Hatchery studies links between ocean acidity and shell formation

Shellfish in Alaska’s near-shore waters have started to show problems growing their shells from the calcium and carbon found in seawater. On shore, Alutiiq Pride Shellfish Hatchery specializes in providing optimum conditions for shellfish — in tanks. The hatchery in Seward has joined a NOAA monitoring program designed to understand ocean acidification. For its part, the hatchery will collect samples to precisely determine the amount of calcium carbonate dissolved in near-shore waters of south-central Alaska. Alutiiq Pride has the right equipment to do that. It also occupies a pivotal location on Resurrection Bay and has a network of sample takers deployed across Prince William Sound and up into Cook Inlet.

Every week for the next year or possibly two, employees of Village Councils will collect samples of seawater from the surface near the shore and send them to the laboratory at the hatchery. The samples will come from Tatitlek, Eyak, Chenega, Seward, Kasitsna Bay, Nanwalek, Port Graham, and other locations in between and farther on. With the same instrument used regularly to monitor the hatchery’s tank water, the laboratory will measure amounts of calcium carbonate, also known as aragonite, in the samples. The data will go directly to the Pacific Region Ocean Acidification program started by NOAA.

Additionally, through its recently established shellfish research laboratory, the hatchery plans to manipulate conditions of acidity (pH) and dissolved calcium carbonate in isolated tanks to learn better, the minimum and maximum conditions various species of shellfish can tolerate. A better understanding of shell problems will come from comparing ocean conditions with tank observations. The shellfish research laboratory has an instrument known as a “burke-o-lator” that can determine the total carbonate chemistry of a sample of seawater in a matter of minutes and then upload the data for display on government and university websites.

The working scientific hypothesis has it that, as carbon dioxide in the atmosphere increases, the ocean absorbs more of it. This increases the amount of bi-carbonate in the water and thereby decreases the amount of free carbonate needed by shellfish. Simultaneously, ocean acidity (lowered pH) also increases in the form of excess hydrogen. Excess hydrogen interferes with the ability of shellfish to form shells made of that form of calcium carbonate known as aragonite. In effect, ocean acidification reduces the saturation of aragonite in the water and shellfish without shells, die.

Jacqueline Ramsay, a UAF graduate, works as a biologist and describes herself as a bench scientist at the Alutiiq Pride shellfish research laboratory. She has always worked with shellfish and worked with snow crab physiology as a graduate student. She wants to understand the saturation of aragonite in seawater from a shellfish perspective.

Ramsay tells the background story of the hatchery‘s scientific monitoring.

“Years ago we started hearing about failures from shellfish growers on the west coast, in Washington … They were trying to find out why the shellfish populations were just crashing, their spat [juvenile shellfish] were just dying overnight. They found out that anthropogenic carbon would come up during upwelling events, carrying bitter water … Since we knew that the oceanographic trend was happening globally, we wanted to find out when it was going to start affecting Alaska. We put the monitoring system in place four years ago to try to find out what does our water look like now and what is coming.”

“The Alutiiq Pride Shellfish Hatchery was approached by Burke Hales [inventor of the burke-o-lator instrument] and Wiley Evans and Jeremy Mathis of UAF. The three of them were working on getting sensors on buoys and ships and we wanted them to put one in our hatchery … since we are the only shellfish hatchery in Alaska … We have monitors on buoys, on moorings, but that open-water environment is continuous, homogeneous … The near-shore environment is very messy … For us, perhaps wanting to do out-plants, bringing species back to areas where they are no longer … we’ll have some data going back, monitoring what those waters were doing at that specific site. We have a lot of interest in putting out clams in Port Graham.“

When asked if sampling could determine whether water chemistry varied site by local site, Ramsay answered, “I have no idea. We don’t really have a hypothesis as to what we’re going to find. We were pretty surprised to find [in Resurrection Bay] that we had two distinct times of year that were opposite [for amounts of aragonite] each other. We attribute that to lots of rain and snow melt events and freshwater outflows … We’re just trying to put the headlights on the car right now to see what’s out there … With the ability to raise a lot of larvae here in the hatchery and the ability to see what our saturation points are and to manipulate those through our dosing laboratory, we can see which species like which saturation levels … We know that the larval stage is the most vulnerable life stage for the shellfish.”

About long-term monitoring, Ramsay said, “Well, one step at a time. Funding being what it is … hopefully, we can keep a monitor like this going. Hopefully, we can have a snapshot for at least a year, maybe two years at these sites to learn what is happening at these sites over an annual cycle.”

Ramsay concluded, “I really think that we need to get the word out that this is happening and we need to be monitoring for it; we need to take it [increasing carbon dioxide in the atmosphere] seriously. We’re changing this planet radically and quite quickly.”

Jeff Hetrick runs the shellfish hatchery and expresses his passion for growing seafood by understanding the underlying science. He seems pleased with his $75,000 monitoring instrument. Hetrick said that a technician from NOAA’s pacific marine environmental laboratory in Seattle calibrates the instrument. NOAA manages the ocean acidity monitoring program that the hatchery has joined. The program has many sponsors and participants.

Hetrick says, “There are other machines out there, but they aren’t operating at near the level we are. We are operating out to four decimal points of accuracy. Through time, we hope to achieve that blue ribbon rating where people will send us samples to find out the real values [of total dissolved carbonates].

The hatchery brought its sample gatherers with their first samples to town for a training session on St. Patrick’s Day. It expects a regular stream of samples as soon as next month.

Rick Smeriglio, Seward City News, 23 March 2016. Article.

  • Reset


OA-ICC Highlights

%d bloggers like this: