Biological sampling gear

The Southern Ocean is the world’s least explored ocean due to its remoteness and inhospitable nature – data coverage is lower than in any other ocean. Polar research ships play a central role in allowing scientists to access the Southern Ocean and study its unique ecosystems and biodiversity, which have an important impact on global climatic and ecological processes.

Bongo nets

RRS Sir David Attenborough has three different types of Bongo nets. The bespoke motion-compensated Bongo net corrects for the pitching and rolling of the ship using a spring mechanism that helps maintain a constant upward velocity of the net through the water. This avoids damage to equipment or samples from sudden acceleration.

The same net can also be configured as a towed Bongo net to sample specific water depths or strata.

Additionally, a small and lightweight mini-Bongo net can be deployed from smaller boats – such as the ship’s workboat – using smaller winches. This is mainly used to sample small zooplankton in good condition from depths of 100m.

Towed bongo nets on the back deck of RRS James Clark Ross on cruise JR177 in the Southern Ocean.
Towed Bongo nets on the back deck of RRS James Clark Ross on cruise JR177 in the Southern Ocean.

The Southern Ocean is the world’s least explored ocean due to its remoteness and inhospitable nature. But, despite the cold waters and harsh conditions, it is teeming with life.

The Biodiversity, Evolution and Adaptation and Ecosystems teams at British Antarctic Survey study how life adapts to extreme polar conditions and how these unique ecosystems are being impacted by global climate-driven change and commercial fishing. Their research provides insights into the impact of environmental change on the natural world and informs policies that regulate fisheries, conservation and ecosystem-based management strategies.

Polar blueing: a negative climate feedback

Bryozoans are tiny filter-feeders that live on the relatively shallow seafloor of the continental shelf and depend on food sinking down from the surface. Like many benthic organisms, bryozoans grow their exoskeletons using carbon they extract from the ocean and convert to calcium carbonate – a process known as carbon immobilisation. When the organism dies, its exoskeleton may be buried by sediment, removing the carbon fixed in it from the global carbon cycle for millions of years.

Because bryozoans depend on food dropping down from above, they can only grow when the sea surface is ice-free. This allows phytoplankton blooms to grow, providing food for the seafloor community.  Over the past thirty years, the duration of sea ice cover has shortened by an average of 80 days on 1 million square km of ocean – that’s roughly four times the size of the UK. This huge area can now support phytoplankton – and bryozoan growth – for much longer every year. Where permanent ice shelves collapse, plankton and benthos can also colonise entire new areas previously uninhabitable to them. As a result, Antarctic benthos can immobilise and fix far more carbon than before as the region’s climate changes. This so-called ‘blueing’ of the polar regions is a rare example of a negative feedback loop where the effects are increasing temperatures help offset the impact of greenhouse gases.

Bryozoans collected during a research cruise on the RRS James Clark Ross. Picture by Dr David Barnes (British Antarctic Survey)
Bryozoans collected during a research cruise on the RRS James Clark Ross. Picture by David Barnes (British Antarctic Survey)

The future: carbon immobilisation around the Antarctic

A recent study by researchers at BAS and the National Oceanography Centre in Southampton found that carbon immobilisation is particularly pronounced around the remote South Orkney Islands, 300 miles off the tip of the Antarctic Peninsula. In 2010, this area became the first marine protected area located entirely in the high seas.

To map the carbon immobilisation effect of benthic communities around the Antarctic, scientists are completed several more research cruises around the entire Antarctic continent, visiting rarely studied areas and adding to our understanding of the complex relationships between Antarctic ecosystems and climate change.

Carbon immobilization in the Antarctic
Carbon immobilization in the Antarctic