Very cool article a couple of weeks back in the NY Times about Laura  Widder, a famed marine biologist, who has discovered that the bioluminescence of thousands of microbial sea creatures can be used to measure the toxicity of marine sludge:

Dr. Widder has found a way to put bioluminescence to work to fight pollution in the Indian River Lagoon, a 156-mile estuary that scientists say is one of Florida’s most precious and threatened ecosystems.

Back in her laboratory here, she mixes the sediment samples with a bioluminescent bacterium called Vibrio fischeri. Using a photometer to measure the light given off by the bacteria, she can quickly determine the concentration of toxic chemicals in the sediment by seeing how much and how quickly the light dims as the chemicals kill the bacteria.

Measuring the level of pollutants in the sediment provides a better indication of the estuary’s health than measuring the level of chemicals in the water, Dr. Widder said. “Pollution in water is transient,” she said, “but in sediment it’s persistent.”

Her samples have revealed high concentrations of heavy metals and nutrients like phosphorus and nitrogen, which can cause runaway algae growth; those organisms consume oxygen and stifle life in the estuary. Dr. Widder has also designed sensors that are placed around the estuary and can beam real-time data like current and flow direction of the water. Pairing those data with the toxicity of the sediment, she can trace the source of pollution. The method is far cheaper and quicker than the more common practice of sending samples to a lab for analysis.

She does most of her work at ORCA [Ocean Research and Conservation Organization] where you can find more about her, and the work of ORCA