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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: ©1991 Elsevier B.V. The final published version of this manuscript is available at http://www.sciencedirect.com/science/journal/00448486 and may be cited as: Gustafson, R. G., Creswell, R. L., Jacobsen, T. R., & Vaughan, D. E. (1991). Larval biology and mariculture of the angelwing clam, Cyrtopleura costata. Aquaculture, 95(3-4), 257-279. doi:10.1016/0044-8486(91)90092-L Aquaculture, 95 (1991) 257-279 257 Elsevier Science Publishers B.V .. Amsterdam Larval biology and mariculture ofthe angelwing clam, Cyrtopleura costata KG. Gustafson"·l, R.L. Creswell", T.R. Jacobsen" and D.E. Vaughan" "Division olCoastal. Environmental and .iquacultural SCiCIICCS, Harbor Branch Oceanographic Institution, 5600 Old DixlC Highway, Fort Pierce, FL 34946, U,)',I "Department otMarinc and Coastal SCiCIICCS, Rutgers Shellfish Research l.aboratorv. New Jcrscv .tgnrultural Evperimcnt Station, Rutgers University, Port Norris, NJ 08349, USI (Accepted 7 November 1990) ABSTRACT Gustafson. R.G .. Creswell, R.L. Jacobsen. T.R. and Vaughan. D.E .. 1991. Larval biology and mari culture of the angclwing clam. Cvrtoplcura costata. Aquaculture, 95: 25 7~2 79. The deep-burrowing angclwing clam. Cvrtoplcura costata (Family Pholadidac ). occurs in shallow water from Massachusetts. USA. to Brazil and has been a commercially harvested food product in Cuba and Puerto Rico. This study examines its potential for commercial aquaculture development. The combined effects of salinity and temperature on survival and shell growth to metamorphosis of angclwing larvae were studied using a 5 X 5 factorial design: salinities ranged from 15 to 35%0 S. in 5OftlO S intervals. and temperatures ranged from 15 to 35C in 5 C intervals. Greatest larval shell growth occurred at 30"C and 20OftlO S over the first 8 days and at 30"C and 25°1<., S over the entire 16 day larval period. Substantial survival (at least 70% of maximal ) occurred at all temperature-salinity combinations below 30'C and 35°1<., S over the first 8 days: and at 15.20 and 25'T combined with all salinities. as well as at 3(YC combined with 20°1<., Sand 25°l<lO S over 16 days. Larvae were competent to metamorphose at 12 days (at optimal temperature-salinity) at a mean shell length of 317 11m. Exposure to a 10- 1 M solution of epinephrine for 1 h induced more than 95(l'" metamorphosis in competent angelwing larvae. Juvenile angclwing shell length increased at a mean rate of 0.190 mm/ day over the first 60 days of post-larval life. Field-planted angclwings reached market size (5~ 7 cm) in 5-6 months. INTRODUCTION Indigenous bivalve populations of the family Pholadidae are harvested for food in various parts of the world, although none are cultured on a commer cial scale. The early Romans used the piddock, Pholas dactylus L., as food (Turner, 1954) and this species is still gathered for human consumption on the Normandy coast (Rogers, 1951), in Brittany, in the Channel Islands 'Current address: Institute of Marine and Coastal Sciences. Rutgers Shellfish Research Labo ratory. New Jersey Agricultural Experiment Station. Rutgers University. P.O. Box 687. Port Norris. NJ 08349. USA. 0044-8486/91/$03.50 C<) 1991 - Elsevier Science Publishers B.V. 258 R.G. CiUSTAFSON ET AL. (Davidson, 1980) and in Italy (Palombi and Santarelli, 1969). P. chi/oensis Molina is harvested recreationally in parts of Chile (Turner, 1954; P. Chan ley, pers. comm., 1984), whereas P. (Monothyra) orientalis Gmelin is sold either fresh or dried in markets in Thailand (hoy pim), Malaysia (siput selat batu), Hong Kong (haw chung), and the Philippines (diwal) (Ablan, 1938; Davidson, 1976; Saraya, 1982; Young and Serna, 1982; Tokrisana et aI., 1985; Amornjaruchit, 1988). The angelwing clam Cyrtopleura costata (Linne 1758) was at one time a staple food item in the markets of Havana, Cuba (Arango y Molina, 1878; Rogers, 1951; Turner, 1954) and was commercially har vested in Puerto Rico (Warmke and Abbott, 1975). The deep-burrowing habit and fragile shell of these edible pholadids have to date prevented their use in aquaculture (Alston et al., 1983). Preliminary studies have shown the angelwing clam, Cyrtopleura costata, to be an excellent candidate for aquaculture (Chanley, 1984; Creswell and Schilling, 1985; Kraeuter and Castagna, 1989). Angelwings burrow in sandy mud and are found in shallow water from southern Massachusetts, USA, to Brazil (Turner, 1954; Abbott, 1974; Rios, 1975). Larvae of the angelwing clam have been successfully reared in a commercial-scale hatchery and expe rience with post-larvae and juveniles indicates that angelwings are capable of reaching market size (5-7 cm ) in 4-6 months (Creswell and Schilling, 1985). Tan Tui et al. (1989) have investigated growth and survival of angelwing larvae in response to known rations of various warm-water-adapted phyto plankton strains. In this paper, we examine: growth of angelwing larvae and ju veniles to market size; the combined effects of temperature and salinity on larval angelwing survival and shell growth; and methods used to induce larval angelwing metamorphosis in the hatchery. MATERIALS AND METHODS , /,' Spawning stock was obtained from indigenous populations in the Banana River Lagoon and Indian River Lagoon, Florida, USA. Mature clams were collected by hand, encircled with an elastic rubber band to maintain lateral pressure on the valves, dry-packed in damp seaweed, and transported to the mollusc hatchery of the Division of Coastal, Environmental and Aquacul tural Sciences, Harbor Branch Oceanographic Institution (HBOI), Fort Pierce, Florida. Spawning ofmature angelwings was induced by thermal stim ulation or, rarely, by injection of 0.4 ml of a 2 mM serotonin solution (crys talline 5-hydroxytryptamine, creatine sulfate complex, Sigma Chemical Co. ). Hatchery, nursery andfield techniques In the case of batch cultures, fertilized eggs were washed in 5 Jim filtered and UV-treated seawater on a 20 Jim screen and placed in 500-1 conical fiber glass tanks. After 24-48 h, density of straight-hinge larvae was adjusted to 7 lARVAL BIOLOGY AND MARlCliLTliRE OF THE AN(iELWING CLAM 259 larvae/rnl. Cultures were gently aerated and seawater was exchanged either every day or every other day, at which time mixed rations of unicellular algal cultures [Nannoehloris oculata Butcher, Thalassiosira pseudonana Hassel et Heimdal (Husdedt) (clone 3H), Dunaliella tertiolecta Butcher, and Isochry sis aff. galbana Green (clone T-ISO) ] were provided at a nominal combined initial density of25000 cells/rnl, which was increased to 50 000 cells/rnl after 72 h. Growth rates were determined from a sample of 100 randomly selected larvae taken at each water change. In early experiments (1983), larvae were maintained at ambient salinity and temperature, which fluctuated between 22-32%0 Sand 22-30°e. In later cultures (1987), larvae were maintained at the optimum salinity-temperature combination of25%0 Sand 30°e. In early experiments (1983), chloramphenicol (6 mg /l ) was added to cultures to re tard bacterial growth. When larvae reached pediveliger stage, shallow fiberglass cylinders (20.3 em diameterX 2.5 ern depth) with mesh bottoms and containing graded sili con sand (300-500 zzm ) to a depth of 2 em, were suspended in the conical tanks to collect competent larvae. In other cases, competent larvae were in duced to metamorphose upon exposure for I h to a 10- 3 M solution of epi nephrine dissolved in natural seawater. These treated larvae were then resus pended within upwellers in the conical tanks until metamorphosis was complete. In early experiments ( 1983), newly settled juveniles were stocked in mesh lined, sand-filled "Nestier" trays (56 X 56 X 5 cm ) at a density of4000 clams/ tray (12755 clams/m') and suspended on racks in concrete raceways (2.1 X 0.72 X 0.53 m). Mixed phytoplankton assemblages [lsoehrysis aff. gal bana (clone T-ISO) and unidentified local diatoms], cultured in 50 000 I semi-cylindrical aluminum tanks, were combined with filtered seawater and continuously supplied to the raceways. Juveniles were placed in the field at a mean shell length of 11.6 mm in shallow, sand-filled trays ( 1.2 X2.4 X0.1 m) at a density of 10000 clams/trr', and submerged in < 1.5 m water depth. Shell growth was monitored monthly from a sample of 50 individuals from each tray. In subsequent experiments (1987-1988), newly settled juveniles were placed directly in a sand-filled tray ( 1.2 X 2.4 X 0.1 m) at a density of 100000 clams/m'; supplied with a combination of filtered seawater and cultured al gae iIsochrvsis aff. galbana (clone T-ISO) ] of varying cell density. Survivors were subsequently field-planted, without protection, when 10-12 mm in shell length. Temperature-salinity combination A 5 X 5 factorial design was utilized for temperature-salinity experiments. Salinities ranged from 15 to 35%0Sin 5%0S intervals and temperatures ranged from 15 to 35 0 C in SOC intervals. Two complete temperature-salinity exper- 260 R.G. GUSTAFSON ET AL. iments were conducted on separate spawnings of Cyrtopleura costata. Dupli cate static cultures of 18-h-old, straight-hinge larvae were established at each of the 25 different temperature-salinity combinations in I-I polystyrene beakers at an initial density of 5 larvae/rnl. Salinities were adjusted with NANOpure (Barnstead/Thermolyne Corp.) water or Instant Ocean (Aquar ium Systems, Inc.) sea salts and maintained within ± 1.0%0S of the desired levels. Beakers were immersed to above their water line in constant tempera ture ( ± 1.0 0 C) water baths; cultures were lightly aerated and exchanged with 0.45 /lm filtered natural seawater at 2-day intervals.