Squids are taking advantage of changing oceans

ADELAIDE, Australia, May 23 (UPI) -- Cephalopods -- the mollusk class that includes cuttlefish, octopi and squids -- are proliferating.

Unlike many fish species, whose populations continue to decline, cuttlefish, octopi and squids have grown in abundance of the last several decades.

Worried by the decline of the iconic Giant Australian cuttlefish among breeding grounds off the coast of southern Australia, researchers at the University of Adelaide set out to measure population growth and decline among cephalopods on a global scale.

"Surprisingly, analyses revealed that cephalopods, as a whole, are in fact increasing; and since this study, cuttlefish numbers from this iconic population near Whyalla are luckily bouncing back," Zoë Doubleday, a research fellow at Adelaide's Environment Institute and School of Biological Sciences, explained in a news release.

Doubleday is the lead author of the latest study of cephalopod abundance, published this week in the journal Current Biology.

Though cuttlefish, octopi and squids are especially sensitive to environmental changes, they're also quite adaptive.

"Cephalopods are often called 'weeds of the sea' as they have a unique set of biological traits, including rapid growth, short lifespans and flexible development," said Doubleday. "These allow them to adapt to changing environmental conditions, such as temperature, more quickly than many other marine species."

"Cephalopods are an ecologically and commercially important group of invertebrates that are highly sensitive to changes in the environment," added lead researcher Bronwyn Gillanders, a professor at Adelaide. "We're currently investigating what may be causing them to proliferate."

Researchers believe rising ocean temperatures and the decline of species overfished by humans may be contributing to the cephalopod rise.

Cephalopods are found in waters all over the globe. They're very effective predators and an important food source for humans as well as many sea creatures.

"As such, the increase in abundance has significant and complex implications for both the marine food web and us," concluded Doubleday.