Interactions between bivalves and seagrass in a changing ocean
For my dissertation, I am studying interactions between bivalves and seagrass in the labs of SDSU marine ecologist Dr. Kevin Hovel and UC Davis marine ecologist Dr. Jay Stachowicz. I primarily focus on interactions between eelgrass Zostera marina (the species of seagrass that grows in California), and the many bivalves that grow among eelgrass, such as clams, mussels and oysters. Studies that have examined interactions between bivalves and eelgrass have sometimes found that bivalves have a positive effect on eelgrass, such as by filter feeding, which increases water clarity and the light that can reach photosynthesizing eelgrass. However, some studies have found that bivalves have a negative effect, such as by competing for space (especially invasive species) or increasing sulfide intrusion in eelgrass routes. I am investigating whether environmental conditions, such as temperature or water clarity, may be key to understanding variability in bivalve-eelgrass interactions. Water clarity is reduced via eutrophication, and climate change is leading to increased temperatures, so these studies will help us understand how human activities will alter species interactions in eelgrass beds.
Seagrass beds are important habitat for many species, and act as nursery grounds for many commercially important species, such as Blue crabs in the Chesapeake Bay. Seagrass also provides a number of ecosystem services, such as carbon sequestration and sediment stabilization. Understanding how anthropogenic changes are affecting seagrass communities is vital for moving forward with conservation of these incredibly important ecosystems.
Ecology of harmful algal blooms
As an undergraduate at the University of Connecticut, I studied how grazing by copepods stimulated toxin production by the dinoflagellate Alexandrium catenella in the lab of biological oceanographer Dr. Hans Dam. A. catenella produces toxins as a defense mechanism; blooms of this algae and other similar species can lead to red tides. Consumption of shellfish which have filter-fed on toxic algae can lead to paralytic shellfish poisoning. We examined the relative importance of nitrogen resources, alarm cues from other algae, and grazer cues on toxin production of A. catenella. We found that grazing by copepods has a large and significant effect on dinoflagellate toxin production, which was much higher in the presence of grazers. Surprisingly, we also found that toxin production was stimulated by exposure to algal alarm cues from other species more than from algae of the same species.
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Publication: Griffin, J.E., G. Park, and H.G. Dam. 2019. Relative importance of nitrogen sources, algal alarm cues and grazer exposure on toxin production of the marine dinoflagellate Alexandrium catenella. Harmful Algae 84: 181-187. https://doi.org/10.1016/j.hal.2019.04.006
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Mysid feeding preferences
Publication: Griffin, J.E., B.P. O'Malley and J.D. Stockwell. 2020. The freshwater mysid Mysis diluviana (Audzijonyte & Väinölä, 2005) (Mysida: Mysidae) consumes detritus in the presence of Daphnia (Cladocera: Daphniidae). Journal of Crustacean Biology 40. https://doi.org/10.1093/jcbiol/ruaa053
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I completed a National Science Foundation Research Experiences for Undergraduates Program at the University of Vermont in 2016, where I studied the feeding preferences of lake invertebrate Mysis diluviana in the lab of aquatic ecologist Dr. Jason Stockwell. Mysids exhibit diel vertical migration, spending the daytime in the benthic zone, and migrating upwards to the pelagic zone at night to consume plankton when fish are less likely to attack. So, researchers have generally thought that food resources available in deep waters were unimportant. By conducting food preference experiments, however, we found that mysids consume benthic detritus even in the presence of pelagic plankton. So, benthic resources are more important for mysid biology than previously thought!
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See my latest work on my Google Scholar page: https://scholar.google.com/citations?user=dWPDFaMAAAAJ&hl=en&oi=sra
and my ResearchGate account: https://www.researchgate.net/profile/Jessica_Griffin9
and my ResearchGate account: https://www.researchgate.net/profile/Jessica_Griffin9