THE SHALLOW-WATER SCLERACTINIA OF JAMAICA: REVISED LIST OF SPECIES AND THEIR VERTICAL DISTRIBUTION RANGE
T. F. GOREAU New York Zoological Society and University of the West Indies, Mona, Kingston, Jamaica
AND J. W. WELLS Department of Geological Sciences, Cornell University, Ithaca, New York
ABSTRACT Recent underwater studies carried out on the coral reefs off the north coast of Jamaica have turned up 62 species of shallow-water scleractinian corals; seven of these are undescribed and three were not previously re- ported from the Caribbean area. In Jamaica, rich and diverse reef-coral populations occur down to 70 meters, and some forms grow down to 100 meters. The species composition and observed vertical ranges of the Jamaican shallow-water coral fauna are summarized in tables.
INTRODUCTION The most recent published list of Jamaican shallow water corals (Goreau, 1959) included 36 hermatypic and 5 ahermatypic species, mostly col- lected from the shallow parts of the reef crest and buttress zone to a depth of about 10 meters (see also Zans, 1959). Up-to-date lists of scleractinian corals from other West Indian localities are those of Duarte Bello (1961) for Cuba with 37 species, Almy & Carrion-Torres (1963) for Puerto Rico with 34 species, Lewis (1960) for Barbados with 34 species, and Roos (1964) for Curacao with 29 species. The investigations of Lewis extended to about 10 meters, those of Roos to about 30 meters, while the other workers cited above based their reports on collections made in less than 10 meters, mostly on the inner lagoon side of reefs. In this paper are listed 62 species of shallow water Scleractinia, includ- ing 48 hermatypes and 14 ahermatypes. Seven of the species are new but their descriptions will be published elsewhere. The collection on which this account is based was made almost entirely on the large coral reefs off the north coast of Jamaica, between Oracabessa (Parish of S1. Mary) in the east and Mangrove Point (Parish of Trelawny) in the west; the most in- tensive studies were made on the reefs off Discovery Bay and Runaway Bay. Supplementary collections were obtained from San San Bay (Parish of Portland), the Port Royal Cays off the Palisadoes Spit near Kingston on the south coast, and in the area of Lucea, Green Island and Orange 1967] Goreau & Wells: Scleractinia of Jamaica 443
) -----,..
FIGURE 1. Map of Jamaica showing the location of reef sites referred to in the text. The dashed line gives the position of the 200 meter (lOa fm) con- tour. The direction of the prevailing trade winds is given by the flagged arrow on the upper right side of the map.
Bay (Parish of Hanover) at the western end of the Island. The location of these places is given on the map in Figure 1. At the time of writing, our information on the abundance and vertical distribution ranges of the scleractinian corals in Jamaica is most complete for the Discovery Bay-Runaway Bay area (see map in Figure 2) where very detailed surveys and collections were made on the seaward face of the reefs at depths from just below the surface to almost 100 meters, i.e., covering almost the entire vertical extent of the tropical reef biotope. All but one of the coral species recorded for Jamaica as a whole have so far been found there, and the present account will therefore be based mainly on observations made in that relatively restricted locality. It must be stressed, however, that extensive surveys carried out in other parts of Jamaica over more than 10 years have shown that the Discovery Bay reefs are representative for the island as a whole and that there are no important departures in species composition and distribution of the corals other than those to be expected from local differences of bottom morphology, sedi- mentation, and exposure to the prevailing trade wind seas.
DESCRIPTION OF THE LOCALITY The reefs bordering the north coast of Jamaica are of the fringing type, perched on the edge of a narrow offshore shelf that is generally less than 500 meters wide and too near the land for the existence of well-developed lagoonal environments. The shelf break is usually at the 25 to 30 meter level: at this point the bottom slope suddenly increases from about 5° and 444 Bulletin of Marine Science [17(2)
17' 25'W CARIBBEAN SEA
3.
FIGURE2. Map of the Discovery Bay-Runaway Bay area of the north coast of Jamaica. Inshore shoals and reefs are shown by the dashed line. The three heavy short bars marked by bold numerals give the position of the fathometer transects shown in Figure 3.
10° to more than 30°. At 55 to 70 meters there is a second major break where the slope steepens abruptly to between 60° and vertical. The reef crest, buttress, and fore-reef zones are all located above the first break, i.e., shallower than 30 meters. Between the first and second breaks, i.e., between 20 and 70 meters, is the fore-reef slope habitat, whereas the deep fore-reef slope environment lies below the second break. The broad con- figuration is often altered by superimposed features, of which the 5 and 20 meter platforms, and a steep drop-off between 30 and 40 meters are most prominent. Figure 3 shows several profiles of reefs in the Discovery Bay- Runaway Bay area as determined with a recording fathometer. Section 1 has an unusually foreshortened 15 meter platform whereas sections 2 and 3 are much more typical profiles. The morphology of the antecedent surface is one of the most important factors controlling biotic zonation as well as distribution and population density of reef corals. The most profuse coral growth generally occurs at the edges of steps where sediment drainage is most efficient, while the least growth occurs on level sites where sediments tend to accumulate. The truism that living reefs exaggerate the pre-existing bottom relief is no- where better illustrated than by the dense coral growth usually occurring near the edges of shelf breaks, resulting in a marked accentuation either through up-building to form sill reefs, or out-building to form buttress-like 1967] Goreau & Wells: Scleractinia ot Jamaica 445
SEA LEVEl------_
1. 2.
o 10 l'O 30 40 ~m,wl lLtJo<'II11\UI
FIGURE 3. Fathometer profiles of reefs in the Discovery Bay-Runaway Bay area. Locations of the traverses are shown in Figure 2. In all three sections, the living shallow water reefs are indicated by the jagged tracings above the 10 meter level. Major steps and inflections of the bottom gradient at the 15 meter, 25 to 30 meter, and 55 to 65 meter levels are largely due to submerged shorelines of Pleistocene and Holocene age. In these tracings, no echo return was registered from below about 55 meters due to the near vertical slope. In general the shallow reef and fore-reef environments extend to about 25 meters, the fore-reef slope lies between 30 and 70 meters, and the deep fore-reef slope, which is not shown on these profiles, extends to more than 100 meters. The rounded elevations at the base of section I are relic buttresses of a drowned coral reef of Holocene age. The imbricate multiple echoes shown on these tracings between 25 and 45 meters are reflections from large corals, chiefly Montastrea and Agaricia. promontories, or both. In Jamaica, all the living shallow-water reefs are recent structures probably less than 5,000 years old and unconformably superimposed upon a succession of older, submerged shorelines and drowned reefs that mark the various eustatic low stands of the Pleistocene and Holocene sea levels (Gareau, 1961; Curray, 1965; Gareau & Burke, 446 Bulletin of Marine Science [17(2) ~ U Z <: 0 ~Z ~ < ~ CI U Z z <: ~<>J d d ~ 00 §§§§§ Z ::J 0 u sa -gaEEE 1= u sa ::lEEEE ~ 0 00 .cooOo ~ (JU
r:: r:: r:: r:: oJ o o (')0 U Z S S E S oJ r:: a: S E E S a: o 00 00 :> u U E UU u ;.-. ;.-.;.-. u •... t'E •...•...
N •...... •V'l,.....,(N N 0 •...•0000000 00
a a r'l a oor'l N N N I NI I e-. I •...• I "'. I I r'l V') N \0 N •...•
00000 000 a •...•oooor- '<1"000'1 r-
•.. G'" ~:o~ .~ c '" " ~~ .~.!:: .•z S t; o o bO j:: .:::-..: « '0 '" u t:'" '" ~ oCo .~" til til '"•.. '"~ « ....l .?I ••.• U g S .~ 0 "';> .•..•••• "''0 ~~o •.. c 0 Co '"'" '" 'u ~•.. "'-Co'" fIl " * ,2 ;> =:'" 448 Bulletin of Marine Science [17(2)
>. .J:: u ~ 0.. c: w c c o U o o Z E § w E 8
V)O V)OOO '<1"V)00 NNN '<1"~- --I I I I I "', I I I I N<") Nt-N N<")OV)- + OOONO t-oo'<1"t-N
on 'E ~•• '0 IJ! .s" ~~,~ -.;'" ,,~';; ,; '- ~ F :S~ ...,til "''''"" Ei l:.e zo o .. 1= .t: ~~ ..: "g ~ ~ u 1:: •••• ii: o v u (jj Co '(;j'Ol en..: ~ e ~ ...J ~~I-) U ,_gee00 "> .•...•..•..••..• •..•'0'0 -Co 1::" 1::" 000 c CoCo "on •...•..."" '0 ~>. "Co --on on * 00. '" »"" •...•... p.,p.,"" 1967J Goreau & Wells: Scleractinia of Jamaica 449
~ u Z ~ ::: '" o '"::> u E u E o o U
M 00 I"-
00 0 o MI/) " .•z o 1= < u ~ '"< oJ U 450 Bulletin of Marine Science [17(2) 1966). There are some regional differences in the distribution of the submarine steps and terraces along the north coast of Jamaica. For ex- ample, near Oracabessa (see Figure 1 for location) we have found a well- developed drowned sill reef at about 80 meters; this is absent from the Dis- covery Bay area where visual observations show no change in gradient be- tween about 70 and 130 meters. In this region the deep fore-reef slope is an almost verical cliff face seamed with deep gullies and chutes through which sediments produced in shallower reef zones cascade into the depths (Goreau, 1964). Marked changes in the biota occur at the major in- flexions of the bottom gradient, thus the reef crest, fore-reef slope, and deep fore-reef slope each have characteristic species assemblages not found anywhere else. Some of the more important habitat-indicator forms are to be found among the Scleractinian corals. ACKNOWLEDGMENTS This work was supported by Office of Naval Research contract Nonr 2306(00) and National Science Foundation grants GB-350 and GB-3542 to the New York Zoological Society, and Office of Naval Research con- tract Nonr 4811(00) with the University of the West Indies. We also thank the Kaiser Bauxite Company and Major J. R. Abbey for their sup- port in providing facilities that made it possible to carry out a heavy and continuous diving programme in the Discovery Bay-Runaway Bay area from mid-1963 to the present. Finally we wish to express our indebted- ness to S. K. Ammann, D. A. Catt, R. and P. Chapman, H. G. Dixon, P. Droz, D. L. Fraser, N. I. Goreau, E. A. Graham, J. C. Lang, T. A. Smith, R. K. Trench, and R. L. Walker whose tireless assistance at various times underwater and above was essential to the success of the project. METHODS In shallow water, collecting to depths of about 8 meters was done mostly by skin diving, and SCUBA was used for working to greater depths. In general, the main collecting localities were chosen after preliminary diving and fathometer surveys, but two of the best sites were discovered fortui- tously. In addition to the corals, biotic surveys included collection of other important reef forms such as the calcareous algae, sponges, hydrocorals, Gorgonacea, Antipatharia, and Zoanthidea. Only the scleractinian corals will be dealt with in this report. Sediment samples were taken to provide information on infaunal groups such as Foraminifera, Brachiopoda, Bryozoa, the smaller bivalve and gastropod Mollusca, etc. Underwater photography was used extensively to record community structure and spe- cies composition in the various habitat zones of the reef biotope. The coral specimens upon which this account is based are available for study in the Physiology Department of the University of the West Indies 1967] Goreau & Wells: Scleractinia of Jamaica 451 and the Department of Geological Sciences of Cornell University. The main collection, including types, will eventually be deposited in the British Museum (Natural History) and duplicate collections with paratypes will go to the Institute of Jamaica, the U. S. National Museum, and the Pea- body Museum of Natural History, Yale University. OBSERVATIONS ON SPECIES DIVERSITY AND DISTRIBUTION OF JAMAICAN REEF CORALS The Jamaican shallow-water Scleractinia known to date are systemati- cally listed in Table 1. Species not previously reported from Jamaica are marked by an asterisk and ahermatypic forms are designated by a dagger. Names are emended where necessary but no synonymy is given in this paper. However, in those cases where well known species names in cur- rent use have been replaced, the former names are given in numbered foot- notes. Table I also summarizes the extreme and optimal depth ranges of Ja- maican shallow water corals, together with comments on their relative abundances. From this, it will be seen that a large proportion of the new species, and of the corals not previously recorded from the Island, are common to abundant. Several of the latter have not been reported from the West Indies before: these include Madracis pharensis, a cavernicolous form known from Brazil, the Adriatic and Ligurian seas and the Western Mediterranean; M. new species, from off S.B. Brazil and Synaraea, a sub- genus of Porites hitherto believed to be confined to the Indo-Pacific. CONCLUDING REMARKS It is widely believed that effective reef-coral growth dwindles to insig- nificance at depths greater than about 50 meters (Vaughan, 1919; Wells, 1957). However we have observed in Jamaica that very dense reef coral populations often occur down to 70 meters, with individual colonies reach- ing large sizes and covering large areas completely in the same manner as do the corals in the Acropora communities of the very shallow reef zones. Below 70 meters however, there is a reduction in coral population density, species diversity, and colony size. Nevertheless, individuals of Montastrea cavernosa, for example, may still grow to more than a meter across at depths as great as 80 meters, but such colonies are scattered and do not achieve the "closed" growth that is a necessary prerequisite for reef-frame- work building. We stress that our observations to date on deep reef coral communities were made almost entirely on the precipitous north face of the Jamaican island slope where the environment is heavily shaded. It is to be expected that in less steeply sloping and better illuminated habitats, rich and di- verse reef coral populations could occur deeper than 100 meters. If this 452 Bulletin of Marine Science [17(2) is so, then the figures for maximum depths of the corals given here may be on the conservative side. The number of shallow water corals now known from Jamaica alone exceeds by almost 50 per cent the number of species previously reported from any other single reef locality in the tropical western Atlantic. More- over, 61 of the 62 corals listed here occur in the same reefs which there- fore have a species diversity comparing favorably with that of many Indo- Pacific coral reefs. Could it be that the post-Pliocene impoverishment of the West Indian coral fauna is not as extensive as has been hitherto be- lieved? It remains an open question whether the species diversity de- scribed above is confined to Jamaica. Careful underwater exploration of other Western Atlantic reef localities will almost certainly bring to light equally rich and diverse coral communities, and additional shallow-water scleractinian species no doubt remain to be discovered in the area. SUMMARY Up to the present, only 41 shallow water corals had been reported for Jamaica but recent studies, especially in the Discovery Bay-Runaway Bay area on the north coast of the island, have turned up 62 species of scleractinian corals, including 48 hermatypes and 14 ahermatypes. Eight of these are undescribed forms and several others have not previously been found in the Caribbean area. Species composition and observed vertical distribution ranges of the Jamaican coral fauna are summarized in tables. The present study is based on observations and collections made by SCUBA-equipped divers at depths ranging from just below the surface to about 96 meters. The reefs on the north coast of Jamaica are perched on the edge of the narrow island shelf, the outer slope falling abruptly to great depths by a series of steep and rugged precipices. Rich and diverse coral communities exist on the fore-reef slope down to about 70 meters, and a more attenuated population extends to about 100 meters. Until the pres- ent, it was believed that 50 meters was the maximum depth reached by reef corals. Sixty-one of the 62 coral species known from the whole of Jamaica have been collected from a single reef near Discovery Bay. Thus the species diversity of these coral communities is comparable with some of the reefs of the tropical Indo-Pacific. SUMARIO ESCLERACTINIOS DE AGUAS SOMERAS EN JAMAICA: LISTA REVISADA DE LAS ESPECIES Y DE SU DISTRIBUCION VERTICAL Estudios submarinos recientes realizados en los arrecifes de coral cerca de la costa norte de Jamaica han evidenciado la presencia de 62 especies 1967] Goreau & Wells: Scleractinia of Jamaica 453 de corales escleractinios de aguas someras, siete de las cuales no estan des- critas y tres no habian sido reportadas previamente para el area del Caribe. En Jamaica, ric as y divers as poblaciones de arrecifes de coral crecen hasta los 70 metros y algunas formas crecen hasta cerca de los 100 metros. Se sumariza en tablas la composici6n de las especies y la distribuci6n vertical observada en la fauna coralina de aguas someras. LITERATURE CITED ALMY, C. C. AND D. CARRION-ToRRES 1963. Shallow-water stony corals of Puerto Rico. Carib. J. Sci., 3: 133- 162. CURRAY, J. R. 1965. Late Quaternary history, continental shelves of the United States. In: Wright, H. E. and D. G. Frey (Eds.), The Quaternary of the United States, pp. 723-735. Princeton University Press. DUARTE-BELLO, P. P. 1961. Corales de los Arrecifes Cubanos. Acuario Nacional, Ser. Educa- cional, Numero 2, 85 pp., 74 figs. Marianao, Cuba. GOREAU, T. F. 1959. The ecology of Jamaican coral reefs: I. Species composition and zonation. Ecology, 40: 67-90. 1961. The structure of Jamaican reef communities: Geological aspects. Final Progress Report to Biology Branch, Office of Naval Research under Contract Nonr (G)-0003-60. 14 pp. 1964. Fore-reef slope: structure, sediment and community relationships. Abstract. Geological Society of America, 1964 Annual Meetings, Miami Beach: Program, p. 76. GOREAU, T. F. AND K. BURKE 1966. Pleistocene and Holocene geology of the insular shelf near Kingston, Jamaica. J. Mar. Geo!., 4(3): 207-225. LEWIS, J. B. ]960. The coral reefs and coral communities of Barbados, W. I. Canadian J. Sci., 88: 1133-1145. Roos, P. J. 1964. The distribution of reef corals in Cura«ao. Studies Fauna Cura«ao, 20: 1-51. VAUGHAN, T. W. 1919. Corals and the formation of coral reefs. Smithsonian Inst. Ann. Re- port (1917), pp. 189-238,37 pIs. WELLS, J. W. 1956. Scleractinia. In: Moore, R. C. (Ed.), Treatise on Invertebrate Palae- ontology, Part F (Coelenterata): Geo!. Soc. Amer., University of Kansas Press, pp. 328-444. 1957. Annotated bibliography of ecology of corals. In: Treatise of marine ecology and paleocology: Geo!. Soc. America, Mem. 67, vol. 1, pp. 1087-1104, 1 fig. 1964. The recent solitary mussid sc\eractinian corals. Zoo!. Medd., 39: 375-384, pIs. 20-23. ZANS, V. A. 1959. Recent stony corals of Jamaica. Geonotes, 2: 43-48.