Science notes for Energies
The following notes were composed with the guidance of marine biologist Jaime Gomez-Gutierrez. They accompanied the screening of the animation, Energies, at the 3rd GLOBEC Open Science Meeting, Victoria, Canada, 22-26 June 2009. Energies was screeened in the Workshop, Krill biology and ecology of the world oceans ( PICES Newsletter).
Energy systems represented in the animation, Energies, are indicated by bold type. Energy systems are physical and biological entities that work together to shape environments.
Diatoms are single celled, or unicellular, organisms that are at the base of our complex food web. They appear in the animation to metaphorically represent the complete microalgae community. Encased within intricate cell walls made of silica, diatoms live in pelagic and benthic Antarctic environments.
The term Pelagic is derived from the Greek word 'pelagos', meaning 'open sea'. The pelagic ecosystem is very large and interacts most directly with the atmosphere and extensive sea ice that forms during the Antarctic winter. The term benthos is derived from the Greek, meaning 'depths of the sea' and refers collectively to organisms which live on, in, or near the bottom of the sea. The benthic community includes of a wide range of plants, animals and bacteria (Census of Antarctic Marine Life, 2005).
Fossil evidence suggests that diatoms originated around the early Jurassic Period. Scientists believe that some phytoplankton cells and planktonic organisms, particularly coccolithophorids and pteropods with calcareous cells, may be eroding due to carbon dioxide (CO2) increasing ocean acidity (Census of Antarctic Marine Life, 2005).
Carbon dioxide (CO2) is the most commonly known greenhouse gas contributing to global warming, but carbon monoxide (CO), methane (NH4) among other gasses are also contributing to human induced global warming.The atmospheric concentration of CO2 is now higher than at any other time in the last 850,000 years.
A consequence of the greenhouse effect is global warming. As temperatures rise, the oceans expand (due to thermal expansion) and the ice coverage of polar regions contracts. Together with water from glaciers melting into the sea, thermal expansion is a major reason for sea levels rising (Church, 2007).
Antarctic sea ice freezes and melts in a rhythmic seasonal cycle, within an inter-annual cyclic pattern of less regular change. This motion and coverage of sea ice determines if and when life forms can breed and feed. Global warming means that ice is melting more rapidly than normal. Scientists do not yet understand the complex mechanisims to be able to predict the full impact global warming will have on marine organisms and humans.
Each year sea ice extends to cover over 10% of the world's oceans, which around Antarctica is 20 million km2. The sea ice microalgae are thought to contribute between 25% and 50% of the total primary productivity. With global warming reducing the extent of Antarctic sea ice, it is likely that the capacity of the Southern Ocean to support its large biomass of whales, seals and seabirds will reduce (McMinn, 2003).
Sea ice drives bottom water circulation through the Southern Ocean. Unlike the ice sheet that inches seawards from inland Antarctica and from which ice bergs break away, sea ice forms from sea water that surrounds the Antarctic continent. The sea ice melts during the southern hemisphere spring and summer, then cold, salt-dense water sinks down to deeper layers. From there it moves outwards and upwards in a spiraling motion from east to west. This is known as the Conveyor belt, or thermohaline circulation, where water circulation is driven by changes in salinity and temperature that determine its density. This ocean circulation shapes the planet's climate through a feedback interaction between the ocean and the atmosphere. Through this complex mechanism, bottom water spirals outwards and northwards to join the circumpolar current, (ACC), or West Wind Drift.
Vital to the well being of Antarctic wildlife is the force of the Antarctic convergence. This is the border or transition zone separating the colder, less salty water around Antarctica from the warmer, relatively more salty waters further north. This circling field of energy draws nutrients upwards towards the ocean surface. The circumpolar current offers a rich feeding ground for fish, marine birds, and mammals. As a perpetually dynamic zone of energy that draws predators and prey together, it can be imagined as a moving feast and natural battle field for survival.
Just as the energy of the Southern Ocean influences the motion of its wildlife, so the energies of marine life forms influence motion of ocean waters (Yen, 2003). Like the whales and seals, krill individuals and schools mix the ocean waters as they go about their daily lives. Krill move vertically along the water column every day, being usually near the surface during the night and in deeper waters during the day. Their continuous biological motion circulates nutrients that feed the diatoms upon which they feed. For this reason, marine scientist and krill expert Steve Nicol describes krill as 'farmers of the ocean' (Nicol, 2009).
More observations are needed to comprehend the mechanisms involved, but scientists agree that reciprocity appears to operate among all organisms and their environments.
Key findings of the research were that:
* Scientists who contributed easily recognised their knowledge in the animations that were made, sometimes feeling a strong sentimental connection with the natural forces portrayed.
* Circles and spirals that trace gestures arising from our physical human structure reflect similar structures that exist in the Antarctic environment.
* People who have not experienced Antarctica can connect to the insights of its research community through drawing dance, and animation.