Thursday, December 8, 2016

Crustacean Devastation!

By Adam Kovarsky, Aquarium Manager and Education Specialist

Crabs have crawled on earth for more than 300 million years; that’s about 295 million years longer than people! Narragansett Bay is habitat for numerous crab species; blue, rock, Jonah, spider, hermit, mud and lady crabs, and that list keeps going. Varieties of crabs found in Narragansett Bay have changed radically over the last three decades. I moved to Rhode Island when I was an awkward teenager wanting to spend most of my time on my own in nature. I recall finding most of these crusty critters during summers on the water. One of those days, I stumbled upon a different kind of crab – tiny, box-shaped with robust claws and purple patterned legs, never larger than around two inches on the upper part of the shell. Later, I learned this was the non-native, introduced Asian shore crab.

Over the years to come, I found more and more Asian shore crabs and fewer and fewer of the crabs I knew and loved in spite of their determined desire to make a banquet of my toes. Now nearly 20 years later, I have a hard time finding native crabs when poking around rocky shorelines in Narragansett Bay. The Asian Shore Crab is an invasive species - a non-native species introduced by humans that causes harm.

Narragansett bay has an extended history with invasive species going back to the Pilgrims who introduced the European green crab. This highly adapted brute was brought here in ballast water on boats nearly 200 years prior and has been causing damage in our bay since. Fast forward to 1988, David Bowie is on tour, Reagan was president and Asian Shore Crabs make their dramatic debut in America. They got here the same way green crabs did, but from further away. That’s why attention to history is vital; we could have prevented this!

But instead, European green crabs alongside the Asian shore crab are now damaging our native Bay life in a vicious tag team. Nothing eats them, they lay almost three times as many eggs as our native crabs, they grow larger faster, they can survive in cooler and hotter temperatures, and they have adapted to flourish in contaminated waters. Now, our exiled, outcompeted native crabs are forced to move to unfamiliar places to simply survive. Many have migrated to deep waters where voracious hunters lie in wait. Larger lobsters, larger fish, octopi, squid, seals and other predators are really talented at eating crabs; they are the masters of the depths of our bay.

In a twisted, sickly turn of the tide, these invasive crabs aren’t all the life in our Bay deals with. In the past century, the temperature of our bay has risen 4◦ Fahrenheit on average. We use electricity, drive cars, and set fire to fossil fuels, all of which form a heat trapping blanket of doom around our planet. These introduced raiding crabs now have a distinct claw up on the competition (pardon the pun) - one they don’t even need. Warming temperatures mean an extended growing season for the invasives, giving them ample time to grow bigger faster, eat the eggs of competing crabs and overtake vital habitat. The native crabs of Narragansett Bay may never exist in the ways they once did. In the future, Narragansett Bay will be something completely different than the Bay I grew up with because of human negligence.

If you’re reading this and wondering why people are doing such a poor job with what Mother Nature provided us, never give up! We still have time to change. Remember, humans need the planet to survive as much as it needs us. If we cut back the scorching of fossil fuels enough, we can avoid reaching conditions that would put cataclysmic levels of carbon dioxide in the atmosphere. Ride your bike to the store, walk, turn down the heat, shut the lights, try alternative energy, start a walking school bus in your town. Put simply; just use less. Fossil fuel burning is not natural, and our planet feels it. With hard work and changes made by each and every community on earth we will make the difference we need, there is still time for hope.

Adam Kovarsky is Save The Bay’s Aquarium Manager and Education Specialist.