Financial Daily from THE HINDU group of publications
Friday, Dec 10, 2004
Financial Daily from THE HINDU group of publications Friday, Dec 10, 2004 |
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Agri-Biz & Commodities
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Environment US scientists link coastal farming with harmful algae Vinson Kurian
Thiruvananthapuram , Dec. 9 RESEARCHERS in the US have found the first direct evidence linking large-scale coastal farming to massive blooms of marine algae that are potentially harmful to ocean life and fisheries. This more or less corroborates the finding by scientists at the Centre for Earth Science Studies (CESS), Thiruvananthapuram, that the so-called `red tide bloom' that blotched beachside seas in Southern Kerala earlier this year could be traced to the leaching of minerals from land. The leached minerals, as do large quantities of sewage flushed out during the rainy season, could create a nutrient-enriched marine environment conducive to the blooming of toxic plankton, the CESS scientists had said. The CESS was asked to study the seaside phenomenon that had created a health scare along the beaches in Kollam and Thiruvananthapuram districts during a monsoon-filled September, triggering mass mortality of fish and foul air. Researchers from US-based Stanford University's School of Earth Sciences made the discovery by analysing satellite images of Mexico's Sea of Cortez, also known as the Gulf of California — a narrow, 700-mile-long (about 1,126 km) stretch of the Pacific Ocean that separates the Mexican mainland from the Baja California Peninsula. Algal blooms occur naturally when cold-water upwellings bring nutrients from the seafloor to the surface that stimulate the rapid reproduction and growth of microscopic algae, also known as phytoplankton. These events often benefit marine ecosystems by generating tonnes of algae that are consumed by larger organisms. `Dead zones' in ocean: But several phytoplankton species produce harmful blooms, known as red or brown tides, which release toxins in the water that can poison molluscs and fish. Excessively large blooms can also overwhelm a marine ecosystem by creating oxygen-depleted `dead zones' in the ocean. Scientists have long suspected that many harmful blooms are fuelled by fertiliser runoff from farming operations, which in many regions pour tonnes of excess nitrogen and other nutrients into rivers that eventually flow into coastal waters. However, some agricultural industry groups contend that there is not enough evidence to link farm runoff to red tides or dead zones. According to the researchers, artificially induced algal blooms could have a major impact on recreational and commercial fishing. Red tides, for example, can cause outbreaks of life-threatening diseases, such as paralytic shellfish poisoning, which can shut down mussel and clam harvesting for long periods. Another concern is hypoxia, or oxygen depletion, which is caused by excessive algae growth. As the algal mass sinks, it is consumed by bacteria, which use up most of the oxygen in the water as they multiply. The result is an oxygen-depleted dead zone at the bottom of the sea where few creatures can survive. Scientists believe that agricultural runoff from the Mississippi river in the US plays a pivotal role in creating an annual dead zone, which measured 22,000 square km in 2002.
More Stories on : Environment | Aquaculture | Kerala
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