Tiny algae that colonise the underside of the Antarctic sea ice play a big part in the health of Southern Ocean ecosystems.
These microalgae absorb large amounts of carbon dioxide by converting it into sugars and oxygen, using the energy of sunlight.
They also kick-start the Southern Ocean food chain as the staple diet of krill – a shrimp-like crustacean – that is itself an important food source for many creatures, including whales, seals, squid, penguins and sea birds.
Checking out the distribution of the sea ice algae is a task of the Antarctic Climate & Ecosystems Cooperative Research Centre (ACE) sea ice research group, with the help of a Saab Seaeye Fibre Optic Falcon ROV in black livery fitted with camera and LED lights.
Black was chosen for the casing, rather than the usual yellow, to avoid reflected sunlight affecting the bio-optical measurements taken by an upward facing light sensor that will be fitted to the vehicle.
The sensor measures the effect of the pigmented algae on the underwater colour spectrum and reveals the amount of algae present in the ice.
By using an ROV for such data gathering, rather than traditional ice core sampling, the ACE scientists expect to collect more accurate data about changes in the algal population than has previously been possible.
Until now, core sampling has restricted data collection to a single narrow point where the sample was extracted.
This has led to Antarctic sea ice algae being poorly understood, despite being an important early season food source at the base of the Antarctic marine food web. Using the easily deployed Falcon ROV to roam under the ice in 300 metre sectors means that more widespread and representative data can be gathered, and collection will be much faster than the usual coring method, thereby saving valuable ship time in difficult conditions.
The under-ice krill population will also be filmed by the ROV’s onboard video camera to help better understand the relationships between the sea ice, ice algae and this key Antarctic species.
High quality filming and light measurements are possible due to five powerful thrusters that hold the Falcon steady in strong cross currents and make it highly manoeuvrable in all directions
With over 260 sold world-wide, the Saab Seaeye Falcon has a long record of working at difficult tasks in hostile conditions using highly complex instrumentation and tooling. It was supplied and will be supported by Saab Seaeye’s Australian distributor, ATSA Defence Services based in NSW.
Its role will be vital in helping the Antarctic team understand the marine ecological processes of the sea ice, which forms a vast skin across the ocean. The sea ice ranges from a centimetre to a metre or two thick and plays a pivotal role in the global climate whilst acting as an important floating habitat for marine birds, mammals and microalgae.
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Source: Seaeye, February 28, 2012; Image: Seaeye