A Long-Term Interdisciplinary Study of the Florida Keys Seascape

BULLETIN OF MARINE SCIENCE. 54(3): 1059-1071. 1994

A LONG-TERM INTERDISCIPLINARY STUDY OF THE FLORIDA KEYS SEASCAPE

John C. Ogden, James W. Porter, Ned P. Smith, Alina M. Szmant, Walter C. Jaap and David Forcucci

ABSTRACT The SEAKEYS (Sustained Ecological Research Related to Management of the Florida Keys Seascape) program is a research framework which encompasses the large geographic scale and long time scale of natural marine processes and ecosystem variation upon which human impact is superimposed. The need for interdisciplinary long-term research in coastal ecosystems is critical as we anticipate extraordinary resource management obligations and scientific opportunities in the next decade. The core of the program is six instrumented, satellite-linked monitoring stations which span the 220 mile-long coral reef tract and Florida Bay and which, since 1991, have documented the potential impact of summer heating, winter cold fronts, storms, and distant floods. Meso-scale physical oceanographic studies have documented the net flow of water from Florida Bay to Hawk Channel which provides a potential mechanism to link water quality in Florida Bay with the waters of Sanctuary. Water column and sediment nutrient studies have shown elevated nutrient levels in nearshore waters de- creasing sharply to low levels near the offshore coral reef tract. There is a potential link of nearshore and offshore via a seaward deflection in the near-bottom flow. Regional nutrient dynamics are complicated by periodic upwelling driven by the Florida Current. A series of long-term photomosaic stations have tracked coral community dynamics for more than 5 years and have indicated a loss of over 40% in coral cover at some sites. This loss may be linked to declining water quality in Florida Bay. As a large marine ecosystem, the new Florida Keys National Marine Sanctuary and adjoining parks and reserves must be studied and managed holistically if human use of the region is to be sustained.

A major problem with marine ecosystem research related to resource management is the difficulty in discriminating natural variation in ecosystems from changes or declines caused by human impacts that may be managed, such as waste disposal, human visitation, boat groundings, and over-fishing. As natural processes vary on a time scale different from research funding cycles, only rarely have studies encompassed the time course of: (1) natural phenomena such as population explosions and declines, diseases, storms, and periodic oceanographic- atmospheric events such as the ENSO; or (2) natural processes, such as produc- tivity, larval dispersal, recruitment, global warming trends, and sea level rise. We now have enough experience to know that long-term data sets are essential to the understanding of the functioning of marine ecosystems and fundamental to their management (D'Elia et aI., 1991; Franklin, 1989; Ludwig et aI., 1993; Primack, 1992). A second problem is that management-oriented marine ecosystem research is too often confined to single sites which may be the best-developed or the easiest to get to, but which are not representative of the range of development of the ecosystems being studied. Sites should be selected over the full range of development of the ecosystem and research should be of sufficient length to encompass the natural variation of those systems (Duarte et aI., 1992; Kenchington, 1990; Ogden, 1987). Declines in environmental quality, while imperceptible on a day-to-day basis, are dramatic on a decade scale and involve large geographic regions. To document and understand these changes, we must integrate research across the appropriate

1059 1060 BULLETIN OF MARINE SCIENCE, VOL. 54, NO.3, 1994

81' BISCAYNE

FLORIDA KEYS NATIONAL MARINE SANCTUARY

25' FT. JEFFERSON • ~ - • ~ / NAT'L. MONIJMENT ..-- .:::::::. ~- - - \ "" ~ /' ;...- ---..••• ------, • ~ - I ' /' ./ • ------.J • ••• /' ,,// .. ; J--=-~.. ~- •...... /' KEYLARGONAT'L. I I DRY TORTUGAS I '~. .)"" MARINE SANCTUARY It"'il .1" ",,--". J- I.J --:::"-1'-ro''-:: -- / " ~ _ _ - - - - - LOOE KEY NAT'L. KEY WEST NAT'L. MARINE SANCTUARY _____ • WILDLIFE REFUGE

Figure I. The South Florida seascape including the Florida Keys National Marine Sanctuary (FKNMS), Everglade:; National Park (including Florida Bay), Biscayne National Park, and other parks, sanctuaries and refuges encompassed by FKNMS, Black dots mark locations of automated monitoring stations (north to south): Fowey Rocks (Biscayne National Park); Molasses Reef; Florida Bay; Som- brero Reef; Sand Key; Dry Tortugas. Arrows indicate major patterns of water circulation discussed in the text. disciplines and direct this effort over the geographic and temporal scales of natural ocean processes upon which human impact, which we seek to manage, is superimposed. Florida Keys Seascape.-Southeast of the Florida Peninsula, stretching for 220 miles from Soldier Key to the Dry Tortugas, lies the only stretch of tropical coastline in the continental United States. The Florida Keys "seascape," a mosaic of interacting ecosystems including the coral reef tract, seagrass beds, mangrove forests, the expanse of Florida Bay, and the adjoining Everglades, is a unique national resource (Fig. 1). The region, now encompassed in the new Florida Keys National Marine Sanctuary, will be an increasingly significant element in tourism in Florida and is critical to regional economic sustainability. The coastal ecosystems (coral reefs, seagrasses, and mangroves) of south Flor- ida south of approximately 26°N latitude typify those of the Caribbean Sea, but they are at the edge of the zoogeographic northern boundary of the tropics. For example, coral reefs in Florida regularly experience winter temperatures well be- low those associated with vigorous coral reef development. Similarly, while thriv- ing coral reefs grew in the central keys 5,000 years ago, the formation of Florida Bay by steady sea level rise has created conditions on the central reef tract that no longer favor coral reef development. To the north and south where the reef tract is sheltered from the waters of Florida Bay by the keys, vigorous coral reef growth can be found (Lidz and Shinn, 1991; Shinn et aI., 1989). This recent geological history of the keys coral reefs and the pivotal influence of Florida Bay is instructive as we attempt to grapple with management of human impact in a context of dynamic, long-term environmental change. There is a clear scientific and public consensus that the Florida Keys seascape is suffering a precipitous decline in environmental health. Any research program addressing the decline must involve long-term integrated, interdisciplinary studies OGDEN ET AL.: LONG-TERM STUDY OF THE KEYS SEASCAPE 1061 of the seascape, particularly the interplay between the land and the sea (Boesch et aI., 1993). Upstream, decades of water management have severely affected the quality, quantity, timing, and distribution of freshwater flow from the Everglades into Florida Bay (Bancroft, 1993; McIvor et aI., 1994; Van Lent et aI., 1993). Periodically, the salinity of the bay increases in the late summer to as high as 70%0, and has been implicated in fish kills (McIvor et aI., 1994). In 1987, the seagrass Thalassia began to die in central Florida Bay and the die-back continues (Robblee et aI., 1991; J. C. Zieman, pers. comm.). Blooms of microscopic algae have increased in frequency and intensity. The human population of the keys has had an increasing impact on nearshore water quality and Lapointe et aI. (1990) and Lapointe and Clark (1992) have speculated that nutrient-rich water may pen- etrate as far offshore as the coral reef tract. The reef tract has suffered dramatic and unexplained decrease in live coral coverage at certain sites in the last 10 years (Porter and Meier, 1992; Porter et aI., in press a, in press b). The reasons for this decline are speculative, but de- pending upon the geographic position of the reef there are likely numerous factors involved including nutrients, direct human impact (fishing, diving, collecting), and the accelerating decline of water quality in Florida Bay through water management (Porter et aI., in press c).

A FRAMEWORK FOR REGIONAL RESEARCH The SEAKEYS (Sustained Ecological Research Related to Management of the Florida Keys Seascape) program grew out of a consensus developed at a meeting of regional scientists and resource managers (Miller, 1988). The consensus was achieved by addressing the question: "What are the critical data that we must have about this region over the next 10 years to take advantage of scient!fic opportunities and to serve resource management obligations?" It was agreed that a framework for research should be established that encompassed the geographic and time scales of the natural processes, often disturbed by human impact, that influence the keys region. The elements of the research framework were: (1) detailed knowledge of the distribution of habitats in the region; (2) understanding of the hydrodynamics; and, (3) automated environmental monitoring. As a major concern was the potential impact of nutrients from human impact on the coral reef tract, two additional elements were nutrient dynamics and coral community dynamics at a series of sites encompassing the coral reef tract. Phase I of the SEAKEYS program ran from 1989 to 1991 and Phase II will run through 1994. As the geographic scale of the program anticipated the 2,500 sq. mi. Florida Keys National Marine Sanctuary (FKNMS), established in 1990, the SEAKEYS research framework will be incorporated in the FKNMS management plan now being developed by NOAA and EPA with the cooperation of the Florida Department of Environmental Protection (FDEP), and other agencies and institutions.

Automated Environmental Monitoring.- The core of the SEAKEYS program is six automated, solar-powered, satellite-linked monitoring stations. Under a cooperative agreement with the NOAA National Data Buoy Center (NDBC) and in consultation with local scientists, the standard NOAA Coastal Marine Automated Network (C-MAN) weather station was enhanced to measure oceanographic parameters in addition to the standard meteorological parameters of air temperature, wind speed (peak gust) and direction, barometric pressure, and light. The under- water sensors, including temperature (l m and 3 m), salinity, and light (1 m and 1062 BULLETIN OF MARINE SCIENCE, VOL. 54, NO. 3, IV~4

3 m), are housed in protective machined stainless steel pods, Open channels per- mit the expansion of the system for other sensors. During 1991-1992 instalIation of enhanced C-MAN stations was completed at Fowey Rocks (Biscayne National Park), Molasses Reef (off Key Largo), Som- brero Key (off Marathon), Sand Key (near Key West), Dry Tortugas, and Florida Bay (north of Long Key; Fig. I). In the first four installations the monitoring equipment is attached to the historic lighthouse structures with special stainless steel brackets. At the Dry Tortugas and Florida Bay special pilings designed to hold the equipment were placed with the cooperation of the U.S. Coast Guard. The subsurface sensors require weekly maintenance as they are quickly fouled with algae which causes drift in the light and salinity measurements. The enhanced C-MAN stations deliver a large amount of data which should be archived in a way which allows easy access to the information. Data are presently validated and archived by NDBC and are eventualIy deposited in the National Oceanographic Data Center (NODC) along with similar monitoring records from NOAA weather stations and buoys country-wide. During periods of interest such as during a hurricane or a winter cold front, data may be directly accessed via telephone line from WalIops Island, Virginia where it is received from the GOES satelIite. These data are analyzed, distributed, and archived at the Keys Marine Laboratory in Long Key. In cooperation with the Atlantic Oceanographic and Meterological Laboratory (AOML), Ocean Chemistry Division, data are made available via e-mail and CoralFax, a daily data summary available on request. Eventually, it is expected that data will be available in real time in a GIS-based format. REGIONALMONITORING:PRELIMINARYPATTERNS.Figures 2 and 3 show patterns of wind direction, wind speed, and seawater temperature (at 1 m depth) from two periods in the winter and summer of 1993. Figure 2 shows at four stations a complex pattern of lowered seawater temperature associated with elevated wind speeds out of the north, a typical winter condition. Severe winter cold fronts have caused mortalities of marine organisms. For example, a 1977 cold front killed most of the reef corals in the Dry Tortugas (Porter et aI., 1982; Roberts et aI., 1982). Figure 3 shows data from July and August 1993 from all six stations. Coin- cident with light and variable winds (and hence little wind-driven water circulation), seawater temperatures rose to over 31°C. This temperature is generally acknowledged to stress stony corals and has been associated with bleaching (Glynn and D'Croz, 1990; Brown and Ogden, 1993). Note how elevated wind speeds and improved water circulation return temperatures to the "normal" range for the season. The station at Fowey Rocks recorded the only reliable over water wind gust of 167 mph for Hurricane Andrew before it failed on the morning of 24 August 1992. The comparative records of the stations at Fowey Rocks (ground zero), Molasses Reef (64 km south of storm track), Sombrero Reef (102 km south of storm track), and Sand Key (126 km south of storm track) show the concentrated nature of the storm (Fig. 4; Ogden, 1992). During the summer of 1993, record floods occurred in the upper Mississippi River, eventually resulting in depressed salinity in the Loop Current in the Gulf of Mexico and hence the Florida Current. Abrupt drops in salinity began on the keys reef tract at Molasses Reef on 2 September and subsequently spread in a complex pattern to all six monitoring stations (Fig. 5). Low salinity water was also recorded offshore of the keys and as far north as Cape Lookout, North Carolina (T. Lee, 1994a; L. Atkinson, pers. comm.). OGDEN ET AL.: LONG-TERM STUDY OF THE KEYS SEASCAPE 1063

SEAKEYS PROGRAM WINTER COLD FRONTS

25 24 20 15 23 10 22 5 21 f 25 24 S 220 23 ~15 e ...... 10 22 ~ 'tI 5 21 ~ E ~ l25 24 •.. ~ 20 ~ 'tI 15 23 ~ .,..= 10 22 ~ 5 e 21 ~ 25 N.W 24 20 15 ~_~~S~~~~,~~s~4~~~_:?~~'?:E-,~23 10 '.'- "E SGndKq '. .- 22 ...... ~ :@.w . 5 21 1 7 14 21 28 January

Figure' 2. Wind direction and speed (dotted line) and seawater temperature data (depth 1 m, solid line) from four stations during January 1993. Increases in wind speed and shifts in wind direction to the NE to NW coincide with sharp drops in seawater temperature.

In addition to the fixed automated stations, program staff based at the Keys Marine Laboratory in Long Key have done additional monitoring during periods of interest. For example, the periodic movement of "green water" from Florida Bay offshore had long been observed (Smith, 1994). Warm, salty water could also be found at depth of 20 m on the reef tract 5 miles offshore of the major passes through the keys at Long Key Channel and Channel 5 (Ogden, pers. obs.). Geologists had speculated on the importance of the connection between Florida Bay and Holocene coral reef development (Shinn et aI., 1989) but the issue gained prominence in 1992 when the decline of water quality in Florida Bay attracted wide attention. Weekly CTD runs from a small boat documented the presence of high temperature, high salinity water inimical to coral growth near the reef tract. 1064 BULLETIN OF MARINE SCIENCE, VOL. 54, NO.3, 1994

S.EAKEYS PROGRAM, SUMMER 1993 Doily meanfrom hourly readings

FoweyRocks 20 ...... , ·········..·············..·.t ·······..············,···· . 31 15 ······························s ·············f···· :.... £.\:~...... i E;~ ~. :: sw SE ':. .:. S, . 30 10 J.:~g~..:: 5 :~~E...::.:~: :.:::::..~.:.~::~~~~::~~~:::::::::.:.:~.::..:..~{::'~: 29

20 31 15 10 30 5 29 e 33 i: ~ 20 32 ~ ~ 15 31 ~ "-'10 ~ 5 30 ~ ~ ~ 29 ~ 31 r.. ~ 20 ! ~ 15 ....= 10 30 ~ ~ 5 ~ 29 ~

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Dry Tortuga.s 20 ...... :::..:::::::::::'.i.~~~f.:::::::::::"::::::'::::::.::.:::" 31 15 .EEf; J 5,E" . 10 30 5 ~l ..:::.....::'.:·~~~~~~l~::::::':~~~::::::::::::::~....·.~~;;';WJ;~~~~i~il:::29 July August

Figure 3. Wind dir,'ction and speed (dotted line) and seawater temperature data (depth I m, solid line) from all six stations in July and August 1993. Periods of light S to SE winds coincide with sharply elevated seawater temperatures which may stress reef corals.

Porter et aI. (in press c) speculate that this phenomenon is in part responsible for the continuing decline of reef corals at some sites on the reef tract. Physical Oceanography.-Meso-scale physical oceanographic studies are central to an understanding of the potential routes of pollutants thorough the keys and to OGDEN ET AL.: LONG·TERM STUDY OF THE KEYS SEASCAPE 1065

SEAKEYS PROGRAM HURRICANE ANDREW Hourly readings 150 ...... ········ ..N············································ . Fowey Roc1cs 1020 70 ..N 60 ...... ···.N················································· . 1000 50 ...... : : . 40 ...... 4>l ..~ ...... •...... 30 980 20 :::::::::::::::::::~~~:.:~::~:.:N...~.:.:~::::::::::::::::..:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: 10 ~~IU~~¢ . 960 150 Molasses Reef 1020 70 ~ 60 .....1000 S ~ 50 ...... :y/....:..~...... ~ " 40 E 30 "- 20 =~~~;~,;;;~~~:0~S:~~;~~~980 i ~ 10 ~ ...... 960 ~ &150 Sombrero Key 1020 ~ 70 e Q ] 60 .... 50 :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::.::::::::::::::::::.1000 e ~ 40 ~ ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::~~;::::~j~~~:~:~::~:~::::::::::::::::::::::::::.:::::::::980 30 . 'rtW "OE .s~e>-ESE ..····It· ,..,.".,." ,.,., ,." '.:*'/Il'N..""., .." ,., "., """" ,····~ISt:', -S~~-£ 20 N-E' "E;..£; ~E"f; .to/'N·N 10 ····· ..·········,E:········"K··N'llI·············· ..····· ,.., , , ,.." 960 150 Sand Key 1020 70 - - -- 60 1000 50 40 30 980 20 10 960

August 23 I August 24

Figure 4. Wind speed (dolled line) and direction and barometric pressure (solid line) from Hurricane Andrew, 23-24 August 1992, at Fowey Rocks (ground zero), Molasses Reef (64 km south of storm track), Sombrero Reef (102 km south of storm track), and Sand Key (126 km south of storm track).

the eventual management of human activities. Physical oceanographic studies of the SEAKEYS program have two principal goals: (1) the definition of the major patterns of circulation for the whole region of the Florida Keys; and (2) deter- mination of water movement through the major channels potentially linking Flor- 1066 BULLETIN OF MARINE SCIENCE, VOL. 54. NO.3, 1994

SEAKEYS PROGRAM SALINITY DROP

SUMMER 1993 Hourly readings POWEr ROCKS, MIAMI 38 38 36 36 34 34 32 32 30 MOlASSES REEF, KEY lARGO 30 38 38 36 36 34 34 32 32 30 ~.····••••••••••·.:~·":~••~~-'~~~~'T••••••~.··.~~30 ~ FLORIDA BAY. LONG KEY .. . 38 38 36 36 ~34 34 ....•32 ...... i}j;~~.·~ 32 •••...... ·••·••••'~2 ~5' 30 .$ ...... SOMBRERO REY. MARATHON . 30 tS 38 38 -CI.l 36 36 34 34 32 32 30 30 SAND REY. KEY WEST 38 38 36 36 34 ••••••••••••••••••~~ ••••••·1•••~ ~~~ ••~.;~ ••••=•.•.;!~.~~.~•••~•••~34 32 32 30 DRY TORTUGAS 30 38 .."' . 38 36 36 34 f::::::: ~:~~:~~:~~~ \,:I::::;i: 34 32 ~:~:::~>:~~::~~~:~~~~:~:7:~~::::~::.::::.:::t~~::::::~ ~~: .. 32 30 L f,.. 30 8 15 22 29 5 12 19 26 3 10 17 24 A.UGUST SEPTEMBER OCTOBER

Figure 5. Salinity data (%0) from all six monitoring sites showing a complex pattern of penetration over the reef tract of low salinity water originating in the Mississippi River flood of July-August 1993 and the Gulf of Mexico. ida Bay with the human populations in the keys and the coral reef tract (Pitts, 1994; Smith, 1994). REGIONALCIRCULATIONPATTERNS.Figure 1 summarizes the regional circulation patterns in the FloJida Keys. In addition to the Florida Current flowing to the NE, the figure shows the counter circulation to the SW in Hawk Channel inside of OGDEN ET AL.: LONG-TERM STUDY OF THE KEYS SEASCAPE 1067 the coral reef tract. The net flow from the Gulf of Mexico and Florida Bay to Hawk Channel through the major passes through the keys are shown at Long Key, Bahia Honda Channel, and Big Pine Key. Although there is significant flood and ebb through the channel, the ebbs (water leaving the Gulf and entering Hawk Channel) are consistently stronger than the floods, resulting in a net flow into Hawk Channel. Circulation in the Lower Keys near Key West has not yet been studied in detail. Note also the water movement into western Florida Bay from the Shark River region west of Cape Sable (Pitts, 1994; Smith, 1994). The other major circulation features of the region include the Loop Current in the Gulf of Mexico, the Pourtales Gyre off of Key West and other gyres in the region of the Upper Keys which are seasonally spun off the Florida Current. Periodically, upwelling driven by the Florida Current occurs throughout the region (Lee et aI., 1992, 1994b).

Inshore-Offshore Nutrient Dynamics Along the Florida Reef Tract.-The nutrient studies conducted in the SEAKEYS program have the objective of documenting inshore to offshore differences in nutrient concentrations and fluxes. A series of eight transects from nearshore natural passes or man-made canals to offshore of the outer reef tract were established from the southern end of Biscayne Bay through the middle Florida Keys. Four of the transects were in the heavily developed Key Largo area, which has the best present-day reef development, and two were off Long Key, an area with minimal Holocene reef growth (Forrester and Szmant, in press). Two types of samples were collected: water column and sediments, with the latter representing longer-term nutrient dynamics of each station. Water column nutrients (ammonium, nitrate, phosphate, total N and total P) and chlorophyll were measured at five or more stations along each transect. Sediment cores were collected at approximately the same stations; profiles of pore-water inorganic nutrient concentrations and total Nand P content of down-core sediment samples were measured for each core. The results show two different patterns of nutrient distribution: from Biscayne National Park through Key Largo, and again in the Ohio Key to Looe Key areas, there were areas of elevated N, P and ChIa concentrations insho.-e,especially near marinas and canals, but N and Chla concentrations returned to oligotrophic levels within circa 0.5 km or less of shore (e.g., ChIa < 0.25 IJ.g·litec'). P concentrations, on the other hand, were often higher offshore. Sediment Nand P contents were low and comparable to those of pristine reef areas in the Bahamas, St. Croix and Bermuda. Pore-water and solid-phase N were higher nearshore and decreased toward the offshore, while P concentrations either varied little along the transects or exhibited the reverse pattern. The pore-water and total sediment N:P ratios were consistently higher (20 to 40) nearshore to low (1 to 10) offshore, indicating that N may be limiting to algal production offshore. These patterns suggest upwelling associated with passage of Florida Current eddies may be a source of P to the outer reef areas. The generally low nutrient (and organic) content of the sediments suggest that either the supply of detrital material to reef tract sediment is low, or that mineralization rates are very high. The second pattern was found in the "middle keys" Long Key area, where two large passes (Long Key Viaduct and Channel Five) allow higher-nutrient Florida Bay water to exit to the Florida Reef Tract. Both water column nutrients and Chla concentrations were circa twice as high as those in the areas north and west of there. The inshore-offshore pattern of sediment nutrient concentrations was similar to that described above except that sediment P content of samples 1068 BULLETIN OF MARINE SCIENCE, VOL. 54, NO.3, 1994 from the Florida Bay side of Long Key and nearshore areas was similar to that of the offshore samples, The middle keys are largely devoid of patch reefs and all the offshore reefs are drowned circa 5 m or more in depth. The higher sediment and nutrient efflux from Florida Bay through the wide passes in this area is likely the cause of the lack of Holocene reef growth in this part of the Florida Keys. Overall, the present data do not support the contention that reef areas in the BNp, Key Largo and Looe Key areas are receiving elevated loads of land-derived nutrients via surface water flow, but does document moderately elevated nutrient and ChIa levels in most developed nearshore areas. Most of the anthropogenically introduced nutrients entering the coastal waters appear to be taken up by nearshore algal and seagrass communities before they reach patch reef areas. Smith (1994) and Pitts (1994) report a seaward deflection in the near-bottom flow in Hawk Channel which may represent a mechanism to move nearshore water offshore. Further work needs to be done to determine whether nutrient-enriched ground- water flow may be reaching the reefs. The consistently low sediment nutrient content, however, suggests that at the present time, nutrient impact to Florida coral reefs is either minimal or highly localized.

Coral Community Dynamics.-Six coral reef locations between Miami and Key West were marked with stainless steel stakes and rephotographed periodically between 1984 and 1991. The monitored areas included two photostations in the Looe Key National Marine Sanctuary, two in the Key Largo National Marine Sanctuary, and two photostations in the Biscayne National Park. Stations were monitored for species number, percent cover, and species diversity of the scleractinian and hydrozoan stony corals. Monitoring began in 1984 for photostations in the National Marine Sanctuaries and in 1989 for stations in the National Park (Porter and Meier, 1992; Porter et aI., in press a, in press b). All six survey areas lost between one and four species; these losses constituted between 13% and 29% of their species richness. Five of the six areas lost coral cover. Based upon photographs taken repeatedly at these locations, net losses ranged between 7.3% and 43.9%. In the one station showing an increase in coral cover, the increase was only for the canopy branches of Acropora palmata; un- derstory branches of the same species lost surface area at the same rate as canopy branches gained area. For most of the common species, there was a reduction in the total number of living colonies in the community, and a reduction in the number of large, mature colonies. Throughout the study period, there was no recruitment to any of the photostations by any of the massive frame building coral species. Sources of mortality identifiable in the photographs include black band disease and bleaching. Porter et aI. (in press c) speculate that a major potential cause of coral decline is the occasional penetration of warm, hypersaline water originating in Florida Bay over the reef tract. Other potential sources of mortality include direct and indirect human impact. The rate of loss reported in these sample quad- rats, if representative of the region, cannot be sustained and unless mitigated, will change the nature of the communities of the Florida reef tract. In contrast, long-term coral monitoring stations established in 1989 by the Flor- ida Marine Research Institute at Bird Key Reef, Loggerhead Key, Pulaski Shoal, Texas Rock, and White Shoal, at Ft. Jefferson National Monument, Dry Tortugas show that coral cover and species abundance and diversity and evenness are rel- atively stable over the 3 years of the investigation (Jaap et aI., in press). OGDEN ET AL.: LONG-TERM STUDY OF THE KEYS SEASCAPE 1069

DISCUSSION

In south Florida, the rapid development of regional environmental management policy has far outpaced the ability of science to provide results to justify complicated, politically controversial, and often expensive management activities. The irony is that the major scientific questions that are being asked related to sustainable use and management of our natural resources are the very ones that are scientifically the most difficult to answer. More and more scientists are recogniz- ing this fact and are approaching environmental problems of great complexity by proposing cooperative, interdisciplinary studies on large geographic and long time scales. Within the huge interlinked network of ecosystems of south Florida which are under varying levels of human exploitation, the Florida Keys National Marine Sanctuary (FKNMS) has focussed attention on the management of the region for sustainable use. To serve management needs research must be coordinated and there must be new systems to insure adequate data management and access. This does not mean that effective management must wait for future research results. In many cases cause and effect are known. For example, boat groundings, human visitation and over-fishing have an obvious impact on coral reefs (Bohnsack, 1990; Hawkins and Roberts, 1992; Talge, 1991; W. Jaap, pers. comm.). In other cases, however, assignment of cause is much more complex and requires scientific consensus and documentation to convince managers and lawmakers of the need for expensive and politically-sensitive management steps. Once implemented, the management effort must be integrated into a long-term research framework to gauge its success and to adjust the management program to achieve the desired result. There is a growing conviction that long-term research, over the time scale of natural variation in ecosystems and processes and the geographic scale of ecosystem development, will provide the best opportunity to discriminate and ulti- mately to manage human impact (Duarte et aI., 1992). The SEAKEYS Program, developed from a consensus of scientists and marine resource managers, provides an example of a framework for research coordination and integration which is necessary to achieve this goal. The results of the program to date have begun to serve more focussed research projects by providing long-term data against which contemporary phenomena may be compared and better understood. The program provides an example of an approach to long-term research that could be applied in other regions of Florida's coastal ocean, such as the West Florida Shelf, where similarly complex interdependencies of land and ocean must be understood in order to take advantage of future scientific opportunities and to serve our management obligations.

ACKNOWLEDGMENTS

The SEAKEYS program is supported by generous grants from the John D. and Catherine T. Mac- Arthur Foundation to the Florida Institute of Oceanography (FlO). We thank numerous colleagues for their contributions and the National Data Buoy Center, particularly Ray Canada for his enthusiastic support of regional automated environmental monitoring. The Florida Marine Research Institute (FMRI, Department of Environmental Protection) provided assistance in the construction of the monitoring stations. The Everglades National Park and Biscayne National Park have helped to maintain the stations at the Dry Tortugas and Fowey Rocks respectively. The staff of the Keys Marine Labo- ratory, jointly operated by FMRI and FlO, contributed in numerous ways to the logistics of this complex field program. Finally, we thank the staff of FlO who somehow always manage to make things work. 1070 BULLETIN OF MARINE SCIENCE. VOL. 54, NO.3. 1994

LITERATURE CITED

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DATEACCEPTED:January 20,1994.

ADDRESSES:(J.e.0.) Florida Institute of Oceanography, 830 First Street South. St. Petersburg, Flor- ida 33701; (J. W,P.) Department of Zoology, University of Georgia, Athens, Georgia 30602; (N.P.S.) Harbor Branch Oceanographic Institution, 5600 South Dixie Highway, Fort Pierce. Florida 34946; (A.M.S.) Rosenstiel School of Marine and Atmospheric Science. University of Miami, 4600 Ricken- backer Causeway. Miami. Florida 33149; (W.C.J.) Florida Marine Research Institute, 100 Eighth Avenue South. St. Petersburg. Florida 33701; (D.F.) Florida 1nstitute of Oceanography, Keys Marine Laboratory. P.O. Box 968. Layton. Long Key, Florida 33001.