Lamouroux (Halimedaceae, Chlorophyta) from San Salvador Island, Bahamas: Species Composition, Distribution and Depth Records
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FAU Institutional Repository http://purl.fcla.edu/fau/fauir This paper was submitted by the faculty of FAU’s Harbor Branch Oceanographic Institute. Notice: ©1988 Springer‐Verlag. This manuscript is an author version with the final publication available at http://www.springerlink.com and may be cited as: Blair, S. M., & Norris, J. N. (1988). The deep‐water species of Halimeda Lamouroux (Halimedaceae, Chlorophyta) from San Salvador Island, Bahamas: species composition, distribution and depth records. Coral Reefs, 6(3‐4), 227‐236. doi:10.1007/BF00302019 Coral Reefs (1988) 6:227-236 Coral Reefs Springer-Verlag 1988 The deep-water species of Halimeda Lamouroux (Halimedaceae, Chlorophyta) from San Salvador Island, Bahamas: species composition, distribution and depth records Stephen M. Blair ~ and James N. Norris 2 Department of Marine Botany, Division of Marine Sciences, Harbor Branch Oceanographic Institution, 5600 Old Dixie Highway, Ft. Pierce, Florida 32946, USA 2 Department of Botany, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560, USA Accepted 26 August 1987 Abstract. Caribbean species of Halimeda from the steep In the Caribbean, with the exception of Howe (1920) slopes of San Salvador Island, Bahamas, were collected and Marshall (1980), little work has been done in Ba- along vertical transects between 25 and 255 m, on the hamian waters. Further, recent investigators have shown northeast, northwest, west, southwest and south sides of that a diverse and often unique, abundant deepwater the island, using the Harbor Branch Oceanographic In- flora exists in many regions of the western Atlantic (Che- stitution's submersible Johnson Sea Link L The charac- ney and Deyer 1974; Schneider 1974; Oliveira Filho 1976; teristics delineating species (segment and utricle size) Oliveira Filho and Qu6ge 1978; Sears and Cooper 1978; were assessed for selected species, and the depth and Eiseman 1979; Eiseman and Norris 1981; Eiseman and western Atlantic distributions of the species reviewed. Earle 1983; Littler et al. 1985, 1986). Halimeda copiosa was found to show a variation of sur- The general lack of information on the Bahamian ma- face utricle diameter with depth, with the deeper plants rine flora, specifically from deep water, prompted a col- having 15% larger diameter utricles than the shallower laborative research program between the Harbor Branch plants. Of the seven species, one variety and one form of Oceanographic Institution and the Smithsonian Institu- Halimeda studied from our submersible dive sites, H. co- tion to examine the species composition and distribution piosa, H.cryptica and H.gracilis grew to the greatest of the deep-water algae off San Salvador Island, Ba- depths, from 120 to 150-m depths. H. lacrimosa vat. glo- hamas. Some results of our first joint expedition have bosa was found growing to 91 m, and H. tuna f.platydisea been reported elsewhere (Littler et al. 1985; Jensen et al. and H. discoidea to a depth of 73 m. Those of lesser 1985; Littler et al. 1986). depth, to 61 m, were H.goreauii, H. tuna f. tuna and Halimeda is an often dominant, ecologically and geo- H. lacrimosa var. lacrimosa. These represent substantial logically important component of the subtropical and increases in depth distribution of the nine taxa found. tropical reef flora. There are 33 species in the genus (Hil- lis-Colinvaux 1980; Dong and Tseng 1980; Ballentine 1982, Noble 1986), with 14 species, 4 varieties and 8 forms reported in the subtropical-tropical western At- lantic (Wynne 1986). The present account describes our Introduction specimens, and gives the depth, regional distribution, and species composition of the deep-water representatives of The benthic marine flora of the Caribbean, in general, the genus Halimeda [Bryopsidales (=Caulerpales, see has received quite a bit of attention. Investigations by Silva 1982); Halimedaceae t] from San Salvador Island, Maz6 and Schramm (1878), Murray (1888, 1889), Bahamas. Borgesen (1913-1920) and Taylor (1942, 1960) estab- lished the bases for our knowledge of the species compo- sition and distribution of the marine algae of the region. More recent studies by, among others van den Hoek et al. (1978), Price and John (1979), Norris and Bucher (1982), Almodovar and Ballantine (1983), and numerous reports 1 Silva (1980; see also Nicolson 1981) has recently proposed the name by Taylor (e.g. 1969; Taylor and Abbott 1973) have con- Codiaceae Kiitzing (1843) for conservation over Halimediaceae Link tributed to the overall understanding of the Caribbean (1832); both names have nomenclatural priority over Udoteaceae marine flora. J. Agardh (1887) 228 Methods camera with strobe, Sony color video camera (3/4"), current meter, con- ductivity-temperature-depth meter, sonar, and ship to submersible com- Study site municator. Samples were collected at 15.2-m (50-ft) intervals along vertical San Salvador Island is located approximately 600 km ESE of Miami, transects at each sampling station, starting at the bottom of algal growth Florida (24002 ' N, 74~ ' W), along the eastern margin of the Bahama (usually above 250-m depth) and ending at the top of the wall structure. Island chain. San Salvador Island has patchy shallow-water fringe reefs Samples were preserved in 5% buffered Formalin/seawater and returned that extend 0.16 to 0.8 km out from the island. At the seaward edge of to the lab for identification. Specimens are deposited in the Algal Collec- the patch reefs, the bottom slopes nearly vertically, producing a wall tion of the U.S. National Herbarium (US) of the Smithsonian Institution structure with numerous ledges and undercuts, to a depth of 135 to and the Harbor Branch Oceanographic Institution Herbarium 165 m. Below this, the bottom slopes at a 30- to 60-degree angle to a (HBFH). depth of approximately 225 to 270 m. An indication of the steepness of the slope around the island is the fact that depths in excess of 1000 m can be found approximately 1.5 to 2 km off its coast. Morphometrics Five locations were selected for sampling, representing the various Two species were chosen for a detailed assessment of utricle size, each directional faces of the island (Fig. 1). The sampling sites were Dixon quantified for a different question. The utricle size and structure of Hali- Hill, on the northeast side (2408.3 ' N, 74o26.2 ' W; Station i), Green Cay, meda tuna f. tuna was examined to test if significant variation existed be-' on the northwest side (2408.5 ' N, 74~ W; Station 2), Cockburntown, tween the San Salvador Island samples, and those of Halimeda tuna on the west side (2403.2 , N, 74032.6 , W; Station 3), Fernandez Bay, on known from elsewhere in the Caribbean and in the Mediterranean. This the southwest side (2400.9 ' N, 74033.4 , W; Station 4) and French Bay, on evaluation was conducted owing to a lack of fit of utricle characteristics the south side (23056.7 , N, 74~ W; Station 5) of the island (Fig. 1). of the San Salvador Island specimens when compared to illustrations These samples were supplemented with incidental samples from the Pin- and descriptions given by Hillis-Colinvaux (1980). To determine if a nacle area, north of the island (24014.0 , N, 74028.9 ' W), and the North- variation existed, three specimens from San Salvador were arbitrarily se- east point (2408.4 ' W; 74026.3 , W). lected for utricle size determination. Three segments from each of these The collections were made with the submersible JOHNSON SEA plants were hand sectioned after decalcification in 10% HC1, and 50 sur- LINK-I. This four-person submersible is equipped with various instru- face utricles, haphazardly selected, were measured for length and width. mentation and pilot controlled equipment, such as a manipulator arm The length and width of supporting utricles were also measured. These with Petersen style grab sampler and a suction collection device, a rotat- measurements were compared with the published utricle size dimensions ing bin system for segregation of samples, a Benthos 35-ram color still of Hillis-Colinvaux (1980) for H. tuna. The utricle organization of the San Salvador specimens was compared with the utricle organization of specimens of H. tuna from the Mediterranean Sea (type locality for g~ H. tuna). /', The second species examined, Halimeda eopiosa, was selected to test if there were any significant differences between utricle sizes of the plants / \ with depth. To determine this, the length and width of 150 surface utricles were measured in each of three plants (50 utricles/segment; three segments/plant) from 76 m and in three plants collected between 122 to 132 m. The Kruskal-Wallis test was used to test if significant differences existed within each depth group (i.e., segment to segment and plant to plant variation) and between each of the two depth groups. 24' Off Results Our study revealed nine taxa, representing seven species of the genus Halimeda, in the San Salvador samples. The Halimeda species present in the deep-water flora and Table 1. Species present and depth range at the five sampling stations around San Salvador Island (depths in meters). DH=Dixon Hill, GC = Green Cry, CT = Cockburntown, FNB = Fernandez Bay, FRB = French Bay Species Stations 24 = 00' DH GC CT FNB FRB N H. copiosa 61-152 76-91 108-122 107-137 61-91 H. cryptica 61-152 76-91 70-107 61-152 107 H. discoidea 73 61 H. goreauii 29 61 H. gracilis 61-152 107 61-107 107 76-122 H. lacrimosa 61 var. laerimosa u H. lacrimosa 37-152 61-70 61 var. globosa ' ' 74"33 ' ' ' ' 74"27 'W H. tuna f. tuna 70-76 100 Fig. 1. Map of San Salvador Island, Bahamas, showing the sampling sta- H. tuna f. 61-70 tions around the island: 1 Dixon Hill, 2 Green Cay, 3 Cockburntown, platydisca 4 Fernandez Bay, 5 French Bay 229 their depth range at each sampling station are summa- rized in Table 1.