2017-08-17 / Nature

What Those ‘Tropical Travelers’ Tell Us About the Future

By Adam Kovarsky

Spotfin butterfly fish. (Photos by Carmen Rugel Spotfin butterfly fish. (Photos by Carmen Rugel Narragansett Bay is rich with hundreds of species of flora and fauna, and late summer is the perfect time to explore some of those that aren’t actually supposed to be here.

At Save The Bay’s Exploration Center and Aquarium, visitors can learn about “tropical travelers,” which are fish that swim in warmer waters along North America’s eastern coast, particularly between the Carolinas and the Bahamas. Also known as “Gulf Stream orphans,” juvenile fish and unhatched eggs get swept northward, 25 to 75 miles per day, by the Gulf Stream current, eventually becoming stranded in Narragansett Bay and nearby waters.

Tropical travelers can survive in Rhode Island’s waters through the summer months, but will perish in the cold New England winter waters. Local fishermen realize this, so when they catch these summer guests, they often take them to the Exploration Center and Aquarium at Easton’s Beach, where the fish find safety and survival in a permanent home with Save The Bay.

Atlantic moonfish Atlantic moonfish In my role as an aquarist at Save The Bay, fishermen have brought us butterfly fish, triggerfish, striped burrfish, crevalle jacks and others, which allows us to teach guests about warming water temperatures and how the biodiversity of Narragansett Bay may change over the next several decades.

Butterfly fish are a favorite among snorkelers and scuba divers, and the Aquarium’s colorful spotfin butterfly fish makes the reason clear. Its vivid yellow margin, extending from its dorsal to anal fin, are among the brightest colors in the tank. It also has a black bar running vertically through its face, hiding its eye, and a black spot near its tail meant to confuse predators, which offers stunning contrast against its white body. The protruding snout lets it search cracks and crevices in the reef for anemones, worms and other invertebrates.

Striped burrfish Striped burrfish The Aquarium’s school of small crevalle jacks are sleek and fast, like five-inch silver bullets in their large tank. In estuaries like Narragansett Bay, they live on muddy bottoms where small prey is plentiful. Crevalle jacks are an important species in commercial fisheries and a valued game fish because of their quick, strong maneuverability.

Northern pufferfish are a commonly known family of fish named for their ability to inflate themselves into round, softball-sized, funny-looking creatures that appear bigger than their predators. Unlike other puffers, northern puffers are non-toxic, but their tiny mouths are equipped with powerful teeth that they use to eat crabs and other hard-shelled invertebrates.

Another favorite among snorkelers and divers is the triggerfish, with its bright colors, interesting shape and peculiar beak that is capable of cutting a lobster in half. In fact, the way a triggerfish ploughs through its prey often leaves a trail of remains that make a perfect meal for smaller fish in its wake. When the trigger fish is feeling grumpy, it pops up a dorsal fin vertically from its back, called a trigger. When a predator tries to swallow a triggerfish, the ejected dorsal fin makes it difficult to swallow and buys it time for an escape.

The striped burrfish, a type of pufferfish, captivates Aquarium visitors with the brown lines of what looks like a maze seemingly drawn all over its cream-colored body, and short yellow porcupine-like spikes that cover it from nose to tail. And that’s not to mention its balloon-like shape and cartoon-character face.

The warm Gulf Stream current has been displacing marine life on earth for as long as it has existed, but today’s Gulf Stream orphans are telling us that things are changing. As Narragansett Bay temperatures have warmed by four degrees in the past 50 years, these tropical fish are arriving earlier each summer and surviving later into the fall and winter.

Only time will tell how changing climate conditions will affect our bay, but we know that when species’ native ranges shift along the coast, myriad interactions are created that are relatively untested, unobserved and unpredictable

What will the Narragansett Bay of the future look like? Will cool water species such as lobster, winter flounder, tautaug and dogfish still reside in Rhode Island years from now? Or will the year-round bay community consist of such critters as blue crab, spikey striped burrfish, toxic trunkfish and aggressive permit, all now found far south of here?

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