- Views 3657
CRY OF THE WATER
Monitoring Broward’s reefs
August 13 2001
Thomas J. Goreau, Ph.D., President, Global Coral Reef Alliance
Dan Clark, President, Cry of the Water
Cry of the Water, P. O. Box 8143, Coral Springs, Florida 33075
E-mail: firstname.lastname@example.org Web site: http://www.cryofthewater.org
Global Coral Reef Alliance, 37 Pleasant Street, Cambridge MA USA 02139
Telephone: 914-238-8788 Fax: 914-238-8768
E-mail: email@example.com Web site: http://www.globalcoral.org
Shallow coral reefs with unexpectedly high live coral cover, coral species diversity, coral sizes and ages, reef fish abundance, and fish species diversity are confined to a short stretch of Broward County shoreline, approximately five and a half miles, that has never undergone dredging and beach filling. Most corals are healthy, but many are being killed by disease epidemics, bleaching, sediments, and algae overgrowth. This small, unique, and effectively unprotected area, the last good shallow coral reef left in East Florida, should be the top coral reef conservation priority in the continental US now that the Keys and the Dry Tortugas are protected. As the northernmost shallow coral reef on the Atlantic Coast, it has many unusual corals whose protection is the only hope for coral reefs to grow northwards as global warming continues. These shallow reefs, which have not been documented by scientific studies or reef maps, are imminently threatened by ongoing plans to dredge and fill (i.e. “renourish”) the adjacent beach, scheduled to start this year by Broward County and the United States Army Corps of Engineers. Dredging, beach filling, fishing, anchoring, and nutrient discharges should be strictly prohibited in this zone in order to protect the beaches from erosion, maintain biodiversity, improve ecosystem health, restore fish populations, permit adaptation to global climate change, and stimulate diving and snorkeling ecotourism in Broward County. Good deep coral reefs with large old corals exist around the proposed dredge pit sites. Immediate emergency steps should be taken to protect all these reefs from imminently planned dredge and beach fill operations. All remaining areas of good coral growth, worm reef, and hardground of importance as juvenile fish habitat should also be mapped and protected. Cry of the Water, the Global Coral Reef Alliance, and all concerned divers, swimmers, fishermen, and environmentally aware individuals and organizations call on the cities of Fort Lauderdale, Lauderdale by the Sea, and Dania, Broward County, the State of Florida Department of Environmental Protection, the http://www.troakley.com/ National Marine Fisheries Service, the US Fish and Wildlife Service, and the US Army Corps of Engineers to implement such protection at every level as urgently as possible, from the Lauderdale by the Sea pier to Port Everglades, from the low water mark to the 120 foot depth contour. Killing the last remaining good shallow reefs in Eastern Florida by unjustified dredging and beach filling would be like dynamiting the last giant redwood stand. All funds allocated to this environmentally and economically irresponsible project should be spent on protecting natural shore protection by living reefs and restoring the damage that has already been done along the remainder of the shoreline.
See the Cry of the Water web site for additional pictures and videos of the dive area.
Field observations of Broward County coral reefs, worm reefs, and hardground were carried out in June-July, 2001. A combination of shore dives and boat dives were made between the following areas (see map):
Dania Beach near Custard Street
Outside edge of the first reef off Fort Lauderdale Beach from NE 14th Street through NE 16th Court
Inside and top of the first reef off Fort Lauderdale Beach near NE 14th Street
Lauderdale by the Sea, south of the pier.
Sites were documented with photographs by Dan Clark, Jim Stilwell, Eddriana Stilwell, Karen Schroeder, and Stephanie Clark (see plates). Video footage of these sites is available from Cry of the Water. These locations all lie on the first hardground ridge just offshore from beach areas where dredging and beach filling is planned in the near future (see Map) by Broward County and the United States Army Corps of Engineers (Broward County Beach Erosion Control Project, Permit application # 199905545). This Project requires dredging approximately 3 million cubic yards of sand (about 300,000 dump truck loads) from 7 dredge sites, located near deep and shallow reefs, and dumping it along about 12 miles of shoreline, all along the edge of the shallowest, and richest, reef. The reef corals shown in the photographs in this report are entirely from the innermost reef, adjacent to the planned dump fill areas (Map). The assumed area of sedimentation and turbidity impacts, according to existing environmental impact assessments, are based on calculated equilibrium positions of the “toe of the fill” (i.e the bottom end) after reworking by waves. The toe of the fill, the limit of movement of the heaviest sand fill according to calculations based on local beach slopes and assumed average wave heights, does not apply in case of a direct hit by a hurricane. If a hurricane were to hit the area, the direction and extent of sand movement would be far greater than that assumed. The toe of the fill could then wind up not at the calculated “equilibrium position” but by being sand dunes on land or burying the entire inner reef, depending on the location of the eye of the hurricane. While 37.1 acres of nearshore hardground identified as Essential Fish Habitat could be directly affected by this dredging project according to standard assumptions (South Atlantic Fishery Management Council, 2000), the total could be even higher after a hurricane, including all the areas described in this report (see photographs).
1) Live hard coral cover was much higher than expected. The top of the first ridge had a very large patch of live staghorn coral (Acropora cervicornis), approximately 100 yards by 50 yards, in a depth of around 12 to 14 feet. This species, formerly one of the most abundant in the Greater Caribbean, is now rare almost everywhere. Live staghorn coral bushes covered the bottom, and were densely packed with vast schools of juvenile grunts and other reef fish (see photographs). All the coral appeared to be from the same clone, which appears to have spread by storm fragmentation from a single mother colony. Towards the south of this patch (about 3 blocks) several cheap oakley colonies of staghorn were found which appeared to have grown from settling larvae rather than fragmentation, but these were the same shape and color as the corals in the large patch. The outer edge of the innermost reef had between 30% and 40% live coral cover, consisting largely of mound corals of many species, dominated by Montastrea cavernosa. In areas on the top of the ridge nearby, dominated by large mound corals, live coral coverage was up to 50%. Live coral cover decreased towards land. In sharp contrast, much lower coral cover was found off areas where beach dredge filling had taken place in the past, no more than a few percent.
2) Coral species diversity was higher than expected, including around half of all the Atlantic reef building species. Those seen included Montastrea cavernosa, Montastrea annularis, Diploria strigosa, Diploria clivosa, Diploria labyrinthiformis, Acropora cervicornis, Colpophyllia natans, Stephanocoenia michelini, Solenastrea bournoni, Madracis decactis, Madracis mirabilis, Oculina difusa, Siderastrea siderea, Siderastrea radians, Favia fragum, Manicina areolata, Dendrogyra cylindrus, Dichocoenia stokesii, Meandrina meandrites, Agaricia agaricites, Mycetophyllia aliciae, Eusmilia fastigiata and Millepora alcicornis (species identification follows Veron, Corals of the World, 2000). More species of corals are known to exist in the area, but were not encountered during this rapid survey. The most diverse areas were the outer ridge edges. Genetic diversity (variety of shapes, colors, and forms) was exceptionally high in Montastrea cavernosa, but most other species were predominantly of only one of the several to many forms known to occur in the Greater Caribbean reef region, some of them rare elsewhere.
3) Corals on top of the ridge included very large heads of Montastrea annularis and Montastrea cavernosa up to 10 feet in diameter (photographs), which are likely to be more than 500 years old assuming a growth rate of around 4 millimeters per year. The most abundant mound corals (photographs), coral heads one to four feet across which covered most of the inner ledge, are probably also at least centenarians. These growth rates are based on analysis of banding patterns of 223 whole Broward County corals (Dodge, 1987). Such ancient corals are rare in coral reefs, and indicate that these are relic survivors from a time of much better coral growth in the past, before the rapid expansion of South Florida’s population in the last 100 years.
4) Despite the high live coral cover, diversity, and size found, and although most corals of all species were healthy-looking, at least six different stresses were clearly seen killing corals:
i) Coral diseases were common and appeared to be killing corals very rapidly and very recently. Large areas of coral had been killed within the last few days, based on the bright white color and lack of fine filamentous algae cover on very recently dead coral (photographs). The diseases seen included White Band, Black Band, White Plague, Rapid Wasting, Yellow Band, Dark Spot, Aspergillosis, and several other diseases that do not fit the classic appearance of the syndromes listed above. White Band was in an epidemic phase, and significant amounts of staghorn coral show death of bases and tips within the last week or less, with the recently dead portions inches to a foot in length (photograph). While some corals showed thin white recently dead rings (photograph), similar to the classic slow progression of the disease, most coral mortality appeared to be moving so fast that algae had not yet been able to overgrow the dead bright white skeleton, which takes only a few days. These white recently-dead corals had not been present a few weeks before during surveys by Cry of the Water, indicating the recent and rapid nature of the outbreak. Black Band also appeared to be moving unusually rapidly, with bright white areas of recently killed coral up to 6 inches or more wide, much wider than usual (photographs). Black Band appeared to be more common in distinct patches of corals, and in some cases affected coral heads showed old circular dead patches, completely overgrown by algae, with new areas of recently dead coral spreading from several cheap oakley sunglasses points around their edges (photograph). It appeared that Black Band disease had killed portions of the colony last year, stopped in the winter months, and resumed attacking the coral when the water warmed up. White plague was also found in isolated patches, killing several species of corals very rapidly from the base upwards (photograph). Only a few cases of very recent Rapid Wasting Syndrome were found, all on Colpophyllia natans, with one two-foot wide colony almost entirely killed in recent days, and a few colonies with old scars that were healing around the edges. Aspergillosis affected a minority of seafans. Yellow Band, Dark Spot, and White Spot diseases were also noted but were relatively rare. All of these diseases are found in the Florida Keys, where they appear to be more common, and are part of the unprecedented spread of coral diseases throughout the Greater Caribbean in recent years (Goreau et al., 1998). Two spectacular six foot tall pillar corals (Dendrogyra cylindrus) had unusual patches where polyp tentacles were exceptionally swollen and tissue appeard to be peeling off the skeleton (photograph), which may be yet another new pathological condition.
ii) Coral bleaching was starting (photograph), affecting primarily the most sensitive colonies of Montastrea cavernosa, Palythoa caribbeorum, Porites astreoides, and Siderastrea siderea. Appearance of bleaching this early in the year is unusual, as warmest conditions and bleaching normally take place later in the year. Bleaching is an indication of severe stress, and bleached corals fail to grow or reproduce while bleached. Corals are being killed on an increasingly large scale worldwide by bleaching mortality following exceptionally high sea surface temperatures (Goreau & Hayes, 1994; Goreau et al., 2000).
iii) Corals were being killed by other reef animals. Many large old corals were completely dead or dying from attack by orange boring Cliona sponges, which destroy the coral tissue from underneath as they undermine the skeleton, producing a dying edge that superficially resembles a band disease in corals (photograph). Increased sponge attack of corals could be due to an increase in the concentration of bacteria which they filter from the water. Some large corals are also being overgrown by large rubbery encrusting mats of Palythoa caribbeorum (photograph). Increases in these stress-indicating organisms suggests that their ability to overgrow corals is being enhanced by increases in the suspended matter that they use as food. Both these overgrowth and undergrowth problems could be indirect consequences of increased pollution due to rapidly increasing human populations nearby if this results in more bacteria and organic detritus in local waters (i.e. more excrement in the water).
iv) Corals were being overgrown by algae in many locations, especially on the landward side of the reef ridge. This is an indication of excessive fertilization of the water by land-derived sources of dissolved nutrients, especially from sewage and fertilizers entering the coastal zone via canals and groundrock discharges to the sea.
v) Sedimentation stress was killing patches of the largest and oldest Montastrea annularis colonies in the best areas. Patches of sediment up to 6 inches across filled depressions on top of the corals, and when fanned away, white recently dead coral polyps were found (photograph). Such damage was noticed on large ancient corals that were otherwise almost entirely healthy and intact over more than 95% of their surfaces. Their smooth upper surfaces (photograph) indicated that such mortality had not happened in the past, which would have caused them to have knobby lobed surfaces. Montastrea annularis heads up to 10 feet across were also found off beach areas that had been renourished in the past, but these were either entirely dead (photograph) or had only very small remaining live patches around the edges. It seems most likely that chronic sediment stress from past beach dredge and fill had killed them, as had been observed in the Pompano area by divers, and documented in old photographs.
vi) Montastrea annularis appeared to be undergoing reproductive failure in that only very old corals of this species were found. All small colonies seen were not young corals at all, but were in fact surviving fragments of larger colonies that had largely died. Most other coral species included a range of sizes suggesting that young colonies were present. However these were common only on the top of the first ridge off the coastal stretch that had never undergone beach dredge-filling, and where the hardground was relatively clean of sediment and algae. In previously renourished stretches there were very few young corals, primarily species that never get large such as Favia fragum and Siderastrea radians.
5) Algae species composition and abundance showed sharply zoned patterns. Only in the north of the study area were slimy cyanobacteria (blue-green algae) clumps common on the landward edge of the hardground. These are an indicator of sewage inputs and relatively high phosphorus to nitrogen nutrient ratios. In this area the hard bottom was virtually completely covered with dense lawns of micro-filamentous algal turfs, allowing no space for baby coral settlement. In areas of higher coral cover the algal turf was much more poorly developed, and there was plenty of reasonably clean limestone rock surface for new coral attachment, allowing both recruitment of new larval corals of many species and the re-attachment and continued growth of staghorn coral fragments broken by storm waves. Both kinds of propagation of corals are virtually impossible where algal turf is well developed. In areas of good coral cover not only were algae low in abundance, but they were dominated by macrophytes (bushy larger algae) instead of low dense algal turf. Over most of the outer part of the ridge where coral cover and young corals were most abundant, algae cover was relatively low and the algae were dominated by Halimeda discoidea, Galaxaura obtusata, and Amphiroa species (algae follow Littler & Littler, 2000). These are all calcareous sand-producing species typical of low nutrient waters. The landward side of the first ridge had less corals than the seaward side, and showed an increase in algae and a change in algae species towards the shore. Moving landward, Bryothamnion triquetrum replaced Galaxaura and Amphiroa. Bryothamnion is a fleshy (non-sand producing) alga typical of moderately high nutrient waters. Halimeda discoidea was replaced by Halimeda incrassata, also indicative of higher nutrients. Moving landward, Bryothamnion was increasingly overgrown with algae turf and then replaced by softer fleshy red algae, such as species of Heterosiphonia, Ceramium, Chondria, Hypnea, and other species typical of higher nutrient levels. Finally on the inward edge of the hardground, green algae such as Chaetomorpha began to appear, which are indicative of very high nutrient levels with elevated phosphorus. Numerous other algae were also seen, such as Dictyota and Padina species, but were less abundant than those mentioned. In addition there were noticeably high levels of greenish-brown algal mats on the surface of the sand inshore of the hard bottom, just deeper than the currently active surf zone. These were denser in the north of the study area than the south, and probably reflect inputs of nutrients in groundwater trickling through the sand.
6) Fish were very abundant and diverse in the areas of high coral cover. Vast schools of several species of grunts packed the staghorn corals (photographs). Triggerfish, including queen triggerfish, were exceptionally abundant. The diversity and abundance of reef fish, including jacks, groupers, grunts, snappers, wrasses, hamlets, porgies, angelfish, damselfish, surgeonfish, parrotfish, gobies, puffers, hogfish, mojarras, and many other fishes were very high in the zone of high live coral cover and diversity, along with dense swarms of very young juvenile fish of many species crowding around large coral heads (photographs). In contrast reef fish abundance and diversity was lower in areas of low coral cover. In areas dominated by algal turf, algae-eating surgeonfish dominated fish populations, but were only a minor portion in coral dominated areas. This probably reflects greater abundance of their algae food due to its fertilization by land-derived nutrient sources. Besides fish, marine invertebrates such as lobster, crabs, and conch, and sea turtles (photograph) were also seen.
7) Worm reefs were exceptionally well developed along Dania Beach. These reefs were covered with live worm tubes, which are growing upwards at a rate much greater than the rate of erosion by waves. These reefs are not composed of solid limestone but are made from sand grains cemented together by an organic glue in tubes built by living worms (Kirtley and Tanner, 1968: Pandolfi et al, 1998). The constant growth of these worms is needed to counteract wave erosion on the seaward side and the boring activities of burrowing clams that live inside the worm reefs. In sharp contrast, areas of Lauderdale by the Sea where the beach had been previously renourished had only thin small crusts of worm reef (typically less than 6 inches across) that covered only a very small portion of the hardground. The inner part of the hardground conisted of crumbling dead worm reef that was being actively eroded away, presumably killed by smothering after previous beach dredge-fill operations.
8) Just offshore from the disintegrating inner ridge of the largely dead worm reef off Lauderdale by the Sea, is a very unusual hardground formation, sparsely covered with many fields of large dead corals (photograph) and only a few live ones. This fossil limestone ridge is full of large cylindrical holes up to a foot in diameter, passing vertically through the rock layer, which appears to be around two feet thick. This “Swiss cheese” rock formation is being undermined by scouring erosion of the underlying sand layer, causing it to crack and collapse. This low live coral hardground is clearly eroding much faster than it is growing, in contrast to the areas to the south where coral growth is raising the height of the ridge. The unusual abundance of holes provides hiding spaces for fishes, such as young nurse sharks, but due to the high amount of dense algal turf on the rock, which attracts large numbers of surgeonfish, the fish species diversity was low.
9) Although this study focused on the shallowest inshore reef, the deeper reefs, down to around 120 feet, are also important habitat in their own right. They also contain large old corals and abundant fish populations. Many of the proposed sites for dredging lie close to these deeper reefs.
1) Given its location so far the north of known coral reefs and its proximity to dense urban populations and Everglades drainage canals, the very high live coral cover, species diversity, size, age, and fish populations are astonishing and unexpected. These reefs are a national treasure, a last surviving relic of ancient times like largest old growth redwood forests. Most coral reef specialists were unaware that such fine coral reef exists in Broward County, as they have not been described in the scientific literature or shown on reef maps. Many were not aware that there was any shoreline left in Broward County which had not already been dredge-filled. Most hardgrounds previously described in southeast Florida have much lower live hard coral (Goldberg, 1973; Goldberg, 1984; Raymond & Antonius, 1977; Raymond et al., 1977). Hardground sites monitored by Broward County and Nova University have an average of only around 1.4% live coral (Broward County Department of Planning and Environmental Protection, 2000). The current condition of these reefs is as good or better than that remaining in the Florida Keys and most of the Greater Caribbean at this time. This makes them of the highest national reef protection priority even though (in fact specifically because) they are limited to such a small area. Nevertheless they are facing several potentially devastating threats, primarily from disease epidemics and bleaching that are being closely monitored by Cry of the Water’s video surveys.
2) These reefs are unique because they are the northernmost coral reefs along the Atlantic coastline. During this time of rising global sea temperature, they are the only potential source that could allow many coral larvae to repopulate the East Florida hardgrounds that were flourishing coral reefs around 4 to 6 thousand years ago (Lighty, 1977, Lighty et al. 1979). Apparently the Gulf Stream was moving more warm water to this coast at that time. With global warming East Florida’s offshore rock could again become coral reef, but this will happen only if they can be kept clean of excessive sediments and nutrients. Otherwise there will be no place for Broward’s surviving good reefs to seed the northward growth of East Florida coral reef ecosystems as global warming continues and warmer areas die. Broward reefs and hardgrounds are central to the survival of many Atlantic coral reef species and hence of global significance.
3) The area of good shallow reef is restricted to the short stretch between Dania and Lauderdale by the Sea that has never undergone beach dredge-filling (see map). The abundance of still identifiable dead corals on the ridge offshore from areas previously dredge-filled suggests that those reefs may have been killed by excessive sediments after the beaches were dredge-filled. Large coral heads hear Pompano that were all alive prior to beach dredge filling, died soon after. Similar destruction of healthy reef followed beach filling all along the Broward coast, as shown by comparison with photographs by old divers. Previous dredge-fill operations in northern and southern Broward County buried large areas of neashore habitat. Buried hardgrounds can just be made out on recent high resolution radar maps of the bottom: inshore hardground in northern and southern beach filled sections are smoothed and buried, but nearshore hardgrounds in central sections that were not filled show well defined ridges in sharp relief. Coral growth rate is strongly depressed by high sedimentation (Dodge et al., 1974), and dredging is known to kill whole coral reefs nearby (Dodge & Vaisnys, 1977). High turbidity markedly increases respiration rates of Broward corals (Telesnicki & Goldberg, 1995), causing the tissue to waste away. Although suspended sediments following dredging have long been known to harm or kill corals, the existing studies of the biological impacts of dredging on corals in Broward County are ambiguous. Direct damage to corals by dredging was reported only in 1977 during dredge-fill operations at John Lloyd Park (Raymond et al., 1977). This damage was caused by dredges that went off course and starting dredging coral reefs, and by spilling of dredge fill from overloaded barges. It is estimated that 36,300 corals were directly damaged (Raymond et al., 1977). No information is available on direct damage to corals from later dredge-fill operations. Information on the effects of resuspended sediments on Broward reefs is even less. Comparison of 12 sites before and after dredging in Lauderdale by the Sea and Pompano Beach by Goldberg (1984) found that reef-building corals showed signs of tissue reduction or were missing at 3 sites, both hard and soft corals had deteriorated at 2 sites, and soft corals alone had deteriorated at 5 sites. However the role of dredging in this ecosystem deterioration was not clear because several other events had happened in the same period, including abnormally low temperatures and extremely high storm-caused turbidity events (Goldberg, 1984). A follow up study at Goldberg’s sites showed an increase in algae species indicative of higher nutrients (Continental Shelf Associates,1984). Although studies of growth band records from 223 whole Broward corals failed to show a relationship between coral growth and earlier dredge and beach fill operations (Dodge, 1987), all the corals studied came from the mid and deep reefs. No corals from the shallow reef were examined. The mid and outer ridges are much further from shore and in much deeper water, so resuspended sediments following beach dredge and fill would have much less impact than on the shallow reef which lies just offshore. Growth records of deeper Broward corals showed strong long-term variations affected by environmental controls more than by dredging (Dodge, 1987). Coral growth rates were found to correlate with salinity records from Miami. This was interpreted as being caused by decreased coral growth rates during high cloud, low sunlight, strong rainy seasons (Dodge, 1987). Studies of a long (1918-1983) coral growth and coral fluorescence record from Broward County found that annual coral growth patterns had a very strong negative correlation with rates of discharge of Everglades water through the New River and Hillsboro canals from South Florida Water Management District records (Goreau et al. 1988). Coral growth was low during years of high canal discharge, during years of high drainage pumping from the Everglades, flood years, and hurricane years, but high during drought years. Broward county corals grew well from 1918 to 1944, but suffered a dramatic decrease of growth rates and increase of boring of their skeletons by clams from 1945 to 1969, during the period of peak canal discharge (with the exception of normal growth only during drought years), but coral growth rates recovered to higher levels after 1969 (Goreau et al., 1988), when Everglades drainage to the sea was greatly reduced by back-pumping water into the newly-diked water conservation areas, greatly reducing the amount of swamp water that flowed over Broward reefs. Growth records of corals near the canals draining Caribbean wetlands similar to the Everglades found that coral growth was lowest near freshwater and peat discharge sources (Goreau et al., 1988). Coral heads taken from the deeper mid reef show considerably reduced growth rates during periods of high Everglades drainage compared to corals from the deepest reefs (data in Dodge, 1987), so it is likely that shallow reefs were even more impacted by sediments, whether from Everglades brown peat waters before 1969 or resuspended beach fill after 1970. The striking year by year negative correlation between Broward county coral growth and hydrological records of Everglades drainage would not be found if the corals had bleached between 1918 and 1983, which would throw the timing off because bleached corals do not grow or form annual bands (Goreau & Macfarlane, 1990). Bleaching was first reported in Broward County during 1987 after high local sea surface temperatures (Goreau and Hayes, 1994) and has since happened frequently. So it does not appear that the high sedimentation from dredging or high freshwater and peat runoff from canals caused bleaching, even at their most severe. Although there has been relatively low coral mortality from bleaching so far, bleaching will become more frequent with global warming. Bleached corals are weakened, less able to clean themselves of sediment, and hence more likely to be killed during future high sedimentation episodes such as would occur near beach fill areas after storms. Preservation of the shallow inshore reefs requires that they be completely protected from beach dredge and fill operations. They are exceptionally vulnerable to human damage because they lie just offshore from an area populated by millions of people, unlike the reefs of the Florida Keys which are much further from the land, and with a smaller population nearby.
4) The strong association of high abundance and diversity of juvenile reef fish with high live coral cover mandates that the best coral areas be the core of any proposed marine protected area designed to restore collapsing populations of locally caught reef fish, especially groupers, snappers, and jacks, as well as lobsters. It is essential that the very best available habitat for juvenile fish, shallow reef and rock (Nagelkerken, 2000) be strictly preserved in order to increase fisheries productivity, enhance biodiversity and overall ecosystem health in surrounding areas. Healthy hardground areas are also major sites of local biodiversity (Nelson, 1989) and essential juvenile fish habitat (Lindeman, 1997). Dredge-filling of nearby beaches caused 30 fold decreases in juvenile fish abundance and 10 fold decrease in fish species diversity on nearby hardgrounds (Lindeman & Snyder, 1999).
5) The distribution of algae strongly suggests that the major source of nutrients is from the land, and is higher in areas nearer to land-based sources of discharges such as canals. The pattern of algae cannot be explained by grazing of sea urchins, as almost no sea urchins were seen in any of the sites. In these observations only two juvenile long black spined urchin (Diadema antillarum), one young short spined white urchin (Tripneustes ventricosus), one young rock urchin (Echinometra lucunter), and one small slate urchin (Eucidaris tribuloides) were seen. However the abundance of algal lawn correlated well with the abundance of the surgeonfish that dominated only the regions of dense algal turf lawns, which they appear to be attracted to and play a role in maintaining. The role of nutrient sources from land in causing algae overgrowth of corals needs to be documented, the sources identified, and their inputs reduced if the reef in the algae-threatened areas is to recover and allow new corals to grow.
6) Although this study focuses on the shallow reefs most likely to be impacted by adjacent beach fill, excellent coral habitat also occurs on the deeper reef ridges and other areas of Broward County. All areas of high coral cover and hardground of importance as juvenile fish habitat should be mapped and protected. Because of the long narrow nature of the sand deposits which are proposed to be used as dredge “borrow pit” sites the proposed excavation pits will have a total perimeter of around 10 miles, and because all pits lie between reef and hardground formations, virtually all the pit edges will be within 200 feet of reef. Many of the deep reefs near the proposed dredging excavation pit sites have large Montastrea and Diploria heads up to 10 feet across.
7) Right now the living coral reefs and worm reefs are actively protecting the beaches in areas that were not dredge-filled in the past (Map). These beaches appear stable and do not need to be dredge-filled wherever healthy coral and worm reefs remain (for example Fort Lauderdale Beach). Once coral and worm reefs are killed by sedimentation from unnecessary dredge and beach fill operations, submarine and beach erosion will increase, and the beaches will have to be dredge filled again and again, at least as long as sand is available to do so. Since hurricane strength and sea level rise closely parallel global warming, even the coarsest dredge fill, not to mention the fine silt and mud, could move across the inner reef in future hurricanes. It would be most unwise, and should be unthinkable in 2001, to run the risk of smothering the last and best shallow coral reefs of East Florida at a time of steadily rising sea levels!
8) Alternatives to dredge and fill operations, such as sand bypassing of the large volumes of sand trapped behind jetties at the entrances to the Hillsboro and New River canals and the Boca Inlet, should be explored instead of steps that destroy natural shore protection. Most of the beaches showing signs of erosion and needing dredge-fill are in areas whose natural supply of sand by longshore drift has been blocked by jetties. The amount of sand now stuck behind the jetties on the north sides of Port Everglades, the Hillsboro Canal, and the Boca Inlet could probably supply most of the sand lost from the beaches on the southern sides, where it would have gone had the jetties not been there. This sand could be pumped, shipped, or even trucked the short distance needed for less than shipping sand from deep pits, many at the other end of the county. John U. Lloyd Park, lies just south of all the trapped sand on the other side of Port Everglades. It was dredge-filled from offshore sand sources in 1977, but this was eroded away so dredge-filling was repeated again in 1989. In 16 months following the 1989 dredge-filling of the severely eroded beach at John Lloyd Park the beach eroded inland at a rate of 52.7 feet per year, but the submerged bottom end of the fill material (the “toe’) moved outward at a rate of 106 feet per year (Broward County, 1990), burying nearshore hardground communities. The monitoring study, which noted that the rate of erosion would require yet another dredge-fill operations by 2001 (when indeed one is planned), pointed out that only regular supplies of sand could hold off severe erosion of the beach, and recommended that sand-bypassing be used. Nevertheless, the current plan is for another round of dredging from increasingly remote sources. Sand bypassing, which is simpler and cheaper, should be the beach sand supply option of choice, with alternatives considered only if these are insufficient, and then only where it is really needed. The section of Broward County which has never been filled, has no erosion problem and does not need to be “renourished”.
1) Protecting the coral reefs off Broward County, and in particular the shallowest reefs off Fort Lauderdale Beach that have never been previously dredge-filled, should be the single highest coral reef conservation priority in the continental United States at this time, now that the Florida Keys and the Dry Tortugas are protected. These small but highly vulnerable reefs deserve protected status similar to the Florida Keys, where degradation may be more severe and rates of coral decline faster (according to EPA surveys). Because they are critical to the survival of Atlantic coral reef species from global warming, Broward’s remarkable reefs are also of international importance and should become a World Heritage Site. Immediate steps should be taken to establish a protected area, even if at the city or county level, in which beach sand dredging and beach fill operations, anchoring, fishing, and land-based discharges of nutrients are strictly banned. Because of the large and varied fish populations easily visible from the surface, a carefully managed and monitored snorkel route could be a major tourist attraction. Because many tourist divers have poor buoyancy skills and may grab, kick, and break fragile corals, only snorkeling with a flotation vest and limited SCUBA diving for video monitoring purposes should be permitted in the best shallow reef areas. Protected area management needs to be implemented immediately because these reefs are close to shore and could easily be destroyed by unregulated overuse by careless divers or irresponsible spear and lobster fishermen once their existence is known.
2) All good coral reefs, worm reefs, and hardgrounds of Broward County should be mapped in detail, their species composition and abundance documented non-destructively by video, and changes in coral growth rates, diseases, bleaching, and the abundance and types of algae should be monitored regularly by video. Cry of the Water is carrying out regular video monitoring of the areas of good coral growth. These should be interfaced with high resolution radar maps of Broward’s nearshore bottom prepared recently by technical consultants to Broward County. Existing monitoring programs by Broward County, Nova University, FIU, the State of Florida Department of Environmental Protection, the United States Environmental Protection Agency, and other agencies could be expanded to include sites in the high coral areas. Nutrient and coastal circulation studies should be made to determine the source and fate of the nutrients causing algal overgrowth of hard bottoms and living corals. Studies need to be made about the spread of diseases and possible means of reducing them.
3) Worm reefs are a rare and important habitat that should also be strictly preserved because of their importance in shore protection (Kirtley &Tanner, 1968; Pandolfi, et al., 1998) and as juvenile fish nursery habitat (Lindeman & Snyder, 1999). All the good growing worm reef that is now protecting the beach at Dania and John Lloyd Park would be buried and killed by current beach dredge and fill proposals. Gorgonian (soft corals like seafans and seawhips) habitat on hardgrounds are also major sites of juvenile fish recruitment and should be classified as essential fish habitat.
4) Large areas of degraded reef habitat near previously dredge-filled beaches and near areas affected by canals and groundwater discharges can and should be restored. These will be attractions for ecotourism and serve as fish nurseries only if the quantity of live growing corals can be increased. Concrete, rock, rubber tire, sunken ships, and other traditional forms of “artificial reefs” do not serve this purpose. Cementing coral transplants in areas of poor water quality will not work because excess sediments and algae will kill coral or prevent high coral growth. Besides cleaning up the water of excess sediment and nutrients, use of methods that increase coral growth rates and resistance to environmental stress (Goreau et al., 2000) will be needed to effectively restore degraded reefs. The only method that can do so, the Mineral Accretion (Hilbertz & Goreau, 1998) or BIOROCK(tm) method, could restore coral and fish growth, and create a solid limestone breakwater protecting the beaches from further erosion or the need for repeated dredge and fill operations. This could be done at a fraction of the cost of the methods now used with so little long term effect that one could almost get the same results by piling the money they cost in the sea (Pilkey, 1996).
5) Coastal protection strategies by Broward County, the State of Florida, and the US Army Corps of Engineers should preserve and increase growth of corals and biological reef, and hardground frameworks instead of damaging or destroying them through dredging and sedimentation. They are mandated to do so under Executive Order 13089 (Coral Reef Protection, 1998). Studies of growth bands should be made from thin cores of the large completely dead coral heads in order to determine the time and cause of death. The leading expert in the field, Dr. R. E. Dodge of Nova University, should head the study. Serious large-scale reef restoration efforts should be made by Broward County, the State of Florida, and the US Army Corps of Engineers to mitigate the large areas of former reef rock that has been killed by previous failed strategies of shore protection. All sand bypassing options should be exhausted before offshore dredging is considered as alternative supply of beach sand in areas that have been eroded because of human interference with their natural sand supplies.
6) Cry of the Water and the Global Coral Reef Alliance, in conjunction with concerned divers, fishermen, swimmers, environmentalists, and concerned individuals and organizations, call for this entire area to be immediately given the highest possible protected status by all concerned public agencies, including the Cities of Fort Lauderdale, Lauderdale by the Sea, Dania, Broward County, the State of Florida Department of Environmental Protection, the National Marine Fisheries Service, the US Fish and Wildlife Service, and the International Biosphere Reserve Program. We urge them to act on an emergency basis because of the beach “renourishment” planned for this year. We call on Broward County and the US Army Corps of Engineers to immediately halt all the planned dredge and fill operations along the remaining areas of healthy shallow coral reef, worm reef, and hardground. Killing the last remaining good shallow reef in East Florida would be like dynamiting the last giant redwood grove!
7) We call for all funds allocated to the dredge and beach fill operations to be re-allocated to protecting these irreplaceable reefs and mitigating the damage that previous dredge and fill operations have caused in the past to East Florida’s reefs.
We thank Stephanie Clark, Susan Epps, Edrianna Stilwell, and James Stilwell of Cry of the Water for assistance in the field and discussions during the field study, Brian Brooks for information and photographs on past conditions of Broward Reefs, R. E. Dodge for many prior discussions on effects of dredging and sediment on corals and growth rates of Broward County corals, Ken Lindeman, Chuck Sultzman, and Ivan Nagelkerken for information and discussion on juvenile reef fish habitat, James Porter, Craig Quirolo, Ray Hayes, and James Cervino for prior information about coral diseases in the Florida Keys, Jocelyn Karazsia for comments and references. The opinions presented here are those of the authors alone and not necessarily of those acknowledged above.
MAP: Showing the location of the areas of good reef, areas where the beach has been dredge-filled in the past, and areas currently proposed for dredge-filling by Broward County and the US Army Corps of Engineers. Based on Broward County Project Location Map, Department of Natural Resources and Planning.
1. Large field of staghorn coral from above, showing extent of coral and several layers of different fish populations around it. Photo: Karen Schroeder.
2. Staghorn bush from below, showing a small part of the dense schools of grunts and other fish that shelter in them. Photo: Karen Schroeder.
3. Edge of staghorn field and large head corals, with a highly experienced coral reef researcher showing typical first response (Dr. James W. Porter of the University of Georgia, a leader of the Environmental Protection Agency team studying long term change of Florida Keys coral reefs from photographic transects). His written message: “this place is just amazing”. Photo: Karen Schroeder.
4. Healthy ancient coral, about 10 feet across, on top of shallow reef, with numerous fish swimming around. Photo: Dan Clark.
5. Ancient pillar coral on top of shallow reef. Photo: Dan Clark.
6. Ancient round coral, showing many pale spots on sides indicating the start of coral bleaching, and some recovering parrotfish bite marks on top. Photo: Jim Stilwell.
7. Large numbers of coral heads over a hundred years old near the outer edge of the shallow reef. Photo: Jim Stilwell.
8. Coral head with juvenile angelfish, surgeonfish, and wrasses on top of hardground. The red and green algae on the hard bottom are primarily sand-producing algae typical of low nutrient clean waters. They are replaced by non sand-producing weeds when water quality deteriorates. Photo: Stephanie Clark.
9. Squirrelfish resting between staghorn bushes. Note low abundance of algae on hard bottom and several young corals. Photo: Dan Clark.
10. Turtle resting on bottom after grazing algae. Photo: Dan Clark.
11. Growing worm reef off Dania Beach that would be buried by the proposed dredge-fill. The narrow parallel dark bands are the openings of the worm tubes. Larger irregular holes are the entrance of tubes of large clams that bore into the worm reef structure. Once worms stop cementing sand grains together into tubes forming the reef, erosion will quickly result in its breakdown. Photo: Dan Clark.
12. Many large dead coral heads off previously dredge-filled beaches. The left foreground on the front and second dead corals are being overgrown by golden-colored Palythoa caribbeorum, a rubber-mat-like encrusting organism that is not a reef builder. Remaining dead coral surfaces are covered with algal turf lawns that are intensively grazed by surgeonfish. A large reddish-purple alga is growing on the soft coral. Note the absence of young hard corals. Photo: Dan Clark.
13. Coral head several hundred years old being overgrown and killed by Palythoa caribbeorum. Note high levels of suspended particulate material in this area. Photo: Dan Clark.
14. Large coral head that is being attacked and killed by a boring sponge. The orange area below the hand is the sponge tissue, which is surrounded by a dead zone. Although the sponge now only occupies a small part of the coral, it will quickly excavate passages throughout the coral head to attack the coral tissue from underneath. In some areas many large corals have been killed by sponges or are under attack. The riddled-out coral skeleton eventually collapses in storm waves. The finger points to an unusual growth that has a much lighter color and much faster growth than the rest of the coral. Photo: Dan Clark.
15. Coral dying from disease, possibly white plague. Photo: Dan Clark.
16. Recently killed white patches on top of 10 foot diameter coral. These white patches were full of sediment that was fanned away by hand, showing recently dead coral tissue. The dead patch at right is older, and the surface has been blackened by toxic hydrogen sulfide gas generated in the mud from bacterial decomposition of coral tissue and detrital organic matter, which has etched the coral surface in layers. Had such events happened frequently in the past, the shape of the entire colony would have been very different. Photo: Dan Clark.
17. Top of large coral head being killed by Black Band disease. The greenish-brown area on the top has been overgrown by fuzzy algae, but the white ring has died too recently to have been overgrown, probably no more than days to a week before. Photo: Dan Clark.
18. Large coral head that is being attacked by Black band disease from four places. The white rims are very recently dead coral. The greenish-brown areas in the centers of the dead patches have been overgrown by filamentous algae. At top right is a large dead patch that is no longer active, which probably died last year, went dormant in the winter, and reactivated when the water warmed. Photo: Dan Clark.
19. Rapidly advancing Black Band disease. The white areas at top are exposed skeleton which has recently died, the brown area at the bottom is healthy tissue. The irregular purple-black band across the middle is the black band consortium of bacteria and cyanobacteria that is attacking coral tissue. Photo: Edrianna Stilwell.
20. Slowly advancing Black Band disease. In contrast with the previous photograph, the black band is much narrower, the white ring of dead coral skeleton is narrower, and there is clear overgrowth by greenish-brown algae. Photo: Edrianna Stilwell.
21. Staghorn coral with White Band disease. The narrow white ring between healthy tissue and dead algae overgrown skeleton in the very center of the photograph is the typical slow progression of the disease. All other dead areas have very broad recently dead areas that appear to be spreading rapidly. This is thought to be a different form of White Band disease. Photo: Dan Clark.
22. Staghorn bush with rapidly progressing type White Band disease. Some are dying from the bases, some from the tips, and some in the middle. Photo: Dan Clark.
23. White plague rapidly killing coral from the edge. Photo: Edrianna Stilwell.
24. Abnormally swollen tissue of ancient pillar coral that appears to be a disease. Photo: Dan Clark.
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Cry of the Water & Global Coral Reef Alliance: Reef protection in Broward County, FL