Hopes Rise as New Species Move Into Sludge Off Coast

Los Angeles city biologists reported Monday that they have detected new animal life in the thick black blanket of toxic sludge surrounding an abandoned sewage discharge pipe in Santa Monica Bay, raising hopes that the severely contaminated ocean floor is staging a comeback.

The biologists said preliminary data from an ongoing study of the two-square-mile swath of gurgling jelly shows that several species of worms and mollusks have ventured into the area, described as the “Black Hole of Calcutta” by one marine biologist.

Less than two years ago, when the city was forced to stop dumping sludge from the underwater pipe seven miles off El Segundo, the most remarkable inhabitant nearby was the solemya clam, a stomachless mollusk that feeds on poison sulfur gas.

The new bottom life includes such creatures as the capitella worm and the parvilucina clam, both of which thrived in the past on sewage in less contaminated sediment outside the sludge field.

The city disposed of hundreds of millions of tons of sludge--a noxious form of condensed sewage--from the pipeline over 30 years before closing it in November, 1987. The sludge blankets a steep chasm on the coastal shelf, known as Santa Monica Canyon.

“When you look at the bottom of the canyon about 300 to 400 feet going down, it used to be a black featureless plain with incredibly soft sediment,” said marine biologist John H. Dorsey during a report to the Board of Public Works. “The submarine would virtually sink half way down because it was very soft. Now it is very firm. We are getting new stuff on top--hills and paths made by organisms.”

The biologists attribute the migration of life to the sludge field in part to a dramatic drop in the level of poison sulfur gas in the sediment. When the city was still dumping sludge, hydrogen sulfide concentrations averaged 600 parts per million in the area. Recent readings showed concentrations at less than one part per million. Uncontaminated sediment has none of the gas, which is a sulfurous byproduct of decaying sludge.

The biologists also detected a drop in the level of PCBs, a pollutant that eventually becomes trapped in the fatty tissue of fish that feed on animals near discharge pipes. But they said levels of polluting heavy metals--such as cadmium, mercury, copper and zinc--have remained the same.

“We have been pretty happy about how quickly things are moving into the area,” said city biologist Scott Johnson in an interview. “To tell you the truth, we weren’t certain what would happen. The hope is to get more animals living in the sediments. They turn the sediment up, which gets oxygen down into it, and further degrades the organic material.”

City biologists began taking tests of the underwater sludge field in February, 1986, to compare levels of contaminants and animal life before and after the closing of the pipeline. The study is being coordinated by the Southern California Coastal Water Research Project.

Bruce E. Thompson, a biologist with the research project, said in an interview that the preliminary data is encouraging, but he cautioned that true “recovery” of the ocean floor will not occur until crustaceans and echinoderms--such as sea urchins and starfish--recolonize there. Those marine animals, he said, are common in uncontaminated portions of the bay.

“It is still a big chemical soup,” Thompson said of the underwater canyon. “A lot of it is puzzling to us, too. It will take a little bit of analysis once we get all of the data together. We are missing some pieces of the puzzle.”

In their report, the biologists also said they have documented animal life migration to the area around the city’s second discharge pipe, which still dumps treated waste water five miles offshore from the Hyperion sewage plant.

Plant officials disclosed in June that improved sewage treatment has resulted in the cleanest waste water ever. The biologists said the cleaner water has attracted new species to the area around the pipe.