NOTES 1013

George, E. L. and W. F. Hadley. 1979. Food and habitat partitioning between rockbass (Anibloplites rupestris) and smallmouth bass (Micropterus dolomieui) young of the year. Trans. Am. Fish. Soc. 108: 253-261. Hess, P. W. 1961. Food habits of two Dasyatid rays in Delaware Bay. Copeia 1961: 239-241. Hyslop, E. J. 1980. Stomach content analysis-a review of methods and their application. J. Fish BioI. 17: 411-429. Pinkas, L., M. S. Oliphant and I. L. K. Iverson. 1971. Food habits of albacore, bluefin tuna and bonito in California waters. Calif. Dep. Fish Game Fish Bull. 152: 1-105. Randall, J. E. 1967. Food habits of reef fishes of the West Indies. Stud. Trap. Oceanogr. 5: 665- 847. Snelson, F. F., Jr. and S. E. Williams. 1981. Notes on the occurrence, distribution, and biology of elasmobranch fishes in the Indian River lagoon system, Florida. Estuaries 4: 110-120. Struhsaker, P. 1969. Observations on the biology and distribution of the thorny stingray, Dasyatis centroura (Pisces: Dasyatidae). Bull. Mar. Sci. 19: 456-481. Thorson, T. B. 1983. Observations on the morphology, ecology, and life history of the euryhaline stingray, Dasyatis gut/ata (Bloch and Schneider) 1801. Acta BioI. Veniz. II: 95-125. Virnstein, R. W. 1987. Seagrass-associated invertebrate communities of southeastern U.S.A.: a review. Pages 89-116 in M. J. Durake, R. C. Phillips and R. R. Lewis III, eds. Proceedings of the symposium on subtropical-tropical seagrasses of the southeastern United States (1985). Fla. Mar. Res. Publ. 42.

DATEACCEPTED: October 26, 1992.

ADDRESSES:(D.G.) Nova University Oceanographic Center, 8000 N. Ocean Drive, Dania, Florida 33004; (K.M.S.), Department oj Biology, University oj Miami, Coral Gables, Florida 33]24.

BULLETINOFMARINESCIENCE.52(3): 1013-1017. 1993

PREDATION BY THE KING HELMET ( TUBEROSA) ON SIX-HOLED SAND DOLLARS (LEODIA SEXIESPERFORATA) AT SAN SALVADOR, BAHAMAS

James B. McClintock and Ken R. Marion

The king helmet Cassis tuberosa is distributed throughout the Bahamas and West Indies (Warmke and Abbott, 1961). This , as well as most other cassids, feeds almost exclusively on echinoids (reviewed by Hughes and Hughes, 1981). Here we report the first quantitative field observation of C. tuberosa feeding exclusively on the sand dollar Leodia sexiesperjorata in a sandy nearshore habitat at San Salvador, Bahamas (original observation by Gerace and Lindsay, 1992). We provide evidence that the king helmet demonstrates highly predictable feeding behaviors when boring into the sand dollar test, ensuring access to the internal tissues. This study also indicates that populations of L. sexiesperforata can suffer high levels of localized predation by the king helmet.

LoCATION AND METHODS

The Bahamian Island of San Salvador (24°04'N; 74°35'W) is surrounded by extensive reef and vegetated and unvegetated soft bottom marine habitats. Populations of the sand dollar, Leodia sex- iesperJorata, are common in sandy substrates at Bamboo Beach, located 1 km south of Cockburn Town on the west coast of San Salvador (D. Gerace, pers. comm.). Observations of the king helmet feeding on sand dollars were made during mid-morning hours in July 1992 by swimming parallel to the shore at a depth of 4-5 m. Swimming continued until 10 Cassis tuberosa were located. Individuals were turned over, noting whether or not each was feeding on an L. sexiesperJorata. Sand dollars which 1014 BULLETIN OF MARINE SCIENCE, VOL. 52, NO.3, 1993

Figure 1. A. King helmet Cassis tuberosa feeding on the sand dollar Leodia sexiesperJorata at Bamboo Beach, San Salvador, Bahamas. B. Oral view of the cleaned test of L. sexiesperJorata (test diameter 68 mm) with a wound from C. tuberosa. C-E. Ontogeny of sand dollar wound formation on the oral side of the test (wound diameters approximately 5 mm).

were in the process of being drilled or fed upon were collected and their test diameters measured. To further quantify the incidence of predation by king helmets, a total of 19 additional sand dollars were haphazardly collected from the sandy substrata, examined for evidence of king helmet wounds, and measured. All of these individuals had spines; no clean (dead) tests were collected. All sand dollars were cleaned of spines by soaking tests in a 50% solution of bleach for I h. The locations of wounds relative to the edge of the test were assessed in 14 haphazardly selected individuals by determining the distance from the wound to the edge ofthe test divided by the diameter ofthe test. The positions of king helmet wounds relative to the nearest lunules were also determined. The hypotheses that wound location on the test was random with respect to proximity to both the test edge and lunule position were statistically tested using G-tests. To document king helmet wounds at progressive stages of ontogeny, a series of test wounds were photographed using a camera equipped with a macro-lens.

OBSERVATIONS Nine of the 10 Cassis tuberosa examined were in the process of boring into the test or were already feeding on soft tissues of Leodia sexiesperforata (mean ± 1 SD test diameter = 70.3 ± 7.2 cm) (Fig. lA). All 10 C. tuberosa examined were large adult individuals measuring at least 15 cm in shell length. None of the gastropods were aggregated, but were well spaced apart from one another (> 20 m between individuals). Among the 19 sand dollars collected haphazardly from the substrata (mean ± 1 SD test diameter = 64.7 ± 7.3 cm), all but one had a king helmet wound in the test (94.7% of those sampled). NOTES 1015

00 c:::? o o o

Figure 2. Line drawing of the oral test of Leodia sexiesperforata showing the specific locations of 14 wounds made by Cassis tuberosa.

Sand dollars which had been attacked by Cassis tuberosa had only a single wound located on the oral surface of the test (Fig. 1B). Mean ± I SD wound diameter was 4.8 ± 0.6 mm (N = 14). Test wounds occurred significantly (G = 31.688; P < 0.001) more often on the side of the 1unu1es closest to the oral opening, and on average 16% closer to the oral opening than to the edge of the test (Fig. 1B). King helmet wounds were not randomly distributed with respect to lunule position, but tended (G = 10.087; P < 0.08) to occur more often in closest proximity to the anterior lunules (Fig. 2). The process of C. tuberosa wound formation on the oral surface of the test of Leodia sexiesperforata is shown in Figure Ie, D, and E.

DISCUSSION These observations indicate that predation by the king helmet Cassis tuberosa on the sand dollar Leodia sexiesperforata at San Salvador, Bahamas occurs in shallow, sandy habitats. Although sample sizes are small, it is evident that the incidence of predation is likely to be high. Ninety percent of the C. tuberosa examined were in the process of feeding on a sand dollar, while almost 95% ofa haphazard sample of sand dollars from the population had distinct feeding wounds clearly caused by C. tuberosa. As C. tuberosa is known to be able to use its proboscis to gain access to all of the internal tissues of its echinoid prey (Hughes and Hughes, 1981), sand dollars, which still possessed spines, must have been recently predated. It is noteworthy that in shallow waters of San Salvador, C. tuberosa actively forages during daylight hours. In contrast, Hughes and Hughes (1981) describe this species as a nocturnal forager which retreats into the sand during daylight hours in Barbados. These differences in foraging activity patterns suggest that C. tuberosa may be food-limited in San Salvador. King helmets have been observed to opportunistically feed on echinoids (Foster, 1947; Moore, 1956; Schroeder, 1962; Snyder and Snyder, 1970; Hughes and 1016 BULLETIN OF MARINE SCIENCE, VOL. 52, NO.3, 1993

Hughes, 1971, 1981; Gladfelter, 1978; Levitan and Genovese, 1989). The sand dollar Leodia sexiesperforata, which contain relatively little tissue due to its com- pressed and flattened shape, may not be the preferred echinoid prey of C. tuberosa. The recent disease-related die-off of Diadema antillarum throughout the Carib- bean (Lessios et al., 1984; Lessios, 1989) has effectively eliminated these once abundant echinoids from San Salvador (D. Gerace, pers. comm.). Moreover, few Tripneustes ventricosus or Lytechinus variegatus were observed in the shallow sand bottom habitats (vegetated or unvegetated) (McClintock and Marion, pers. obs.). Therefore, C. tuberosa in San Salvador may be limited to exploiting sand dollars, rather than more energy-rich regular echinoids. One potential advantage of feeding on sand dollars is their apparent inability to escape. Hughes and Hughes (1971) found that C. tuberosa penetrated the tests of Trip- neustes ventricosus and approximately 50% of the time through the side, 13% through the aboral side, 13% through the oral side and the remainder through the peristomial membrane. Our findings differed markedly, as all penetrations occurred on the the oral side of the test, slightly closer to the oral opening than the edge of the test. Moreover, the penetration usually occurred towards the antl'eriorportion of the test (Fig. 2). This precise positioning is probably related to ensuring access to the internal body tissues. Penetration any closer to the edge of the test, where there is predominately calcium carbonate skeletal material, would preclude access to the soft tissues. The oral position oftest wounds may simply reflect constraints associated with prey manipulation. However, the positioning of the wound in the anterior portion of the test coincides with the positioning of the echinoid stomach and may ensure ready access to these energy- rich tissues. Our study indicates that populations of Leodia sexiesperforata can suffer high levels of mortality as a result of predation by Cassis tuberosa. There are no other known predators which have been documented foraging on this species. In Florida, the five-holed sand dollar Mellita quinquiesperforata is preyed upon by the Scotch Bonnet Pha/ium granulatum (Moore, 1956), while the sand sea star Luidia clath- rata feeds on M. quinquiesperforata in direct relation to their abundance and shows selectivity for smaller specimens (McClintock and Lawrence, 1984). Size selective foraging of C. tuberosa on L. sexiesperforata needs to be investigated further, but was not apparent in the present study. Size selection was not found in C. tuberosa feeding on the irregular echinoid Cassidulus caribbaearum (Glad- felter, 1978).

ACKNOWLEDGMENTS

We wish to thank D. and K. Gerace of the Bahamiam Field Station for their generous support. We also thank R. Angus for providing statistical expertise and S. Beddingfield for preparing the line drawing. J. Nybakken brought pertinent references to our attention. This research was supported by NSF EPSCoR grants R11-8996152 and EHR-9108761 awarded to both authors, as well as the De- partment of Biology at the University of Alabama at Birmingham.

LITERATURE CITED

Foster, R. W. 1947. Cassis tuberosa L. feeding on an echinoid (Clypeaster rosaceus L.). Nautilus 61: 35-36. Gerace, D. T. and W. Lindsay. 1992. Cassis in captivity: an ongoing research project. Pages 59-66 in D. T. Gerace, ed. Proceedings of 4th symposium on the natural history of the Bahamas. Bahamian Field Station, San Salvador. Gladfelter, G.A. 1978. General ecology ofthe cassiduloid urchin Cassidu/us caribbearum (sic). Mar. BioI. 47: 149-160. NOTES 1017

Hughes, R. N. and H. P. 1. Hughes. 1971. A study of the gastropod Cassis tuberosa (L.) preying upon sea urchins. J. Exp. Mar. BioI. Eco1. 7: 305-314. -- and --. 1981. Morphological and behavioural aspects of feeding in (Tonnacea, Mesogastropoda). Malacologia 20: 385-402. Lessios, H. A. 1989. Mass mortality of Diadema antillarum in the Caribbean: what have we learned? Ann. Rev. EcoL Syst. 19: 371-393. --, D. R. Robertson and J. D. Cubit. 1984. Spread of Diadema mass mortality through the Caribbean. Science 226: 335-337. Levitan, D. R. and S. J. Genovese. 1989. Substratum-dependent predator-prey dynamics: patch reefs as refuges from gastropod predation. J. Exp. Mar. BioI. Eco1. 130: 111-118. McClintock, J. B. and J. M. Lawrence. 1984. Size selectivity of prey by Luidia clathrata (Say) (Echinodermata: Asteroidea): effect of nutritive condition and age. Pages 533-539 in Proceedings of the fifth international echinoderm conference, Galway. Balkema Press, Rotterdam. Moore, D. R. 1956. Observations of predation on echinoderms by three species ofCassidae. Nautilus 69: 73-76. Schroeder, R. E. 1962. Urchin killer. Sea Frontiers 8: 156-160. Snyder, N. and H. Snyder. 1970. Alarm response of Diadema antillarum. Science 168: 276-278. Warmke, G. L. and R. T. Abbott. 1961. Caribbean seashells: a guide to the marine mollusks of Puerto Rico and other West Indian Islands, Bermuda and the lower Florida Keys. Livingstone Pub1. Co., Wynnewood, Pennsylvania. 346 pp.

DATEACCEPTED: January 12, 1993.

ADDRESS: Department of Biology, University of Alabama at Birmingham, Birmingham, Alabama 35294-1170.

BULLETINOFMARINESCIENCE,52(3): 1017-1021, 1993

MULTIPLE SPECIES SPAWNING ON CURACAO REEFS

Manfred L. J. Van Veghel

In the summer of 1991 I set up a nocturnal reef monitoring program to inves- tigate aspects of spawning behavior such as timing of Montastrea annularis mor- photypes. The study site was "Slangenbaai," a typical fringing reef on the leeward coast of Curacao (Bak, 1977). Monitoring took place the first 5 days following the full moons of August (26th) and September (23rd) between about 8:30 pm and 10:30 pm. Subsequently days 6, 7 and 8 were monitored between about 6:00 pm and 1:00 am. In October the reefwas monitored on days 6, 7 and 8 after the full moon (23rd) between about 9:00 and 11:00 pm. The 75 local divers who partic- ipated in this project were asked to swim a 260 m long trail along 284 numbered M. annularis colonies at depths between 5 and 15 m. If spawning was observed, the divers recorded colony identification number and spawning time. Sunset on Curacao is close to 7:00 pm. Besides spawning of M. annularis, of which details will be published elsewhere, 1 over a dozen other species were observed spawning in the monitoring periods. Such observations usually remain in scientific notebooks, which are not generally available to those interested. Patterns in species spawning behavior, e.g., spawning of M. annularis and the cryptic Ophiomyxa flaccid a on the same night, are over- looked if such data are not published.

I Van Veghel, M. L. J., 1993. Intraspecific variation in reproductive characteristics of a dominant Caribbean reef building coral, ..Yontastrea annularis: I. Gametogenesis and spawning behavior (manuscript).