The bad news first: As climate change, over-fishing, and pollution ravage the oceans, many species—from the largest whales to the smallest shellfish—are suffering. However, new research from Australia offers a potential silver lining, or at least unexpected positive spin, on the state of marine life. It turns out, over the last 60 years the number of cephalopods (octopus, cuttlefish and squid) has increased in the world’s oceans.
Published in the journal Current Biology on Monday, the study found that cephalopods, often deemed the 'weeds of the sea', possess a unique set of biological traits, including rapid growth, short lifespans, and flexible development that may be allowing them to adapt quickly to changing environmental conditions. The researchers found the increase in cephalopod numbers to be "remarkably consistent" across the highly diverse range of species that fall under the taxonomic umbrella.
Project leader Professor Bronwyn Gillanders, a scientist at the University of Adelaide in Australia, said that the results of the analysis suggest the increase in cephalopods is related to "large-scale processes" such as human-caused climate change that's warming the oceans. She said a decline in fish stocks globally may also mean fewer fish to prey on the creatures or less competition between cephalopods and fish for food.
"I think the increase in cephalopod numbers is a potential sign that any change in the ocean whether it be through warming, fishing, or habitat modification can cause changes in the distribution and abundance of organisms," she said.
According to the study's lead author Dr. Zoë Doubleday, also at the University of Adelaide's Environment Institute, they initially started the investigation to look into the declining numbers of Giant Australian cuttlefish.
“To determine if similar patterns were occurring elsewhere, we compiled this global-scale database," she said in a statement. "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.”
Gillanders said their findings make it all the more important to understand how human-driven changes to the oceans are impacting marine life. Better comprehending these causes and effects will help researchers and policymakers develop solutions to both protect the oceans and sustain the many types of life, including humans, that rely on them.
While octopuses and squid may be thriving in their slightly warmer conditions, if the oceans continue to heat up, the temperature could eventually exceed their "optional range" according to the study. Scientists have predicted that some parts of oceans could warm by almost a full degree Celsius (1.8˚F) by the end of the century. The negative effects of these changes are already being seen in the massive global coral bleaching underway over the last year, especially along Australia's Great Barrier Reef.
At the same time, if food becomes limited it could inhibit cephalopod grown.
Then there's the issue of direct human impacts. The study notes that as fish stocks decline, cephalopods have increased in importance to fisheries, with "catch peaking in recent years and cephalopod fisheries showing signs of over-exploitation."
"Therefore, as fisheries continue to refocus their efforts towards invertebrates, it will be critical to manage cephalopod stocks appropriately so they do not face the same fate as many of their longer-lived counterparts," states the study.
This study comes just as scientists are beginning to realize the true intelligence of certain cephalopods, such as octopuses, which are social creatures with amazing physical and mental attributes. In one recent display of these faculties, an octopus recently escaped from an aquarium by sneaking through a drainage pipe.