You Can Find More Octopus And Squids In Oceans Now---Maybe Due To Global Warming?

Even though scientists have observed a fall in the population of fish species, it is interesting that cephalopods - including octopus, cuttlefish, and squid, have actually risen in the past 60 years.

According to experts from the University of Adelaide, who investigated the global database of cephalopod catch rates to check out their long-term trends: "Our analyses showed that cephalopod abundance has increased since the 1950s, a result that was remarkably consistent across three distinct groups," said Zoë Doubleday of the University of Adelaide and lead author of the study. "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.

"These allow them to adapt to changing environmental conditions (such as temperature) more quickly than many other marine species, which suggests that they may be benefiting from a changing ocean environment."

With plummeting ocean temperatures, scientists are concerned about the habitability of the world's oceans for its marine species. Still, the study shows that all the species are not declining.

The study stemmed from research on the decreasing population of the Giant Australian cuttlefish, which is currently on the rebound.

"There has been a lot of concern over declining numbers of the iconic Giant Australian cuttlefish at the world-renowned breeding ground in South Australia's Spencer Gulf," Doubleday said. "To determine if similar patterns were occurring elsewhere, we compiled this global-scale database. 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."

Have human activities, such as global warming and climate change caused the rise in cephalopod numbers?

"Cephalopods are an ecologically and commercially important group of invertebrates that are highly sensitive to changes in the environment," said Bronwyn Gillanders of the University of Adelaide and co-author of the study. "We're currently investigating what may be causing them to proliferate - global warming and overfishing of fish species are two theories. It is a difficult, but important question to answer, as it may tell us an even bigger story about how human activities are changing the ocean."

The findings were published May 23 in Current Biology.