The effects of phytoplankton patches and fluctuating salinity on protein expression and the behavior of echinoderm larvae in haloclines

Dr. Sophie George
Georgia Southern University

A regular occurring event in the coastal waters of the Pacific Northwest is a decrease in salinity to less than 15‰ in some areas, as a result of increased precipitation and ice melts during the spring and summer months. George and Walker (2007) and Pia, Johnson, and George (2012) observed salinity-induced morphological changes for Dendraster excentricus and Pisaster ochraceus larvae.









For example, Pisaster larvae reared at 20‰ were shorter and wider while those reared at 32‰ were longer and slender. The development to metamorphosis and the production of juveniles by larvae exposed to 20‰ (juvenile P. ochraceus) in of itself is intriguing given that these species cannot regulate the osmolarity and ion content of their internal fluids. These studies indicate that the timing, magnitude and duration of ice melts and rainfall in the Pacific Northwest could alter larval morphology, larval feeding and swimming, and possibly the quality of new P. ochraceus recruits into the intertidal zone in the Puget Sound.

During the summer of 2017, research will continue looking at larval behavior of P. ochraceus in haloclines with and without food. Students will also investigate the effect of multiple low salinity events on protein expression in P. ocraceus larvae. Knowledge on larval behavior in haloclines would enhance our understanding of how echinoderm larvae will respond to changes in surface salinity as a result of climate change.

The participating student would learn to prepare algal cultures; rear larvae to metamorphic competency, observe larvae in haloclines, prepare samples for protein determination and gel electrophoresis, and photograph larvae from the various treatments.









Past students have presented their research at regional (GAS) and international meetings (SICB), and are coauthors on 3 recent articles from research at FHL with one submitted to Marine Ecology Progress Series with minor revision and two in preparation:

  • George, Sophie B. & Walker, Devoc. 2007 Short-term fluctuation in salinity promotes rapid development and metamorphosis of Dendraster excentricus larvae Journal of experimental marine Biology and Ecology. 348:113-130.
  • George, Sophie B., Fox, Colleen & Wakeham, Stuart 2008. Fatty acid composition of larvae of the sand dollar Dendraster excentricus (Echinodermata) might reflect FA composition of the diets Aquaculture 285: 167-173.
  • Tanya Pia; Johnson, Tiffany and George, Sophie 2012. Single and multiple fluctuations in salinity affect growth, development and metamorphosis of the sea star Pisaster ochraceus. Journal of plankton research 34:590-601.
  • Sam Bashevkin, Daniel Lee, Paul Driver and Sophie George. Vertical distribution of brachiolariae larvae in haloclines is influenced by prior exposure to low salinity. In prep.

Past Blinks-REU-BEACON interns and graduate students listed in bold.

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