Woods Hole (global-adventures.us): In the first genome sequencing of a harmful algal bloom species, researchers found that the microscopic phytoplankton ‘Aureococcus anophagefferens’ unique gene complement allows it to outcompete other marine phytoplankton and thrive in human-modified ecosystems, which could help explain the global increases in harmful algal blooms (HABs).
The brown tides caused by Aureococcus do not produce toxins that poison humans. But the long-lasting blooms are toxic to a class of marine and freshwater mollusks known as Bivalvia and have decimated sea grass beds and shellfisheries, leading to billions of dollars in economic losses. Blooms are now chronic, annual events in estuaries along the heavily populated coastlines of the eastern United States and South Africa.
While HABs occur naturally,
impacts from human activities, such as increased pollutants and excess nutrients from fertilizer runoff, have been linked to the rise in HAB outbreaks. Like many other HABs, Aureococcus blooms in shallow, partly enclosed coastal bodies of water with one or more feeding rivers or streams. Where light levels and inorganic nutrients are low, and organic carbon and nitrogen concentrations are high (estuary).
For example, it’s well-adapted to low light conditions and can survive for long periods in no light. Aureococcus had 62 light-harvesting genes whereas its competitors had, on average, a couple of dozen.
The photosynthetic
microalgae also shows advantages when it comes to metabolizing organic matter, particularly organic nitrogen and organic carbon, and handling what would normally be toxic amounts of metals, like copper. Aureococcus also has a larger number of selenoproteins, which use the trace element selenium to perform essential cell functions.
“When we looked at the coastal ecosystems where we find Aureococcus blooms. We found they were enriched in organic matter, were very turbid and enriched in trace metals,” Gobler said. “And when we looked at the genome of Aureococcus. The surprise was the concordance between the genome and the ecosystem where it’s blooming.”
New advances in the field of genomics have allowed researchers to better address difficult questions in environmental biology. Gobler described this new “ecogenomic” approach applying molecular techniques to ecological. Environmental science as a particularly powerful tool for understanding the dominance of different harmful algal blooms within different ecosystems around the world.
Here’s a species that blooms and for years people have been trying to understand why 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.”
We’re hoping to provide the next piece in the puzzle understanding. How the genes are responding to the environment and what is fueling and causing the demise of blooms, Dyhrman said.
The long-term goal is to be able to keep blooms from occurring. At least be able to better predict and manage when blooms occur. We also know the characteristics are there because of activities of man, Gobler said. If we continue to increase, for example, organic matter in coastal waters.
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