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Coastal Studies Center

Jonathan Allen: Research at the marine lab

Principal Reseacher: Jonathan Allen
Randolph Macon College
Summer 2009

Research Team: Jonathan Allen, Jill Dixon '09 (Ramdolph Macon), Amanda Santoni '10 (Randolph Macon), and Cara Carne '10 (Randolph Macon)

Jonathan D. Allen, Assistant Professor of Biology at Randolph Macon College (RMC), (and Bowdoin's Doherty Marine Biology Scholar ‘06-‘08) returned to the Marine Lab with three RMC students. Jill Dixon ‘09 worked to investigate the effectiveness of encapsulation as a defense against predation for the embryos of Nucella lapillus, the dogwhelk. She found that egg capsules are, on their own, insufficient to prevent significant levels of predation from occuring. This result is contrary to the common wisdom described in prior literature. Jill's work followed up on work done by Doherty fellow Rachel Dicker (Bowdoin '08) that showed that Nucella laying behaviors in the field are non-random and are likely influenced by tidal height and exposure to predators and environmental stresses such as heat and desiccation.     Amanda Santoni ‘10 focused her research on another intertidal gastropod, the mudsnail Ilyanassa obsoleta. Amanda studied the effects of the presence of several predators on the laying behavior of Ilyanassa. She found that mudsnails respond to crab predators by increasing their investment in reproduction by laying more eggs in their benthic egg capsules. Amanda also found that Ilyanassa produce longer spines on their egg capsules in response to hermit crab predators, presumably as a mechanism for deterring predation on the eggs.     Cara Carne ‘10 investigated the effects of environmental changes in temperature and salinity on development in the seastar Asterias forbesi. Cara found that under some combinations of elevated temperature and reduced salinity, Asterias embryos undergo a dramatic twinning at the two-cell stage. This results in twin embryos that develop within a single fertilization envelope and hatch as normal looking embryos. This research has significant implications for changes in the recruitment of Asterias under changing climate conditions. Cara also examined the effects of natural variation in egg size on the larval development of Asterias. Unusually, this species produces eggs that vary up to twofold in volume within a singe clutch. The size of the egg leads to significant changes in developmental rate, as predicted by theory, but this has only rarely been demonstrated empirically.