Climate change is bad news for many species. Environments are changing more rapidly than plants and animals can adapt to—or move out of—them.
Octopuses, however, reproduce so quickly (and multitudinously) and have such short generation times, they are generally well primed to adapt and move.
The common Sydney octopus (Octopus tetricus), for one, is expanding its range poleward as the surrounding oceans warm. But could a shift south actually eventually limit this octopus's ability to adapt in the future? A team of Australian-based researchers investigates this question in a new paper, published this August in PLoS ONE.
Octopuses in cooler climes usually grow larger and live longer than those in warmer waters. (One deep-sea octopus, for example, brooded her eggs for four-and-a-half years—more than four times as long as many octopus species live.) A shift from warmer waters to the cooler ones at the edge of the new range might mean that the octopus would start living longer, lengthening generations, and thus perhaps soon adapt itself out of adaptability to climate change.
The Australia-based research team assessed some 527 common Sydney octopuses to see how water temperatures were affecting their growth. And results suggest that this octopus is, so far, remaining a lean, mean invading machine, even at the far southern reaches of its new domain.
This species, also known, sadly, as the gloomy octopus, lives for only about 11 months and is but a wee 2.2 millimeters long at hatching.
In its early mini stage, it floats in the currents for a month or two, largely at the mercy of the currents—and habitable water conditions. The species has historically lived from southern Queensland to southern New South Wales. However, the researchers note, "its distribution has extended polewards to south-eastern Australia, along the coasts of Victoria after 2000 and eastern Tasmania in 2006."
The team attributes this shift to the southern expansion—by some 350 kilometers in the past 60 years—of the warm water-carrying East Australian Current, which "is consistent with expected changes in distribution promoted by climate-driven warming." The Tasmanian Sea, which lies between New South Wales and New Zealand, has thus far been warming at three to four times the rate of global ocean temperatures.
The fate—and location—of the common Sydney octopus is of interest not only to biologists, but also to local fisheries, which depend on this species for a sizable chunk of their catches.
Given the "fast growth rates and short lifespan," of the octopuses caught for the study—even those in the southernmost locations—the species seems primed for a "rapid population expansion" and an "'invasion' into new environments," the researchers note.
Although this is good news for the common Sydney octopus, it could be bad news for species that have been trying to make their living in this range for much longer.
Read more about how octopuses have spread throughout the globe in Octopus! The Most Mysterious Creature In the Sea.
Illustration courtesy of Ivan Phillipsen