EFFECT OF SEVERAL DIETS ON SURVIVAL, 



DEVELOPMENT TIME, AND GROWTH OF LABORATORY-REARED 



SPIDER CRAB, LIBINIA EMARGINATA, LARVAE 



Thomas E. Bigfordi 



ABSTRACT 



Survival, development time, and growth were determined for larvae of the spider crab, Libinia 

 emarginata, reared with nine diet combinations of algae, rotifers, copepods, ciliates, and Artemia. 

 Percent survival was greater and development times shorter for diets of A. salina nauplii, either alone 

 or in combination with other food sources. Zoeal survival was higher in diets of Artemia at 6 nauplii/ml 

 than at 3 nauplii/ml. Megalopal survival was more variable, being highest in cultures with Artemia 

 and the rotifer Brachionus plicatilis as food. No significant differences were noted in carapace mea- 

 surements of larvae reared on the six diets which supported development beyond stage I zoea. 



The literature includes many descriptions of de- 

 capod crustacean larval culture in the laboratory. 

 Much of this work has been directed at deriving 

 culture techniques and optimum levels of factors 

 such as temperature and salinity. The "standard" 

 diet has been newly hatched Artemia nauplii, a 

 highly successful, convenient, but increasingly 

 expensive food source. Research trends have been 

 to seek substitute or supplemental diets for the 

 brine shrimp. Foods investigated have included 

 barnacle nauplii (i,awiriski and Pautsch 1969; 

 Reed 1969), the rotifer Brachionus plicatilis (Brick 

 1974; Sulkin 1975; Sulkin and Epifanio 1975), 

 various ciliates (Sulkin 1975), polychaete larvae 

 (Roberts 1974; Sulkin 1975), and oyster larvae 

 (Roberts 1974). 



This study was designed to evaluate possible 

 diets, in addition to Artemia nauplii, which will 

 support larval development of the spider crab, 

 Libinia emarginata Leach. Normal larval de- 

 velopment of this species consists of two zoeal 

 stages and one megalopa (Johns and Lang 1977). 

 Parameters used to estimate diet success were 

 survival of larvae to each stage, time to each molt, 

 and carapace size. 



Development of a satisfactory diet, in combina- 

 tion with the short larval development time, could 

 establish Libinia as a very suitable bioassay or- 

 ganism. The culture methodology described is re- 

 latively simple, further increasing the potential 

 for continued laboratory study. 



MATERIALS AND METHODS 



Ovigerous female L. emarginata were collected 

 by otter trawl in Narragansett Bay, during July 

 and August 1976. Females were placed in contain- 

 ers of aerated seawater and immediately trans- 

 ported to the laboratory; storage in the laboratory 

 was in a 1.2-m diameter ( 195-1 volume) Fiberglas^ 

 tank provided with flow-through ambient temper- 

 ature (approximately 20°C) seawater. As the eggs 

 ripened, the females were transferred into tubs 

 containing 8 1 of filtered seawater at 20° and 29- 

 31%o. After hatching occurred the female was re- 

 moved and the water changed. 



Within several hours of hatching, the larvae 

 were placed 5/dish in 8.75-cm diameter culture 

 dishes containing 75 ml of filtered seawater. 

 Temperature and salinity were maintained at 

 20°C and 29-3 l%o. This type of static system has 

 been used commonly to rear other species of crabs 

 (Brick 1974; Sulkin and Norman 1976; Sulkin et 

 al. 1976). The density of 1 larva/15 ml was chosen 

 to allow sufficient room for developing megalopae. 



Food organisms used included newly hatched 

 San Francisco Bay Brand Artemia salina nauplii, 

 the cihate Euplotes vannus, the copepod^urj'^em- 

 ora affinis, the green flagellate algae Dunaliella 

 viridis, and the rotifer Brachionus plicatilis (Table 

 1). These organisms are available at the Environ- 

 mental Research Laboratory (Narragansett, R.I.) 



'U.S. Environmental Protection Agency, Environmental Re- 

 search Laboratory, South Ferry Road, Narragansett, R.I.; 



present address: The Center for Natural Areas, 1525 New 

 Hampshire Avenue, NW, Washington, DC 20036. 



2 Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA or USEPA. 



Manuscript accepted May 1977. 



FISHERY BULLETIN: VOL. 76. NO. 1, 1978. 



59 



