2016-12-01 / Nature

A Crabby Day on the Bay

By Adam Kovarsky

The Asian shore crab infiltrated Narragansett Bay about 30 years ago. 
(Photo by Timothy Borkowski, kickingdesigns.com) The Asian shore crab infiltrated Narragansett Bay about 30 years ago. (Photo by Timothy Borkowski, kickingdesigns.com) The kinds of crabs that are found in Narragansett Bay have changed drastically over the last 25-plus years. Crabs have been on our planet over 300 million years, about 295 million years longer than humans! Narragansett Bay is home to a myriad of crab species: blue, rock, spider, hermit, mud and mole crabs, and the list goes on.

I moved to Rhode Island when I was 13 and I recall finding many of these crabs during summers on Narragansett Bay. One day, I found a new kind of crab – small, square shaped with sturdy claws and purple striped legs, never bigger than about two inches on the top part of the shell. I later learned this was the Asian shore crab. Over the next few years, I found more and more Asian shore crabs and fewer of the crabs I knew and even loved despite their persistent desire to make a meal of my toes. Now nearly two decades later, I struggle to find the native crabs when poking around rocky shorelines in Narragansett Bay.

The Asian shore crab is an invasive species – a non-native introduced species that causes harm. Our bay has a long history with invasive species dating back to the Colonists who introduced the European green crab. This critter was brought here in water on boats about 200 years ago, and have caused harm in the bay ever since.

Fast forward to 1988 and insert the Asian shore crab. It got here the same way, just from further away. That is why history is important – we could have prevented this. Now European green crabs along with Asian shore crabs are harming our native bay life in a destructive tag team. No animals know how to eat them, they lay nearly three times as many eggs as our native crabs, and they get bigger faster. They can live in colder and hotter waters, and even manage to thrive in polluted waters.

Our displaced out-competed native crabs are forced to live in unfamiliar places. Many have moved to deeper water where hungry predators lie in wait, which is not good. Larger fish, larger crustaceans, octopuses and other hunters are really good at eating small crabs, and they are all over the deeper water of our bay.

In a sick twist of events, this is not all that life in our bay has to deal with. In the past 100 years, the average temperature of the bay has risen 4 degrees Fahrenheit. We drive cars, we use electricity, we burn fossil fuels, and all of this creates a heat-trapping blanket around our planet making everything warmer, including our bay.

These invading crabs now have a claw up on the competition (pardon the pun), one they don’t even need. Warming waters mean a longer growing season for the invaders. This gives them more time to grow larger faster, consume the eggs of competing crabs, and take over vital habitat. Our native crabs may never live the ways they once did. In time, Narragansett Bay will become something entirely different than the bay I grew up with because of human disregard.

Many of you may read this and think about how humans are really doing a poor job with what Mother Nature gave us. Here’s the deal for those who doubt the human race: Never give up hope. There is still time to make a difference; our planet’s death sentence has not been signed. Don’t forget, humans need the planet to survive as well.

If we reduce the burning of fossil fuels enough, we can avoid reaching conditions that would create catastrophic levels of carbon dioxide in the atmosphere. Walk to the store, ride your bike, turn off the lights, try solar energy, try meatless Mondays, start a walking school bus in your community, and simply use less.

Fossil fuel burning is unnatural, and our planet is attempting to hold on to what it has left. In time at our current pace, will it also become uninhabitable for humans? Will it someday become too toxic for the highly adaptable invasive species? With efforts made by each and every community on our planet, we can make a difference. Change can be made, and there is still time for hope.

Adam Kovarsky is a student at the University of Rhode Island and is Save The Bay’s aquarium manager and education specialist.

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