Mussels uncover pollution

Mussels react quickly to changes in the environment. By measuring heart rate and how frequently shells open and close, scientists can determine if an area in the ocean is polluted with toxic pollutant chemicals.

In a tank with the Latin name Mytilus edulis written on it, there are clusters of blue mussels. We are in the pilot hall of the IRIS Biomiljø in the environmental research station, Akvamiljø, located at Mekjarvik outside Stavanger. Shells are among the species most used in the research done here on the effects of pollution. By means of mussels one can find out what happens when various kinds of pollutant chemicals are released in the environment.

Water filtration

At IRIS Biomiljø they conduct research on how oil spills and chemical discharges affect the marine ecosystem. Mussels feed on microscopic plankton algae, and each shell can filter up to sixty liters of water a day to get hold of the algae. One major reason why mussels are so useful in environmental research is that they, because of the filter feeding, easily take up pollutants from the sea water.

Another advantage is that most mussel species, unlike fish, are stationary, and therefore they can say something about the environmental conditions at a particular place in the sea. Researchers examine how mussels respond to environmental pollutants.

Studying biological responses

The biological responses that pollutant exposure may cause in the shell are called “biomarkers”, and these biomarkers can tell a lot about the environment which the shells live in.

- By studying pollutants or biomarkers (most often both) in blue mussels obtained from multiple positions within a coastal region, we can decide how much of the area which has been contaminated and how serious the pollution effect is. A biomonitoring survey can uncover how mussels respond to pollution, like an oil spill, over time. We put sensors on the mussels and examine their heart rhythm and how often they open and close. Then we can compare the performance of shells from different locations including a clean control area where we know that the mussels are healthy, Jonny Beyer says, senior researcher at IRIS Biomiljø and associate professor at the University of Stavanger.

Biomarker investigations can also be done with fish, but then we need to employ different biomarker methods than in mussels of course, he says.

Finding PAHs in mussels

IRIS Biomiljø wants in particular to examine mussels and fish in Karmsundet. In the summer of 2009 Hydro Aluminum had to close down the Søderberg hall at Karmøy. Investigations carried out by IRIS several years earlier discovered high concentrations of the carcinogenic substance polyaromatic hydrocarbon (kPAH) in the sea outside the factory where seawater from the gas scrubber facility of the aluminium smelter was discharged.

The types of kPAH that were found, was, among other things, benzo[a]pyrene, a substance which has been studied extensively in connection with cancer in humans. The researchers found kPAH and environmental damage from these substances by analyzing mussels, wrasse and cod in Karmsundet. Today it is still illegal to catch sea animals in Karmsundet in order to sell them, but IRIS now wants to examine the development in the area since a decreasing trend in the pollution level is foreseen.

- We want to find out how long it takes before the situation improves and one may once more catch fish, crabs and mussels in Karmsundet both for consumption and sale, Beyer says.

Provided by University of Stavanger