AQUARIUS HABITAT SITE AT CONCH REEF: POSSmILITIES FOR RESEARCH ON FORAMINIFERA WITH ALGAL SYMBIONTS

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1 AQUARIUS HABITAT SITE AT CONCH REEF: POSSmILITIES FOR RESEARCH ON FORAMINIFERA WITH ALGAL SYMBIONTS St. Petersbur~ Pamela Hallock Eljzabeth M CockCJI Helen K. Talge Department of Marine Science University of South Florida 140 Seventh Ave. S. FLORIDA U.S.A. Rubble bottom and proximity to reefal habitats makes the Florida Keys site selected by the NOAA-NURC/UNCW program for initial deployment of the AQUARIUS habitat an excellent location to collect and conduct experiments on reef-associated benthic foraminifera, particularly larger species that host algal symbionts. Symbiont-bearing species most abundant at the site are Amphistegina fibbosa and Asteriferina carinata, and Laevipeneroplis protea. Other common larger species are Cyclorbiculina compressa, Heterostefina antillarum, Laevipeneroplis brady;' Parasorites orbitolitoides, and Sorites orbiculus. Common attached species include Homotrema rubrum and Planorbulina mediterranensis. A diverse assemblage of smaller hyalline and porcellaneous species is also present, The abundance of rubble substratum facilitates non-destructive foraminiferal sampling by SCUBA or NITROX divers equipped with small brushes and plastic bags, Sediment, foraminifera, and other loosely attached benthos can be concentrated in collecting bags and rubble returned to the reef, Interest in use of foraminiferal-algal symbioses as surrogates for coral-algal symbioses may increose as coral populations continue to decline in the Florida Keys. Introduction Foraminifera are shelled marine protozoans (Class Sarcodina, Order Foraminiferida) whose study can have geological, environmental, and biological significance, As a result of their relatively small size and preservation potential, they are useful in comparing present and past environments, Studies of modern species, populations and assemblages can be used to interpret changes observed in the fossil record. In addition, studies of changes in foraminiferal faunas in sediment cores can be used to interpret the recent past, including environmental changes associated with anthropogenic influences in an area. Benthic foraminiferans are abundant and important members of coral-reef communities. Like corals, many foraminiferal species host algal endosymbionts upon which they are dependent for growth and calcification (e.g., Lee and Anderson, 1991). As a result, these foraminiferans are Significant primary (Sournia, 1976) and calcium carbonate producers (McKee et al., 1959; Hallock, 1981) in reef systems. Because foraminiferans with algal symbionts can be sensitive to many of the same environmental stresses that influence corals, e,g" heavy metal (Alve, 1991) and nutrient pollution (Hirshfield et al., 1968), thermal stress (Hallock and Larsen, 1979), and increases in ultraviolet radiation (Hallock et ai" 1992), these protists may be useful surrogates for corals in studies of human impacts on reef systems. Foraminiferans may be particularly valuable in studies of western Atlantic and Caribbean reefs, because coral populations are severely declining (e.g., Liddell and Ohlhorst, 1992; 93

2 Diving for Science Porter, 1992) and managers of reef resources are becoming increasingly reluctant to sacrifice corals for research. Foraminiferans, particularly larger species with algal endosymbionts, are relatively easy to collect alive for physiological, cytological and culture experiments. The purpose of this paper is to discuss the foraminiferal species that are readily collectible in the vicinity of the site that has been selected by the National Oceanic and Atmospheric Administration's National Undersea Research Center at the University of North Carolina, Wilmington (NOAA-NURC/UNCW) for deployment of the AQUARIUS Underwater Habitat (Miller and Hulbert, 1992). With this information, other researchers interested in foraminiferans may be able to plan experiments using the in situ capabilities of the Habitat. Site Description and Methods The site selected for the AQUARIUS Habitat is in the vicinity of Conch Reef, which is offshore of the southern end of Key Largo in the Florida Keys. Primary substratum types include coral-algal reef, reefal sands, and reef rubble. While foraminiferans can be found on all of these bottom types, reef rubble is the subject of this report because it provides a permanent, relatively immobile substratum for both attached and motile foraminiferal species, which can be sampled with minimal environmental impact. Mobile sediments have a more restricted biota, while continuous hard substratum is very difficult to sample nondestructively. Because the Conch Reef site ranges in depth from 15 to 30 m, sampling is carried out by divers using SCUBA or enriched air (NlTROX) containing 36% oxygen (NURC/UNCW, 1991). Two techniques are routinely employed to collect living foraminiferans (Hallock et al. 1992), depending upon depth, available bottom time, and purpose for sampling. Either pieces of reef rubble are directly collected or debris concentrates are obtained from the rubble. Rubble samples consist of roughly hand-sized pieces (i.e., covering cm2 of bottom) of coral debris or algal nodules, whose upper surfaces are coated with a stubble of filamentous algae. Each piece is carefully placed into a plastic bag to avoid detachment and loss of living foraminifera. Debris concentrates are collected by placing pieces of reef rubble, one at a time, inside a 4 liter plastic bag and brushing the rubble free of sediment, algae, and meio- and microfauna; the rubble is returned to the substratum. Samples are taken to the surface where they are further processed. For faunal surveys, samples consisting of one or two pieces of rubble are either frozen or treated with preservative to kill the foraminiferans quickly, and later washed in freshwater, dried on filter paper at 40-SOOC, examined microscopically and picked for foraminiferans (e.g., Hallock et al., 1986a). Useful quantities of living foraminiferans for experimental studies require debris concentrates, either collected directly or obtained from bulk rubble samples by brushing the rubble in a bucket filled with seawater. Rubble is disposed of and debris is washed several times to remove as much loose organic matter as possible. The remaining debris concentrate is spread thinly over the bottom of large, flat dishes (e.g., 150 x 20 mm Petri dishes), covered with 1-2 em of seawater and allowed to sit overnight. Many of the foraminiferans are negatively geotaxic, so they climb the walls of the Petri dish or to the top of the layer of sediment and algal debris, where they can be readily picked. If species that attach directly to the rubble are desired, rubble pieces must be saved. Results and Discussion Table 1 presents relative abundances of symbiont-bearing foraminiferal species commonly collected live at Conch Reef. Individuals of symbiont-bearing species that are living when collected are readily distinguished by their color in fresh or dried samples (Hallock et al., 1986a). Chlorophyte-bearing species retain at least some of their grass-green color, rhodophyte-bearing species are red and white 94

3 Hallock et d.: Foraminifera research possibilities "candy stripe", diatom-bearing species are golden brown, and dinoflagellate-bearing species are usually a purplish brown. Table 1. Attached and symbiont-bearing foraminiferal species collected from rubble at Conch Reef, Florida Keys. A = >10 individuals/5ocm2 rubble piece; C = 1-10/50 cm2; P = typically find several in rubble concentrates from 5-10 pieces of rubble. Attached species are noted by. Suborder Species Symbiont Abundance Rotaliina Amphistegina gibbosa d'orbigny Diatom A Asterigerina cannata d'orbigny Diatom A Heterostegina antijjarum d'orbigny Diatom P Homotrema rubrum*(lamarck) None C Planorbulina medirerraneansis" None A d'orbigny P. \'ariabilis" d'orbigny None C MiJiolina Archaias angularus (Fichtel and t-1011) Chlorophyte C Borelis pulchra (d'orbigny) Diatom P Cyclorbiculina compressa (d'orbigny) Chlorophyte C Laevipeneroplis prorea (d'orbigny) Chlorophyte A Laevipeneroplis bradyi (Cushman) Chlorophyte C Parasorires orbirojiroides <Hofker) Chlorophyte C Peneroplis pertusus (Forskal) Rhodophyte C Sorites orbiculus (Forskal) Dinoflagellate P Amphistegina gibbosa, Asterigerina carinata, and Laevipeneroplis protea are the most abundant species with algal endosymbionts. Parasorites orbitolitoides and 1.. bradyi are also relatively common. Dead tests of Archaias an&ulatus and Cydorbiculina compressa are abundant, but living individuals are much less common. Of these species, Amphist~na ~bbosa is the most studied (e.g., Hallock et al., 1986b) followed by A. an&ulatus.~. compressa. and Sorites orbiculus (Hallock and Peebles, in press). Virtually nothing is known of the biology, symbionts, and life history of the other species. Attached species are also relatively large and abundant at Conch Reef, particularly Homotrema rubrum and Planorbulina spp. (Table 1). Smaller species are taxonomically diverse; typically tests of species can be found in a fully picked sample, As is typical for reef samples (e.g., Murray, 1973), rotaliine and milioline smaller taxa are about equally represented, while agglutinated individuals are few. Unfortunately, because most of these species lack symbionts and because the reliability of vital staining techniques is questioned (e.g., Martin and Steinker, 1973), careful observation of live samples is required to determine living assemblages with full confidence. Common and easily identified taxa are listed in Table 2. Detailed species lists and species illustrations of Florida Keys foraminiferans can be found in Bock et al. (1971). 95

4 Dit1ing for Sci~nc~ Table 2. Common smaller foraminiferal species observed in samples from Reef, Florida Keys. Conch Suborder Textulariina Textularia agglurinans d'orbigny VaNulina o\'iedoiana d'orbigny Suborder Miliolina Articulina mexicana Cushman A. mucronata (d'orbigny) Hauerina bradvi Cushman Hauerina speclosa (Karrer) Miliolinella circularis (Bornemann) M. flchteliana (d'orbigny) Nodobaculariella cassis d'orbigny Pyrgo fornasinii Chapman and Parr Quinqueloculina agglutinans d'orbigny Q, bicarinara d'orbigny Q, bicostara d'orbigny Q, bosciana d'orbigny Q, horrida Cushman Q, subcuneata Cushman Q, polygona d'orbigny Quinqueloculina spp. Schlumbergerina alveoliniformis Cushman Triloculina oblonga (Montague) Triloculina trigonula (lamarck) Triloculina. spp. Suborder Rotaliina Boli"ina spp. Buliminella elegantissima. (d'orbigny) Discorbis rosea (d'orbigny) Discorbis spp. Bphidium spp. Haynesina depressula (Walker and Jacobs) Neocorbina terquemi (Rzehak) Nonionoides grateloupi (d'orbigny) Rosalina fjoridana (Cushman) Rosalina. spp. Treromphalus atlanticus (Cushman) The abundance and diversity of readily collectible foraminiferans at the Conch Reef site provide the potential for a variety of kinds of studies. We are currently monitoring symbiont loss (bleaching) in Am~histe~ina ~ibbosa (Hallock et Ill. 1992) and are collecting this species for physiological and cytological studies to document the bleaching process and its causes. We are also using specimens of several species in biochemical taxonomic research aimed at determining the affinities among taxa.with chlorophyte endosymbionts and their relationships to other porcelaneous taxa (Toler dill., 1991). Once the AQUARIUS Habitat is operational, the kinds of studies that can be conducted jnmnt are limited only by the imagination of the potential researchers and their ability to promote their ideas to NURC/UNCW and other funding agencies. jnjidl growth rate, sediment production rate, habitat specificity, competition, and disturbance-recovery rate studies are a few examples that would provide ecologists and paleoecoloists with insight into niche separation in these fascinating protists. Determining the effects of transplantation or small-scale release of fertilizers or other chemicals on foraminiferal assemblages are also possibilities. The outcome of such studies will make foraminiferans even more useful in paleoenvironmental analysis of ancient reefs, and also more useful for predicting environmental impacts on benthic communities. 96

5 Hallock et at.: Foraminifera research possibilities Acknowledgements This research was supported by NOAA-NURC/UNCW. identifications. M.W. Peebles assisted with taxonomic Literature Cited Alve, E Benthic Foraminifera in sediment cores reflecting heavy metal pollution in Sorfjord, western Norway. J. Foram Res. 21: Bock, W.O., W.W. Hay, J.I. Jones, G.W. Lynts, S.L. Smith, and R.c. Wright A Symposium of Recent South Florida Foraminifera. Memoir 1. Miami Geological Society. Hallock, P Production of carbonate sediments by selected large benthic foraminifera on two Pacific coral reefs. J. Sed. Petrology 51: Hallock, P. and A.R. Larsen Coiling direction in Amphiste&ina. Marine Micropaleontology 4: Hallock, P. and M.W. Peebles. Habitats of Archaiasinae in the Florida Keys. Mar. MicropaleontoI. (in press). Hallock, P., T.L. Cottey, L.B. Forward and J. Halas. 1986a. Population biology and sediment production of Archaias an&ulatus (Foraminiferida) in Largo Sound, Florida. J. Foram Res. 16: 1-8. Hallock, P., L.B. Forward and H.J. Hansen. 1986b. Influence of environment on the test shape of AmphisteiPna. J. Foram Res. 16: Hallock, P., H.K. Talge, K. Smith and E.M. Cockey Bleaching in a reef-dwelling foraminifer, Amphiste~na ~bbosa. Proc. 7th Internat. Coral Reef Symp., Guam (in press). Hirshfield, H.I., R. Charmatz and L. Henson Foraminifera in samples taken from Enewetak Atoll in J. Protozoology 15: Lee, J.J. and O.R. Anderson Symbiosis in foraminifera. pp , in J.J. Lee and O.R. Anderson (eds.), Biology of Foraminifera. Academic Press, London. Liddell, W.O. and S.L. Ohlhorst Ten years of disturbance and change on a Jamaican fringing reef. Proc. 7th Internat. Coral Reef Symp., Guam (in press). Martin, R.E. and O.c. Steinker Evaluation of techniques for recognition of living foraminifera. Compass 50(4): McKee, E.O., J. Chronic and E.B. Leopold Sedimentary belts in the lagoon of Kapingimarangi Atoll. Am. Assoc. Petrol. GeoI. Bull. 43: Miller, S.L. and A.W. Hulbert NOAA's National Undersea Research Program: Research support for a comprehensive long-term science program in the Florida Keys National Marine Sanctuary. Proc. 7th Internat. Coral Reef Symp., Guam (in press). Murray, J.W Distribution and Ecology of Living Benthic Foraminiferids. Crane, Russak &: Co., New York, 274 pp. 97

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