Impact of ocean acidification on marine life

Increasing acidification of the world’s oceans has the potential to significantly disrupt the way marine life communicates, with as yet unknown consequences for the ecosystem.

Researchers at the University of Hull say increasing acidification of the world’s oceans has the potential to significantly disrupt the way marine life communicates.

Increasing levels of CO₂ pumped into the atmosphere are being absorbed by sea water and increase the acidity of our oceans.

Chemistry and biological science experts at Hull investigate how the change is affecting marine life’s ability to smell, which the organisms rely on to find food, to avoid predators and to mate. The researchers compare the organisms’ impairment of smell to a world without sight or sound for humans.

The potential implications are vast, potentially affecting areas from aquaculture to ecosystem management and conservation.

Investigating the impacts of acidification on biological interactions has been a core research area of Dr. Jörg Hardege’s research group over the past decade.

Recent work, led by Dr. Christina Roggatz and published in the journal Global Change Biology, is the first of its kind to use interdisciplinary methods, including quantum chemical calculations and chemical and biological techniques. 

In close collaboration with Dr. David Benoit and Prof. Mark Lorch, Christina showed that acidification changes the actual smell molecules used by marine organisms. 

Christina said: ”this is a completely new and additional mechanism of how ocean acidification can affect marine life.

“What this study shows is that peptide signalling molecules used by marine invertebrates for egg ventilation and hatching of the larvae are altered by acidification of the oceans.

“Similar signalling cues are involved in mating, finding food or settlement of a wide range of marine animals and are likely to be affected too.

“Imagine you are a little crab, living on a shore with large rocks, deep pools and battled by tides and waves. The only way to find your lunchtime snack would be to smell it from a distance.

“But the same applies to the octopus on the hunt for you. So you as the little crab rely on smelling the octopus first to avoid being eaten.”

If this was no longer possible it has the potential to significantly affect animal behaviour and interactions, adding to the well-known effects of ocean acidification on fitness, physiology and reproduction of marine organisms.

Christina’s research observing shore crabs’ behaviour in response to a solution of smell molecules revealed that in water mimicking the lower pH conditions expected in the ocean by 2100, the crabs’ reactions were significantly impaired.

To translate these findings, Christina recently started a collaboration with Dr. Chris Skinner of the Energy and Environment Institute’s SeriousGeoGames lab.

Supported by BetaJesterLtd., the two researchers developed a game that enables the player to experience the effects of acidification on marine life.

Crabby’s Reef is based on the famous arcade game pac-man and features crabby, the crab, which has to be guided through the reef-like maze to pick up its food while avoiding to be eaten for dinner by the octopuses.

Christina said: “With progressing levels the screen becomes increasingly blurry and the game harder to play to simulate increasing acidity levels, which impact the crab’s senses. In a very simple way, it’s a good representation of what we assume future oceans might feel like for these animals.’

Chris added: “Games are powerful communication tools, able to directly place you into someone or something else's situation and make distant things feel closer. In this case, it helps alert people to ocean acidification, an issue many are unaware of as they see it happening long into the future and in a corner of the world they are never likely to visit."

With the game, Christina and Chris also hope to support The Deep, Hull’s aquarium, which has been particularly affected by the Covid-19 lockdown.