Learning the Lesson from Louisiana's Oysters

by Kieran Mulvaney

Originally published in the Montgomery Advertiser on 2/27/97.

---

It has not been a good few months for Louisiana's oyster industry. Through no fault of their own, oyster fishermen have watched as beds have been closed and their produce recalled following two major health alerts. Beds at the center of the recent Norwalk virus scare have been re-opened, but red tides continue to hinder the extended season in many places elsewhere.

Unfortunately, these are not isolated occurrences. Nationwide, both seafood-related illnesses and harmful algal blooms have apparently increased over the last couple of decades. And at least some cases point to an ongoing and growing problem: too many wastes are entering our coastal waters, with serious and increasing impacts for the marine environment and human health.

It isn't just sewage. Fertilizers, urban runoff (mostly heavy storm runoff washed down drains and out to sea), emissions from power plants and car exhaust fumes all n like human and animal wastes n contain nutrients such as nitrogen. Whether expelled into the air and re-distributed via rain, or leached into the soil and then washed into rivers and streams, many of these nutrients eventually find their way to the coast. Numerous estuaries now receive levels of nitrogen one thousand times greater than a heavily fertilized agricultural field.

In the right quantities, nutrients like nitrogen and phosphorous are essential for the growth and health of living things. Problems arise when they enter the environment at such unnaturally high concentrations.

Many scientists now agree that harmful algal blooms - similar to the one causing red tides in the Gulf - are occurring more frequently, growing larger, lasting longer and appearing in areas where they were previously unknown. And a number of these experts believe strongly that an influx of nutrients in coastal waters is playing a major role.

In North Carolina, a newly discovered algal species called Pfiesteria produces toxins that are known to cause severe stomach cramps, behavioral abnormalities and immunosuppression, helping it earn the nickname, "the cell from hell." Pfiesteria appears to be more common around sewage outfall pipes. In late 1995, after floods washed tons of hog wastes into the state's Neuse River, the organism grew to huge numbers, killing millions of fish and causing severe illness in a number of people.

Not all harmful algal blooms involve toxic species like Pfiesteria. Most species have natural predators that keep their numbers in check, but under conditions of extreme nutrient enrichment, the growth of algal blooms can outpace their predators. When the algae die and decompose, they consume so much oxygen that the water finally becomes completely oxygen-deprived. Those fish and animals that can do so, flee. The rest die. The result is a complete watery wasteland, devoid of all life and known as a "dead zone." You don't have to go far to find an example of a dead zone: the largest in the world is in the Gulf, several hundred square miles of marine life killed off by river water laden with fertilizers, running off farmlands from Minnesota through Louisiana and into the Mississippi.

Nutrient pollution can be reduced. The agriculture industry can use less fertilizer, and compost animal wastes or plant debris for use on fields. Resorts and suburban residents don't have to use fertilizers on lawns. Industry can eliminate production methods that result in nitrogen emissions. Even driving less can help, by reducing pollution from the tailpipes of cars and trucks.

These are all steps worth taking. Without them, nutrient pollution will continue to increase, and so will the odds that the experience of the past few months will be repeated on a larger and far more costly scale.