Posted by D on June 16, 2007, 8:45 am, in reply to "Red Tide"
A bit more on this|
Here is a copy of an article and a couple of links at the bottom.
US set to track toxic algal blooms
* 10:00 16 June 2007
ON A computer screen, the California coastline bleeds pools of vivid red. As I watch, some of the red swirls out into the open ocean and disappears, while some seeps ominously into bays and inlets along the shore. "You can see how the ocean is concentrating it and diffusing it," says Raphael Kudela, as he clicks the replay button.
The red stain is in fact a simulation of the emergence and movement of massive amounts of chlorophyll in the ocean, a telltale sign of an algal bloom. Blooms of algae have long been a part of life in the waters off California, but in recent years they have become increasingly toxic, killing thousands of marine mammals and birds. Last month the region was hammered by a bloom twice as poisonous as anything it had seen before.
To understand why, Kudela, a phytoplankton ecologist at the University of California, Santa Cruz, has combined satellite images with information on ocean dynamics, such as winds and currents, to predict and track the toxic blooms. His models are now set to plug into a federally funded network currently in development that aims to provide a better understanding of what is happening in the waters off the west coast of the US. "The idea is to do for the ocean what the weather service has done for the land," he says.
Algal blooms are made deadly when photosynthetic diatoms of the genus Pseudo-nitzschia produce a powerful neurotoxin called domoic acid. This accumulates in fish and shellfish without apparent harm, but can cause seizures and death in marine mammals, birds and humans that eat them. The California Department of Health Services monitors the amount of toxin in mussels and issues warnings if levels rise above 20 parts per million. This year mussels were found with more than 600 ppm of toxin in their tissues, the highest on record.
"There's been a pretty dramatic change over the past six years," says Gregg Langlois, head of the state's monitoring programme. Domoic acid was first detected in California waters in 1991 and began appearing regularly in 2000. Monitoring efforts keep the poison from reaching humans, but seabirds are often killed in their hundreds when a toxic bloom erupts. Whales, dolphins, seals and sea otters are also affected, says Tracey Goldstein, a veterinarian at the Marine Mammal Center in Sausalito, California. Her centre deals with many sick sea lions that survive the initial poisoning but end up brain damaged following the seizures.
This year animal rescue centres were inundated with sick and dying animals after the record spike in domoic acid levels. The reasons behind the increasing intensity of the blooms remain elusive, but many think human activity is to blame. Kudela's team has discovered that the diatoms produce toxin in response to increasing levels of urea and copper. Urea is a fertiliser ingredient widely used in California that enters the ocean in run-off, and copper is a component of boat-bottom paint.
Other factors that can affect diatoms include rising temperatures and falling levels of silicic acid, which diatoms need to build cell walls. "There are so many ways to make them toxic," Kudela says. He hopes to predict where and when a bloom is likely to become toxic and how bad it will be. The information will help health officials and animal rescue teams organise their efforts.
The challenge for Kudela is learning to distinguish the toxin-producing organism from other phytoplankton, using satellite images alone. His computer models will soon feed into the Ocean Observatories Initiative, a $330 million project that will integrate and disseminate information gathered continuously about the ocean. This will include wind speeds taken from buoys, currents measured with radar, and data from autonomous vehicles, hydrophones and seismic stations - all made available in near real time. "It's about getting the information in one place so you don't have to call up 15 people to find out what's going on with the ocean," says Kudela.
|By posting, you confirm that you have read and |
Be sure to visit www.lamanzanilla.info