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New Research Involving TCD Scientist Shows Global Oceans in More Fragile State

29th November 2023
Prof Micha Ruhl of Trinity College, Dublin
Prof Micha Ruhl of Trinity College, Dublin

Global oceans could be in a more fragile state than previously apparent, new research published today suggests.

An international team involving Trinity College Dublin (TCD) has shown that current de-oxygenation levels are very similar to those that were implicated in one of the world’s largest ever mass extinctions.

The research published in international journal Nature Geosciences suggests that oceanic anoxia played an important role in ecosystem disruption and extinctions in marine environments during the Triassic–Jurassic mass extinction.

Sampling of the Carnduff cores, which were drilled in the Larne Basin, Northern IrelandSampling of the Carnduff cores, which were drilled in the Larne Basin, Northern Ireland

This was a major extinction event that occurred around 200 million years ago, and one of a series linked to the collapse of global ecosystems and extinction of species.

The international research team led by scientists from Royal Holloway in Britain, and involving scientists from Trinity College Dublin’s School of Natural Sciences and the Netherlands Utrecht University was able to link two key aspects associated with the Triassic–Jurassic mass extinction.

The team used chemical data from ancient mudstone deposits obtained from drill-cores in Northern Ireland and Germany.

The scientists say they discovered that pulses in de-oxygenation in shallow marine environments along the margins of the European continent at that time “directly coincided” with increased extinction levels in those places.

A core sample of ~201 million year old sediments obtained from the Carnduff-2 core, drilled in the Larne Basin (Northern Ireland), showing the shell of an animal that lived on the seabed shortly after the Triassic–Jurassic global mass extinction.A core sample of ~201 million year old sediments obtained from the Carnduff-2 core, drilled in the Larne Basin (Northern Ireland), showing the shell of an animal that lived on the seabed shortly after the Triassic–Jurassic global mass extinction

The team also found that the global extent of extreme deoxygenation was rather limited, and similar to the present day.

“Scientists have long suspected that ocean de-oxygenation plays an important role in the disturbance of marine ecosystems, which can lead to the extinction of species in marine environments,” Micha Ruhl, assistant professor in Trinity’s School of Natural Sciences and a member of the research team, has said.

“The study of past time intervals of extreme environmental change shows this to be the case, which teaches us important lessons about potential tipping points in local, as well as global ecosystems in response to climatic forcing,”Ruhl said.

“Crucially however, the current findings show that even when the global extent of de-oxygenation is similar to the present day, the local development of anoxic conditions and subsequent locally increased extinction rates can cascade in widespread or global ecosystem collapse and extinctions,”he warned.

He said this can happen “even in areas where de-oxygenation did not occur”.

“It shows that global marine ecosystems become vulnerable, even when only local environments along the edges of the continents are disturbed,”he said.

“Understanding such processes is of paramount importance for assessing present day ecosystem stability, and associated food supply,”he said.

He said this was especially so “in a world where marine deoxygenation is projected to significantly increase in response to global warming and increased nutrient run-off from continents”.

This research was supported by a Natural Environment Research Council Doctoral Training Partnership award and the National Natural Science Foundation of China. 

Published in Marine Science
Lorna Siggins

About The Author

Lorna Siggins

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Lorna Siggins is a print and radio reporter, and a former Irish Times western correspondent. She is the author of Search and Rescue: True stories of Irish Air-Sea Rescues and the Loss of R116 (2022); Everest Callling (1994) on the first Irish Everest expedition; Mayday! Mayday! (2004); and Once Upon a Time in the West: the Corrib gas controversy (2010). She is also co-producer with Sarah Blake of the Doc on One "Miracle in Galway Bay" which recently won a Celtic Media Award

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Marine Science Perhaps it is the work of the Irish research vessel RV Celtic Explorer out in the Atlantic Ocean that best highlights the essential nature of marine research, development and sustainable management, through which Ireland is developing a strong and well-deserved reputation as an emerging centre of excellence. From Wavebob Ocean energy technology to aquaculture to weather buoys and oil exploration these pages document the work of Irish marine science and how Irish scientists have secured prominent roles in many European and international marine science bodies.


At A Glance – Ocean Facts

  • 71% of the earth’s surface is covered by the ocean
  • The ocean is responsible for the water cycle, which affects our weather
  • The ocean absorbs 30% of the carbon dioxide added to the atmosphere by human activity
  • The real map of Ireland has a seabed territory ten times the size of its land area
  • The ocean is the support system of our planet.
  • Over half of the oxygen we breathe was produced in the ocean
  • The global market for seaweed is valued at approximately €5.4 billion
  • · Coral reefs are among the oldest ecosystems in the world — at 230 million years
  • 1.9 million people live within 5km of the coast in Ireland
  • Ocean waters hold nearly 20 million tons of gold. If we could mine all of the gold from the ocean, we would have enough to give every person on earth 9lbs of the precious metal!
  • Aquaculture is the fastest growing food sector in the world – Ireland is ranked 7th largest aquaculture producer in the EU
  • The Atlantic Ocean is the second largest ocean in the world, covering 20% of the earth’s surface. Out of all the oceans, the Atlantic Ocean is the saltiest
  • The Pacific Ocean is the largest ocean in the world. It’s bigger than all the continents put together
  • Ireland is surrounded by some of the most productive fishing grounds in Europe, with Irish commercial fish landings worth around €200 million annually
  • 97% of the earth’s water is in the ocean
  • The ocean provides the greatest amount of the world’s protein consumed by humans
  • Plastic affects 700 species in the oceans from plankton to whales.
  • Only 10% of the oceans have been explored.
  • 8 million tonnes of plastic enter the ocean each year, equal to dumping a garbage truck of plastic into the ocean every minute.
  • 12 humans have walked on the moon but only 3 humans have been to the deepest part of the ocean.

(Ref: Marine Institute)

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