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Heidi Waite

Undergraduate Major: Biology

Future Plans: Ph.D. in Marine Biology

Heidi Waite

Heidi Waite was born in Redmond, Washington and moved to Naples, Florida at the age of nine. She is currently pursuing a bachelor’s degree in Biology at the University of Central Florida. Her passion for marine wildlife and ecology has led her to participate in undergraduate research focused on oyster reef and shoreline restoration. She is currently conducting research in the Coastal Estuarine and Ecology Laboratory under the supervision and mentorship of Dr. Walters. Heidi plans to obtain a Ph.D. in Marine Biology in hopes of pursuing a career in marine research and academia.

Rhythmic Larval Release in the Estuarine Crab Dyspanopeus Sayi: Entrainment By Temperature Cycles

Conducted at Duke University Marine Lab, REU in Estuarine & Coastal Marine Sciences

Mentors: Dr. Richard Forward, Nicholas School of the Environment, Duke University

Abstract: Marine and estuarine crabs brood attached eggs and release larvae at precise times relative to environmental cycles. The crab Dyspanopeus sayi has a circadian rhythm, in which larvae are released within the 4 hour interval after the time of sunset. Previous studies demonstrated that the rhythm can be entrained by the light-dark cycle. Since subtidal crabs are also exposed to temperature fluctuations, an unstudied question examined in this study was whether the circadian rhythm could be entrained by the diel temperature cycle. To answer this question ovigerous D. sayi were collected from subtidal traps and placed in darkness in an environmental chamber with the temperature cycle reversed from the ambient cycle. High temperature occurred at the predicted times of night and low temperature during the day. After a minimum of 3 entrainment cycles, crabs were placed in clear columns in constant conditions (darkness and constant temperature). The columns were videotaped with a time lapse video system and times of larval release determined. The times shifted as crabs released larvae to the first few hours after predicted time for the beginning of the cold and light phase. Thus, the circadian rhythm was entrained by the temperature cycle. The second research question was whether the temperature or light:dark cycle is stronger for entrainment. Collectively, this study was the first to demonstrate that the circadian rhythm in larval release by crabs can be entrained by the diel temperature cycle and further experiments will establish the hierarchy among entrainment cycles.