Guest Post: Who's Killing the Krill?

The joys of a parent in assisting with a homework assignment. Tarryn Clancy is in year 8 Geography exploring Antarctic and Marine Science. As some of my blogging has concerned the southern ocean, whales and Antarctica, and I had recently completed the Open2Study Marine and Antarctic Science online course I was able to assist her with some source material and format of references at the end. But the writing and presentation is all hers. Written By Tarryn Clancy

Whales. Each day they eat tons of krill. And that is only one whale. But what would you say if I told you that 'Mr Bigs' is not the one who is responsible. It is in fact, something much closer to home. Climate Change. We overlook It because some people still do not believe it exists. But it does. And the declining number of krill is evidence of that.


The southern ocean is warming due to climate change. This is Melting Antarctic ice sheets.



These changes are disrupting phytoplankton, causing changes to krill numbers. Climate change and changes to sea ice in the Southern Ocean are causing food shortages that could threaten Whales, Seals and Penguins. The changes in the Southern Ocean ecosytem has resulted in an 80 per cent decline in the number of krill. If the temperature and level of the ocean becomes too high, and too hot, then the world is looking at billions of krill dying. But not only will it affect the krill, but most Antarctic animals as they rely on them for food.

"This is the first time that we have understood the full scale of this decline," said Dr Angus Atkinson, a marine biologist at the British Antarctic Survey who reported the research in the journal Nature.

Species have two choices. Evolve, or die out. And sadly, the latter is highly more likely. Rapid climate change that is occurring means that many species will not be able to adapt in the time available and many will not be able to move latitudes fast enough.

In addition, recent research has shown that whales recycle nutrients - particularly iron – in the upper layers of the ocean, enhancing the productivity of phytoplankton and krill. This is called the 'Whale Pump'. Industrial whaling last century reduced whale population to a vast extent, and thus reduced numbers of phytoplankton and krill in recent years due to reduced whale population which is still recovering.



A recent 2014 study - The Whale Pump: Marine Mammals Enhance Primary Productivity in a Coastal Basin - revealed whales as marine ecosystem engineers. Study co-author Joe Roman said:

“This warrants a shift in view from whales being positively valued as exploitable goods – or negatively valued because they compete with people for marine fish – to one what recognises that these animals play key roles in healthy marine ecosystems, providing services to human societies.”

So, as well as having to worry about the effects from climate change. We also have to add in the factors of industrial whaling last century, and continuing this century by Japan.

"We found that krill concentrated the iron they consumed in their bodies and because they swim near the surface, they keep the iron in the top layer of the ocean," Dr Nicol said. "Approximately 24% of the total iron in the Southern Ocean surface water is currently stored within krill body tissue. When whales consume the iron-rich krill, they excrete most of the iron back into the water, therefore fertilising the ocean and starting the whole food cycle again," Dr Nicol said.

Another study from 2011 - Penguins in peril: variability in krill biomass links harvesting and climate warming to penguin population changes in Antarctica – highlighted that not only whales were affected, but also a number of penguin species and other top level predators.

The heart warming movies, Happy Feet and Happy Feet 2 also highlighted part of the problem is human harvesting of krill in the southern ocean resulting in food shortages for many marine predators.



Assistance with source material and referencing provided by John Englart

References:

British Antarctic Survey. Discovering Antarctica: 5.1 Impacts of Climate Change http://www.discoveringantarctica.org.uk/alevel_5_1.html Retrieved 19 August 2014

Englart, John (Climate Citizen Blog) (April 13, 2011) Penguin numbers suffering with krill decline due to Global Warming http://takvera.blogspot.com.au/2011/04/penguin-numbers-suffering-with-krill.html Retrieved 19 August 2014

Englart, John (Climate Citizen Blog) (April 26, 2010) Whales and Climate Change: the role of Whale poo in absorption of CO2 http://takvera.blogspot.com.au/2010/04/whales-and-climate-change-role-of-whale.html Retrieved 19 August 2014

NASA Science News (May 12, 2014) West Antarctic Glaciers in Irreversible Decline http://science.nasa.gov/science-news/science-at-nasa/2014/12may_noturningback/ Retrieved 19 August 2014 See also video on Youtube: http://youtu.be/W2pYHMx5bN8

Reaney, Patricia. (4 November 2004) Antarctic warming killing off fish food
http://www.abc.net.au/science/articles/2004/11/04/1234914.htm Retrieved 19 August 2014

Roman J, McCarthy JJ (2010) The Whale Pump: Marine Mammals Enhance Primary Productivity in a Coastal Basin. PLoS ONE 5(10): e13255. doi:10.1371/journal.pone.0013255 http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0013255 Retrieved 19 August 2014

University of Hawaiʻi media release (July 3, 2014), New study reveals whales as marine ecosystem engineers http://www.hawaii.edu/news/article.php?aId=6606 Retrieved 19 August 2014