NECAN industry webinar series: OCA impacts on shellfish hatcheries

Time: Tue, Sep 18, 2018 8:00 PM – 9:00 PM CEST

Presentation Abstracts:

Michael Congrove, Oyster Seed Holdings
In Search of a Solution to the Shellfish Hatchery Water Quality Puzzle
Shellfish aquaculture production has seen a steady rise worldwide for the last 40 years. Integral in this has been the ability to consistently produce vast amounts of shellfish larvae in increasingly sophisticated shellfish hatcheries. The fact that these hatchery’s primary task is culturing a calcifying larval organism, a fraction of a millimeter in ultimate size, make them uniquely susceptible to the effects of ocean acidification and/or coastal acidification. Increasing frequency of unexplained poor larval production has spurred commercial shellfish hatcheries in Virginia to loosely organize around the common goal of better understanding the effects of variable ambient water quality on larval production success. Carbonate chemistry being one, albeit big, piece of the total water quality puzzle. This presentation will explore the water quality puzzle and efforts to solve it, as it pertains to shellfish hatcheries from the perspective of Oyster Seed Holdings, a commercial oyster hatchery located on the western shore of Chesapeake Bay in mesohaline waters.

Alan Barton, Whiskey Creek Shellfish
Over the past decade, the Pacific Northwest Shellfish Industry has been grappling with the effects of Ocean Acidification on commercial production of Pacific oyster larvae. The region is characterized by strong summertime upwelling, which brings naturally acidic deeper ocean water up onto the Oregon and Washington continental shelf. As such, our region is already ‘on the edge’ of the saturation state threshold required for normal larval shell development. The added impacts of human-induced acidification observed over the past decade pushed our coastal bays over this threshold, leading to devastating seed production failures from 2007-2009. Our industry has made a great deal of progress in understanding, and adapting to OA in recent years, and have restored much of our historic production through coordinated monitoring up and down our coastline along with development of treatment systems in commercial hatcheries. These efforts have not only allowed us to address the direct effects of OA on initial larval shell development, but have greatly improved our understanding of secondary and tertiary factors affecting production, as the advance of OA in our region alters the way our coastal ecosystems function.

Bill Mook, Mook Sea Farm
In 2009, Mook Sea Farm, an oyster farm and hatchery in Maine, began experiencing larval production problems. These problems included the occasional failure of fertilized eggs to become viable larvae, but more often, prolonged larval durations. Larval production was highly unpredictable. West Coast hatcheries had recently experienced similar larval production problems which were determined to be caused by decreased calcium carbonate saturation states in their incoming water. In contrast to the West Coast, our water’s decreased saturation states resulted from a combination of increased atmospheric CO2 and increased freshwater runoff from heavy precipitation events. Hatchery production was restored to better than pre-2009 levels by buffering all seawater used for larval and juvenile production in the hatchery. We use inexpensive pH meters and controllers to maintain the pH in our hatchery culture systems. Along with increasing atmospheric CO2, precipitation in the Northeast is projected to increase in spring and fall months. While we can control seawater chemistry in the hatchery, many questions remain about the extent to which coastal acidification will affect juvenile and market oyster grow out at our lease site. In 2014, working with Dr. Joe Salisbury of UNH we installed sophisticated seawater monitoring equipment to help us answer some of these questions.

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