Seahorses: Climate Change Threatens these Ocean Treasures

By: Michele Berger

Published: July 26, 2013

 

 

 

 

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A seahorse is seen in this undated photo. (Flickr/MattChan)

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Seahorses, those rainbow-hued, color-changing fish that seem to scoot through the ocean, are some of the ocean’s most charismatic creatures. Sadly, a host of factors, from climate change to water pollution, are causing population declines. “Seahorses are especially vulnerable to disturbances,” reports conservation organization Oceana. “They commonly live in seagrass beds, mangroves and coral reefs in coastal shallow waters, which are all highly sensitive [ecosystems].”
When you picture one, you’re likely thinking about something like the hedgehog seahorse. But nearly 50 species exist — 14 of which science just discovered in the past decade — plus seadragons, pipehorses and pipefishes, all of which belong to the Syngnathidae family.
Though we don’t have specific data on many seahorse species, for those we have studied, the outlook doesn’t look good: All but one are vulnerable or threatened, according to the International Union for Conservation of Nature. The two seadragon species are both near threatened, one due indirectly to climate change.
Seahorses are a good indicator of the health of our oceans, according to Project Seahorse. To help protect them, we must first learn about them.
Are They Fish?
Other than knowing what these swimmers look like, you may have heard that the male seahorses are the ones that get pregnant and give birth, but if you don’t know much more, you’re not alone. “Usually people don’t even think they exist,” says marine biologist Christopher Paparo, director of Stony Brook Southampton’s Marine Sciences Center. “To see one, [something] that they thought was a figment to most people is extremely fascinating.”
The first question Paparo typically gets is, are they fish. “They are true fish,” he says. They have fins for steering and gills to breathe, though no scales, according to the Monterey Bay Aquarium (MBA). But unlike other fish, they also have a coronet and a snout. “The coronet, the crown-shaped piece of skin on top of its head, is the unique ‘thumbprint’ of each individual seahorse,” notes an MBA factsheet. “The toothless snout of a seahorse is used to slurp up food that it spots with its special eyes.”
These creatures are predators, so they use their large eyes and camouflaging ability — they can change colors and skin texture — to hook onto and blend in with seaweed, Paparo says. “They’re hunting small little fish and shrimp. By holding onto a piece of seaweed and looking like seaweed they can easily hunt down their favorite prey items.” They, themselves, are prey for bigger fish, so the disguise protects them, too.
It also makes differentiating between species difficult. “Because of this [camouflaging], some researchers previously thought there were as many as 200 seahorse species in the world, while others thought there were as few as 20,” writes Smithsonian’s National Museum of Natural History.
The Other Fish in the Family
That doesn’t even get into the species of pipehorses, pipefishes and seadragons, the last of which falls into a very special group. Only two true seadragons exist: the weedy and the leafy. “Like seahorses they have chameleon-like eyes, a horse-like head, and a fused jaw. They feed by sucking tiny marine animals such as sea lice and mysid shrimp through these snouts,” according to Project Seahorse. “Unlike seahorses, they swim in a horizontal position and the males do not carry their eggs in pouches, instead using a brood patch under their tails to transport them.”
They’re captivating to watch, Dr. Keith Martin-Smith told Project Seahorse in 2012. “Weedy seadragons gather in large groups of 20 or more individuals to breed,” he said. “They also have a fascinating ‘mirroring’ behavior during courtship where the male and female hold their bodies in identical postures but in mirror image of each other.” They live only in southern Australia, preferring rocky reefs, seagrass meadows and seaweed beds for habitat.
Seahorses, on the other hand, live in many places, native to the waters off of 130 different countries, notes the U.S. Fish and Wildlife Service. That’s not just tropical waters, either, according to Smithsonian. “They can be found in colder waters like those found off New Zealand, Argentina, Eastern Canada and the United Kingdom.”
Serious Threats to their Future
Importantly, there are threats to these fish, including exploitation for medicine and as souvenirs, Project Seahorse reports. In parts of Asia, for example, seahorses are thought to help treat ailments like asthma, sexual dysfunction and pain, according to Oceana. “The demand for seahorses has exploded in the past few decades, mirroring China’s economic growth.”
Plus, habitat degradation and accidental bycatch in shrimp trawl nets are playing a role, too. Human activity and climate change have severely depleted the places where seahorses thrive. “Seahorses are flagship species, charismatic symbols of the seagrasses, mangroves, coral reefs, estuaries and seaweeds where they make their homes,” Project Seahorse explains. “Protecting seahorses means protecting these diverse habitats all of the marine life that lives therein.”
To Paparo and the many who helped get these creatures protection under environmental agreements like CITES, they’re worth fighting for: “Seahorses are some of the most fascinating fish found in our waters,” Paparo wrote in New York State Conservationist in 2011. “Next time you tangle with that ‘sea monster,’ or see a mass of seaweed washed up on shore, take a closer look. You might just find a treasure: a live seahorse.”
MORE: Beautiful Images of Sea Slugs

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An unidentified northern sea slug is seen in an image taken in September 2008. The sea slug was found on the seafloor of the White Sea, located near the northwest coast of Russia. (Flickr/Alexander Semenov)