fauna begin to change behavior in order to reach sections of water with higher oxygen levels. Once DO declines below 0.5 ml O2/liter in a body of water, mass mortality occurs. With such a low concentration of DO, these bodies of water fail to support the aquatic life living there. Historically, many of these sites were naturally occurring. However, in the 1970s, oceanographers began noting increased instances and expanses of dead zones. These occur near inhabited coastlines, where aquatic life is most concentrated.
Cyanotoxins are toxins produced by cyanobacteria. Cyanobacteria are found almost everywhere, but particularly in lakes and in the ocean where, under high concentration of phosphorus conditions, they reproduce exponentially to form blooms. Blooming cyanobacteria can produce cyanotoxins in such concentrations that they can poison and even kill animals and humans. Cyanotoxins can also accumulate in other animals such as fish and shellfish, and cause poisonings such as shellfish poisoning.
Algal mats are one of many types of microbial mat that forms on the surface of water or rocks. They are typically composed of blue-green cyanobacteria and sediments. Formation occurs when alternating layers of blue-green bacteria and sediments are deposited or grow in place, creating dark-laminated layers. Stromatolites are prime examples of algal mats. Algal mats played an important role in the Great Oxidation Event on Earth some 2.3 billion years ago. Algal mats can become a significant ecological problem, if the mats grow so expansive or thick as to disrupt the other underwater marine life by blocking the sunlight or producing toxic chemicals.
Taylor Slough, located in the southeastern corner of the Florida Everglades, along with the much larger Shark River Slough farther to the west, are the principal natural drainages for the freshwater Everglades and the essential conduit for providing overland freshwater to Florida Bay.
Aphanizomenon flos-aquae is a brackish and freshwater species of cyanobacteria of the genus Aphanizomenon found around the world, including the Baltic Sea and the Great Lakes.
Cyanophages are viruses that infect cyanobacteria, also known as Cyanophyta or blue-green algae. Cyanobacteria are a phylum of bacteria that obtain their energy through the process of photosynthesis. Although cyanobacteria metabolize photoautotrophically like eukaryotic plants, they have prokaryotic cell structure. Cyanophages can be found in both freshwater and marine environments. Marine and freshwater cyanophages have icosahedral heads, which contain double-stranded DNA, attached to a tail by connector proteins. The size of the head and tail vary among species of cyanophages. Cyanophages infect a wide range of cyanobacteria and are key regulators of the cyanobacterial populations in aquatic environments, and may aid in the prevention of cyanobacterial blooms in freshwater and marine ecosystems. These blooms can pose a danger to humans and other animals, particularly in eutrophic freshwater lakes. Infection by these viruses is highly prevalent in cells belonging to Synechococcus spp. in marine environments, where up to 5% of cells belonging to marine cyanobacterial cells have been reported to contain mature phage particles.
The St. Lucie River is a 35-mile-long (56 km) estuary linked to a coastal river system in St. Lucie and Martin counties in the U.S. state of Florida. The St. Lucie River and St. Lucie Estuary are an "ecological jewel" of the Treasure Coast, central to the health and well-being of the surrounding communities. The river is part of the larger Indian River Lagoon system, the most diverse estuarine environment in North America with more than 4,000 plant and animal species, including manatees, oysters, dolphins, sea turtles and seahorses.
Anatoxin-a, also known as Very Fast Death Factor (VFDF), is a secondary, bicyclic amine alkaloid and cyanotoxin with acute neurotoxicity. It was first discovered in the early 1960s in Canada, and was isolated in 1972. The toxin is produced by multiple genera of cyanobacteria and has been reported in North America, South America, Central America, Europe, Africa, Asia, and Oceania. Symptoms of anatoxin-a toxicity include loss of coordination, muscular fasciculations, convulsions and death by respiratory paralysis. Its mode of action is through the nicotinic acetylcholine receptor (nAchR) where it mimics the binding of the receptor's natural ligand, acetylcholine. As such, anatoxin-a has been used for medicinal purposes to investigate diseases characterized by low acetylcholine levels. Due to its high toxicity and potential presence in drinking water, anatoxin-a poses a threat to animals, including humans. While methods for detection and water treatment exist, scientists have called for more research to improve reliability and efficacy. Anatoxin-a is not to be confused with guanitoxin, another potent cyanotoxin that has a similar mechanism of action to that of anatoxin-a and is produced by many of the same cyanobacteria genera, but is structurally unrelated.
Before drainage, the Everglades, a region of tropical wetlands in southern Florida, were an interwoven mesh of marshes and prairies covering 4,000 square miles (10,000 km2). The Everglades is both a vast watershed that has historically extended from Lake Okeechobee 100 miles (160 km) south to Florida Bay, and many interconnected ecosystems within a geographic boundary. It is such a unique meeting of water, land, and climate that the use of either singular or plural to refer to the Everglades is appropriate. When Marjory Stoneman Douglas wrote her definitive description of the region in 1947, she used the metaphor "River of Grass" to explain the blending of water and plant life.
A harmful algal bloom (HAB), or excessive algae growth, is an algal bloom that causes negative impacts to other organisms by production of natural algae-produced toxins, mechanical damage to other organisms, or by other means. HABs are sometimes defined as only those algal blooms that produce toxins, and sometimes as any algal bloom that can result in severely lower oxygen levels in natural waters, killing organisms in marine or fresh waters. Blooms can last from a few days to many months. After the bloom dies, the microbes that decompose the dead algae use up more of the oxygen, generating a "dead zone" which can cause fish die-offs. When these zones cover a large area for an extended period of time, neither fish nor plants are able to survive. Harmful algal blooms in marine environments are often called "red tides".
Microcystis aeruginosa is a species of freshwater cyanobacteria that can form harmful algal blooms of economic and ecological importance. They are the most common toxic cyanobacterial bloom in eutrophic fresh water. Cyanobacteria produce neurotoxins and peptide hepatotoxins, such as microcystin and cyanopeptolin. Microcystis aeruginosa produces numerous congeners of microcystin, with microcystin-LR being the most common. Microcystis blooms have been reported in at least 108 countries, with the production of microcystin noted in at least 79.
The Everglades Agricultural Area Environmental Protection District, better known as simply the Everglades Agricultural Area (EAA), is an area extending south from Lake Okeechobee to the northern levee of Water Conservation Area 3A, from its eastern boundary at the L-8 canal to the western boundary along the L-1, L-2, and L-3 levees. The EAA incorporates almost 3,000 square kilometers of highly productive agricultural land. The EAA was established by the State Legislature as a special district representing landowners within the EAA Basin for the purposes of ensuring environmental protection. Means include conducting scientific research on environmental matters related to air and water and land management practices and implementing the financing, construction, and operation of works and facilities designed to prevent, control, abate or correct environmental problems and improve the environmental quality of air and water resources.
Aureoumbra lagunensis is a unicellular planktonic marine microalga that belongs in the genus Aureoumbra under the class Pelagophyceae. It is similar in morphology and pigments to Aureococcus anophagefferens and Pelagococcus subviridis. The cell shape is spherical to subspherical and is 2.5 to 5.0 μm in diameter. It is golden-coloured and is encapsulated with extracellular polysaccharide layers and has a single chloroplast structure with pigments.
Susanna Wood is a New Zealand scientist whose research focuses on understanding, protecting and restoring New Zealand's freshwater environments. One of her particular areas of expertise is the ecology, toxin production, and impacts of toxic freshwater cyanobacteria in lakes and rivers. Wood is active in advocating for the incorporation of DNA-based tools such as metabarcoding, genomics and metagenomics for characterising and understanding aquatic ecosystems and investigating the climate and anthropogenic drivers of water quality change in New Zealand lakes. She has consulted for government departments and regional authorities and co-leads a nationwide programme Lakes380 that aims to obtain an overview of the health of New Zealand's lakes using paleoenvironmental reconstructions. Wood is a senior scientist at the Cawthron Institute. She has represented New Zealand internationally in cycling.
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