Stony Brook, NY, July 13, 2011 - Brown tide, which is caused by a proliferation of single-celled marine plants called phytoplankton, is in the news again this summer season.
In a recent Newsday
article, Stony Brook University (SBU) researcher Dr. Christopher Gobler says brown tide has an edge over rival microscopic organisms because its genes allow it to thrive in shallow estuaries. And he should know: This past February, Gobler announced findings from a New York Sea Grant- funded investigation that he led on sequencing and annotation of the first complete genome of a harmful algal bloom species, Aureococcus anophagefferens
. This phytoplankton species has bloomed in such densities since early June that it has turned the color of the water dark brown, a condition known as "brown tide." It has become what Suffolk health officials said is one of the most intense - though localized - brown tides in recent years.
Brown tide has clouded normally clear waters from western Shinnecock Bay to eastern Moriches Bay, with the highest concentrations found off Quogue, in Quantuck Bay. Water samples taken from the affected bays showed cell concentrations are well above A. anophagefferens
' bloom density level of 400,000 cells per milliliter of water. According to the Suffolk health department, levels exceeded 2.7 million cells per milliliter in Moriches Bay and 2.1 million cells per milliliter in Quantuck Bay.
"These numbers are the highest they've been in years," said Michael Jensen of the department's bureau of marine resources wrote in an email. "The good news is that it seems very localized to those areas."
While not harmful to humans, concentrated brown tide blooms have made it harder for bivalves to feed and can kill juvenile clams and scallops. Scientists suspect repeated brown tides in the Great South Bay - where it last bloomed in 2008 - are hampering efforts to restore the decimated clam population.
According to findings from NYSG's Hard Clam Research Initiative synthesis report
, released in 2009,lab studies have shown that A. anophagefferens
inhibits feeding and growth of hard clam larvae in a concentration-dependent manner. But, while high densities are expected to cause issues for larvae, the algae species at its bloom density level can support relatively good growth of juvenile hard clams as well as excellent shell growth of larvae during planktonic development.
Farther east, it is not yet clear if the blooms have harmed shellfish in the estuaries along the South Shore. Few population surveys have been done here, so estimates are based mostly on anecdotal reports from fishermen.
"This now marks the fifth consecutive year of a bloom of over 1 million cells per milliliter in this particular area," said Gobler.
Brown tide is also bad news for eelgrass, the underwater plants that serve as coastal nurseries for young finfish and shellfish. The blooms turn waters opaque, blocking the light plants need for photosynthesis. Eelgrass plots in some bays along the eastern South Shore have fared poorly in recent years, said Gobler.
For more on the cause, problems and history of brown tide, for which New York Sea Grant is cited the source, see the "Brown Tide Primer" section of the recent Newsday article (pdf
) [7.9 MB file].
Also, NBC News Channel 4 also featured a segment on brown tide, along with Gobler's insights ...
New York Sea Grant, now in its 40th year, is 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. One of 32 university-based programs under the NOAA’s National Sea Grant College Program, NYSG is a cooperative program of the State University of New York and Cornell University.