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The Hunt for Oxylipins

Updated: Aug 7

NOAA Salstonstall-Kennedy Grant

Virginia Institute of Marine Science 2022-2023


Objectives:

1. Characterize oxylipins and potential sources in incoming seawater at three East Coast hatcheries

2. Relate oxylipin abundance with hatchery performance during two seasons at MSF.

3. Determine the effect of oxylipin on larval development and water-treatment solutions experimentally.




OSH Contributing Research to NOAA Fisheries Grant


In 2022, Dr. Juliette Smith, a VIMS associate professor in the Aquatic Health Sciences Department, received a NOAA Salstonstall-Kennedy Grant to better understand how a suspected harmful byproduct of phytoplankton is impacting hatchery larvae.

Hatcheries are particularly vulnerable to changes in water quality because they rely on a sole source of water, adjacent to their ‘bricks-and-mortar’ hatchery site. One of the constantly changing dynamics of water quality is phytoplankton populations, which change in type and quantity all through the year. Some of these phytoplankton populations produce compounds that are highly bioactive and can impact other planktonic organisms.


Shellfish larvae are planktonic organisms, except that in a hatchery they are of course contained in a manmade system. Nonetheless, bioactive compounds that occur in the water can wind up in the hatchery, in various ways.

Hatcheries have water purification techniques, of course. But some of those techniques can actually make the problem of bioactive compounds worse. For example, mechanical filtration can break open phytoplankton cells and release internal compounds that would normally be present in miniscule quantities. Also, UV irradiation, used to suppress bacterial populations, can modify bioactive compounds by photo-oxidation and release them into the hatchery tanks.




Looking for Oxylipins


It was UV filtration that first caught the attention of a team that was assembled to accomplish this work. One of the east coast’s leading oyster hatcheries, Mook Sea Farms in Walpole, ME, determined that some of the larval issues they were seeing was a result of UV treating the water. The symptoms they observed were that larvae were not digesting their food (algae that the hatchery supplies to them) and did not grow, ultimately dying. This was further traced to a bioactive compound in the water categorized as an oxylipin, a class of fatty acid that regulates a variety of physiological processes in plants and animals.

Do oxylipin compounds cause issues with larval feeding and health? OSH, through its many seasons of existence, has seen symptoms in larvae nearly identical to those observed by Mook Sea Farms, although there has never been an attempt to identify causative suspects. Through Smith’s project, the hunt is on! Oxylipins, the suspect. Since the initial observations, Smith’s lab has identified ~5 more oxylipins in hatchery water.

OSH is one of three east coast hatcheries participating in the research to search for oxylipins along with Mook and Fishers Island Oyster Farm in New York. Smith’s lab is also collaborating with a University of California Berkeley lab that has complimentary special instrumentation to detect oxylipins.


One very good reason that these compounds have remained at large is that they are exceedingly difficult to detect – remaining silent killers for a commercial hatchery. Information gained about oxylipins will be used by VIMS researchers to test mitigation strategies for dealing with this problem and, for Smith Lab, to explore ways for growers to avoid or minimize its symptoms and impacts.


See more about about funding sources and team here.



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