Ongoing efforts to clean up the Baltic Sea are at last having some tangible success, according to scientists studying the so-called ‘dead zones’ in the Baltic Sea which have too little oxygen to support life.
“It’s quite safe to swim and fish, the pollution is kind of hidden” says Marko Reinikainen, Director of Helsinki University’s Tvärminne Zoological Station near Hanko, which conducts ongoing research into the health of the Baltic.
“You find the pollutants at the bottom of the sea, but not only at deeper depths. You also find pollution in the flesh of the fish” he says.
Tvärminne is opening its doors to the public this weekend, an event that only happens once every five years. This year, the zoological research station is celebrating it’s 115th birthday, and the work that scientists undertake there, has helped form an important picture of the state of the sea.
The situation in the Baltic was at its worst right after World War II, when pesticides, farm waste run-off and sewage were being dumped from the shore, into the water. Ships were leaking pollutants into the virtually unchecked. But still, there wasn’t a strong understanding of the effects human mismanagement of the sea was having.
“When I was a student in the 1980s my professors were really worried about the Baltic Sea” recalls Reinikainen.
“They were telling politicians about it, but it took 20 or 30 years until some very efficient methods were put in place. It took a long time from the point where we know about the problem until we started to do something about it, and finally we are catching up” he says.
Dead Zones Explained
When large amounts of nutrient runoff or sewage goes into the water, it acts as fertilizer for algae, which flourishes in these conditions. This process is called eutrophication.
When the algae dies, it sinks to the bottom and is consumed by bacteria and animals, consuming oxygen, until all the oxygen in that part of the sea is gone and not capable of supporting life any more.
Sea Quality Improvement
There is some good news for Finnish scientists who study the dead zones in the Baltic.
Things are slowly getting better, thanks to robust action to limit runoff pollution; build improved sewage treatment plants on land; and stop cruise ships dumping their sewage at sea.
“We have tried in many countries to affect the amount of nutrients going into the sea” says Marko Reinikainen. “And can see some positive effects in the dead zones, we can see the lower amount of nutrients”.
As life slowly returns, some of the first creatures to venture back are worms, which dig into the sand on the sea floor, and create tiny pockets of oxygen, and making it possible for other animals to live there, increasing the richness of the sea environment for other species.
And what would life look like if the dead zones cleared up completely?
“I don’t know if anybody is able to calculate when that could be […] I can only take a wild guess maybe 20 or 30 years until the dead zones will start to shrink” says Reinikainen.
“There would be huge numbers of mussels, different species. Different kinds of worms. Some crustaceans related to shrimp and crayfish who would be living there, and of course these are all important food for fish” he says.
Tom Blom has been fishing the archipelago waters off the coast of Vaasa in north west Finland for 15 years.
He tells News Now Finland that he noticed the effect that pollution has had, specifically on his herring catch.
“The deep water, where there isn’t any life, that’s 60 to 80 metres deep. But that’s the places that herring goes to eat, and then they come in the spring up to shallow waters”.
Blom has seen how small and underfed the herring are, for their age. They should be larger. But lack of food at their feeding depths has stunted their growth.
“Fifty years ago, everything from the factories making plastic and whatever they made, they put all their waste straight into the sea water. No filtering. Nothing. Everything out” says Blom.
“This shit they put in the sea, it went to the deep places in the water. So the small fish die out. And if you take away something small then the bigger ones haven’t any food. You take away one link in the chain”.