August 03, 2025

Trench nutrient cycling with Ronnie N. Glud

55 minutes

In this episode…

Welcome back to the Deep-Sea Podcast, your punk take on all things deep sea! Join Dr. Thom Linley and Professor Alan Jamieson as they dive into the latest from the abyssal plain and beyond.

Deep Sea News Highlights: We kick things off with a rethinking of the deep-sea boundary! Professor Alan Jamieson discusses his recent "food for thought" paper that challenges the long-held 200-meter definition, arguing for a more scientifically relevant boundary of 1,000 meters. Find out why this seemingly arbitrary line might be doing "a lot of damage" to our understanding and attitude towards the deep sea.

Also in the news, get ready for updates on:

A new story map on mesophotic reefs following the Deepwater Horizon spill in the Gulf of Mexico.

An exciting project charting shipwrecks in the Great Lakes using cutting-edge ROV technology for 3D modelling.

The discovery of a deep-sea limpet named after a One Piece character, found at an astonishing 6 kilometres deep!

How Earth's deep-sea microbes are being used to model potential life on Jupiter's moon Europa.

Groundbreaking research on a new bioplastic that vanishes by over 80% in extreme deep-sea conditions, offering hope for sustainable solutions.

Guest Interview: Nutrient cycling in the hadal trenches (6 to 11 km) and the crucial role they play in global element cycling. Professor Ronnie N. Glud, a leading biochemist and Director of the Danish Centre for Hadal Research (HADAL), talks us through how the trenches, once thought to be barren, are actually "dynamic deep-sea hotspots with intensified microbial activity and diversity". Learn about:

How hadal trenches act as "depocenters" for organic material, leading to microbial activity that's 2 to 6 times higher than in adjacent abyssal sites.

The surprising diversity of microbial "generalists" that easily adapt to the immense pressure and low temperatures, aided by viruses that facilitate "horizontal gene transfer".

The return of full anaerobic diagenetic processes (like sulphate reduction and anammox) in trench sediments, making them significant sinks for fixed nitrogen.

The role of marine snow and seismic activity in efficiently transporting organic matter and, surprisingly, pollutants like PCBs and heavy metals to these remote depths.

Why these trenches are not isolated environments but are highly connected to surface ocean processes, even responding to climate-driven changes in primary production.

We also have a surprise blobfish guest!

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Thanks again for tuning in; we’ll deep-see you next time!

Find out more

Social media

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Keep up with the team on social media

Twitter:

Alan - @Hadalbloke

Thom - @ThomLinley

Instagram:

Thom - @thom.linley

Inkfish - @inkfishexpeditions

BlueSky:

Thom @thomaslinley.com

Reference list

The graves of Edinburgh

John Young Buchanan - Chemist on the Challenger Expedition

Edward Forbes - Deep-sea naturalist

Sir John Murray - Father of modern oceanography

Notable people buried in Dean Cemetery

Discord Updates

Join our Patreon to get access to the Discord

The supergiant amphipod wiki page

News

Interview

Flourishing chemosynthetic life at the greatest depths of hadal trenches

Element cycling and microbial life in the hadal realm

News/Further Reading

Reconsidering the term ‘deep sea’ | ICES Journal of Marine Science | Oxford Academic

Mesophotic and Deep Benthic Communities Expeditions

Historic Shipwrecks Come to Light in the Great Lakes - The New York Times

Lake Ontario National Marine Sanctuary -- Live!

Deep-sea Limpet named after OnePiece character

Microbial Life on Earth: A Model for the Cosmos

Reef Chat from Moku Art Studio with Paola Santiago Padua and Meghan Jones

Scientists find bioplastic that vanishes 80% even in extreme deep-sea conditions

Unveiling deep-sea biodegradation of microbially produced lactate-based polyester (LAHB) via plastisphere metagenomics and metatranscriptomics - ScienceDirect

Alan appeared on another podcast too:

We've Only Explored 0.001% of the Deep Sea - What's Lurking Below? | Discover Magazine Podcast

Credits

Theme: Hadal Zone Express by Märvel

Logo image: Ronnie N. Glud

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By Thomas Linley

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