When I lived in Madison Wisconsin, I would walk my dog along Starkweather creek, and it always made me sad. Runoff from farms and from city streets had combined with bottom-churning carp to turn the channel into a turbid, stinking canal, filled with algae. I don’t have a fundamental problem with algae, but this was (and is) clearly a body of water whose ecosystem had been severely damaged by a combination of eutrophication, and having any plants rooted in the bottom being un-rooted by invasive carp. This mean that the stream was sluggish, and foul-smelling, and when the water was clear enough to see through, every stick or shopping cart on the bottom was draped with green goo. I stuck a stick in once, and it turned out the bottom was a foot or two beyond where I expected because of the layer of slime coating what turned out to be struggling water weeds, replete with everything except sunlight.
In that same summer of 2009, a mysterious blob of goo appeared in the Chukchi Sea off Alaska. This wasn’t just any blob of goo – it was at least 15 miles long, made of some kind of black, oily slime, and smelled unlike anything anyone there had ever encountered. It turned out to be algae, in the end, but the presence of so large a blob of algae in arctic waters was certainly something to give me pause. I’ve spent a fair amount of time around ponds and canals and lakes and rivers that had eutrophied, and it is never pretty. The Connecticut River is another example – when I dove in at a waterfall after a week backpacking with no shower, I came out smelling worse than I went in.
Many of these bodies of water feed into the ocean. How long would it take for the Chukchi Blob to become commonplace around the world. In addition to beach closures for sharks or the red tide, will we someday have closures because some poor soul got tangled in a mixture of algal slime and sea trash?
In general, warm waters with lots of pollution are good places for colonies of microorganisms, which often manifests as some form of slime or goo. As the ocean warms, and begins to lose oxygen, vertebrates will have a harder and harder time surviving, and invertebrates and unicellular organisms will have the seas to themselves. For another example, there’s this story from July of 2010, of an algal bloom in the Baltic Sea that was clearly visible from space. It’s not the first time this has happened, but it is almost guaranteed to happen again, and to happen more often.
The chain reaction that leads to eutrophication of a body of water tends to leave the water very murky, and so not much light gets in. This means that the only oxygen being put into the water comes from the scum on the surface, and that doesn’t penetrate very deep. If you know of a pond that receives farm runoff nearby, go look at what lives in it. It’ll be mostly creatures that can breathe air, because the water itself has no dissolved oxygen.
Of course, this situation is mainly caused by a surplus of energy, but warmth speeds it along, as it eases algal growth, and warm water holds less oxygen than cold. Just imagine, some day the ocean could look like your local cow pond!
Part two will deal jellyfish, nudibranchs, sea cucumbers and salps, part three with with bacteria and their ilk, and then we’ll do a nice, descriptive wrap-up. Coming soon to an extremist blog near you!