What will extra cephalopods mean for marine ecosystems?

Octopus vulgaris resting on a reef. This mollusc can be found in the Mediterranean Sea and in the Atlantic Ocean Octopus vulgaris resting on a reef. This mollusc can be found in the Mediterranean Sea and in the Atlantic Ocean MattiaATH/Shutterstock
03 Jun
2016
A delicious opportunity or proof of human impact on the ocean? The news of booming cephalopods (octopuses, cuttlefish and squid) has already divided seafood lovers and environmentalists. Whatever your opinion, cephalopods appear to be thriving while other marine species flounder, raising questions about the state of underwater ecosystems

A recent study published in Current Biology shows that cephalopod numbers have increased over the last six decades. By analysing numbers of cephalopods caught as bycatch in fishing vessels, researcher Zoë Doubleday of the University of Adelaide’s Environmental Institute, observed population rises all over the world. ‘Cephalopods are notoriously variable, and population abundance can fluctuate wildly, both within and among species,’ she says. ‘The fact that we observed consistent, long-term increases in three diverse groups of cephalopods, which inhabit everything from rock pools to open oceans, is remarkable.’

oie 6froxBbBE57EOctopus numbers are on the increase (Image: Kerry L Werry)

Cephalopods are flexible, both physically and ecologically. They have rapid growth and relatively short lifespans, leading scientists to speculate that they can keep up with the changes to their environment, especially warming oceans. In fact, warmer waters are thought to accelerate their life cycles, so long as it does not surpass their tolerance and food is not limited. Cephalopods may also be less at risk from predators, thanks to the global depletion of fish stocks. ‘It is relatively well documented that many fish species have declined in abundance due to overfishing,’ they write, ‘and several regional studies have suggested that cephalopod populations have increased where local fish populations have declined.’

Because they occupy the middle of the food chain, a boom in cephalopods will undoubtedly have an impact on marine ecosystems. ‘All cephalopods are carnivores and they eat lots of different types of prey including fish, other molluscs, and crustaceans,’ says Doubleday, ‘so it may reduce those animals. However, they are also an important source of food for many animals including seals, whales, predatory fish and sharks, and seabirds.’ She is wary, however, that their increase will go unchallenged for long, ‘they are becoming an ever-more important component in global fisheries, and feature increasingly on menus, so we might eat them before they increase too much.’

Share this story...

Submit to FacebookSubmit to Google PlusSubmit to Twitter

Related items

Leave a comment

ONLY registered members can leave comments and each comment is held pending authorisation before publishing. Please login or register to voice your opinion.

EMAIL NEWSLETTER

Get the best stories from Geographical delivered straight to your inbox each week.

Subscribe Today

EDUCATION PARTNERS

Aberystwyth UniversityUniversity of GreenwichThe University of Winchester

TRAVEL PARTNERS

Ponant

Silversea

Travel the Unknown

DOSSIERS

Like longer reads? Try our in-depth dossiers that provide a comprehensive view of each topic

  • REDD+ or Dead?
    The UN-backed REDD+ (Reducing Emissions from Deforestation and Forest Degradation) scheme, under which developing nations would be paid not to cut dow...
    The true cost of meat
    As one of the world’s biggest methane emitters, the meat industry has a lot more to concern itself with than merely dietary issues ...
    Long live the King
    It is barely half a century since the Born Free story caused the world to re-evaluate humanity’s relationship with lions. A few brief decades later,...
    London: a walk in the park
    In the 2016 London Mayoral election, the city’s natural environment was high on the agenda. Geographical asks: does the capital has a green future, ...
    The Money Trail
    Remittance payments are a fundamental, yet often overlooked, part of the global economy. But the impact on nations receiving the money isn’t just a ...

MORE DOSSIERS

NEVER MISS A STORY - follow Geographical

Want to stay up to date with breaking Geographical stories? Join the thousands following us on Twitter, Facebook and Instagram and stay informed about the world.

More articles in NATURE...

Geophoto

This winter has seen frequent storms and flooding hitting many…

Wildlife

The bison, Poland’s symbol of nature conservation, already faces controversial…

Wildlife

Wolves have arrived at a wildlife park in Devon as…

Climate

An unassuming beach in Denmark is absorbing record-breaking levels of…

Energy

The environmental cost of military activities is significant. Could new…

Wildlife

Latest figures suggest that there are more than twice as…

Tectonics

How does the proposed allocation of ‘Zealandia’ as an independent…

Wildlife

Is extinction forever? While most would assume that yes, extinction…

Geophoto

Wide-angle photography is perhaps the best way to recreate the…

Wildlife

New book aims to follow in the success of last…

Wildlife

With Queensland koala numbers in free-fall, a novel idea suggests…

Climate

Geographical’s regular look at the world of climate change. This…

Tectonics

Fears that volcano eruptions in Iceland are set to regularly…

Oceans

Now we can all experience diving to the deepest point…

Wildlife

The new President of the United States has a namesake…

Geophoto

17,000 photographs from over 50 countries have been whittled down…

Wildlife

Red squirrels are found to be afflicted with a stubborn…

Polar

The toll, as a response to melting sea ice, would…

Climate

Could rail be the sustainable long-distance freight transport the world…

Energy

Abandoned oil and gas wells in the US are leaking significant…