The ocean’s own environmental sensor

Tiny copepod crustaceans have a major role to play when the effects of oil-spills are being calculated.

Posted by Christina Benjaminsen

Since 2004, SINTEF scientists have been studying the use of copepods both as feedstuff for farmed fish and as a raw material for marine oils, due to their high content of protein and fat, and not least, the enormous numbers in which they exist.

However, Bjørn Henrik Hansen is interested in quite a different aspect of these tiny creatures. Hansen is an ecotoxicologist and a specialist in marine environmental monitoring, and he and his colleagues use copepods as environmental sensors.

“Copepods – tiny crustaceans – are Norway’s most common animal, if we take biomass as the measure,” says the SINTEF scientist. “The Norwegian Sea contains 15 million tonnes of herring, but as many as 300 million tonnes of copepods!”

Copepods eat phytoplankton (plant plankton) and they themselves are food for fish. Since they are an important part of the marine food web, they can also act as a good indicator of the state of the marine environment; for example, following an oil-spill. For copepods eat and filter tiny oil droplets, a habit that can be of vital importance for the task of monitoring the environmental consequences of events of this sort.

Fluorescing oil

SINTEF’s laboratories on Brattora Quay in Trondheim are home to the world’s oldest, and perhaps only, laboratory culture of Calanus finmarchicus – the scientific name of one species of copepod. There, the scientists are studying how these tiny creatures react to environmental toxins in the wake of an oil-spill.

“This tells us what we can expect the environmental impact to be, at individual, population and ecosystem levels in the oceans,” explains Hansen.

The scientist shows me an image of a copepod that had been exposed to a high concentration of oil droplets for 96 hours before being photographed under a fluorescence microscope. The tiny oil droplets in the animal’s body light up like golden specks in the photo – and they cover much of its surface.

“These specks demonstrate the potential of this species as a living sensor,” says Hansen.

The little room where the copepods live in tanks of water from Trondheim Fjord is dark and cool. To the untrained eye, they look like little water-fleas, and their reddish colour makes them difficult to discern. The thousands of tiny animals swimming around in front of us are the scientists’ most important tools in SINTEF’s internally financed Calanomics project – an interdisciplinary bioscience effort.

Diagnostic tool

The Calanomics project has already led to a number of chemical analytical methods that will enable the scientists to study in detail what happens to these millimetre-sized bodies when they are exposed to oil.

Just as a hospital can make a diagnosis by measuring disease-related molecular effects in a blood sample, the scientists are currently developing diagnostic tools that will tell us something about the impact on copepods of being exposed to oil. Levels of hormones and amino acids, for example, can indicate possible changes within the organism, such as whether its ability to reproduce is affected.

“Many different species of Calanus are found in all the oceans of the world, and they play equally central roles everywhere. We assume that the results that we find in our copepods will also be valid for species in the Gulf off Mexico,” says Hansen.

Chemical dispersal is important

Among the petroleum industry’s most important tools in the fight against oil-spills are chemical dispersants, which dissolve the oil so that it ends up as tiny droplets in the water column. These chemicals are part of Norway’s oil-spill contingency planning arsenal, and they were deployed in large quantities in the recent Gulf of Mexico spill, where more than five million litres of dispersants were released into the sea around the catastrophe well. But even if they remove the oil from the surface, its potentially hazardous components do not disappear; they merely change their form.

“Oil is a complex mixture of several chemical compounds, some of which are extremely toxic. Dispersing the oil creates tiny droplets, from which various chemicals leak out over time. This means that it is essential to study whether these chemicals have any effects on animals, and just how toxic they are.

“Our hypothesis is that oil droplets that have been chemically dispersed are no more toxic than those that nature itself has dispersed mechanically through wave action. Our experiments will be the first in the world that are capable of revealing whether this really is the case,” explains Hansen.

The invisible boundary

The SINTEF SeaLab scientists have been working together for some years with the petroleum industry in developing mathematical models to estimate the risk of environmental damage after an oil-spill. Much of the uncertainty in their estimates is related to knowing how much oil marine organisms can actually tolerate.

“Our experiments will reveal just how much copepods can withstand over a period of time. This is because we are measuring not only whether they live or die, but are also detailing other types of injury that might be of great importance for the environment.”

The findings will be incorporated into the existing mathematical model, so that in the future, the scientists will be able to predict the environmental impact of an oil-spill much more accurately than they can today.

Fact box:

The Calanomics project is a SINTEF Group joint effort in bioscience, in which SINTEF scientists will develop methods for studying the molecular effects of environmental toxins on copepods. As a result of an internal project, a NOK 7.85 million main project involving SINTEF, NTNU, BioTrix, NIVA and the University of Stockholm has been launched; it is financially supported by the Research Council of Norway.

Christina Benjaminsen has been a regular contributor to the science magazine Gemini for 11 years. She was educated at Volda University College and the Norwegian University of Science and Technology, where she studied media and journalism.

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