Sea Slug Populations Explode With Warming Seas

It's official, climate change is upon us, with sea levels rising, harsh storms abound, and the hottest years in history. Even the US Senate is admitting that climate change is a reality that we must deal with. Now, a new consequence of warming temperatures has appeared, and it's a strange one. Sea slug populations are growing to unfathomable numbers, and researchers are investigating what that could mean.

Sea slugs are funny looking, inch-long creatures that can be found making thier slow way across the ocean floor around California and other eastern Pacific Ocean coastlines. The slugs in question are actually bright pink nudibrachs - a group of alien-looking gastropod mollusks which have no shell as adults. They are tiny carnivores, feeding on sea sponges, other sea slugs, and even jellyfish.

According to a team of researchers in a collaboration between four different Californian labs, this year's tide pools from San Luis Obispo to Humboldt Counties are boasting an exceptionally large number of these slugs, spotting dozens per square meter of sea floor.

And while these vibrant and beautiful animals are a sight to behold, it is unusual to see them in such large numbers so far north. (Scroll to read on...)

"While we are thrilled to see this beautiful bloom of normally-rare nudibranchs, we are concerned about the long term consequences of our changing coastal environment," researcher Terry Gosliner explained in a statement. He went on to add that because these slugs thrive in warm waters, they are a strong indicator that California's waters are warming far more than usual.

The conditions Gosliner and his colleagues are seeing right now exactly mirror predictions made in a report published in the journal Limnology and Oceanography back in 2011.

The team had predicted that if climate change stayed on its worrying track, it could shift entire ecosystems further north, disrupting local systems in the process, with sea slug population explosions serving as a harbinger of this trend.

And while similar nudibrachs blooms in the past have indeed occurred, they have always been associated with El Niño conditions. What makes this bloom different is that, while the ocean is priming for another bout of future El Niños, 2014 and 2015 did not experience any.

This leaves warming global temperatures to blame, with the researchers looking to confirm their suspicions when the slugs move even further north at the onset of the next El Niño.

"Our current climate conditions are great for some of my favorite slugs, but we can't ignore that warming seas mean less food for sea birds, and adverse impacts for all marine ecosystems," Gosliner added. "California's unique marine life can't always adapt to so much instability."

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