|Erin Kelly - Crab Lab
St. Francis College, Loretto, PA
Blue crab, callinectes sapidus , megalopae in the wild exhibit daily swimming patterns with peak swimming at night (Forward et al 1996). Swimming patterns are very important to the blue crab in their early life stages. However, considering that hatchery blue crabs do not spend their early life cycle in the wild there is concern that they will not have experience to the photoperiod cues to ensure higher chances of survivorship. In this study, swimming patterns of C2 and C4 hatchery raised crabs were analyzed throughout a 24 hour period using video surveillance. Two video sessions occurred in daylight and two during the night. To see if there was any indication of endogenous swimming patterns, there was an additional treatment of constant darkness. Each treatment was done for four trials; each trial consisting of a 24 hour period. Six crabs were used in each trial (3 C2/3C4) and each placed in their own individual plexiglass chamber (4.6cmX4.6cmX35cm). The percentage of time swimming was calculated by noting presence or absence of the crab in 15 min intervals. There was a slight suggestion of higher swimming percentage during the night hours and during the dark treatment. The smaller crabs indicated a stronger suggestion of higher percentage of swimming during the night hours and dark treatment. However, after statistical analysis using ANOVA repeated measures, there were no significant results considering the P values.
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