Seamount nematodes

Project summary

• Focus: Studying nematodes from Indian Ocean seamounts to assess the impact of fishing
• Funding: NERC, National Oceanographic Centre

We are studying nematodes from five seamounts as part of the Southwest Indian Ocean (SWIO) seamounts project. We hope to compare the ecosystems of fished and pristine seamounts.

Seamounts are important diverse deep-sea habitats. Due to the logistical challenges associated with reaching and examining seamounts, they remain largely unstudied despite being scattered throughout the Earth’s deep oceans.

Seamounts have been exploited by commercial fishing and other human activities such as mining. Since they lie in the open ocean, their exploration is poorly regulated.

Their unique ecosystems are threatened as they recover from impacts very slowly.

Aims

The SWIO seamounts project aims to determine the biological and physical factors important to species diversity and abundance on seamounts. It has sampled five seamounts on the southwest Indian Ocean ridge, two of which are voluntarily protected by the Southern Indian Ocean Deep-Sea Fishers Association (SIODFA).

The project spans several institutions. At the Museum we are studying nematodes, with a specific focus on why different nematodes colonise different seamount locations.

We will compare the biodiversity and biogeography of nematodes with those of the polychaetes and corals studied by other project groups.

Methods

We are studying nematodes because they are abundant and several different species are likely to live close together.

In one cup of deep-sea mud there may be 200-600 nematodes covering 150-500 different species. Many of these species do not have scientific names as they have not been studied before.

Using genetic identification, we hope to identify cryptic species of nematodes. These are two or more species that appear similar hidden under one species name. DNA analysis is often the only way to tell them apart.

We will compare the abundance, diversity and proportion of cryptic species across the five seamounts and look for patterns related to environmental factors such as:

• temperature
• current speed
• size of sediment.

Watch microscope videos of nematodes found at the seamounts we visited.

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