You can imagine making forecasts for toxic algal blooms much as you do for the weather, says Erik Selander, an ecologist at Lund University.
The crustacean is only a few millimeters long, but it is algae's number-one enemy.
Algae form the basis of the ocean's food web, much like green plants on land, and crustaceans are the most common zooplankton that feed on algae. Algae therefore see grazing crustaceans as a threat. When algae detect their scent, they produce toxins to defend themselves.
Protected by toxins
It is an effective defense; when they are toxic enough, the grazers reject them, says Erik Selander.
The method of measuring the scent of crustaceans to predict toxic algal blooms has been tested in a research collaboration in both Gullmarsfjorden in Bohuslän and Monterey Bay in California.
The study used small sampling units that passively collect odorants from the water, but the scent of the crustaceans also accumulates in mussels. Since samples are regularly taken from mussels in areas where food companies farm and harvest mussels and oysters, Erik Selander believes the measurements could be adapted relatively easily, without major additional costs, to provide information on the level of crustacean odorants.
Causes diarrhea
Better toxin forecasts would be of great value to the seafood industry, according to Erik Selander. On the west coast, algal toxins that cause diarrhea occur.
Erik Selander, senior lecturer in ecology at Lund University.
Some algal toxins also kill fish, for example in fish farms. It would be fantastic if we knew a couple of weeks in advance that the risk was high, so that we could take action.
So what do crustaceans smell like? It is not a smell the human nose can detect, Erik Selander explains. The substance is found only in the water and in very low concentrations - but algae detect it immediately.
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