Page 12. MAINE COASTAL NEWS May 2013


Commercial Fishing News MISCELLANEOUS COMMERCIAL FISHING NEWS


Continued from Page 11.


Center for Sponsored Coastal Ocean Research. “It is a clear example of how research authorized by the Harmful Algal Bloom and Hypoxia Research and Control Act can protect both public health and local


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economies through collaborations between academic scientists, state and federal regu- latory agencies, and the shellfi sh industry.” An elevated area of the sea fl oor be- tween Cape Cod and Nova Scotia, Georges Bank is one of the best fi shing grounds on Earth. But since 1990, it has been closed to harvesting of surf clams and ocean quahogs after harmful algal blooms (also referred to as “red tides”) caused paralytic shellfi sh poisoning (PSP) that sickened fi shermen. For decades scientists speculated the blooms on Georges Bank were fueled by coastal blooms in the Gulf of Maine. More recent research by GOMTOX investigators, however, has shown that Georges Bank is home to a separate and distinct population of the toxic algae, which is described in a recently published paper by Woods Hole Oceanographic Institution (WHOI) scientist Dennis McGillicuddy and other members of the GOMTOX team. It has been known for many years that the phytoplankton Alexandrium fundyense is the cause of the harmful algal blooms that occur to varying severity each spring and summer along the coastal Gulf of Maine, sometimes extending as far south as Cape Cod and the adjacent islands. The algae’s seed populations or “cysts” germinate from seabeds starting in early spring and bloom at the sea surface, until all of the necessary nutrients in the water are consumed. As the nutrients run out, the cells form cysts and fall to the seafl oor, as seed for the following spring. High concentrations of the toxic al- gae can cause closure of shellfi sh beds and cost the region many millions of dollars. Precisely why the blooms vary in sever- ity has been much more diffi cult to deter- mine, and has involved extensive seasonal sampling of water and sediments, study of coastal currents, environmental and oceano- graphic conditions, availability of nutrients, and the development of a computer program to model all of the variables. Researchers got the fi rst signal that something very different was happening on Georges Bank during a research cruise to count Alexandrium cells in sea water sam- ples in spring/summer 2007. “We devised our sampling strategy to look at the cells’ transport pathways from coastal waters onto the Bank,” says McGillicuddy. Throughout the coastal Gulf of Maine, the numbers were very low. But when the research team started sampling at Georges Bank, they found very high concentrations of Alexandrium in the water, despite the fact that the bloom had not really begun along the coast of Maine. “I’ll never forget the moment we hit a big patch of cells on Georges Bank,” says Dave Townsend, a GOMTOX scientist from the University of Maine and co-author of the paper. “We extended our sampling to go all


the way across Georges Bank and we were still hitting them. We had to turn around and completely reorganize our sampling strategy based on what we were seeing in the microscope.” For such a large bloom to occur, the researchers reasoned the number of cysts on Georges Bank must be similar to the quan- tities needed to initiate a bloom along the coast. Yet, their fall 2007 survey to map the cyst distribution in the seabed on the Bank found very few cysts – quantities not likely to cause a large bloom along the coast. In the three-year course of intensive


study on Georges Bank since then, blooms have occurred every year, in concentrations that would typically lead to toxicities in coastal shellfi sh beds. Yet, a parallel effort by the fi shing industry and federal testing labs to analyze shellfish samples from Georges Bank found the bivalves to be clean of toxins. So while toxins were produced at and near the surface, they were not delivered to the surf clams and ocean quahogs in the seabed in quantities suffi cient to threaten human health.


The system on Georges Bank was in- deed a riddle: Few cysts, yet large blooms; a large bloom, yet little to no toxicity in the shellfi sh. Applying the same detailed analyses to the offshore population of Alex- andrium that they applied to coastal popula- tions, the scientists discovered the optimum growing conditions for Alexandrium on Georges Bank were colder and saltier than those of their coastal relatives. Their analy- sis uncovered how the currents in the region can isolate Georges Bank to create colder and saltier conditions. If the conditions are favorable, the researchers say, Alexandrium populations can double every three days, and in a month’s time, grow from concentrations of 10 cells per liter to 10,000. Further setting the Georges Bank pop- ulation apart was the fi nding by GOMTOX colleagues at University of Massachusetts, Dartmouth’s School for Marine Science and Technology (SMAST), working in col- laboration with the FDA, who determined that the toxin content of algae on Georges Bank was different than the coastal Gulf of Maine populations. “The toxins present in Alexandrium cells from Georges Bank were, on average, two times lower than those in the coastal Gulf of Maine,” said Chrissy Petit- pas, a doctoral student working in Professor Jefferson Turner’s lab at SMAST. Despite this new information and the knowledge that the clams have been shown to be safe for humans to eat at the present time, the fact remains that concentrations of the toxins in the clams on Georges Bank in 1989 and 1990 did reach dangerous lev- els. Scientists know that coastal shellfi sh populations are directly exposed to the


toxins when the blooms make landfall, but they remain uncertain about the conduit for toxicity from the surface ocean to the deep shellfi sh beds on Georges Bank, located at about 50m depth.


But, thanks to an innovative screening protocol and regulatory structure developed collaboratively by the FDA, NOAA’s Na- tional Marine Fisheries Service, the fi shing industry, and testing labs approved by the National Shellfi sh Sanitation Program, a system is now in place to monitor, test, and verify that clams harvested from Georges Bank are safe. The clams are checked by fi shermen at sea using the newly avail- able test kit, and re-checked by regulators when the fi shing vessels reach the dock. Combined with the weekly monitoring of shellfi sh beds along the coast during the bloom season to protect human health, these monitoring systems are extremely effective at keeping toxic shellfi sh off the market. Toxin levels in shellfi sh on Georges Bank have been very low over the last few years. We are confi dent that this new testing protocol will serve to protect public health should toxin levels rise again in the future,” said Stacey DeGrasse, seafood research co- ordinator in the FDA’s Offi ce of Regulatory Science and a major participant in the devel- opment of the new offshore testing protocol. “We intend to continue to work closely with NOAA to ensure that the shellfi sh from this region are harvested safely.”


“I’ve run over 2,500 samples from


Georges Bank since mid-March, and all of them have been clean of toxin,” says Darcie Couture, a former manager of the marine biotoxins program at the Maine Department of Marine Resources, who now operates the federally permitted testing lab. “We’ve been fortunate in fi nding a way that we can safely harvest that product out there.” “Although we can’t predict when conditions on Georges Bank will favor a large bloom, our knowledge of the bloom dynamics was used in establishing a suitable management approach,” says Don Ander- son, a senior scientist at WHOI and the lead investigator on the GOMTOX project. For the scientists, the work to under- stand the dynamics of the Georges Bank population continues. New DNA evidence uncovered by Woods Hole Center for Oceans and Human Health researchers Dea- na Erdner (University of Texas) and Mindy Richlen from Don Anderson’s laboratory at WHOI, suggests the Georges Bank Alexan- drium population is genetically distinct. “We thought the Georges Bank popu- lation was just the little toe at the end of the coastal population, but it’s not. It is separate, and it occupies a distinct niche from the rest of the Alexandrium in this region,” says McGillicuddy. “This was a big surprise to us.”


The research was funded, in part, by


NOAA’s NCCOS, with additional support provided by NSF and NIEHS through the Woods Hole Center for Oceans and Human Health.


The Woods Hole Oceanographic Insti- tution is a private, non-profi t organization on Cape Cod, Mass., dedicated to marine re- search, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the oceans and their interaction with the Earth as a whole, and to communicate a basic under- standing of the oceans’ role in the changing global environment.


Explorer and Filmmaker James Cam- eron Gives DEEPSEA CHALLENGER Sub to Woods Hole Oceanographic Institution


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