Unsung heroes under threat
Ocean floor-dwelling sponges and worms might not be the first thing that come to mind when people think of Antarctica.
But Auckland University scientist Dr Jen Hillman believes the little-known benthic community – organisms that live in and on the sea floor – deserve just as much attention as the ‘‘charismatic megafauna’’ normally associated with the region.
What’s more, they are just as at-risk. ‘‘Benthics are not the seals or the whales which everyone cares about. They’re not a cute, cuddly penguin,’’ Hillman said.
‘‘But what we’re finding is these really marked shifts in this benthic community every time we go [to Antarctica].’’
After two months of diving under the ice at the bottom of the world, Hillman surfaced with a message shared almost unanimously by the scientific community: climate change did not bode well for the future of the animal kingdom.
For the unsung heroes of the Antarctic underworld – the benthic community – that future was particularly precarious due to their inability to cope with change.
‘‘These animals are known to have the poorest ability on earth to respond to changes in temperature,’’ Hillman said. ‘‘They’re 12 times slower at adapting.’’ Unlike the waters surrounding New Zealand, temperatures under the Antarctic ice remained stable year-round, so for benthics, irregularities could have drastic effects.
Warming temperatures also posed another problem – an increase in the number of icebergs.
Icefields melting en masse were a normal and important part of seasonal change in Antarctica, but large icebergs breaking off at random were now interrupting seasonal breakouts.
Some icebergs were even becoming embedded in the ice flow as it froze over, confining animals that would otherwise be free to move around.
On one recent trip, scientists stumbled on thousands of baby scallops that had been trapped for 15 years.
The irregular outbreaks were also problematic because of the inconsistencies they created in how much light could get through to benthics living underneath.
When ice flows weren’t able to break out, the snow on top built up.
This created problems for the algae under the ice – an important first link in the Antarctic food chain and staple for many benthics, Hillman said.
‘‘When it does break off, everything’s better . . . lots of new animals come in, babies and larvae hatch and food and organic matter flood in.’’
But even though most of the issues were caused by humans, Hillman still had a challenge getting people to care about the creatures that would never feature on a postcard. In a final bid, she said she brought the conversation back to the much-loved giants of the ocean – whales.
‘‘The whales go down there to feed. If there’s nothing for them to feed on, then there’ll be no whales,’’ Hillman said.
‘‘One whale doesn’t affect a global cycle but communities of animals living in the sediment really do.’’
Her message was simple: don’t feel so far removed.
‘‘If you think about the sea, it’s all connected. Someone fishing in their backyard is actually affecting the whole ocean.’’