Conservation status of coral reef fishes in the Florida Keys.
This article identifies coral reef fishes that may deserve a high conservation priority in the Florida Keys. Expert observations between 1993 and 2004 from the REEF database (n = 5,783) identified 114 coral reef fishes that occur in the Florida Keys. Of these, four restricted-range coral reef fishes and a number of rare species based on incidence may deserve a high conservation priority in the Florida Keys. Large-bodied species with low abundance and small range size have been hypothesized to be associated with extinction-proneness, but there were few large-bodied species that meet these criteria in the Florida Keys. The Serranids, Mycteroperca venenosa and Mycteroperca interstitialis are exceptions. Most large coral reef fishes have high incidences and have large ranges that extend throughout the Western Atlantic.
Este articulo identifica los peces del arrecife de coral que merecen un alto nivel de prioridad en los esfuerzos de conservacion de los cayos de Florida. Con observaciones hechas por expertos entre los anos del 1993 hasta 2004 en la base de datos REEF (n=5,783) se identificaron 114 peces de arrecife de coral que se hallan en los cayos de la Florida. De estos, cuatro peces de arrecife de coral con extension limitada y un numero de especies raras, debido al nivel de incidencia, puede que merezcan una alta prioridad de conservaci6n en los cayos de la Florida. Se cree que especies grandes con poca abundancia y de poca extension tienen una mayor propensidad de extincion, pero hay pocas especies grandes que tengan estos requisitos en los cayos de la Florida. Los serranidos, Mycteroperca venenosa, y Mycteroperca interstitialis son excepciones. La mayoria de los peces de coral tienen una alta incidencia y grandes extensiones que se distribuyen por todo el Atlantico occidental.
Marine species are generally viewed as less prone to extinction than terrestrial species (Culotta 1994, McKinney 1998, Roberts & Hawkins 1999). This appears to be true for Florida Keys coral reef fish based on international-, national-, or state- level conservation priorities. On an international level, the International Union for the Conservation of Nature and Natural Resources (IUCN) has not identified any threatened or endangered species associated with coral reef in the Florida Keys (Hilton-Taylor 2000). Nationally, there are over 200 species of fish listed as endangered or threatened in the United States, but no species associated with coral reef are listed under the Endangered Species Act (NOAA 2001). At a state level, there are 22 fish species identified as endangered, threatened, or rare in Florida, but none of these fish species are associated with coral reef (Gilbert 1992). However, coral reefs in the Florida Keys have experienced a significant decline in coral cover from 1995 to 2000 and it may be that some coral reef fishes are currently threatened or endangered (Porter et al. 2002).
A number of biogeographic theories and natural history characteristics can be used to identify species that deserve a high priority for conservation (Gaston 1994, Angermeier 1995). Species with small or restricted-ranges have been identified as extinction prone and of particular conservation importance (Angermeier 1995, Brown 1995, Long et al. 1996, Gaston & Blackburn 2000). Restricted-range species that occur on coral reefs in the Florida Keys should receive a high priority for conservation at an international level (Hilton-Talyor 2000). At a national level, rare species have been identified as extinction prone and it may be the case that rare fish on coral reefs in the Florida Keys may deserve a high conservation priority (Gaston 1994). Furthermore, large bodied species with low abundance, and small geographic range have been shown to be associated with local extinction, and the same may be true for fish in coral reef ecosystems (Angermeier 1995, Gaston 1996, Roberts & Hawkins 1999, Rosenfield 2002).
In an attempt to assess whether certain species may deserve a high conservation priority within the United States, we undertake a conservation assessment to identify coral reef fish with restricted-ranges, rare coral reef fish, and coral reef fish with natural history characteristics associated with extinction prone species.
This study analyzes data collected on coral reefs in the Florida Keys, which is the only shallow water coral reef tract on the continental shelf of North America (Jaap & Hallock 1990). The Florida reef tract is the most extensive living coral reef system in North American waters and the third largest system in the world. Coral reefs in the Florida Keys form an archipelago that runs southwest from Biscayne Bay to Dry Tortugas (Figure 1). These coral reefs are composed of bank or barrier reefs with spur and groove formations located 7 to 13 km offshore of the Florida Keys and patch reefs located between the Florida Keys and bank reefs. The Florida reef tract contains over fifty species of corals comprising over eighty percent of all the coral reef species in the Tropical Western Atlantic and over two hundred species of fish.
[FIGURE 1 OMITTED]
Data on fish diversity from coral reefs sites were collected between 1993 and 2004 by the Reef Environmental Education Foundation (REEF) volunteer surveys using the roving diver technique (Schmitt & Sullivan 1996). The roving diver technique entails a diver swimming freely throughout a coral reef site (500 [m.sup.2]) for at least 30 minutes and recording every fish species the diver can positively identify. Between January 1, 1993 and December 10, 2004, expert REEF observers completed a total of 5,783 surveys using the roving diver technique, at 292 coral reef sites, for a total bottom time of 13,623 hours. All native fish recorded by "Experts" according to REEF criteria in the Florida Keys from 1993 to 2004 were included with "Novice" data excluded.
Natural History Characteristics
Natural history data on habitat preference, body size, range size, incidence, and sighting frequency were compiled for all fish species identified in the REEF database (REEF 2004). All fish were classified as species that use coral reef as their primary habitat (herein called coral reef fishes) or species that use other habitats (i.e., seagrass beds, sandy substrates, pelagic) as their primary habitat. Classifications of these coral reef fishes came from habitat descriptions in Lieske & Myers (1997), Humann & Deloach (2002) and FishBase (2002). Only fish that use coral reefs as their primary habitat were used in this analysis. The total incidence of each species recorded by an expert observer within the Florid a Keys between 1993 and 2004 (n = 5,783) was used as a measure of species incidence. Body sizes were collected for all species based on mean species length (Humann & Deloach 2002). Range size was quantified by incidence in nine biogeographic regions in the Western Atlantic following REEF classification: 1. Florida, 2. Bermuda, 3. East Coast of the United States, 4. Gulf of Mexico, 5. Northwest Caribbean, 6. Bahamas, Turks, and Caicos, 7. Greater Antilles, Virgin Islands, 8. Lesser Antilles, 9. Continental South America. Data on species distribution in nine biogeographic regions are from the Tropical Western Atlantic distributional database (REEF 2004) and other sources (Lieske & Myers 1997, Humann & Deloach 2002). These expert observers also collected sighting frequency was also collected for coral reef fishes in the Florida Keys. Sighting frequency is a measure of how often a species is observed during a specified time period. It indicates the percentage of times out of all surveys that the species gets recorded (REEF 2004). For this research, we divided sighting frequency for this research into three time periods: January 1, 1993 to June 1997, July 1997-June 2001, and July 2001- December 10, 2004.
Our research undertakes three conservation assessments to identify coral reef fishes that may deserve a high conservation priority in the Florida Keys. First, we selected restricted-range species in order to identify ones that may deserve a high priority for conservation at an international level. Second, we ranked all coral reef fishes recorded from 1993 to 2004 by incidence to identify rare species in the Florida Keys. Third, we selected the first quartile of coral reef fishes with large body sizes and ranked them by incidence and range size to identify species that have natural history characteristics associated with extinction-prone species (Gaston 1994).
Using the roving dive technique, observers recorded 114 coral reef fishes in 25 families in the Florida Keys. Range size can be used to rank the coral reef fishes, in order to identify species in the Florida Keys that might be of global conservation importance. (Table 1). Few restricted-range species occur in the Florida Keys with most coral reef fishes occurring in six or more biogeographic regions and only four species occurring in five or fewer regions. Two species, Apogon pillionatus, and Labrisomus kalisherae appear to have restricted-ranges and have a low incidence in the Florida Keys and may be of particular conservation importance. The Gobiid Gobiosoma saucrum and the Labrisomid Hemiemblemaria simulus appear to have permanent populations in the Keys and relatively low incidence. There is minimal data to assess trends in the two species with the smallest range, but Gobiosoma saucrum and Hemiemblemaria simulus do not appear to be declining based on sighting frequency.
There were 21 coral reef fishes identified as rare based on the coral reef fishes with an incidence of 100 or less (Table 2). Five species were recorded only once or twice, and 11 species were recorded ten times or less. The list of rare species is primarily composed of species in the Goby (7 species), Cardinalfish (5 species) and Blenny (3 species) families. The sighting frequency for species recorded ten times or less is too low to make an assessment of the trends in species' populations. Most species with an incidence of 10 or more appear stable, with the exception of Apogon planifrons and Balistes vetula, which appear to be decreasing in sighting frequency within the Florida Keys.
The largest coral reef fishes based on body size were ranked by incidence and range size to identify species that have natural history characteristics associated with extinction prone species (Table 3). Most of these species are in the Parrotfish (5 species) and Grouper (4 species) families. Most large coral reef fishes have high incidences and have large ranges that extend throughout the Western Atlantic. Balistes vetula again appears to be the most endangered species on the list due to low incidence, relatively restricted range, and a decline in sighting frequency. Two species of Serranids, Mycteroperca venenosa and Mycteroperca interstitialis, have a low incidence, however, their sighting frequency suggests that their numbers have been increasing in the Florida Keys. For large coral reef fishes recorded less than 1,000 times, all appear to be relatively stable or increasing in number based on sighting frequency, with the possible exception of Balistes vetula and Cantherhines macrocerus, which appear to be declining. There are six species (Lactophrys bicaudalis, Lutjanus mahogoni, Aulostomus maculates, Scarus vetula, Halishoeres radiatus, and Pomacanthus arcuatus) with an incidence greater than 1,000 that appear to be declining based on sighting frequency. However, a majority of large coral reef fishes do not appear to have natural history characteristics associated with extinction prone species because of high incidence and large range sizes.
There are no endemic coral reef fishes in the Florida Keys and only four restricted-range species, which would support Callum et al. (2002) findings that coral reef tracts in the Florida Keys deserve a relatively low priority for conservation at a global spatial scale. Nonetheless, these restricted-range coral reef fishes should be closely monitored throughout the Florida Keys in the future. Apogon pillionatus is nocturnal and generally recorded on coral reefs below 20 m, which may be the reason that it has a low incidence based on REEF surveys (Humann & Deloach 2002). Labrisomus kalisherae is usually found among fire coral branches and usually found near continental coasts where it can be common (Humann & Deloach2002, Brice Semmens pers.com.). Both Gobiosoma saucrum and Hemiemblemaria simulus are range restricted and relatively rare but appear to have stable populations based on sighting frequency. Gobiosoma saucrum perches on boulder corals and Hemiemblemaria simulus resides in holes in the coral reef where it waits for small prey, however, more research is needed on their distribution and habitat preference to identify their regional conservation importance (Humann & Deloach 2002).
Our research identifies a number of species that should be considered for national- or state-level conservation priorities. In particular, detailed population data for the coral reef fishes from Table 2 are needed to identify species with permanent breeding populations in the Keys and not simply vagrants, misidentifications, or species that only appear rare because of the survey method. First, a number of species with an incidence of one or two may simply be vagrants that do not have permanent populations within the Florida Keys and should not be included on threatened or endangered species lists in the United States. Second, it may also be the case that some species with an incidence of one could be misidentifications given the fact that error is possible when over 100,000 fish were identified to species. This is especially true for Blennids (Starksia), Gobiids (Gobiosoma) and Serranids (Hyoplectrus), all of which can appear very similar. Third, there are a number of species such as Starksia hassi, Risor ruber, Priolepis hipoliti, and Labrisomus kalisherae that are very cryptic and difficult to identify in the field. Furthermore, Apogon pillionatus, Liopropoma carmabi, and Centropyge argi generally are most common in deep reefs and may appear rare in REEF surveys that are usually not undertaken deeper than 30 meters (Humann & Deloach 2002, REEF 2004). Finally, caution should be used when assessing the rarity of the five nocturnal Cardinalfish that may not have been seen during predominately diurnal surveys.
Official national- and state-level conservation priorities for terrestrial ecosystems have focused on identifying species that may have small population sizes, declining population trends, and species whose habitat has been fragmented or disappeared (Hoekstra et al. 2002). Our study identifies species that have small population sizes, however, population trends of these species appear relatively stable, with the exception of Apogon planifrons and Balistes vetula, which appear to be decreasing in sighting frequency throughout the Florida Keys. Detailed searches for these specific species would reveal whether or not they are as rare as our data suggests. Large-bodied species with low abundance and small range size have been hypothesized to be associated with extinction-prone species (Gaston 1994, Brown 1995). There were surprisingly few large-bodied species that meet these criteria in the coral reefs of the Florida Keys. The Serranids Mycteroperca venenosa and Mycteroperca interstitialis had the lowest incidence of all large-bodied species of coral reef fishes, and should be considered a species of concern within the United States and Florida. However, their numbers appear to be increasing based on sighting frequency. Most species have incidences of over 300 and this suggests that they may be relatively abundant throughout the Florida Keys.
In conclusion, coral reef species identified as restricted-range should be further researched to determine if their populations are declining. Further data is needed on rare species, particularly the easy to identify Balistes vetula, which appears to be declining in the Florida Keys. Most large bodied coral reef fishes appear to be stable in the Florida Keys but game fish like the Serranids need to be closely monitored, as do the species that have shown a generally declining trend, such as Cantherhines macrocerus, Lactophrys bicaudalis, Lutjanus mahogoni, Aulostomus maculates, Scarus vetula, Halishoeres radiatus, and Pomacanthus arcuatus. The REEF database can provide high-resolution data on the distribution and abundance of species in the Florida Keys and their database in Western Atlantic and other regions such as Pacific has been rapidly growing. Currently REEF has undertaken over 60,000 surveys in over 30 countries (REEF 2004). This will provide an excellent dataset for undertaking conservation research in other regions and larger spatial scales.
Table 1. Restricted-range coral reef fishes in the Florida Keys and total incidence from 1993 to 2004 and sighting frequency (SF%) for three time periods. Table courtesy of the author. Common Name Scientific Name Broadsaddle Cardinalfish Apogon pillionatus Downy Blenny Labrisomus kalisherae Leopard Goby Gobiosoma saucrum Wrasse Blenny Hemiemblemaria simulus Range SF% SF% SF% Common Name Incidence Size 93-97 97-01 01-04 Broadsaddle Cardinalfish 2 4 0.01 Downy Blenny 31 4 0.8 0.4 Leopard Goby 171 5 2 3.3 2.9 Wrasse Blenny 564 5 9.3 7.7 11.1 Table 2. Rare coral reef fishes based on incidence from coral reef sites in the Florida Keys and sighting frequency (SF%) for three time periods. Table courtesy of the author. Common Name Scientific Name Orangesided Goby Gobiosoma dilepsis Sharknose Goby Gobiosoma evelynae Yellowtail Hamlet Hypoplectrus chlorurus Broadsaddle Cardinalfish Apogon pillionatus Spotlight Goby Gobiosoma louisae Ringed Blenny Starksia hassi Yellowbelly Hamlet Hypoplectrus aberrans Yellowline Goby Gobiosoma horsti Diamond Blenny Malacoctenus boehlkei Candy Bass Liopropoma carmabi Roughlip Cardinalfish Apogon robinsi Sawcheek Cardinalfish Apogon quadrisquamatus Pale Cardinalfish Apogon planifrons Peppermint Goby Coryphopterus lipernes Downy Blenny Labrisomus kalisherae Tusked Goby Risor Tuber Cherubfish Centropyge argi Roughhead Triplefin Enneanectes boehlkei Rusty Goby Priolepis hipoliti Sponge Cardinalfish Phaeoptyx xenus Queen Triggerfish Balistes vetula SF % SF % SF % Common Name Incidence 93-97 97-01 01-04 Orangesided Goby 1 0.1 Sharknose Goby 1 0.1 Yellowtail Hamlet 2 0.1 Broadsaddle Cardinalfish 2 0.01 Spotlight Goby 2 0.1 0.05 Ringed Blenny 3 0.1 Yellowbelly Hamlet 3 0.05 0.1 Yellowline Goby 3 0.1 Diamond Blenny 4 2.2 Candy Bass 6 0.1 0.05 0.1 Roughlip Cardinalfish 7 0.2 Sawcheek Cardinalfish 13 0.8 0.2 Pale Cardinalfish 22 1.4 0.05 0.3 Peppermint Goby 27 0.9 0.2 0.4 Downy Blenny 31 0.8 0.4 Tusked Goby 35 0.9 0.5 Cherubfish 52 0.6 0.6 1 Roughhead Triplefin 67 1.4 1.2 Rusty Goby 93 0.8 0.5 2.3 Sponge Cardinalfish 95 0.1 0.6 1.9 Queen Triggerfish 98 1.6 4 0.4 Table 3. The first quartile of coral reef fishes by large body size with data on incidence, range size, and sighting frequency (SF%) for three time periods. Table courtesy of the author. Common Name Scientific Name Queen Triggerfish Balistes vetula Tiger Grouper Mycteroperca tigris Yellowfin Grouper Mycteroperca venenosa Whitespotted Filefish Cantherhines macrocerus Yellowmouth Grouper Mycteroperca interstitialis Goldentail Moray Gymnothorax miliaris Nassau Grouper Epinephelus striatus Dog Snapper Lutjanus jocu Spotted Trunkfish Lactophrys bicaudalis Rainbow Parrotfish Scarus guacamaia Blue Angelfish Holacanthus bermudensis Mahogany Snapper Lutjanus mahogoni Princess Parrotfish Scarus taeniopterus French Angelfish Pomacanthus paru Trumpetfish Aulostomus maculatus Redtail Parrotfish Sparisoma chrysopterum Queen Angelfish Holacanthus ciliaris Queen Parrotfish Scarus vetula Schoolmaster Lutjanus apodus Doctorfish Acanthurus chirurgus Puddingwife Halishoeres radiatus Gray Angelfish Pomacanthus arcuatus Spanish Hogfish Bodianus rufus Hogfish Lachnolaimus maximus Ocean Surgeonfish Acanthurus bahianus Stoplight Parrotfish Sparisoma viride SF % SF % SF % Common Name Incidence Range 94-97 97-01 01-04 Queen Triggerfish 98 7 1.6 4 0.4 Tiger Grouper 183 8 1.4 4 3 Yellowfin Grouper 241 8 0.8 3.9 5 Whitespotted Filefish 263 9 6.2 5.1 4.3 Yellowmouth Grouper 401 9 1.2 7.7 7.7 Goldentail Moray 510 8 9.9 9.8 8.2 Nassau Grouper 795 7 10.6 18.3 12.1 Dog Snapper 1026 9 12.7 17 19.4 Spotted Trunkfish 1069 8 27.9 21.6 15.3 Rainbow Parrotfish 1643 8 22.6 34.5 26.7 Blue Angelfish 1751 9 32.4 30.4 30.9 Mahogany Snapper 2457 8 54.3 51.7 36.5 Princess Parrotfish 2468 8 47.5 40.2 43.8 French Angelfish 2595 9 51.1 50.9 41.3 Trumpetfish 2652 8 68.3 53.1 38.7 Redtail Parrotfish 2821 8 35.2 57.2 47.7 Queen Angelfish 2946 9 51.2 52.6 50.9 Queen Parrotfish 3047 8 69.7 58.9 48 Schoolmaster 3401 8 64.6 71 52.3 Doctorfish 3442 9 58.3 63 59 Puddingwife 3701 9 72.5 75 57.6 Gray Angelfish 3720 9 77 70.6 59.8 Spanish Hogfish 4245 9 74.2 76.8 72.7 Hogfish 4333 9 64.1 80 75.6 Ocean Surgeonfish 4881 9 86 89.5 82.9 Stoplight Parrotfish 5057 8 87.2 93.9 85.6
The authors would like to thank all REEF volunteers. Brice X. Semmens provided invaluable comments on an earlier revision of this manuscript and James Van Tassell helped with natural history characteristics for Gobies. Jim Krolick, Jesse Johnson, and Po Fung aided in validation of natural history data. We thank Christine Farris for reviewing this manuscript and Chase Langford for help with graphics.
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Thomas W. Gillespie
Department of Geography
University of California Los Angeles
Los Angeles, CA 90095-1524
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|Author:||Gillespie, Thomas W.; Smith, Anais|
|Publication:||Endangered Species Update|
|Date:||Jan 1, 2005|
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