Largest red tide outbreak in 12 years in Massachusetts Bay monitored
Woods Hole Center for Oceans and Human Health cruise provided timely data for shellfish managers
With shellfish beds from Maine to Cape Cod coast closed from the largest outbreak of red tide in12 years in Massachusetts Bay, scientists from the Woods Hole Oceanographic Institution (WHOI) are studying the algae that causes these "red tides" and providing information to coastal managers using new molecular techniques and oceanographic models.
After a recent research cruise in which the extent of the bloom was revealed, the WHOI team will head to sea again Memorial Day weekend to continue monitoring the outbreak and sample areas throughout the Bay, including waters in Cape Cod Bay that rarely become toxic, but which are closed to shellfishing in some areas because of this bloom. Their data will again be shared with state officials and local shellfish managers given the significant public health concerns from this bloom. Shellfish contaminated with the red tide toxin, if eaten in enough quantity, can cause illness or death – a poisoning syndrome called paralytic shellfish poisoning, or PSP.
"The nor'easter May 7 and 8 off the New England coast was the perfect storm in terms of Massachusetts Bay red tide outbreaks," said WHOI Biologist and Senior Scientist Don Anderson, who has studied red tides and other harmful algal blooms for decades and is co-chief scientist of the current project. "All the conditions were right for a major outbreak of Alexandrium fundyense, the predominant red tide species in the Gulf of Maine. We've seen patches of red tide cells at the entrance to Massachusetts Bay just south of Cape Ann on other occasions, but often the winds and circulation patterns take them offshore. This time, we had high cell concentrations to the north, evidenced by very high levels of toxicity along the NH coast, and then the unusual winds and currents brought them into the Bay, where we found them in a broad distribution from Cape Ann to Stellwagen Bank."
As luck would have it, a WHOI team headed by Associate Scientist Dennis McGillicuddy and Anderson had a long-planned research cruise May 9-18 in the Gulf of Maine and Massachusetts Bay as a project for the Woods Hole Center for Oceans and Human Health (COHH). The cruise aboard the Institution's research vessel Oceanus was the first in a five-year COHH study of harmful algal blooms and their genetic diversity across the Gulf of Maine.
The team on Oceanus began collecting samples in the Bay about 2 a.m. on May 10 right after the nor'easter had passed through and immediately saw cells - more cells than expected.
"The cell counts we're getting are the highest they've been since the late 1980's," reported Bruce Keafer, leader of the at-sea Alexandrium sampling effort. Through daily email and cell phone contact with Anderson and state officials, the team relayed their cells counts so they could be compared with toxicity readings ashore. As his colleagues continued sampling to the north for Alexandrium cells, eventually reaching the Bay of Fundy, Anderson worked with state officials who were anxious for information on the nature of the outbreak, given the need to protect public health through timely shellfish harvesting closures. Anderson heads the U.S. National Office for Marine Biotoxins and Harmful Algal Blooms and is director of the Institution's Coastal Ocean Institute.
McGillicuddy, an Associate Scientist in the WHOI Applied Ocean Physics and Engineering Department, combined the biological observations from the cruise with ocean conditions into a computer model to help investigate these events. As the team measured ocean currents during the Oceanus cruise and incorporated that information into the model, other data was being received from a series of instrumented buoys from the Gulf of Maine Ocean Observing System (GoMOOS). By combining the cell counts and oceanographic and metrological conditions, McGillicuddy's team was able to quickly map the extent of the red tide bloom, continually updating the model as new data was received.
The Massachusetts Division of Marine Fisheries and other state agencies monitor Massachusetts Bay shellfish for annual red tide outbreaks. This year, these agencies were alerted to the possibility of Massachusetts Bay toxicity, given the patterns of toxicity in western Maine and New Hampshire. What they didn't know until the WHOI cruise was the extent of the outbreak and how abundant the toxic cells were.
The WHOI team filled in some of the information gaps by collecting samples at 160 stations along a series of transects from the coast offshore from Massachusetts Bay north to the Bay of Fundy, taking samples at three different water depths at each station. Samples were then quickly analyzed in the ship's laboratory under a microscope for visual identification and live red tide cells were counted. Using a novel method called a sandwich hybridization assay to unequivocally identify and count the Alexandrium fundyense cells, the shipboard team confirmed that toxic cells were indeed present in the Bay, and in waters to the immediate north.
Simultaneously, Anderson and his research team ashore were helping to map the toxic cell distribution with a different method they had developed several years ago for rapid cell identification and enumeration. Funding to develop this method, known as whole cell hybridization, was provided by the NOAA National Ocean Service's Center for Sponsored Coastal Ocean Research (CSCOR). In the past, it would have taken weeks or even months to count the many samples that were coming ashore, but with the new method, the maps of cell abundance were available in 1-2 days. This information was of direct value to health officials, who otherwise would have had to make difficult decisions about possible shellfish closures based only on the toxin levels measured in the shellfish. Knowledge of the widespread distribution and high abundance of the bloom convinced officials to err on the safe side and close the shellfish beds quickly and expand their sampling into areas that are not typically monitored.
"Using the information from sea and this new technique, we were able to map out the distribution of Alexandrium fundyense within a very short time," Anderson said. "This is the type of information shellfish managers need quickly so they can make informed decisions."
"The current bloom is big, much larger in fact than the last outbreak in the Bay 12 years ago, and much more widespread" added Anderson. "This is an unusual event."
The reasons why are unclear. Both Anderson and McGillicuddy say the current outbreak could reflect a number of factors. They include the "perfect storm" idea where all the conditions were right to introduce cells into the Bay from the north, but also point out that there may be more "cysts" of Alexandrium in the western Gulf of Maine sediments than in the past, as a result of a major red tide bloom last fall. Cysts remain dormant in sediments until conditions are favorable for germination and growth, leading to a bloom in subsequent years. Another possibility is that there is more freshwater entering the coast of the Gulf of Maine this year than has been the case for over a decade, reflecting the abundant rainfall this spring and the heavy snowfall over the winter. This freshwater provides the hydrographic conditions that can lead to optimum growth of Alexandrium cells.
The scientists may get more answers when they head to sea again this weekend. This time the WHOI researchers will use the Institution's new 60-foot coastal vessel Tioga, designed for rapid response to such events. They plan to revisit some of the same sites and resample, as well as fill in the gaps by mapping and sampling areas further to the south into Cape Cod Bay to see how far the bloom has penetrated. Toxicity has already been detected in shellfish in Sandwich on Cape Cod for the first time since the last major red tide outbreak in 1993. The WHOI efforts will be part of a coordinated sampling program involving the Massachusetts Department of Marine Fisheries, the Center for Coastal Studies in Provincetown, and other agencies.
NOAA's CSCOR program is helping again, this time by providing the rapid response funds for McGillicuddy and team to get out into the Bay to sample directly after another nor'easter passes through the region. What the next storm will do to the conditions and how it will affect the bloom is unknown.
Anderson says the ability to respond rapidly to these outbreaks, to collect and share data quickly with state agencies and local officials, is the wave of the future. "This project is a great example of how some of the new technologies we are developing can help these groups to work together to meet a societal need." He says he expects to see automated instruments on buoys at sea in the future, collecting information and relaying it ashore where it can then be used in numerical models to make forecasts - a huge technological step forward in red tide research. The sandwich hybridization technique that they used on board the Oceanus can be run in automated fashion inside moored instruments in these observatory arrays, providing early warning of red tide cells and toxins.
Despite the shellfish closures, "the public should not be afraid to eat shellfish, as the states have very good monitoring programs," Anderson said. "People should just be aware of and observe the signs posted at areas closed to shell fishing. If they are going to harvest shellfish, check with their local officials for the latest information."
Long after this bloom has dissipated, Anderson and McGillicuddy plan to conduct a series of sampling cruises in 2007 as part of the five-year COHH program in the Gulf of Maine and Massachusetts Bay. PSP has long been a problem in the region, and is not expected to disappear any time soon. The Woods Hole COHH, which McGillicuddy serves as deputy director, is one of four such centers in the nation funded by the National Science Foundation and the National Institute of Environmental Health Sciences (NIEHS), one of the National Institutes of Health. Scientists from the Woods Hole Oceanographic Institution (WHOI), Marine Biological Laboratory (MBL) and the Massachusetts Institute of Technology (MIT) formed the Woods Hole Center for Oceans and Human Health (COHH) in 2003. With administrative offices at WHOI, the Woods Hole COHH serves as a focal point for research on issues at the intersection of oceanographic, biological and environmental health sciences, such as red tides , harmful algal blooms and other organisms in coastal waters and estuaries that cause human illness and death.
Source: Eurekalert & othersLast reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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