Warm Water and Small Sea Creatures
A typical zooplankton species found in the North Sea. (Courtesy of the Alfred Wegener Institute)
Tiny plankton play an important role in the ocean ecosystem. Scientists believe they may be able to witness some of the effects of climate change by tracking the size and number of these and other organisms and fish living in the water. Radio Deutsche-Welle's Andrew Ryan took a trip to the islands of Helgoland with researchers to see what they could see at the bottom of the North Sea.
GELLERMAN: It’s Living on Earth. I’m Bruce Gellerman.
Plankton get no respect. The tiny marine animals aren’t charismatic like polar bears, cuddly like pandas or awe-inspiring, like whales. But without plankton, the whole ocean food web would unravel, which is starting to happen in some places. One of them: Helgoland in the North Sea, where Radio Deutsche Welle’s Andrew Ryan traveled for our story.
[WATER NOISES; MOTOR ROARING]
RYAN: Our small white research vessel pitches across the channel that divides the two islands of Helgoland. Storm clouds are gathering overhead but with our fluorescent orange rain gear we’ll stay dry as a bone. This is a typical research run, and our mission is to check the water temperature and salinity and pull in samples of both water and marine life.
WILTSHIRE: What you see now is a big net which has just been put in and we will tow it, it’s called a cuckofie where we’ll actually sieve out all the small organisms. And when it comes back on board, you’ll see that it’s sort of like a big soup.
RYAN: That’s Professor Karen Wiltshire, one of the director’s of the Alfred Wegener Institute’s Helgolan Marine Research Station. She’s my guide for today’s sea excursion.
RYAN: What’s gonna be in our soup today?
WILTSHIRE: Well my guess is that there will be very, very many microalgae, little tiny algae, and you won’t actually see them with the naked eye except that you’ll see this sort of sludge and if you look at it under a microscope there are millions and millions of little cells.
RYAN: It doesn’t sound like the most delicious soup, but for marine creatures this is a veritable buffet. But as we’ll find out the menu is changing, and with those changes come new customers.
Workers hoist in a long, white gauze net which looks a bit like a windsock. Then they pour the contents into a bucket.
WILTSHIRE: There’s not very much in it at the moment actually.
RYAN: So it’s kind of a brown, sludgy color.
WILTSHIRE: Yeah, actually the brown in it is most likely microalgae because they have pigments because they photosynthesize.
RYAN: Is this the phytoplankton?
WILTSHIRE: Yeah, exactly, it’s the phytoplankton. Those are the ones that we’re looking at very closely here because they’re at the bottom of the food chain, it’s what basically everyone feeds on. So if something changes at the bottom, you can expect an upward cascading effect. So that’s why we look at it everyday.
RYAN: Marine biologists have been monitoring changes in the waters around Helgoland everyday since 1962. And the biggest change they’ve noticed has been the temperature, which has gone up 1.5 degrees Celsius in the last fifty years. And even more dramatically, the winter temperatures alone have increased by four degrees. As a result, fish like Cod, which like cold water, have moved north. And near Helgoland, researchers have seen an influx of warm water fish like Red Mullets and a diverse array of jellies and little crustaceans. Karen Wiltshire says that warmer water has also had a profound effect on the ocean’s microalgae, the phytoplankton.
WILTSHIRE: Well what we see is that the timing of the spring bloom is very much affected by how warm it is in winter. It’s just like on land, you end up having the plants starting to grow in early spring and here it’s the same in the sea. You’ve got microalgae, which will start to grow and then things feed on it and then everything starts to get going. And if that timing is changed you have shifts in the whole food chain structure.
RYAN: She says that if it’s warm in winter then the algae are prematurely eaten away. That means they don’t have time to build up biomass. And then other organisms who rely on them for food suffer. Some researchers say that those changes even have an effect on the largest animals in our world’s oceans: the whales.
[FLAPPING WATER NOISES]
RYAN: Back on the boat, workers have brought the net in once again.
And it looks like they’ve pulled in a new catch here and this one seems to be full of…
WILTSHIRE: Lots of jellyfish, big jellyfish. It’s ten, twenty five degrees which is warm.
RYAN: The water is warm.
WILTSHIRE: Yeah it is warm, and these are HUGE jellyfish for this time of the year. I mean, they’ve been feeding well. So the water’s been warm all winter.
WILTSHIRE: Oh yeah, that must have been there all winter.
RYAN: And it’s transparent.
RYAN: And probably about, what, four centimeters long?
WILTSHIRE: In this case, yeah. There’s a smaller one here, I’m used to these small ones. Look there, see? That’s more what I’m used to in size.
RYAN: A little smaller than a grape.
WILTSHIRE: Exactly, yeah.
RYAN: Maybe about the size of an almond.
WILTSHIRE: Exactly. That means this guy has been here for a while. So he had a good winter.
RYAN: He’s been having some good dinners on phytoplankton there.
WILTSHIRE: Yeah, exactly. They can eat a whole bookish of phytoplankton, or zooplankton mostly.
RYAN: The question is then, with new, larger feeders munching on it all winter, is the phytoplankton endangered?
WILTSHIRE: Ah, I would say its certain species are endangered, not the whole group of phytoplankton. It’s biodiversity that you have to worry about. And changes in species composition of phytoplankton populations. It’s not actually the fact that they’re all going to die out.
RYAN: But Karen Wiltshire says that the real danger is, and they know this from land-based food chains, if you remove one link from the chain it could cause the whole system to collapse.
RYAN: Now it’s time to go back to the Alfred Wegener Institute with our buckets of water and seafood…I mean, marine life.
WILTSHIRE: Okay, this is the lab where we count all our samples.
RYAN: Marine biologists are busy preparing the water sample that we caught earlier. They fix it with a few drops of iodine, which kills the organisms, and then pour a tiny amount onto a glass tray. That’s what goes under the microscope and gets counted.
WILTSHIRE: Maybe you would like to just have a look in.
RYAN: Okay, so I’m going to have a look into the microscope. Are those plankton?
WILTSHIRE: That’s plankton, phytoplankton!
RYAN: I’ve seen it! I’ve seen it, I’ve seen phytoplankton.
WILTSHIRE: Yeah, exactly.
RYAN: For a moment, just one, short, magical moment, I marveled at how the weight of our oceans rests on the wellbeing and proliferation of this tiny organism known as plankton.
Andrew Ryan, Helgoland.
GELLERMAN: Our story about plankton comes to us courtesy of Radio Deutsche Welle.
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