Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Underwater drones map ice algae in Antarctica

05.01.2015

New robot technology leads Antarctic exploration into a new epoch. It is now possible to study the underside of sea ice across large distances and explore a world previously restricted to specially trained divers only.

Splash. A Weddell seal weighing almost 500 kg lands inside the tent and blocks the hole laboriously sawn out by researchers in the two-metre-thick ice to launch drones under the sea ice. The tent is lovely and warm. Small petroleum ovens provide heat to keep the hole free from ice. Outside the Antarctic sea ice stretches for miles around and the thermometer shows -15 degrees. The seal finally glides back into the water foraging for more fish and the researchers have access to the open water. The advanced technology drone is carefully lowered into the icy cold sea.


Ice algae have a fantastic ability to grow with very little light. Even under several meters of sea ice, mats of ice algae are formed.

Photo: Lars Chresten Lund Hansen

Working here (right next to the old hut used by polar explorer Robert Falcon Scott in the Antarctic winter) are researchers Lars Chresten Lund Hansen, Brian Sorrell and PhD student Bibi Ziersen, Aarhus University, along with their colleagues from Australia and New Zealand. They are developing and testing a new method to map the distribution of ice algae on the underside of the sea ice in Antarctica.

The tent covers a hole in the ice measuring 3m x 1m, and the researchers send their torpedo-shaped underwater drone down through the hole to map the underside of the sea ice. Making the hole takes most of a day and requires a major equipment package with an oil burner and steam drill.

"The drone was actually designed to study the sea bed and map factors such as sediment types, but our Australian colleagues modified the drone so that it now looks up towards the bottom of the sea ice and measures the light coming through the ice with a radiometer," says Associate Professor Lars Chresten Lund Hansen, Aarhus University.

Ice algae on the underside of the ice absorb light at certain wavelengths, and the radiometer measures how much or how little light is absorbed at these wavelengths. Based on the light measurements, the researchers can calculate the amount of algal biomass under the ice, and thereby get an idea of where the ice algae are located and how many there are. The drone follows a pre-programmed course and it maps the distribution of ice algae over very large areas where studies have not previously been possible.

An important part of the project is controlling the drone's measurements by conventional methods where ice cores are drilled out. The algae are scraped off the underside of the cores and a chlorophyll measurement reveals the number of algae. The chlorophyll figures are subsequently compared with the drone's radiometer measurements.

The aim of these investigations is to understand which factors regulate the distribution of the algae. There are some indications that the rough texture on the underside of the ice plays an important role in the algal colonisation of the sea ice. On the underside of some areas of the ice, there are thin plate-like ice crystals protruding 5 to 10 centimetres out of the bottom. The crystals are wedged between each other, forming a large surface that provides a good habitat for the diatoms that make up the bulk of the ice algae community.

Ice algae are the Antarctic's harbingers of spring

The Antarctic is completely white above the ice, but there is an abundance of colour below the ice. The small greenish-brown unicellular diatoms can grow into large colonies that form entire mats on the underside of the ice.

Ice algae are an important component of the Antarctic ecosystem. They begin to grow under the ice as soon as the Sun emerges in early spring, and survive on the small amount of sunshine that penetrates the compact layers of ice. They are also the year's first producers of food for krill and other zooplankton in the food chain. They get life going so to speak under the ice, where small creatures can frolic in the hanging garden and feast on the algae and bacteria associated with algal life.

"The ice algae account for 15-20% of the primary production in the Antarctic sea ice area. They're particularly important because they utilise the weak light in spring, when there are no other primary producers to provide food and energy for the rest of the food chain," explains Associate Professor Brian Sorrell, Aarhus University.

There are promising signs from the initial data provided by the underwater drone, and the plan is to extend the project to Arctic locations in the coming field season - either at Station North in Greenland or north of Svalbard on the research vessel R/V Lance.

###

Lars Chresten Lund Hansen and his colleagues used a GoPro camera to record the launching of the underwater drone and the seal's visit. See the video on Youtube: http://youtu.be/FJfNdP9NDyQ

Lars Chresten Lund Hansen | EurekAlert!
Further information:
http://www.au.dk

Further reports about: Aarhus Antarctica crystals drone primary sea ice underwater underwater drone wavelengths

More articles from Earth Sciences:

nachricht A close-up look at an uncommon underwater eruption
11.01.2018 | Woods Hole Oceanographic Institution

nachricht Environmental history told by sludge: Global warming lets the dead zones in the Black Sea grow
10.01.2018 | Leibniz-Institut für Ostseeforschung Warnemünde

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

Im Focus: A thermometer for the oceans

Measurement of noble gases in Antarctic ice cores

The oceans are the largest global heat reservoir. As a result of man-made global warming, the temperature in the global climate system increases; around 90% of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

Morbid Obesity: Gastric Bypass and Sleeve Gastrectomy Are Comparable

17.01.2018 | Health and Medicine

Researchers identify new way to unmask melanoma cells to the immune system

17.01.2018 | Health and Medicine

Genetic discovery may help better identify children at risk for type 1 diabetes

17.01.2018 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>