Researchers at the Woods Hole (Mass.) Oceanographic Institution plan to use genome technology to examine how nutrient pollutants may cause brown tides and influence their duration on the U.S. East Coast. The U.S. National Oceanic and Atmospheric Administration (NOAA) awarded the institution $120,000 for the anticipated 3-year, $500,000 project to determine how nitrogen and phosphorus promote brown tides, according to a NOAA news release.
According to NOAA’s project summary, despite many years of study and knowing that brown tides are caused by the algae species Aureococcus anophagefferens, fundamental questions remain regarding how nutrients drive harmful algal blooms (HABs).
The Woods Hole Oceanographic Institution’s research uses the recent completion of the HAB genome sequence for A. anophagefferens and preliminary gene expression work on the species to track the nutritional physiology of the algae in its natural environment.
“Until gene activity of individual organisms could be monitored, it was only possible to measure nutrient utilization of the whole community of organisms in the water,” said Quay Dortch, an oceanographer at NOAA’s National Center for Sponsored Coastal Ocean Research office. “It was nearly impossible to determine what specific nutrient(s) were fueling the growth of the brown tide. This new approach will allow the specific nutrient requirements of the brown tide to be determined.”
Brown tides cause damage to coastal habitats and to scallop and hard-clam fisheries from Rhode Island to Virginia, the news release says. However, brown tides are unusual because they occur when a certain type of inorganic nitrogen is in low supply.
It is hypothesized that excesses of other nutrient types, mainly organic phosphorus and nitrogen in aquatic ecosystems, contribute to the development of brown tides, the news release says. Determining the nutrient conditions that trigger brown-tide blooms will help with predicting and preventing them. Knowing the genome sequence of the brown-tide organism also enables researchers to observe changes in the cells’ genes as conditions change, the news release says.
The Woods Hole Oceanographic Institution’s research seeks to answer the question of what types of dissolved inorganic nitrogen and phosphorus are preferentially transported and metabolized by cells during blooms, and how nutrient transport and metabolism change as a function of ambient conditions as blooms initiate, are sustained, and decline, according to the project summary.
“Gene activity of all organisms changes as they respond to their environment,” Dortch said. “In this project, knowing the genome sequence allows researchers to observe changes in the genes being actively used by the cell as nutrient conditions change in nature. By monitoring which genes are ‘turned on’ over the course of a bloom, they can track how and which nutrients are used by the organism for growth.”
Brown-tide algae are unusual, blooming when inorganic nitrogen, usually preferred by algae, is in low supply. The algae also grow well when consuming organic nutrients, such as urea and amino acids, Dortch explained.
“The aim in the long run is to understand the nutrient requirements of the brown tide so well that you can predict their occurrence, or even better, prevent them from occurring,” Dortch said. The approach developed in the study is expected to provide a blueprint for monitoring other HABs, according to the expected results from the study description.
The research is funded through the Ecology and Oceanography of Harmful Algal Blooms program, a multiagency partnership among NOAA’s Center for Sponsored Coastal Ocean Research, Office of Protected Resources, and Sea Grant, as well as the U.S. National Science Foundation, U.S. Environmental Protection Agency, NASA, and the U.S. Navy Office of Naval Research.
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