feasibility of hatching, rearing and breeding a laboratory population of the 

 shrimp for use as experimental animals. Of primary consideration in this study 

 was the development of flow-through culture systems for the various life 

 stages. Static designs represent poor simulations of field conditions and may 

 impose unnecessary stresses on the animals (8). A secondary concern was to 

 determine suitable diets for the juvenile and adult grass shrimp. Broad (1) 

 found brine shrimp, Artemia salina, nauplii to be a very satisfactory larval 

 food. Success for the project must be measured in terms of growth, survival, 

 and population reproduction. 



The advantages of using lab-reared organisms are countered by several 

 anomalous characteristics of organisms maintained in the lab. Morphological 

 changes, as compared to field animals, have been noted by Paul Yevich 

 (Environmental Research Lab, Narragansett, R.I.; personal communication) in 

 many marine animals. However, the increased control of age, nutrition, and 

 prior exposure to environmental variables would appear to outweigh slight 

 changes in morphology. 



The grass shrimp , Palaemonetes vulgaris (Say), was selected for these studies 

 for several reasons: the shrimp is a common estaurine species available to 

 researchers along the Atlantic and Gulf of Mexico coasts (9); the animal is 

 relatively easy to rear in the laboratory; and the life cycle can be greatly 

 compressed in the lab (4). 



EXPERIMENTAL 



Several ovigerous grass shrimp were collected by dip net on 14 July 1976 in 

 the Pettaquamscut River estuary adjacent to Narragansett Bay, Rhode Island. 

 Mid-summer salinities at the collection site range from 25-30o/oo depending 

 on the tidal cycle; water temperature was 21.5^C. 



Egg-bearing females were isolated in six 2 (1.6 U.S. gal.) tubs at 21.0- 

 23.5°C and oceanic salinities (29-34.5 o/oo). Photoperiod was maintained at 

 ambient levels of L14:D10. Water was changed daily and aerated gently. 

 Shrimp were offered food during this holding period but they rarely fed. 



Larvae hatched after 1 to 17 days of holding and were immediately pipetted 

 into the flow-through system shown in Figure 14-1. About 200 larvae were 

 held in this two C system for 21 days, by which time all shrimp had reached the 

 late larval stages. Developing larvae were fed excess quantities of newly hatched 

 and one-day old brine shrimp nauplii, Artemia salina (San Francisco Bay 

 Brand). 



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