Tropical fish have started to appear off the coast of Nova Scotia, Canada, startling one experienced scuba diver who has been swimming in those waters for the past two decades.
Scuba diver Lloyd Bond spoke to Phys.org about his discoveries, which have included seahorses, cornet fish, triggerfish, and butterfly fish — none of which are native to the cool northern climate of Nova Scotia.
Bond said he spotted his first tropical fish around eight years ago and that the sightings have increased dramatically over the last five years.
"I caught a triggerfish in Mexico one year and then I saw one here the next year and I was thinking, 'Something's not right here — I shouldn't be seeing this here,'" he said.
Instances of animals turning up in climates that they are not native to have been on the rise, not just in Nova Scotia but worldwide, as human-caused pollution has led to changing weather and warmer temperatures. This has resulted in many animals changing their migratory patterns and others seeking out comfortable temperatures in places that would have traditionally been too cold for them.
While this does not always necessarily spell doom for the animals doing the migration, in a broader sense, introducing new animals to an ecosystem can have ripple effects that cause trouble for the existing life there.
"It is a phenomenon that has been observed in other temperate regions where you get regular incursions and, in some cases, permanent settlement of these species," Dr. Boris Worm, a marine biologist, told Phys.org. "It is one of the many, many indicators of the ongoing effects of climate change in our waters — it is a symptom, not the disease."
Dr. Worm cited lionfish, which are invasive and disruptive, as marine animals to keep an eye on in this case, as they have been known to expand their habitat because of warming ocean waters.
Other similar instances include a tropical wetland bird being spotted in Pennsylvania and another bird that is more commonly seen in South America showing up in Wisconsin.
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