Because of their vastness and depth, the oceans are favored by many as a dumping ground for the byproducts of technological ingenuity. Most of us might not agree with their actions, but we’re aware of what happens when profiteers cut regulatory corners; we’ve seen the effects of chemicals dripping into the water.
Too many times, we’ve witnessed oil spills blacken entire ocean habitats, and over the years we’ve watched our discarded garbage congeal into trash patches larger than whole states. We also know who the sum of this environmental malpractice is levied against, as nearly every sea creature is now contaminated with varying amounts of toxic runoff.
It’s unfortunate that even today, as concern for the environment catches on, the price of modern comfort remains steep for so many of the ocean’s residents. If any good can come of the current situation, it’s that the damage so far only clarifies a dire need for new initiatives. Luckily, researchers are hard at work pinpointing fresh strategies for detecting threats of contamination within ocean waters. One particular tactic–under study by analysts from the Norwegian Institute of Water Research–involves the talents of one of the seas’ most observant shellfish: mussels.
In Kristiansand, Norway, a team of researchers have spent months deploying, collecting and studying thousands of caged blue mussels. As environmental monitors, mussels are ideal. Their gills filter in pollutant-containing seawater, and their bodies accumulate trace chemicals present in the brine. It’s a process so efficient that wild mussel tissue can be analyzed to gauge the development of aquatic pollution levels.
However, for accurate readings, many mussels are required. So many, in fact, that researchers working out of the Kristiansand harbor found that they could not rely on the harbor’s scant supply. Instead, they decided to bring in cages of farmed blue mussels to determine whether accurate pollutant readings could be obtained from a non-native mussel population. The harbor was the perfect setting, as years of metal industry runoff has polluted its waters with nickel, copper, cobalt, and organic compounds.
The researchers deployed two cages, each containing one thousand mussels. One cage was placed in Kristiansand harbor, and the other was left in a fjord near Svensholmen. Over the next six months, mussel samples were collected from both cages, as well as the natural population. Final results following experimentation revealed that levels of metals and organic compounds had increased substantially in both samples; the average nickel level of the caged mussels deployed closest to the harbor was measured at 35 times higher than that of “clean” mussels.
Of primary concern, however, was the amount of time it took the caged mussels to accumulate the proper amount of pollutants necessary for an accurate reading. If the mussels took too long to equalize with the environment, their use as monitoring tools would be impractical. The findings revealed that while metal concentrations in caged mussels were identical to the natural population within a month, organic compound accumulation was markedly slower, and still non-representative in the caged mussels even after six months.
However, researchers noted that, using toxicokinetic modeling, it could be possible to estimate pollutant levels present in a given population by analyzing the toxic buildup in caged mussels deployed for short periods.
Following the experiment, a pair of studies were published in Marine Environmental Research detailing the use of caged mussels in environmental research. The studies–part of an ongoing collaboration between NIVA researchers and the Norwegian Environment Agency–concluded that more experimentation is needed, particularly into how annual variations in pollutant levels might affect the quality of the monitoring data.