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Sydney's Endangered Seahorses Find Protection in Underwater Hotels

White's seahorse, also called the Sydney seahorse, is native to the Pacific waters off Australia's east coast. Sylke Rohrlach / Wikimedia Commons / CC by 2.0

By Manuela Callari

It can grow to a maximum of six inches (16 centimeters), change color depending on mood and habitat, and, like all seahorses, the White's seahorse male gestates its young. But this tiny snouted fish is under threat.

White's seahorse, also called the Sydney seahorse, is native to the Pacific waters off Australia's east coast. In recent years, populations have decreased drastically. It and the South African Knysna seahorse are the only two out of around 50 seahorse species to be listed as endangered.

A wild storm season from 2010 to 2013 left the Sydney seahorses' habitat in tatters, wiping out 90% of the population in the area. Several large storms shifted huge volumes of sand, smothering the soft corals, sponges and seagrass they call home.

That's why researchers in Sydney Harbor have built special seahorse hotels to help restore their habitat and encourage would-be White's seahorse dads to fall pregnant.

"There are two things that we're trying to gain from this project," said Robbie McCracken, an aquarist at Sydney Sea Life Aquarium, who's working with researchers from University of Technology Sydney and the New South Wales DPI Fisheries on the program.

"Number one is that we can breed these animals in an aquarium to release them into the wild. And number two is that the seahorse hotels provide a suitable environment for them to live on."

Building an Ocean Seahorse Destination 

Seahorses are found in tropical and temperate coastal water worldwide, but are most abundant around Australia, China and the Philippines.

Trade in the tiny creatures is strictly regulated because of their use in traditional medicine, aquariums and their sale as dried curios. But because they are poor swimmers and cannot easily move elsewhere, habitat loss is a particular threat for these curious animals.

Seahorses wrap their tails around seagrass and corals to avoid being carried away on currents. They use the habitat to spawn and hide from predators such as crabs, while also feeding on riches of plankton and small crustaceans living in the reef.

Where corals aren't available, scientists found seahorses taking up residence in fishing nets and old crab traps abandoned at the bottom of the ocean.

This inspired the Sydney team to increase available habitat in the famous Australian harbor by building cages of net and steel. Over time, algae, sponges and corals colonize the structures, creating a safe, welcoming environment for the seahorses, say the researchers. The hotel frame will eventually corrode, leaving behind the coral mounds that have grown around them.

The researchers trialed the first hotels in 2018. Within two months, seahorses had begun to move in and soon a few males fell pregnant. Knowing that the hotels were a hit, the next step was to boost seahorse numbers.

In 2019, the team caught eight pairs of White's seahorses — the creatures are monogamous and, so, mate with one partner for life. The babies were born in September and October of last year.

"We were able to watch them court with each other, and mate with each other, and then we were able to watch the dads deliver," said McCracken, "so, it was always quite exciting."

Mixing With the Locals  

Baby seahorse mortality is high in the wild because they are easily caught, so those bred in the protected environment of the aquarium weren't ready to be released into the wild until early May.

The team released 90 new arrivals into Sydney Harbor, placing some directly into the purpose-built hotels, and others onto a net that wild seahorses had already settled on.

Before setting them free, the researchers marked each young seahorse with a fluorescent tag with unique IDs inserted just beneath the skin to track how they get on in the different environments.

"The most exciting part was being able to put these animals into the wild and then go back a month later and still see them surviving and growing," said McCracken.

The seahorses will be old enough to mate and reproduce around October or November 2020. And researchers hope that by then, they will be able to breed with the wild population.

Building a Global Seahorse Hotel Chain  

With seahorses everywhere facing the loss of their coral reef homes, similar projects have sprung up in places like Greece and South Africa, home to the world's most endangered seahorse, the Knysna seahorse.

"The endangered South African seahorse is benefiting from something quite similar, even though it wasn't intentional," said Peter Teske, professor at the Department of Zoology, University of Johannesburg.

In the South African case, seahorses have bedded down in "Reno mattresses" — wire cages filled with rocks — that were used to build a new marina. Researchers from NGO Knysna Basin Project found the structures acted as a refuge for the animals.

While Teske describes the seahorse hotels as "a positive news story" and a great way to create public awareness of conservation, he added that establishing artificial habitats in some areas will only prevent the extinction of local populations.

"For a complete recovery, it is necessary to give the natural habitat a chance to regenerate," said the seahorse expert.

Underwater Mascot 

In Australia, the researchers hope the project could provide an opportunity to raise awareness not only of the plight of the Sydney seahorses but the other animals with which it shares its ocean habitat.

The waters around Sydney and the east coast are rich in biodiversity and include several threatened species like the weedy seadragon ⁠— a relative of the seahorse ⁠— and the grey nurse shark. Like the seahorse, they're also under pressure from pollution, ocean traffic and habitat loss through storms and coastal construction.

"It's a good thing to get people's support and interest. The seahorses are a useful vehicle to get people concerned if the harbor is in trouble," said David Booth, professor of marine ecology at the University of Technology Sydney who is also working on the project.

The hotels have become an attraction for divers hoping to catch a glimpse of these small but near mythical creatures.

"Everyone loves seahorses," added Booth, "they are so popular."

Reposted with permission from Deutsche Welle.

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Warming temperatures on land and in the water are already forcing many species to seek out more hospitable environments. Atlantic mackerel are swimming farther north; mountain-dwelling pikas are moving upslope; some migratory birds are altering the timing of their flights.

Numerous studies have tracked these shifting ranges, looked at the importance of wildlife corridors to protect these migrations, and identified climate refugia where some species may find a safer climatic haven.

"There's a huge amount of scientific literature about where species will have to move as the climate warms," says U.C. Berkeley biogeographer Matthew Kling. "But there hasn't been much work in terms of actually thinking about how they're going to get there — at least not when it comes to wind-dispersed plants."

Kling and David Ackerly, professor and dean of the College of Natural Resources at U.C. Berkeley, have taken a stab at filling this knowledge gap. Their recent study, published in Nature Climate Change, looks at the vulnerability of wind-dispersed species to climate change.

It's an important field of research, because while a fish can more easily swim toward colder waters, a tree may find its wind-blown seeds landing in places and conditions where they're not adapted to grow.

Kling is careful to point out that the researchers weren't asking how climate change was going to change wind; other research suggests there likely won't be big shifts in global wind patterns.

Instead the study involved exploring those wind patterns — including direction, speed and variability — across the globe. The wind data was then integrated with data on climate variation to build models trying to predict vulnerability patterns showing where wind may either help or hinder biodiversity from responding to climate change.

One of the study's findings was that wind-dispersed or wind-pollinated trees in the tropics and on the windward sides of mountain ranges are more likely to be vulnerable, since the wind isn't likely to move those dispersers in the right direction for a climate-friendly environment.

The researchers also looked specifically at lodgepole pines, a species that's both wind-dispersed and wind-pollinated.

They found that populations of lodgepole pines that already grow along the warmer and drier edges of the species' current range could very well be under threat due to rising temperatures and related climate alterations.

"As temperature increases, we need to think about how the genes that are evolved to tolerate drought and heat are going to get to the portions of the species' range that are going to be getting drier and hotter," says Kling. "So that's what we were able to take a stab at predicting and estimating with these wind models — which populations are mostly likely to receive those beneficial genes in the future."

That's important, he says, because wind-dispersed species like pines, willows and poplars are often keystone species whole ecosystems depend upon — especially in temperate and boreal forests.

And there are even more plants that rely on pollen dispersal by wind.

"That's going to be important for moving genes from the warmer parts of a species' range to the cooler parts of the species' range," he says. "This is not just about species' ranges shifting, but also genetic changes within species."

Kling says this line of research is just beginning, and much more needs to be done to test these models in the field. But there could be important conservation-related benefits to that work.

"All these species and genes need to migrate long distances and we can be thinking more about habitat connectivity and the vulnerability of these systems," he says.

The more we learn, the more we may be able to do to help species adapt.

"The idea is that there will be some landscapes where the wind is likely to help these systems naturally adapt to climate change without much intervention, and other places where land managers might really need to intervene," he says. "That could involve using assisted migration or assisted gene flow to actually get in there, moving seeds or planting trees to help them keep up with rapid climate change."

Tara Lohan is deputy editor of The Revelator and has worked for more than a decade as a digital editor and environmental journalist focused on the intersections of energy, water and climate. Her work has been published by The Nation, American Prospect, High Country News, Grist, Pacific Standard and others. She is the editor of two books on the global water crisis. http://twitter.com/TaraLohan

Reposted with permission from The Revelator.


An illustration depicts the extinct woolly rhino. Heinrich Harder / Wikimedia Commons

The last Ice Age eliminated some giant mammals, like the woolly rhino. Conventional thinking initially attributed their extinction to hunting. While overhunting may have contributed, a new study pinpointed a different reason for the woolly rhinos' extinction: climate change.

The last of the woolly rhinos went extinct in Siberia nearly 14,000 years ago, just when the Earth's climate began changing from its frozen conditions to something warmer, wetter and less favorable to the large land mammal. DNA tests conducted by scientists on 14 well-preserved rhinos point to rapid warming as the culprit, CNN reported.

"Humans are well known to alter their environment and so the assumption is that if it was a large animal it would have been useful to people as food and that must have caused its demise," says Edana Lord, a graduate student at the Center for Paleogenetics in Stockholm, Sweden, and co-first author of the paper, Smithsonian Magazine reported. "But our findings highlight the role of rapid climate change in the woolly rhino's extinction."

The study, published in Current Biology, notes that the rhino population stayed fairly consistent for tens of thousands of years until 18,500 years ago. That means that people and rhinos lived together in Northern Siberia for roughly 13,000 years before rhinos went extinct, Science News reported.

The findings are an ominous harbinger for large species during the current climate crisis. As EcoWatch reported, nearly 1,000 species are expected to go extinct within the next 100 years due to their inability to adapt to a rapidly changing climate. Tigers, eagles and rhinos are especially vulnerable.

The difference between now and the phenomenon 14,000 years ago is that human activity is directly responsible for the current climate crisis.

To figure out the cause of the woolly rhinos' extinction, scientists examined DNA from different rhinos across Siberia. The tissue, bone and hair samples allowed them to deduce the population size and diversity for tens of thousands of years prior to extinction, CNN reported.

Researchers spent years exploring the Siberian permafrost to find enough samples. Then they had to look for pristine genetic material, Smithsonian Magazine reported.

It turns out the wooly rhinos actually thrived as they lived alongside humans.

"It was initially thought that humans appeared in northeastern Siberia fourteen or fifteen thousand years ago, around when the woolly rhinoceros went extinct. But recently, there have been several discoveries of much older human occupation sites, the most famous of which is around thirty thousand years old," senior author Love Dalén, a professor of evolutionary genetics at the Center for Paleogenetics, said in a press release.

"This paper shows that woolly rhino coexisted with people for millennia without any significant impact on their population," Grant Zazula, a paleontologist for Canada's Yukon territory and Simon Fraser University who was not involved in the research, told Smithsonian Magazine. "Then all of a sudden the climate changed and they went extinct."