New light on

the algae summer of 1988

Anne Berit Bjørken

The algae that invaded the Norwegian coast in the summer of 1988 produced a toxin that laboratory studies have demonstrated cause definite injury to membranes in nerve and blood cells.

Professor Sverre M. Myklestad of NTH's Dept. of Biotechnology believes that for this reason, we should be careful about letting small children bathe in seawater during any further heavy invasions of this species of alga.

He emphasizes that this warning is based on the early warning principle. So far, research results do not give us any grounds to claim that these algae can injure people.

"We still know too little. At the cellular level we can observe a clear toxic effect on cells of large mammals. There is little reason to assume that human cells would react any differently. However, we know too little about how this toxin might be taken up by the human body. The reason that I would be careful about letting children bathe is that they can easily get water in their mouths, and from there it is not far to the lungs," says Myklestad.

Competitive advantage

Norways most notorious alga - Chrysochromulina polylepis - which has even been debated in the Norwegian Parliament, is basically a perfect alga that is clever at producing organic material, which is the basis of all marine life. But it has built up a bad reputation in Norway after it knocked out all life in the upper layers of the waters along much of the coast of Southern Norway in summer 1988. After the algae invasion a research programme was launched in 1989 to find out what had happened, and whether it would be possible to reduce or avoid the damage caused by new algal blooms.

Professor Myklestad decided to study the effects of the environment on the inner life of the algae, and to investigate some of the theories and hypotheses that were put forward during the last invasion.

The N/P ratio of the sea, which is usually fairly constant, was much higher than normal that spring and summer and also concentrations were high. This was caused by the addition of nitrates and other sources of nitrogen from rivers in regions surrounding the North Sea, in Germany and The Netherlands. A very wet spring leached large quantities of such compounds out of the soil and washed them down the rivers to the North Sea. Then the Jylland Current carried them northwards to the Skagerrak.

Declared war

Scientists have cultivated the algae in the laboratory in water containing different combinations of nutrients. The relationship between nitrogen and phosphates in the sea, is expressed as a ratio: N/P. The N/P ratio is normally about 15. In these tests, the algae were exposed to N/P ratios ranging from 2.5 to 100. "What surprised us was that C. polylepis did not show great changes in growth rate, irrespective of the N/P ratio, while other algae which we tested in the same way were obviously not comfortable and grew more slowly when the N/P ratio was high," says Myklestad.

"This means that Chrysochromulina polylepis is at a competitive advantage when the nutrient content of the ocean is dominated by N-salts. This is one factor that helps to explain the huge algal bloom of 1988. Our studies also showed that the algae declared war on other organisms in the water by producing an extracellular toxin that reduced the growth rates of other forms of life in the ocean. The result was inhibited growth of "our" alga, which led in turn to its ability to knock out all other types of algae, bacteria and fish. It killed practically all other life-forms in the upper layers of the water."

Algal blooms on the coast are now being intensively monitored. Myklestad believes that the chances of preventing algal invasions are small, but that it ought to be possible to prevent or at least reduce the scope of damage, for instance to fish farms, by means of physical measures.