By Alyssa Gehman
The Byers lab is gearing up for summer, growing from the three of us over the winter to a team of three graduate students, Alyssa Gehman, Jenna Malek and Linsey Haram, and two technicians, Kaitlin Kinney and Aaron Penn. In addition we have a great team of interns that will each be working with us. All are UGA undergraduates: Sarah Perry, Morgan Walker, Justyna Syzmonik, Jessica Story, Tim Montgomery, Allison Capper, Rachel Usher, and Lucas Montouchet.
Jeb Byers is here for a month, helping out with his students’ projects and tying up loose ends on some projects that have been going in full force out of SKIO over the last several years. These projects include work on oyster reefs, invasive seaweed, and marine parasites.
There are three main projects going on this summer:
Alyssa is working with parasites and their hosts that live in the marshes of coastal Georgia. She is interested in how host-parasite interactions will change with the increasing temperatures that will come with climate change. The parasite, Loxothylacus panopaei, is a barnacle that settles on its crab host, Eurypanopeus depressus, injects itself into the crab as a small worm-like animal which then grows tendrils that go through the crabs internal organs. When the parasite has established its adult infection the host is then castrated, and if it happens to be male it will be morphologically changed into a female (female crabs are also castrated, but they get to stay female). Once established the crab will live the rest of its life only producing parasite offspring. Alyssa will be working with this system to see whether parasites have thermal upper limit on reproduction, like their free-living counterparts.
Linsey studies the effects of the invasive seaweed, Gracilaria vermiculophylla, on salt marsh communities. The seaweed can be found in mats attached to native tubeworms in estuaries from the Southeast to New England. This summer, she and technician, Kaitlin Kinney, will investigate how decomposing G. vermiculophylla alters the biogeochemical characteristics of our mudflats. With the help of an REU student, Linsey will also investigate which invertebrate and fish species consume live G. vermiculophylla, if any.
Jenna is studying how environmental factors influence parasite infections and immune response in the Eastern oyster, Crassostrea virginica. For the last 2 summers she has conducted field experiments in Romerly Creek Marsh looking for effects of air temperature and predators on patterns of the oyster parasites Perkinsus marinus (casuese Dermo disease) and Haplosporidium nelsoni (causes MSX). The results of these experiments were largely inconclusive, leading to the development of an extensive laboratory project this summer trying to pinpoint the threshold of air temperature necessary to cause biologically significant changes in parasite infection incidence and severity, as well as immune response. Oysters collected from Priest Landing will be exposed to air temperature treatments ranging from 27-53 Celsius for 4.5 hrs each day to simulate intertidal exposure. Mortality, growth, and infection status will be determined for each individual oyster and a subsample of oysters will be tested for immune response. Her hope is to determine where along the air temperature gradient changes begin to occur, which will help to interpret her previous research and may have important implications for future restoration and conservation efforts in the face of climate change.