Stony Brook, NY, May 9, 2011 - Harmful algal blooms, increasing globally, have negative effects on fisheries and economies. In a recent article in The Southampton Press, Stony Brook University (SBU) researcher Dr. Christopher Gobler, discusses some related water quality issue influences (such as nitrogen inputs feeding waves of algae blooms) and effects (such as shellfish population reductions).
“Harmful algal blooms are not a new phenomenon, although many people may know them by other names such as red tides or brown tides,” says Gobler. “These events can harm humans by causing poisoning of shellfish and can damage marine ecosystems by killing fish and other marine life.”
Brown tides are caused by a proliferation of single-celled marine plants called phytoplankton. One species of phytoplankton, the microscopic alga Aureococcus anophagefferens, blooms in such densities at times that the water turns dark brown, a condition known as "brown tide."
It has been hypothesized that A. anophagefferens blooms establish and maintain themselves at least in part by drawing concentrations of recycled nitrogen from the ecosystem - in the form of ammonium, urea, and other dissolved organic nutrients - down to such low levels that no competing phytoplankton can match its net growth rate. However, prior to a 2010 New York Sea Grant (NYSG)-funded research project, no field study had examined how the whole plankton community changes during brown tides or had measured the incorporation of specific nitrogen compounds by individual species during brown tides, despite the important managerial implications of how these blooms acquire nitrogen.
This study, conducted by SBU's Gobler and Dr. Jackie Collier, combines traditional and molecular genetic techniques to characterize the entire plankton community (phytoplankton, bacteria, small zooplankton) during bloom and non-bloom conditions, to track the incorporation of nitrogen from nitrate, ammonium, urea, and glutamate into the DNA of A. anophagefferens and other plankton, and to directly examine the physiological status of A. anophagefferens. Analysis is currently underway for samples collected in 2008 and 2009.
In a separate project - part of $1.28M in Long Island Sound Study research grants awarded this past March by Sea Grant programs of Connecticut and New York - Gobler has begun a study to determine possible anthropogenic causes of fundamental changes in the Sound that may encourage toxin-producing algal bloom events. The blooms can cause PSP and DSP, two different types of shellfish poisoning that impact human health. In early May 2011, Gobler discussed findings from this and other related Sound studies at the New England Estuarine Research Society meeting in Port Jefferson, NY.
"Nitrogen plays an invaluable role in society as fertilizer, but we know that too much nitrogen in coastal waters such as Long Island Sound can degrade water quality and contribute to harmful algal blooms," says Mark Tedesco, director of the Environmental Protection Agency's Long Island Sound Office, which manages the Long Island Sound Study partnership, and provided the funds for the Sea Grant-administered research projects.
In another recent study, Gobler and SBU's Dr. Robert Aller examined the role of sediments in nitrogen cycling and eutrophication in the Peconic Estuary, a system of bays on eastern Long Island. Over the last three decades, the bays have seen an increase in nuisance or harmful algal blooms — first brown tide and more recently, red tide. This may indicate that there are more nutrients in the water, perhaps caused by nitrogen-rich runoff and groundwater inputs which hasten the process of eutrophication and “feed” algal blooms.
Perhaps one of the biggest brown tide findings, though, came this past February, when Gobler announced findings from another investigation, one in which he led a team of researchers that had sequenced and annotated the first complete genome of a harmful algal bloom (HAB) species, A. anophagefferens. The article, entitled, “Niche of harmful alga Aureococcus anophagefferens revealed through ecogenomics,” appeared in the February 21 online Proceedings of the National Academy Sciences.
"I think this paper says it all,” says Don Anderson, Director of the U.S. National Office for Harmful Algal Blooms and a senior scientist at Woods Hole Oceanographic Institution in Falmouth, Massachusetts. “Here’s a species that blooms and for years people have been trying to understand why it blooms, when it blooms, how it is able to do that when there are so many other competing species in the water with it? With this new genomic data you have a new approach. You’re getting answers based on the genes, though you still need other approaches that are more oceanographic and chemical to go along with the inferences drawn from the presence and absence of genes. It’s a great advance. It’s a great resource for our community – the more we learn about Aureococcus, the easier it’s going to be learn about the other HAB species.”
Dr. Gobler’s genome study also opens the door for future research. One specific field of study that arose from the data involves nitrogen utilization genes. “We know as a bloom occurs, the level of organic nitrogen in the estuary are high, but do we see organic nitrogen utilization genes expressed in Aureococcus as a bloom occurs?” questions Dr. Gobler. “Beyond gene expression, proteomics and looking at proteins synthesized during blooms are also other areas of future research.”
The study provides a greater understanding of this organism and how the information can be used to protect our waters. “We now know that this organism is genetically predisposed to exploit certain characteristics of coastal ecosystems,” notes Dr. Gobler. “But we also know the characteristics are there because of activities of man. If we continue to increase, for example, organic matter in coastal waters, then it’s going to continue to favor brown tides since it’s genetically predisposed to thrive in these conditions. We believe the same genome-enabled approach used for this study can be applied to other HABs in the future.”
New York Sea Grant (NYSG), a statewide network of integrated research, education, and extension services promoting the coastal economic vitality, environmental sustainability and citizen awareness about the State's marine and Great Lakes resources, is currently in its 40th year of "Bringing Science to the Shore." NYSG, one of 32 university-based programs under the National Sea Grant College Program of the National Oceanic and Atmospheric Administration (NOAA), is a cooperative program of the State University of New York and Cornell University.