Catch It If You Can! – Amphipods in the Deep-Sea

Let's get to know a deep-sea scavenging crustacean! Photo: Tasnim Patel Let’s get to know a deep-sea scavenging crustacean! Photo: Tasnim Patel

by Tasnim Patel, RBINS

Life in the deep-sea is no picnic and dedicating your life to studying our last truly unexplored wilderness isn’t easy either. To sample fauna in the abyssal plains requires courage, expertise, commitment, financial backing and in my case …a pinch of luck. I’m studying deep-sea scavenging crustaceans, which are not only exceptionally interesting morphologically and genetically, but also quite evasive little critters.

There are few papers on deep-sea amphipods, unsurprising given the challenges of sampling this remote environment. I am faced with trying to sample and deploy equipment in high hydrostatic pressures and low temperatures, a feat which would be impossible without the joint initiative set up by JPIOceans and spearheaded by the brilliant minds at the GEOMAR institute (Kiel, Germany).

Together with the ROV and Elevator teams, I am able to deploy baited traps at 4500 m depths to attract my species of interest from the Lyssianasoidea family.  I am investigating whether deep-sea mining of manganese nodules and subsequent sediment plumes, would affect the biodiversity and recolonisation ability of these crustaceans.

My samples are from two abyssal basins, in the NE and SE Pacific. Firstly, the Clarion-Clipperton Fracture Zone (CCZ, six million km2, 7000 km wide), an economically important manganese nodule field in the NE Pacific, comprising several different contractor claim areas and nine designated Areas of Particular Ecological Interest (APEIs) and secondly, the DISturbance and re-COLonisation (DisCOL) Experimental Area (DEA, 11 km2, 4 km wide), a mining disturbance proxy in the Peru Basin.

Working at sea can be challenging, but I am always happy to retrieve my traps and find some Lyssianasoidea specimens within. The catch can range from 50 – 1000 individuals, contingent on the productivity of the area. On retrieval, time is of the essence. DNA can degrade fast, so the specimens must be sorted, identified, measured, photographed, dissected and appropriately fixed in a matter of hours. Since this is the case, nights can blend into days but it honestly flies by if you’re having fun at the microscope!

Amphipods have been around since the Eocene, and are an important part of the deep-sea nutrient cycle. Thus far, I have been able to study the Cytochrome Oxidase I gene for two deep-sea amphipods. I can now use these reference sequences to design custom nuclear primers and then use Next-Generation Sequencing techniques, to analyse several Single Nucleotide Polymorphisms (SNPs) at once. This process will allow me to investigate their evolution and mutations for adaptability in extraordinarily fine detail.

One of the Amphipods under a microscope. Photo: Tasnim Patel
One of the Amphipods under a microscope. Photo: Tasnim Patel

I think they look like little dragons, but most will say they resemble shrimps. Despite this, I don’t recommend eating these carrion-feeders. Instead, let the RBINS team make you the yummy chocolate version!

The chocolate version. Photo: Tasnim Patel
The chocolate version. Photo: Tasnim Patel