Down in the bottom of the deep blue sea

15 August 2017 by Sylvie Kruiniger, Kerry Howell, Nicola Foster and Huw Griffiths

Deep sea covers most of our planet and yet we know more about the surface of the moon than its dark depths. Its inhabitants form ecosystems essential to life on earth and the race is on to understand and conserve it.

NERC funds scientists working to map the sea floor, examine its geology, currents, chemical processes and more. We hear from scientists on two huge projects - Deep Links and SO-AntEco - half a world away from each other, but with a similar quest: to understand the deep's diverse lifeforms.

We know the deep sea provides essential habitats and resources for countless species, many of which we rely on for food. But we also know that plastics are invading these systems and certain fishing practices can cause huge damage. Until we fill the gaps in our knowledge, we can't know the impact of human activity or what measures could protect these ecosystems.

To get that information, these scientists have been out on research ships being battered by the elements while they film, catch and preserve samples of marine life, working in shifts day and night to make the most of their time on board.

Deep Links

Dr Kerry Howell and Dr Nicola Foster, Plymouth University

Infographic summary of items collected from the Deep Links project
  • 5,800km[2] of seabed mapped
  • Over 360 hours of HD video footage recorded
  • 4,000 samples collected

For the Deep Links project, we're looking at how well connected the marine protected areas are along the west of the British Isles. There's a wealth of life that reproduces by sending out millions of larvae, relying on currents to drift them towards a new area to settle and grow.

We want to find out how closely related animals are between different regions or if the distances are too great for the larvae to travel, making the areas genetically isolated. Isolation eventually leads to species evolving and their genetic code diversifying. This work will help us to know whether marine protected areas would still work if the areas between them become unable to support life.

Specimen collection device, known as the slurp gun

Life at these depths can be fragile and samples must be collected with great care. We had a great piece of kit for that kind of work: the slurp gun!

Reef

A fragile cold-water coral reef stretching as far as the eye can see on Anton Dohrn Seamount. Reefs such as these provide food and shelter for a variety of fish and invertebrates. However, their fragile structure and very slow growth rate mean they are very vulnerable to damage.

Scientists processing samples

Understanding how populations are connected is important when setting up a network of marine protected areas so this is us in the cold lab (4°C) processing and preserving samples for genetic analysis.

South Orkneys - State of the Antarctic Ecosystem (SO-AntEco)

Dr Huw Griffiths, British Antarctic Survey

Infographic summary of items collected from the SO-AntEco project
  • 38,000 invertebrates and fish collected
  • 700 seafloor habitat photographs
  • 3,900 live specimen photos

The SO-AntEco team has been sampling species on the seafloor between 500m and 2,000m, investigating the biodiversity of a deep-sea marine protected area around the Southern Ocean's South Orkney Islands. We were focused on species known to be vulnerable to human activity, finding out where they lived and what habitats they relied on.

One of our key findings was that many vulnerable species provided habitats for other species, so protecting them could promote biodiversity and support a range of other life. This part of the ocean is teeming with so much life that we're running out of names for all the new species - I've had two types of sea cucumber named after me!

Pencil urchin

Corals, sponges and pencil urchins could be even more important that we thought. They provide a home, hiding place, food and nursery for hundreds of other species. Here you can see a brittle star living on coral so it can reach higher up to feed. We also spotted pencil urchins moving across the muddy sea floor acting as mobile homes for other species. It's important to map out all these relationships to get an idea of how the whole system works, and so how to conserve it.

Sea spider

Sea spiders can reach the size of a dinner plate and they're pretty amazing creatures. Although they aren't related to the spiders we see on land, if you pull one up from the deep ocean it'll nimbly scramble across the table.

Amphipods

These are amphipods, they're related to the sandhoppers you find on the beach and they're an important food source for many fish and invertebrates. Around 10,000 species have already been described worldwide.


Deep Links is a collaborative project between Plymouth University, Oxford University, the Joint Nature Conservation Committee (UK Government advisors), and the British Geological Survey.

SO-AntEco was a British Antarctic Survey (BAS) led expedition undertaken alongside an international team of scientists from the Scientific Committee for Antarctic Research.