On the remote rocky shores of the western United States, low tide brings visitors to wave-splashed tide pools to marvel at ocean wonders usually hidden from view.
But recently, largely missing from the bounty are the biggest draw: a rainbow-hued array of starfish.
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"I don't know what you would call it other than catastrophic," says Drew Harvell, a biologist at Cornell University, describing what is widely regarded as one of the worst marine disease events ever recorded.
"It's staggering, really, the millions of stars that have died. It is not apocalyptic or extreme to say that."
In recent years, millions of the starfish, also called sea stars, have had their legs curl up and pull away from their bodies, breaking the animals to pieces before they turn to mush, often in a matter of days.
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Scientists have been left racing to figure out why.
Once densely packed onto the rocks and on the ocean floor, the key predators are simply missing from some locations, their numbers cut by 95 percent or more.
The phenomenon, called Sea Star Wasting Syndrome, was first noticed by rangers in Olympic National Park in Washington state in 2013.
It has now been documented from California to Alaska, and led to die-off that is bigger and more widely spread than any seen before.
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Late last year, a group of researchers published findings in the Proceedings of the National Academy of Sciences saying they had found strong evidence that a virus was causing the disease.
Researchers now are looking into why the virus is suddenly so much more widespread and deadly. A primary consideration is how warmer water, brought about by climate change, is affecting the stars, the virus and the wider ecosystem.
"There are components that certainly track with temperature," Harvell said. "We think the magnitude in our waters is due to temperature. We know that under warmer conditions, they die faster."
"We've had anomalously warm oceans for the last two years. Really, what we would call hot water. It is really the dominant thing to consider," she said.
A primary challenge for researchers is simply the massive amount of data needed to get a good understanding of what is happening. The animals are found on thousands and thousands of miles of coastline, and sufficient funding is simply not available to thoroughly count them and consider all the possible variables.
But scientists are nevertheless trying.
They are tracking the numbers of stars in locations over time, gauging the temperature and chemistry of the water, and logging the data as part of ongoing research into the ecosystem. They are even recruiting "citizen scientists" to help search for the stars and record their condition.
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Melissa Miner, a researcher with the University of California at Santa Cruz, is one of the people leading the data collection, but said the widespread nature of the outbreak adds to the challenge.
"It is pretty difficult to collect the data we need on a big scale," she said. "I really want to stress that it isn't understood at all what it is causing this disease."
Harvell agreed that money for the extensive research is scarce. It doesn't help that the starfish are not an animal humans eat, and thus there is no industry raising the alarm about their decline.
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"Out of sight, out of mind," she said. "We need to be concerned about the health of our oceans. We could be so much farther ahead if there had been enough money available."
Congressman Denny Heck, whose district in Washington state includes much of the inland waters where starfish have been dying off in huge numbers, is trying to help by establishing a framework for declaring a marine disease emergency. Such a declaration would come with money for research and possible recovery.
"When disease like this breaks out underwater, we have no established process to stop it," Heck told AFP.
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He has found allies on both coasts, as well as among his fellow Democrats and Republicans, as a disease outbreak could hit fisheries and devastate a local economy.
"We are encouraged by the response we've gotten from people across the country that care about a clean and sustainable marine environment," he said.
For her part, Miner is hopeful that the colorful sea stars have a high enough profile to draw attention to their demise.
"They are as charismatic as you can be as an intertidal species," she said. "They are what connects people to ocean. The sea star is kind of the mascot of the intertidal."
Tissue is disintegrating within this sea star affected by sea star wasting syndrome.
Tourism, bottom-trawl fishing, rising sea temperature, and ocean acidification -- all of these wreak havoc on coral reefs around the world. Australian designer Alex Goad, who also dives, witnessed the devastation first hand and wanted to help. He designed the Modular Artificial Reef Structure (MARS) a LEGO-inspired habitat meant to give ocean plants and animals a chance to thrive in areas devastated by humans and climate change.
Goad created modules from ceramic, a material known to resist the corrosive effects of seawater. The modules can be clamped together to form three-dimensional lattice structures as big or as small as needed.
Portable and affordable, the units can be deployed from small boats and snapped together underwater by divers. This eliminates the need for big boats and costly, heavy-duty machinery otherwise needed to submerge artificial reefs.
The modular reefs provide a foothold for growth and speed up the recovery of underwater communities. "What may have taken 100 years to restore naturally can be reduced to an estimated eight to 15 years using the MARS system," Goad told
.
The surface of the modules has many dents, nooks and crannies that offer the very first colonizing organisms -- typically the smallest -- protection from predators.
"Many people do not agree with the use of artificial reefs for restoration, believing that reef systems should be left alone to restore themselves," Goad told Dezeen. "In many cases this is an acceptable practice, however when the rate of destruction far exceeds the rate of natural coral growth then we must intervene." MARS has been tested in Melbourne's Port Phillip Bay, as well as sites in Cairns and at local aquariums. It also won the graduate prize for Best Product Design from Monash University as well as the Hills Young Australian Design Award for Sustainability 2014.