FISHERY BULLETIN: VOL. 76, NO. 1 



in mass cultures. Each species is an active swim- 

 mer, thereby satisfying the raptorial feeding re- 

 quirements oiLibinia. As noted in Table 1, several 

 of the diets were replicated with 40 larvae (8 

 dishes of 5) in each of two trials; the remaining 

 diets were investigated only once. Different trials 

 utilized zoeae from different hatches; all 40 larvae 

 in each diet replicate were from the same hatch. 

 Concentrations of food organisms listed in Table 1 

 remained constant and were not adjusted as mor- 

 tality occurred. One exception was diet BD/ABD, 

 where the food organism composition was altered 

 after the molt into stage II to include Artemia 

 nauplii. Food and culture water were changed 

 daily. Culture dishes were scrubbed clean in 

 freshwater twice weekly. Larvae were transferred 

 by wide-bore pipette to minimize body damage. 

 Molts were recorded when exuviae appeared in the 

 dishes and were verified under a compound mi- 

 croscope. The criteria for death was complete ab- 

 sence of a heartbeat. 



Larvae and juvenile crabs were preserved in 

 10% buffered Formalin for carapace measure- 

 ments. These measurements were determined 

 with an ocular micrometer, with the carapace 

 lengths and widths taken at maximum dimen- 

 sions (Figure 1). Comparisons of development 

 times and measurements were made by one-way 

 analysis of variance, with significant differences 



Figure l. Body proportions oi Libinia emarginata measured 

 and the lines of measurement used. (A) zoea, (B) megalopa, (C) 

 juvenile, (SH) spine height, (CW) carapace width, (CL) carapace 

 length. 



(P<0.05) between diets tested by a Scheffe pos- 

 terior comparison test (Nie et al. 1970). 



RESULTS 



Survival 



Figure 2 shows the survival of spider crab larvae 

 reared on each of the nine diets. Experiments con- 

 tinued for 25 days, at which time all larvae had 

 either metamorphosed into the first crab stage or 

 died. Survival data after each stage are shown in 

 Table 2. Only six of the nine diets permitted de- 

 velopment to proceed beyond stage I; in three diets 

 (EED, D, and S) all zoeae died in the first stage. 



Starved control larvae survived a maximum of 7 

 days, by which time mortality was 100% (Figure 

 2). After day 3, all larvae were moribund. 



Addition o{ Dunaliella viridis (D) did not en- 

 hance either survival or molting. All stage I zoeae 

 were motionless by day 4, but a heartbeat was 

 observed up to day 10. No molts occurred. The dark 

 red or orange chromatophores typically observed 



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