Pressures on the Sanctuary
Numerous human activities and natural events and processes affect the condition of natural and maritime heritage (archaeological) resources in marine sanctuaries. This section describes the nature and extent of the most prominent pressures in Florida Keys National Marine Sanctuary, many of which originate outside its boundaries.
Pressures on Water Quality
Water quality is a key element that unites all sanctuary resources and is essential to maintaining the richness and diversity of its varied environments. Water quality is both a spatial and temporal phenomenon and can be affected by both natural and anthropogenic influences. Under certain conditions, external sources adjacent to the sanctuary (e.g., Gulf of Mexico Loop Current and Florida Current, land based activities, and atmospheric inputs) can dominate water quality patterns. Pressures on water quality in the sanctuary are described below:
Point Sources of Pollution and Contamination
Point source pollution results when a pollutant is discharged directly into surface waters from a definite location, such as the pipes of industrial waste facilities or domestic sewage treatment plants. Pollutants can be natural substances, like nutrients, that are present in unusually high quantities due to human influence. Contaminants are typically chemicals not found normally in the environment such as industrial chemicals, pesticides, PCBs, and other toxicants. Point source pollution can also include discharge resulting from urban stormwater runoff if coming from a drainage pipe. The effects of point source effluents on receiving surface waters may include the introduction of additional flow, increased microbial abundance, suspended sediments, nutrients (e.g., nitrogen and phosphorus), metals, and organic compounds. In the Florida Keys, wastewater and stormwater treatment and solid-waste disposal facilities were highly inadequate, directly affecting nearshore water quality (Kruczynski and McManus 2002).
When the sanctuary was designated in 1990, there were 19 facilities actively discharging effluent directly into nearshore waters, including water treatment plants, power plants, a desalination plant, and other industrial facilities (NOAA 1996). Today, Monroe County and local municipalities are undergoing extensive upgrades in wastewater infrastructure that provide advanced wastewater treatment, significantly reducing wastewater impacts and pressures in the area (Figure 11).
Nonpoint Sources of Pollution
Unlike point source pollution, nonpoint source pollution comes from many diffuse sources. Nonpoint source water pollution is usually due to rainfall moving over and through the ground and carrying various chemicals. As the runoff moves, it picks up and carries away pollutants, finally depositing them into surface and subsurface (groundwater) waters. Pollutants and contaminants include excess fertilizers, herbicides, and insecticides from agricultural lands and residential areas; oil, grease, and toxic chemicals from urban runoff and energy production; sediment from improperly managed construction sites and dredging operations; bacteria and nutrients from birds and other wildlife: pet wastes; and faulty septic systems. Eutrophication (an outcome of excess nutrients in the water, such as fertilizers) of nearshore waters has been an ongoing, documented problem in the nearshore waters of the Florida Keys. The process of eutrophication has the potential to shift primary productivity from the slower-growing flora (e.g., seagrasses) to faster-growing species (e.g., macroalgae and microalgae). In time, eutrophication may result in a shift from one type of biological community to one that is adapted to the higher-nutrient conditions (Fourqurean et al. 2003, Wagner et al. 2008).
Because they are generally more soluble than toxicants such as oil and lipid-soluble contaminants, nutrient and organic inputs may affect the environment over a greater spatial area. In addition, while toxicants affect localized environments such as marinas, canals, and areas surrounding industry, nutrients are more susceptible to transport and represent a greater threat to seagrass and coral reef communities (NOAA 1996). Residential canals in the Florida Keys were often dug too deep, and the length and complexity of the residential canal systems also limit flushing with nearshore waters of the sanctuary. They frequently experience microalgal blooms and have anaerobic sediments containing accumulated chemicals and organic matter. While some studies have been conducted, the exact extent to which residential canals affect sanctuary waters has not been fully studied at this time (Chesher 1974, Lapointe and Clark 1990 and 1992).
Domestic wastewater from illegal cesspits and outdated septic systems has been contributing to nonpoint source pollution in the Keys, but is expected to decline due to improvements being made in wastewater treatment, which involves decommissioning the septic systems and cesspits. Other sources of nonpoint source pollution include abandoned landfills, marinas and live-aboard vessels (collectively), and stormwater runoff (NOAA 1996).
Swimming Advisories
Runoff and spills have periodically resulted in high levels of fecal coliform and enterococci bacteria in the Florida Keys, resulting in swimming advisories for nearshore waters and beaches (Figure 12). Enterococci bacteria and fecal coliform bacteria are often used as indicator organisms in nearshore water quality monitoring, and while they may not cause diseases in humans, their presence can indicate that water may be contaminated with organisms that cause human health impacts such as fever, flu-like symptoms, ear infection, respiratory illness, rashes, gastroenteritis, cryptosporidiosis, and hepatitis. Sources of polluted and contaminated water include runoff from urban, suburban and rural areas, aging sewer infrastructure systems pressed to meet increasing demands, and contaminated flows from other upland sources. Contributing factors that generate these sources include illicit storm drain connections, improper disposal of materials or maintenance that clog pipes and cause overflows, cracked or damaged pipes, overflow of sewer systems during storm events, septic system leaching, and various domestic and wildlife sources.
External Input
External sources of pollutants and contaminants also affect the sanctuary's water quality. Examples of this input could include Florida Bay, Biscayne Bay and canal structures operated by the local water management district. Additionally, the sanctuary is considered downstream of currents in the region, like the Loop and Florida currents that transport much of the water from the western coast of Florida, Mississippi River outfall, contributions from Central America and northern South America (Orinoco Flow), and various islands of the Caribbean. Lastly, eddies that form along boundary currents paralleling the shore line can cause periodic upwelling of cold, nutrient-rich waters (e.g., Tortugas and Pourtales gyres) (NOAA 1996, Szmant and Forrester 1996, Leichter et al. 2003).
Harmful Algal Blooms
A harmful algal bloom (HAB) can occur when certain types of microscopic algae grow quickly in water, forming visible patches that may harm the health of the environment, plants, or animals. HABs are attributed to two primary factors: natural processes such as warm water and poor water circulation and flow, and anthropogenic causes such as nutrient loading leading to eutrophication. These processes can result in large amounts of certain types of macroalgae or phytoplankton (e.g., dinoflagellates) accumulating in the water. Aggregations of these organisms can discolor the water, giving rise to red, mahogany, brown, or green tides. Red tides occur every year off Florida and are known to deplete the available oxygen supply and block sunlight. In addition, some HAB-causing algae (e.g., dinophytes) can release toxins into the water that adversely impact aquatic organisms and humans. Impacts include fish kills, coral stress and mortality, and skin and respiratory problems in humans. HABs have occurred in the waters of almost every U.S. coastal state. Over the last several decades, HABs have caused more than $1 billion in economic losses in the U.S. due to closures of shellfish beds and coastal fisheries, detrimental impacts on tourism and service industry revenues, and public illnesses (Abbott et al. 2009a). Data suggests that HABs are increasing in frequency within the last couple of decades (Harvell et al. 1999).
Of significance, the sanctuary had high concentrations of the microscopic alga that causes red tide (Karenia brevis) at the offshore reefs during the 2009 and 2010 annual red tide 'seasons.' Although the first red tide was officially recorded in Florida in 1844, these recent occurrences of K. brevis on the reef-line are the first on record. Karenia brevis kills fish by producing a powerful toxin (brevetoxin) that affects the central nervous system of fishes. In addition, brevetoxins can become concentrated in the tissues of shellfish that feed on K. brevis. People who eat these shellfish may suffer from neurotoxic shellfish poisoning, a food poisoning that can cause severe gastrointestinal and neurologic symptoms, such as tingling fingers or toes. It can also affect birds, mammals, and other marine animals higher up the food chain.
In early 2002, a patch of "black water" more than 60 miles (100 kilometers) in diameter formed off southwestern Florida (Figure 13). Currents carried the black water to the ocean side of the Florida Keys, where it resulted in severe coral reef stress and death (Keller and Causey 2005). Microscopic organisms and toxins contained in the dark water stressed the coral reef system resulting in a 70% decrease in stony coral cover, a 40% reduction of coral species, and a near-elimination of clionid sponge colonies at two reef sites after the dark water passed (Hu et al. 2003). Though a similar black water event was blamed for declines in Acroporid species in the Dry Tortugas in 1878, its origin and composition were never discovered (Jaap et al. 1989).
Marinas and Boats
Water pollution from activities associated with marinas and boating within the sanctuary is also a threat to sanctuary resources (Figure 14). Boater-generated impacts on water quality generally fall into four categories: toxic metals primarily from anti-fouling paints, hydrocarbons from motor operations and maintenance procedures, solid waste and marine debris from overboard disposal, and bacteria and nutrients from boat sewage.
Cruise Ships
A few cruise ships started visiting the Port of Key West infrequently in the late 1980s, by 2010 between five and 13 cruise ships visit Key West weekly. Each ship can carry more than 3,000 people and arguably provide local businesses with positive economic benefits. For example, from 1995 to 1996 approximately 350,000 cruise ship passengers arrived at the Port of Key West, 90% of which departed the ships to participate in recreational activities in Key West (Leeworthy and Wiley 1996). By 2008, numbers nearly doubled and 740,000 passengers visited Key West on the 346 cruise ships that ported that year (Leeworthy et al. 2010). In 2003, cruise ship passengers reached a peak of over 1 million passengers (City of Key West, Finance Department 2005).
Concerns exist about environmental impacts of cruise ships, including discharges impairing water quality and sediment erosion. Cruise ships are floating cities that are capable of carrying as many as 3,000 passengers and crew members, and thus need to provide many of the same services as their land-based equivalent. The main pollutants generated by cruise ships include bilge water (water that collects in the lowest part of the ship's hull that may contain oil, grease, and other contaminants), blackwater (sewage), graywater (waste from showers, sinks, laundries, and kitchens), ballast water (water taken onboard or discharged from a vessel to maintain its stability), and solid waste (food waste and garbage). Ocean currents have the potential to transport these pollutants into sanctuary waters. Although cruise ships are capable of generating volumes of waste comparable to a small city (though many incinerate large portions of their wastes), they are not subject to the same environmental regulations and monitoring requirements as a land-based equivalent. Cruise ships also have the potential to cause benthic disturbances with each porting. Wakes generated by vessels and propeller turbulence re-suspends sediment and transports it elsewhere.
Petroleum (hydrocarbons) and Other Chemical Spills
Petroleum (oil, gasoline, other hydrocarbons) and chemical spills in the sanctuary can potentially range from small, localized spills to large events that span hundreds of miles of coastline. The most common and chronic form of spill is from small boat engine operations and usually involves small discharges of fuel, oil, or hydraulic fluid. Other small spills tend to be associated with oil and fuel discharges due to small vessel (<65 feet or 20 meters) groundings or sinkings and plane crashes. Effects of small spills have not been adequately documented. A larger oil or chemical spill may result from offshore shipping traffic, a cruise ship disaster, or offshore oil and gas drilling and production operations (e.g., upstream Gulf of Mexico sources and potential Cuban sources). A large spill could have a major impact on sanctuary biota including coral reefs, foraging birds, marine mammals, fishes, and fringing mangrove habitat. Tourism and the coastal economy would be also negatively affected by this type of spill.
Live-aboard Vessels
Disposal of wastewater from live-aboard vessels has historically been a significant localized problem because of the low level of treatment, the tendency for live-aboard vessels to congregate in certain marinas or anchorages, and the potential adverse health effects of discharging untreated wastewater. Many live-aboard vessels are permanently anchored and mobile pump-out facilities are required to service those vessels (Figure 15).
Mosquito Control
Application of insecticides to control mosquito-borne pathogens like West Nile virus, Dengue fever, and viral encephalitis affect nearshore waters of the sanctuary. Waters are vulnerable to insecticide runoff and overspraying, while toxic effects may affect non-target organisms, such as the queen conch (Strombus gigas) (McIntyre et al. 2006, Glazer et al. 2008).
Commercial and Recreational Fishing
Fishing is the most widespread exploitative activity in coastal ecosystems and poses significant threats to the biodiversity and condition of marine ecosystems (Ault et al. 2005a, Chiappone et al. 2005). Threats are in the form of direct take, by-catch, indirect effects, and habitat damage from the use and loss of fishing gear (Figure 16). For example, the removal of targeted species and coincident mortality of non-target species (by-catch) may result in cascading ecological effects (Frank et al. 2005). Because fishing is also size-selective, concerns exist about ecosystem disruption by removal of ecologically important key species such as top predators (e.g., groupers, snappers, sharks, and jacks) and their prey (e.g., shrimps and baitfish).
Marine debris in the form of derelict fishing gear can destroy benthic organisms, entangle both benthic and mobile fauna (Donohue et al. 2001), and reduce the structural complexity of habitats (Chiappone et al. 2002a). For example, commercial fisheries targeting lobsters and stone crabs utilize traps that are deployed in habitats adjacent to reefs. Currents associated with strong storms can move traps onto reefs, where corals and other benthic organisms are damaged or killed (e.g., Sheridan et al. 2005). In 2005, it was estimated that approximately 300,000 lobster traps were lost during a series of hurricanes and strong storms (Clark 2006). The ecological impacts caused by fishing gear that is lost when cut or broken after snagging on the bottom is a growing concern to managers and scientists (Chiappone et al. 2005).
Bleaching Events and Climate Change
Seasonal and yearly seawater temperature extremes, increasing UV penetration in the water column, and atmospheric changes all affect the Florida Keys ecosystem. These impacts are most evident in coral disease and bleaching events, which have increased in frequency, duration and range, coinciding with the 10 warmest years on record (1999 to 2009). However, additional human-induced stresses are likely affecting the ability of these organisms to adequately recover from climate fluctuations (Wagner et al. 2010).
During the 20th century, the global mean near-surface air temperature over land and mean sea surface temperature (SST) increased 0.6 ± 0.2°C, with the 1990s constituting the warmest decade in the instrumental record and 1998 the warmest year since instrumental records began in 1861 (IPCC 2001). Additionally, so far in the 21st century, mean monthly global ocean temperature anomalies have been 0.45°C above the 20th century mean (NOAA NCDC data). These increasing temperatures have the potential to increase the frequency and intensity of both coral bleaching events and summertime tropical weather disturbances. Coral diseases and hurricane damage have been identified as the main source of mortality of two important reef-building corals in the Caribbean region: elkhorn coral and staghorn coral. These coral species have undergone such a drastic decline in abundance that the NOAA Fisheries Service listed these corals as 'threatened' species under the U.S. Endangered Species Act in 2005.
Elevated water temperatures cause corals and other reef organisms such as sponges and gorgonians to bleach, a process characterized by the loss of zooxanthellae (a symbiotic microalgae) from coral tissues (Figure 18). High ultraviolet irradiance, typically from unusually calm, clear waters, may exacerbate the impact of increased temperatures (Lesser and Lewis 1996). Although corals may recover from brief episodes of bleaching, if ocean temperatures warm too much or remain high for an extended period, bleached corals will often die. Several correlative field studies show a close association between warmer-than-normal conditions (at least 1°C higher than the annual maximum) and the incidence of bleaching (Hoegh-Guldberg 1999). In 1997 and 1998, an estimated 16% of the world's coral reefs were seriously damaged in one of the most geographically extensive and severe bleaching events in recorded history (Wilkinson et al. 1999), which caused significant mortality worldwide (Baird and Marshall 2000). The stress for many of these coral reef systems was associated with high sea surface temperature over a 12-week period that was apparently enhanced by an extreme El Niño Southern Oscillation event (Wilkinson et al. 1999). A U.S. Department of State report to the U.S. Coral Reef Task Force (Pomerance et al. 1999) concluded that the severity and extent of the 1998 event cannot be explained by El Niño alone, and that the "...geographic extent, increasing frequency, and regional severity of mass bleaching events are likely a consequence of a steadily rising baseline of marine temperatures...". There is some debate whether or not coral bleaching is a disease, but we know it is a physiological response to stressors. While records show that coral bleaching events have been occurring for many years in the Florida Keys (Jaap 1979, 1984), indications are that the frequency, duration, and severity has steadily increased over the past 20 years (Waddell and Clark 2008). Large-scale coral bleaching was first recorded in the lower Keys in 1979 along the outer reef tract, where shallow fore-reef habitats were the most affected areas (Jaap 1979). Bleaching expanded and intensified with events in 1987 and 1990, and culminated with mass coral bleaching events in 1997 and 1998 that impacted nearshore and offshore reefs throughout the Florida Keys. Coral bleaching and the secondary impact of coral disease is likely responsible for some of the dramatic declines in stony coral cover observed sanctuary-wide in the last two decades (Causey 2008).
Sponges are also susceptible to bleaching events. The Caribbean barrel sponge (Xestospongia muta) is a large and common member of coral reef communities at depths greater than 10 meters, and has been called the "redwood of the reef" (McMurray et al. 2008). Like reef corals, this sponge is subject to bleaching in which it expels the symbiotic microorganisms living within its tissues, often resulting in death. Tissues of X. muta contain very primitive cyanobacterial symbionts belonging to the Synechococcus-Prochlorococcus clade (Gómez et al. 2004, Steindler et al. 2005) that impart the reddish-brown to brown-gray coloration of the sponge. The first report of a massive die-off of X. muta in the Florida Keys was in 1979 (Causey 2008). Hundreds of X. muta were observed dying in a one-month time frame on the reef tract, south of Bahia Honda Pass. Other reports of bleaching of X. muta, along with other symbiont-containing sponges, began to appear along with reports of coral bleaching events over a decade ago (Vincente 1990). In some cases, bleached sponges deteriorated and disintegrated. Moreover, bleached X. muta were more susceptible to predation by parrotfishes and generalist predators (Dunlap and Pawlik 1998). Bleaching and subsequent mortality of sponges has since been observed throughout the Caribbean (Nagelkerken et al. 2000).
Coral communities are also susceptible to cold water. For example, in January 1977, an extreme cold "front" passed through southern Florida, causing water temperatures to drop to 14 - 16°C. Following this thermal stress event there was extensive mortality of branching scleractinia corals. Major mortality of Staghorn coral (Acropora cervicornis) was observed, with over a 90% loss from 1976 numbers. In addition, there was also a significant loss of Elkhorn coral (A. palmata), with over two-thirds being killed by the cold water. (Davis 1982)
Along with extreme temperature fluctuations from a changing climate, ocean acidification may also affect coral reefs in the Florida Keys as atmospheric carbon dioxide levels continue to increase. The ocean takes up around 25% of atmospheric CO2 produced by humans through land use changes and the burning of fossil fuels, which then dissolves in seawater to form carbonic acid. Since humans have contributed to greater amounts of CO2 into the atmosphere over the past century, the ocean has absorbed CO2 at an increasingly rapid rate, changing the ocean's chemistry and leading to ocean acidification. The acidity of seawater has increased by 30% since the beginning of the Industrial Revolution over 250 years ago, lowering the ocean's natural basic (alkaline) status to an acidic imbalance (Ocean Acidification Reference User Group 2009).
Due to the increased acidity of seawater, many of the animals and plants in the ocean that have calcium carbonate skeletons or shells, such as corals, may experience reduced growth or ability to generate hard shells. For example, in Australia's Great Barrier Reef, corals have already reduced their calcification rates, most likely in response to elevated water temperature and ocean acidification impacts (De'Ath et al. 2009). In a study by Hoegh-Guldberg et al. (2007), it is predicted that if atmospheric CO2 levels continue to increase, the structure and function of coral reef ecosystems around the world will be compromised and some coral species will become extinct. Ocean acidification could prompt a chain reaction of impacts through the marine food web, beginning with larval fish, shellfish, and corals, cutting valuable ecosystem services provided by coral reefs such as food security, tourism, shoreline protection, and biodiversity (Ocean Acidification Reference User Group 2009).
Weather Disturbances
The record breaking 2005 Atlantic Hurricane Season produced a total of 28 named tropical storms, 15 of which attained hurricane strength throughout the Atlantic, Caribbean Sea, and Gulf of Mexico. Five tropical cyclones (Arlene, Dennis, Katrina, Rita, and Wilma) directly impacted the Florida coastline and sanctuary resources. Hurricane Wilma (Figure 19) produced a six- to eight-foot storm surge throughout the middle and lower Keys.
Diseases of Marine Organisms
Mass die-offs of marine life due to disease outbreaks have increased in frequency and intensity in the past two decades, affecting numerous taxa in the oceans (Harvell et al. 1999). For many marine organisms, including corals and marine mammals, reports of the frequency of epidemics and the number of new diseases is increasing. Recently, the Caribbean basin has emerged as a disease "hot spot" (Harvell et al. 1999, Weil 2004). Mass mortalities of plants, invertebrates, and vertebrates can result in dramatic shifts in community structure. Additionally, diseases affecting benthic marine species such as corals and seagrasses can have disproportionate impacts on the ecosystem because of the changes in habitat and ecosystem function that can result. Despite these impacts the causative agents and the factors contributing disease outbreaks are poorly understood due to lack of information on normal disease levels in the ocean. However, it is believed that factors such as long-term warming trends and human activities, including habitat degradation and pollutant inputs, may play important roles in the transport and spread of diseases (Harvell et al. 1999).
The first documented epizootic event in the Caribbean was the mass mortality of commercial sponges in the northern Caribbean. In December 1938, a blight resulting from a fungus-like filament struck sponge beds in the Bahamas, causing their skeletons to disintegrate (Witzell 1998, McClenachan 2008). The blight quickly reached epidemic proportions, leaving the ocean floor covered with thousands of bleached and rotten sponges, and by February 1939 all sponge-bearing banks were affected (McClenachan 2008). In March, signs of the disease appeared in Key West, and by May sponges showed considerable damage from blight. By the end of 1939, yellow and vase sponges had suffered nearly 100% mortality, while 70% of the commercially valuable sheepswool sponges had been eliminated from the Florida Keys altogether. The disease eventually spread northward and caused extensive mortality to sponges as deep as 70 feet (20 meters). By the end of 1940, the sponge fishery was nonexistent in Florida due to the devastating effects of disease on sponge populations (Shubow 1969).
Another well-studied marine epidemic was the virtual eradication of the long-spined sea urchin. This Caribbean-wide event in 1983 - 1984 spread rapidly in about one year and was caused by an unidentified pathogen which appeared in the Florida Keys in July 1983 (Lessios et al. 1984, Miller et al. 2009). The pathogen was circulated widely throughout the Caribbean by surface currents that connect the southwestern Caribbean with the Florida Keys. In many Caribbean locations, loss of this keystone herbivore contributed to phase shifts from coral- to macroalgae-dominated reefs, especially noticeable in areas where herbivory was nearly solely dependent upon sea urchin grazing because of overfishing (Hughes 1994). Due apparently to low larval supply, recovery of the long-spined sea urchin has generally been slow and incomplete in the Florida Keys since the 1983 and 1991 mortality events (Miller et al. 2009).
Coral diseases have been identified as a significant contributor to coral mortality (Weil 2004, Voss 2006). Although little is known regarding the factors that drive coral disease distributions and dynamics, monitoring of coral diseases in the Florida Keys indicates that there has been an increase in the number of new diseases (Goreau et al. 1998). Coral diseases were first described in the Caribbean in the early-to-mid-1970s (Antonius 1973, Weil 2004). The white plague was the first epizootic event occurring in 1975 and resulted in significant coral mortality. In the 1980s, a white-band disease epizootic event significantly reduced populations of acroporid corals (A. palmata and A. cervicornis), leading to a reduction in habitat and refuge space and biodiversity (Santavy et al. 2001). The loss of coral cover was correlated with significant increases in algal cover and lack of herbivory, thus changing the community structure and dynamics of shallow coral reef habitats. The first widespread outbreak of black-band disease in the Florida Keys occurred in May 1986 from Looe Key Reef to Western Dry Rocks (Causey 2008). Prior to this outbreak, only scattered, isolated outbreaks had been reported (Antonius1973, 1981, Dustan 1977). Following the 1986 massive outbreak, black-band disease became one of the more common coral diseases observed in the 1990s and 2000s. In the 1990s, several new coral diseases were reported, including red-band disease, white-band type II, white plague type II, yellow blotch, dark spots, and white-pox disease. As of 2010, causative agents have only been identified for black-band disease (Bruckner 2000), white-band (Ritchie and Smith 1998), white plague II (Denner et al. 2003), and white pox disease (Patterson et al. 2002). Tumors, as well as lesions associated with parasites, ciliates, bacteria, and fungi, have also been found on a number of coral species. Gorgonians such as sea fans have also been affected by increased disease incidence since 1981 (Nagelkerken et al.1997), primarily due to exposure to a terrestrial fungus (Aspergillus sydowii) (Geiser et al. 1998). Increasing anthropogenic impacts and increasing ocean temperatures may contribute to disease occurrence.
Fibropapillomatosis (FP) is a viral disease specific to sea turtles, although it most commonly affects juvenile green turtles in nearshore habitats around the world (Herbst 1994, Ene et al. 2005). In some localities, such as the Indian River Lagoon, Florida Bay, and the Florida Keys, 50 to 70% of the green turtles are affected (Ene et al. 2005). FP is a debilitating neoplastic disease that can result in benign cauliflower-like tumors on the soft and hard tissues of turtles, both internally and externally. These tumors can disrupt locomotion, feeding, respiration, and vision. While external tumors can be surgically removed, internal tumors cannot and are nearly always fatal. Since the early 1980s, the percentage of green turtles stranded in Florida with FP has been escalating at a rate of 1.2% per year, and based on research from the Florida Sea Turtle Stranding and Salvage Network database, 22% of dead or debilitated green turtles (sample size = 6,027) found in Florida between 1980 and 2005 had tumors (Foley et al. 2005). Although the cause of FP is still not fully understood, recent research has strongly indicated a viral origin. The virus may be spread through biological vectors and specific biotoxins may increase the prevalence of tumors (Foley et al. 2005). Turtles affected by FP are often found in shallow water with poor water circulation, leading to the speculation that environmental factors may play a role in the distribution or prevalence of the disease (Foley et al. 2005).
Panulirus argus virus 1 (PaV1), a lethal herpes-like virus, infects juvenile Caribbean spiny lobster (Behringer et al. 2006). It is transmitted among lobsters via inoculation, prolonged contact with infected lobsters, ingestion of infected tissue, and over short distances in the water (Butler et al. 2008). Because Caribbean spiny lobsters are social and share communal dens, the virus can spread quickly with devastating consequences. PaV1 is the first naturally occurring, pathogenic virus known to infect the Caribbean spiny lobster (Behringer et al. 2008, Butler et al. 2008) affects as many as 16% of the juvenile Caribbean spiny lobster populations sampled from the mid- to lower Florida Keys (ICES 2003). The virus attacks haemocytes, blood cells that are part of the animal's immune system, causing the blood to become milky white, and appears to affect juveniles only. The virus is highly lethal in experimental conditions. Given its virulence, PaV1 represents a serious threat to both commercial and recreational fisheries (Butler et al. 2008).
Cleaner fishes and shrimp in tropical marine habitats assist in keeping the levels of most pathogens and parasites quite low in wild fish populations (Peters 1997). However, injured or weakened reef fish species may become infected with marine bacteria, fungi, protozoans or parasites resulting in lesions, tumors or mortality. In 1980, 1993 and 1994, mass mortality of tropical reef fishes occurred in coastal regions of southeastern Florida and the Florida Keys (Burns 1981, Landsberg 1995, Causey 2001). The affected fish were adult herbivores and omnivores such as angelfishes, parrotfishes, surgeonfishes, and butterflyfishes. Some piscivores and cleanerfishes were also affected. Fishes were observed to have lesions and ulcerated body sores, fin and tail rot, and a heavy mucus coating on the body surface (Landsberg 1995). Causey (2001) noted the close association of these fish mortalities with elevated temperatures that also caused widespread coral bleaching. Landsberg (1995) detected parasites and bacterial infestations in preserved tissues of these fishes, but suggests that ingesting toxins from macroalgae or dinoflagellates may have compromised their health, and the infestations resulted from the fishes' weakened state caused by these toxins.
Vessel Use
A significant threat to the protection and health of sanctuary resources is the impacts from vessels including oil pollution, vessel groundings, noise pollution, and dredged material resulting from maintenance of shipping channels. The Florida Straits have historically been the access route for all commercial vessels entering the Gulf of Mexico from the north and east and, consequently, these waters are some of the most heavily trafficked in the world. It is estimated that 40% of the world's commerce passes within 1.5 days sailing time of Key West (U.S. Department of the Navy 1990). In addition, oil tankers transit the coast daily, including very large and ultra-large crude carriers.
Large commercial vessels are of particular concern because of the potential for oil spills. These vessels often travel close to shore and can carry upwards of 1 million gallons of bunker fuel, a heavy, viscous fuel similar to crude oil that is used to power the ships. As described earlier in this report, a large spill could have a major impact on foraging birds, marine mammals and fishes, as well as important habitats like sandy beaches, mangroves and other intertidal habitats, seagrass beds, and coral reefs, and therefore could have serious consequences for tourism and the coastal economy.
In addition to the threat of oil spills, more than 300 vessel groundings (vessels 50 feet or less; FKNMS unpub. data) are reported annually within the sanctuary, causing physical damage to sanctuary resources such as seagrass, hard-bottom, and coral reef habitats. There are also many grounding incidents that damage resources but are not reported (NOAA 2007). Although large vessel groundings often result in highly visible, immediate resource devastation with long-term impacts, the vast majority of grounding incidents are caused by smaller recreational vessels. Even so, the cumulative detrimental effect of smaller groundings can also have long-lasting impacts. Vessel groundings from large tankers play a role in the history of the sanctuary. Within a three-week period in 1989, the M/V Elpis and the M/V Alec Owen Maitland ran aground on two different shallow bank reefs, and a third vessel, the Mavro Vetranic, ran aground in Dry Tortugas National Park, killing and displacing corals, gorgonians, and other benthic organisms, in addition to destroying the physical structure of the underlying reef. These three large vessel groundings were important factors in the congressional designation of Florida Keys National Marine Sanctuary and led to the creation of an "Area to be Avoided," which, through sanctuary regulations, prohibits ships greater than 50 meters in length from entering certain areas of the Florida Keys.
Large commercial shipping traffic and recreational and commercial vessels can also affect noise levels in the marine environment. Certain anthropogenic noise is thought to mask sounds used by marine mammals for mating, feeding, and avoiding predators. Responses vary depending on the acoustic frequency, decibel level, proximity to the source and other species-specific sensitivity factors. Long-term cumulative impacts are uncertain and range from minimal impacts in some situations, to possible physical damage to hearing structures, to stranding events.
Most of these impacts from vessel use correlate with the ever-increasing number of vessels transiting within and around the sanctuary. Recreational vessel registrations in Monroe County increased more than 1,000% from 1964 to 2006, whereas commercial vessel registrations increased by about 100% from 1964 to 1998, but have since decreased by 37% (Figure 17). There were 25,370 pleasure and 2,653 commercial vessels registered in Monroe County in 2007 (Federal Register Vol. 74 No 219). These statistics are also reflected in the number of derelict and abandoned vessels located in the Florida Keys in any given year. Monroe County typically has the highest number of derelict or abandoned vessels in the state of Florida, and like marine debris these vessels pose threat to the marine environment, human health, and navigation. From a criminal viewpoint, derelict and abandoned vessels have the potential to be locations for illegal activity, illegal housing, and opportunities for theft and vandalism.
Combined with transits around the sanctuary each year by large shipping vessels (greater than 300 gross tons), cruise ships, and military ships, vessel traffic affecting the sanctuary is continuing on an upward trend. For example, from 2000 to 2005, cruise ships based out of Miami ferried approximately 24.5 million passengers to various locations throughout the greater Caribbean region, including Key West. Additionally, the potential for extremely large vessels traveling the Florida Straits exists when the Panama Canal expansion project is completed over the next few years. Expansion of the Port of Miami is underway to accommodate larger ships en route from the Pacific Ocean.
Coastal Development
Changes to Hydrologic Patterns Associated with Important Nearby Estuaries
South Florida has experienced drastic changes to its freshwater wetlands of the Everglades, and such changes threaten its estuaries (especially Florida Bay), which ultimately could affect the entire sanctuary. During the past century, the pattern (timing, volume, and quality) and intensity of freshwater flows to these estuaries has been significantly altered and reduced due to intense municipal and agricultural activities plus the construction of the Central and Southern Florida Project for Flood Control and Other Purposes (commonly known as the Project). The Project is a surface-water management facility designed by the U.S. Army Corps of Engineers in the 1950s to drain land, provide flood protection, and regulate South Florida's water supply. Through the Project, enormous volumes of fresh water originally destined for the Everglades and its estuaries have been drained, diverted, or stored in "water conservation areas." The resulting alteration of the natural freshwater cycle has interrupted the distribution, flow, timing, and quality of freshwater delivery through South Florida's wetlands.
Altered flows and drainage canals have also reduced the natural recharge of fresh water to the Biscayne aquifer, the water-bearing limestone beneath southeast Florida and the Everglades. The aquifer is the source of drinking water for all of southern Florida and the Florida Keys via an aqueduct. This long-term reduction in groundwater recharge has gradually allowed salt water to intrude inland from the coast and has reduced freshwater wetlands. A recharged aquifer serves to prevent saltwater intrusion and helps sustain wetlands in times of drought. Reduced freshwater flows over a long period of time and pulses of large amounts of fresh water during heavy rains for flood control have had significant ecological impacts on the two main estuaries adjacent to the sanctuary: Florida Bay and southern Biscayne Bay. Card and Barnes Sounds, which are part of the southern Biscayne Bay system, lie within sanctuary boundaries and have also been affected by reduced freshwater input (USACE 1999). These once-productive estuarine systems have become more marine in species composition over time; negatively affecting their function as a nursery for certain key species like pink shrimp. The impact of this loss of estuary function is not fully known, but restoration projects on the mainland are expected to begin improving flow conditions to both bays in the future.
Nearshore Construction
In addition to altered water flows, shallow, nearshore habitats of the Florida Keys continue to be affected by coastal construction. Rate of growth ordinances for several incorporated Keys communities and Monroe County prevent rapid and uncontrolled development and associated impacts, but some new construction does continue to occur. The small land mass comprised by the individual islands of the Keys, along with the desire by most homeowners to have easy water access, have directed most development to the land-water interface. As such, existing structures such as residential docks, seawalls, and other shoreline protection features are abundant throughout the Florida Keys and are in constant need of repair. Commercial fish houses and similar businesses may be re-purposed for high-end private marinas, often necessitating expansion into nearby coastal habitats. Public infrastructure projects, including bridge and utility line repairs, may encroach into sanctuary waters.
New construction, repairs, or rehabilitation of existing structures in the coastal zone can result in impacts to mangroves, seagrass beds, submerged aquatic algae, nearshore hard-bottom habitat, and coral reefs. While regulations on mangrove destruction and limits on trimming have been in place for many years by the FDEP (Chapter 403 Florida Statutes), protections to less visible, or what may be perceived as "less valuable," species are not consistent among resource agencies. Specific jurisdictions of various agencies and the natural resources they protect may vary, and exemptions to permitting rules for small projects may inadvertently result in impacts to nearshore resources. For example, several ubiquitous stony coral species will recruit to artificial structures such as concrete seawalls and bridge pilings, and may be injured or destroyed during the course of permitted repairs. The manner by which these nearshore corals contribute to the health of the marine ecosystem is an under-studied topic.
Interestingly, some research indicates that corals found in nearshore habitats have higher growth rates and lower partial mortality, despite living in an environment of seemingly poorer water quality (Lirman and Fong 2007). Continued observation of these "hardy" nearshore corals has prompted inquiries about connectivity to their offshore counterparts. While impacts to corals and other species during coastal construction projects may be found to be individually insignificant, this could represent a cumulative threat over space or time to species and habitats, many with unidentified ecosystem worth.
Dredging
As noted in the "Vessel Use" section, an increasing number of boats are operating within the sanctuary every year. Dredging activities in the Keys are usually limited to small, private projects, many associated with dock or seawall construction discussed above. Dredging is also occasionally required for maintaining canals or expanding dockage of a local marina. In 2007, the U.S. Navy finished maintenance dredging on the main shipping channel into Key West in preparation for increased fleet presence. The sediment removed from this operation was disposed of at both an upland and offshore disposal site, the latter of which was outside sanctuary boundaries and permitted by the EPA, U.S. Army Corps of Engineers and FDEP. Dredging impacts seafloor communities both at the dredging site and at the disposal site. The physical disturbance of dredging damages or removes organisms living in or on the seafloor and can resuspend buried chemical contaminants. The disposal of dredge material can smother organisms and introduce chemical contaminants at the disposal location. Pipelines or barge routes necessary for upland disposal may impact natural habitats, as can discharges from dredge spoil containment areas. In addition, dredging to deepen channels in harbors can alter water flow dynamics and future sediment deposition rates in the harbor and adjacent habitats.
Beach Nourishment
Sandy beaches are not a prevalent shoreline habitat type in the Florida Keys in comparison to many other counties in the state of Florida. Florida boasts 825 miles of sandy beach, but just 26 of those miles (42 kilometers) are located within Monroe County. However, several active hurricane seasons, most notably in 2005 and 2006, exacerbated beach erosion and led to the need to supplement local beaches with imported sand. A 2010 report by the Florida DEP Bureau of Beaches and Coastal Systems categorized around 10 miles (16 kilometers) of beach in Monroe County as "critically eroded." The economic benefits of lush sandy beaches in a tourism community are well recognized. However, replenishing beaches with sand may result in direct impacts such as burial of natural, functional nearshore habitats (seagrasses, algae, and hard bottom), especially if unsuitable sediment is used (Wanless and Maier 2007). Indirect impacts may include localized turbidity and increased sedimentation at both the beach and borrow sites (Jordan et al. 2010), as well as a decrease in resident fish assemblages when habitat is lost (Lindeman and Snyder 1999). Sand placement may also change beach attributes, such as burying sea turtle nests, if it is conducted during the active nesting season due to nest burial or changes in beach attributes.
Non-Indigenous Species
Non-indigenous species are recognized worldwide as a major threat to ecosystem integrity when they become invasive. Non-indigenous species in the marine environment can alter community composition, reduce the abundance and diversity of native marine species (Olden et al. 2004), interfere with ecosystem function, alter habitats, disrupt commercial and recreational activities, and in some instances cause extinctions of indigenous plants and animals (Clavero and Garcia-Berthou 2005). They can cause local extinction of native species either by preying on them directly or by out-competing them for food or space. Once established, non-indigenous species can be difficult, if not impossible, to eradicate.
Invasions by non-indigenous aquatic species (e.g., lionfish, orange cup coral, Red-tipped Sea Goddess) are increasingly common worldwide in coastal habitats due to shipping traffic, world travel, and intentional or accidental releases by individuals. Though the most significant global mechanism for the introduction of aquatic species is ship ballast water, it can occur via other mechanisms such as improper disposal of household aquarium pets, commercial aquaculture operations, and research activities.
Wildlife Disturbance
The sanctuary provides many opportunities for wildlife observation, thus the 3 million annual visitors to the region results in a high level of visitation that can have significant direct and indirect effects on the ecosystem. Both motorized (e.g., party boats, jet skis and other personal watercraft) and non-motorized vessels (e.g., kayaks and canoes) are used throughout the sanctuary, often for viewing marine mammals and seabirds. With the multitude of opportunities for observation come the potential for wildlife disturbance including flushing birds from their nests or roosts and harassing marine mammals. Other tourism activities such as diving and snorkeling can also impact resources. The former Key Largo and Looe Key National Marine Sanctuaries included prohibitions on damaging coral in response to increasing threats by recreational visitors.
In addition to physical impacts, some wildlife species are undergo behavioral changes after they are fed by well-intentioned humans. Sharks, manatees, and numerous bird species (most notably pelicans and herons) are routinely fed fish, fish carcasses, lettuce, fresh water, and other items for the purposes of attraction and viewing, or inadvertently though improper disposal. These species may develop unnatural behavioral patterns leading to unsafe interaction with humans or vessels (e.g., sharks and manatees). Wild birds often suffer from punctured gizzards or other internal organs from digesting fish carcasses at marinas and docks where fish are cleaned and carcasses are discarded.
Artificial Reefs
A number of artificial reefs (primarily intentionally sunken ships) have been placed in the sanctuary. General agreement exists in the scientific community that artificial reefs can be effective fish attractants; however, most published research addresses the building of artificial reefs or descriptive studies detailing successional changes in fish species composition (Bohnsack and Sutherland 1985, Kruer and Causey 1992). The effects of artificial reefs on fish and invertebrate populations and habitats, and the longevity of these structures, are not fully known. Whether artificial reefs attract fish from nearby natural habitats or serve as a "production" point where new fish can settle remains a debate among the scientific community, but likely depends on multiple factors (Bohnsack et al. 1994b, Osenberg et al. 2002, Powers et al. 2003). Research in nearby Miami-Dade County found that fish assemblages on an artificial reef are more variable than those on nearby natural reefs, leading to additional questions about whether artificial structures can replace lost reef function (Thanner et al. 2006). As such, thorough research is needed on these topics to determine whether the placement of artificial reefs is consistent with the goals and objectives of the sanctuary.
The sanctuary has experienced first-hand that stability of artificial reefs can be variable despite the best attempts to ensure proper deployment. In 1998, the passing of Hurricane Georges caused the Eagle, a Dutch freighter sunk in 1985 six miles (nine kilometers) off Lower Matecumbe Key, to break in half. The USS Spiegel Grove, scuttled in 2002 as an artificial reef off Key Largo, landed upside down upon sinking. An unplanned, unfunded salvage effort successfully moved the ship onto its starboard side, and the force of Hurricane Dennis in July 2005 righted the ship to its originally intended position. Federal and state permit requirements for artificial reefs typically include thorough stability analyses and the ability for the structure to withstand 100-year storm events. However, it is not until after deployment that these parameters can be tested in the environment and in the face of unforeseen natural events. Logically, the NOAA administration supports a precautionary approach when considering the deployment of artificial reefs, and notes that "NOAA will continue to emphasize the protection, restoration, and enhancement of natural habitats, as opposed to constructing artificial habitats" (J. Dunnigan, pers. comm. NOAA, Dec. 8, 2009).
Some socioeconomic research on the human-use patterns of artificial reefs on nearby natural reefs has been completed for the USS Spiegel Grove off Key Largo. The results indicated that visitation declined by 13.7% on the surrounding natural reefs, lead to a 160.5% increase in artificial reef use, and a net increase in total artificial and natural reef use of 9.3% (Leeworthy et al. 2006). While the recreational use of the surrounding natural reefs decreased, the local dive charter business increased, and the local economy grew in terms of both income and employment (Leeworthy et al. 2006). This represents a positive increase to total business, while reducing pressure on the natural reefs. Similar research is underway for the USS Vandenberg, sunk off Key West.
Marine Debris
While the effects of fishing on marine ecosystems are a continuing concern for resource management, the wide-ranging effects of lost or discarded (derelict) fishing gear on organisms and ecological processes is still largely unknown in many coastal areas. Marine debris, in the form of derelict fishing gear, can reduce the structural complexity of habitats and devastate benthic organisms. Derelict gear can also smother and entangle both benthic and mobile fauna, including endangered species (Donohue et al. 2001, Chiappone et al. 2002a).
Derelict gear can also create long-term entrapment mechanisms that continuously kill mobile fauna (e.g., fish, lobsters, sea turtles) for several years. Because net materials are constructed to be strong and resilient, they can persist in the environment for decades and prevent the escape of entangled wildlife. Angling is the predominant form of recreational fishing in the Florida Keys and most of the environmental impact to the benthos from derelict gear results from lost monofilament line, fishing wire, leaders, lead sinkers, and hooks; however, a large percentage of impacts also stem from lost stone crab and lobster traps (DiDomenico 2001, Chiappone et al. 2002a). Lost cage traps catch prey on a continuing cycle as predators enter the traps to feed on previously entrapped organisms that are dead or dying. Nets and traps, when combined with high wave energy, can also physically scrape organisms such as sponges and corals or sweep immobile invertebrates from sandy areas (Chiappone et al. 2002a, Miller et al. 2010).
In a recent study by Miller et al. (2010) of 145 hard-bottom and coral reef sites from northern Key Largo to Key West, surveys of 480 belt transects comprising 77,500 square feet (7,200 square meters) of hard bottom and coral reef habitat yielded a total of 218 marine debris items, comprising 28 different items or combinations of items. Of these 28 diverse debris types, 10 were hook-and-line angling gear and five were lost lobster and crab trap gear. Debris was encountered on the seabed at 85% of the surveyed reef and hard-bottom sites, indicating the pervasive pattern of debris entangled in benthic habitats.
Military Use
Military use of the sanctuary includes surface and underwater activities. Under normal circumstances, pressures to sanctuary resources are related to conflicts and disturbances with marine life or benthic habitat, and disturbance of seabird roosting areas by aircraft. In the worst case, military pressures to sanctuary resources can include the direct and indirect effects of military aircraft crashes, possible grounding of military ships, jet fuel pipeline ruptures caused by storms, maintenance dredging of shipping channels or harbors, and habitat loss due to facility improvements or expansion. Military presence in the Florida Keys is detailed in the following paragraphs.
The U.S. Department of Defense (DOD) has played an important role in Monroe County (Florida Keys) since the early 1800s, when the federal government established a small naval operation in Key West to control piracy in nearby waters. The DOD currently maintains several sites in the Keys, including the largest unencumbered airspace available for training on the East Coast. Although all of the military departments are represented in the region, the Navy's presence is the most significant.
The Navy's location in the Keys has international significance, as it maintains the closest military installation in the continental United States to Cuba, Central and South America, and the Caribbean. All of the Navy's facilities are in the lower Keys, with the majority in Key West. The largest is the Naval Air Station Key West (NAS Key West) on Boca Chica Key (Monroe County Board of County Commissioners 1986). Key West harbor, including piers at Trumbo Point Annex and the Truman Annex, is also the site of the only active Navy facility within the sanctuary, where Navy vessels conducting operations in the area are berthed, and where naval acoustic research vessels conduct operations. Fuel deliveries and other logistical actions are also conducted to support training and operations. The Navy recently needed to restore to original capability as well as modernize and update its infrastructure and facilities to provide both improved and additional capabilities essential to support aircraft squadrons and ships visiting at NAS Key West. The modernization was completed by 2006 and required maintenance dredging of the main shipping channel into Key West and Truman Harbor, and refurbishing seawalls and mole piers.
NAS Key West's fuel supplies come by sea by way of Key West's main shipping channel. One Military Sealift Command (MSC) tanker every eight to 12 weeks delivers aviation fuel. Diesel is delivered solely via tanker truck to U.S. Coast GuardSector Key West two to three times per year. The Key West Pipeline Company owns three tender tanks for receipt and storage of aviation fuel and a pipeline that runs between Trumbo Point Annex and Boca Chica Field. The pipeline is four inches in diameter and approximately seven miles of it runs underwater in the sanctuary.
The U.S. Army operates the U.S. Army Special Forces Combat Divers School in Key West. They parachute into the sanctuary at Shark and Sand Key Drop Zones, and occasionally into other areas of the Gulf.
The Coast Guard (Department of Homeland Security) also maintains a significant presence in the region. It has five primary missions: search and rescue, law enforcement, marine safety, marine environmental protection, and the operation and maintenance of navigational aids (e.g., channel markers, navigational lights, and lighthouses). Because of these responsibilities and the vast expanse of waters along the Keys, the Coast Guard provides an important public function in the sanctuary. It is responsible for more than 560 miles (900 kilometers) of coastline and 34,170 square miles (88,500 square kilometers) of ocean area, and typically has several vessels and over 600 personnel located at three stations (Islamorada, Marathon, and Key West) in the area. The largest vessels operate out of Trumbo Annex in Key West.
The U.S. Air Force operates a Tethered Aerostat Radar System (TARS) at Cudjoe Key for aerial surveillance radar. The system is designed to detect low-altitude aircraft, providing detection and monitoring capability in the Florida Straits and a portion of the Caribbean. The TARS surveillance data are used to support customs and border protection.
Pressures to Maritime Archaeological Resources
As modern underwater technology such as scuba gear, metal detectors and remote-sensing devices are developed, both professional and amateur treasure hunters are able to improve their search for lost and submerged maritime archaeological resources (Gerard 1992). For the purposes of this report, three general types of treasure salvors were categorized, each assumed to exert different (but unquantified) levels of pressure on these resources: 1) souvenir collectors/hobbyists who combine the search for treasure with their recreational diving activities; 2) paraprofessionals who hunt for treasure on a regular part-time basis, but for whom treasure salvage is not their primary source of income or full-time job; and 3) professional treasure hunters whose search, recovery, sale and display of recovered items is a full-time endeavor and primary source of income. While not a common practice, the development of propeller-wash deflection devices (e.g., "mailboxes") have enabled professional treasure hunters to excavate crater-like holes in the seafloor, allowing the discovery of shipwreck materials more than 20 feet (6 meters) below the surface on the seabed. Indiscriminate use of mailboxes can cause significant damage to natural resources as well as cultural resources, including reducing the quality and amount of contextual information. In addition, recreational wreck divers may illegally remove resources from a deepwater shipwreck to keep as a souvenir. Although the degree to which looting occurs is not quantified, the cumulative impacts of this activity can affect the condition of wrecks.