Category Archives: Oceans

Stopping starfish virus ‘almost impossible’

By John Upton

Nearly 18 months into the worst marine epizootic that humanity has ever seen, scientists appear to have found the cause of death. A virus is being blamed for the mass die-off of starfish along North America’s western coastline. Sickened sea stars grow lethargic and their limbs start to curl. Next comes lesions and the shedding of limbs. The body deflates, then melts into puddles of slime and bone-like ossicles. More than a million starfish, coming from at least 20 species, have succumbed. Some local populations of the keystone predators, whose hunting prowess keep populations of plant grazers in check, have been decimated.

Hopes that the new diagnosis will usher forward a cure, however, are about as low as the deep-sea habitat of a brisingida.

Research described Sunday in Proceedings of the National Academy of Sciences blames the heretofore mysterious deaths on a densovirus — a type of virus that typically plagues crabs, shrimp and other invertebrates. The scientists gave the pathogen the name ‘sea star-associated densovirus,’ or SSaDV.

Illustrated by Perry Shirley.
Illustrated by Perry Shirley.

The scientists discovered that loads of the densovirus were higher in sick starfish collected from the wild than in asymptomatic specimens. They also found that exposing lab starfish to the germ “consistently” induced the hallmark symptoms of sea-star wasting disease, while exposing specimens to heat-killed viruses remained healthy.

When the scientists turned their attention to ethanol-preserved sea stars collected as early as 1923, they discovered that the disease has been infecting starfish since at least 1942.

So why would it suddenly turn into such an ecosystem-rattling problem?

That’s just how viruses roll.

“This is the case for many viruses, including HIV and Ebola, which were present in populations since at least the 1930s but only became epidemics in the 1970s and 80s,” said Ian Hewson, an associate professor in Cornell University’s microbiology department, the leader of the recent research.

Perhaps the virus chanced upon a powerful genetic mutation. An improvement to the way it builds capsids, which are shells that protect viruses during their extracellular ventures, might explain its virulence boost.

Perhaps the manifest changes underway in the ocean, where pollution, carbon dioxide and heat are piling up, has weakened the victims’ natural defenses.

The scientists can’t say, yet, which of these factors is to blame. But they do note that large populations of starfish jammed into small habitats appear to be more vulnerable to outbreaks.

They point to a booming sunflower seastar population prior to the first large outbreak.

“We speculate that the current disease event has been exacerbated by an overpopulation of adult sea stars in the Salish Sea immediately prior to the current disease event,” Hewson said. “The Salish Sea was indeed the first population in which the disease was seen; it was noted in June 2013 on the Olympic coast. The first mass mortality occurred in the Vancouver region shortly thereafter.”

That suggests that preventing sea star populations from booming might help protect against future outbreaks. Given that it’s not clear why the Salish Sea population boomed, that’s a daunting task.

Assuming the scientists have accurately identified the cause of the wasting disease, how else could the discovery be used to squelch the current outbreak?

The answer to that question will not fill you with joy.

Infected mottled stars from Washington. Photo by Ian Hewson.
Infected mottled stars from Washington. Photo by Ian Hewson.

“Protecting sea stars in nature from an established pathogen, like the virus seen here, is almost impossible,” Hewson said.

Because the virus is so geographically widespread, Hewson said it would be unfeasible and impractical to remove and protect healthy sea stars. “Likewise, inoculating stars against the virus to build resistance would also not be feasible on a large scale,” he said.

Still, the benefits of finally finding the cause of the disease shouldn’t be understated. “The identification of the causative agent of sea star wasting disease enables accurate diagnosis and more effective management,” said University of Washington professor Carolyn Friedman, one of the new study’s coauthors.

For cheerier sea star times, let’s all tune out of reality for just a moment, and tune into the uninfected antics of Patrick — SpongeBob SquarePants’s friend .

Natural History of Sex

By John Upton

If you could exchange the orgasmic gift of mammal-style intercourse for the messy ritual of dribbling fluids together, would you?

If you were the lineage of the world’s fish, then the latest evidence suggests that the answer to that unlikely conundrum would be, ‘Yes,’ to the great surprise of scientists documenting backbone-baring animals’ earliest known instances of internal fertilization.

We’re not talking about pudgy, panting penetration following happy hour pitchers. We’re talking rock-hard prehistoric fish, dermal claspers and paired dermal plates — locked, hundreds of millions of years ago, in ocean-floor embraces.

Bow guppy bow wow.

antiarchs
Illustrated by Perry Shirley.

A new scientific study peers into the most intimate moments in the lives of fish of several closely related ancient fish genii — MicrobrachiusPterichthyodes and Bothriolepis. Each was an antiarch, which was a heavily-armored order of fish known as placoderms. Placoderms were early gnathostomes, an infraphylum also called boned vertebrates, which includes all the fish alive today.  Gnathostomes started the branch on our evolutionary family tree that blossomed into lizards, birds and apes.

These long-dead fish were caught in the act of possessing the organs needed for sexual penetration. In a question over which came first, be it fish intercourse or external spawning, the answer would seem to be the former.

(The word antiarch means “opposite anus,” by the by, because a scientist once mistook a fossil’s mouth for its ass. And, while we’re at it, one of the species studied was M. dicki. Because somebody couldn’t help themselves.)

We’ve included a sketch of this primal love making below. Just make sure there are no underaged fish fossils in the room.

Mating Microbrachius
Adapted from a figure in Nature showing Microbrachius mating.

Is there anything cuter than fish that lock arms like that at a time like that? In real life, the width of that embracing scene would have been an adorable inch and a half.

We’re not sure if those are expressions of ecstasy — or the shocked looks that are to be expected when scientific method walks through the doors of ancient history during the most intimate of hypothesized moments. But we did confirm with Flinders University paleontology professor John Long that those big holes are where the eyes and nostrils would be. Because we didn’t want to get anything ass-backwards.

By now you might be wondering such things as, What does this have to do with me? If I took the right medicine, could I lead a life like that? And, How can I not think about this next time I’m bonking my boyfriend, or rolling in the hay at that haystack that my wife and I both like; won’t somebody please come and scoop the vision of adorable ancient randiness from my braincase? Aarrrggghhhhh.

We don’t know the answers to all your implied imaginary questions. What we do know comes from a study published Sunday in Nature by a large team of scientists led by Long.

The scientists analyzed fossils of the three genii that we mentioned earlier, and found in the males what they believe to be evidence of dermal claspers. They also found what they take to be the paired dermal plates of their female counterparts. Place those together and you’ve got yourself some internal fertilization, Velcro style.

The researchers write that the claspers found in these fossils resemble those of ptyctodonts, an order of placoderms that came after the unfortunately-named antiarchs. Those similarities, they wrote, suggest that “all placoderm claspers are homologous,” and that “internal fertilization characterized all placoderms.”

And they say that implies that spawning, which is so popular with the gnathostomes of today, must be an evolutionary adaptation that began with internal fertilization, even though such a transformation had been regarded as implausible.

“The complex physiology of fish that internally fertilize precludes a reversion back to spawning in water,” Long told us. “Yet our analysis shows it was the most likely explanation.”

Ocean reserves help with acidification

By John Upton

Our power plants and cars have pumped so much carbon dioxide into the atmosphere that the oceans are becoming more acidic. Something like a quarter of our carbon dioxide pollution dissolves into the seas, where it reacts with water:

CO2 (aq) + H2\leftrightarrow H2CO3 \leftrightarrow HCO3 + H+ \leftrightarrow CO32− + 2 H+

Those leftover hydrogen ions at the right of the equation add up. The hydrogen ion concentration at the surface of the world’s oceans has increased by 26 percent since pre-industrial times, leading to a pH decline of 0.1. That might not sound like much, but it has been enough to kill off billions of farmed shellfish and punch holes in the shells of wild sea snails.

Illustrated by Perry Shirley
Illustrated by Perry Shirley

Shellfish and corals are especially vulnerable to ocean acidification because they rely on calcium carbonate to make their shells and skeletons. Ocean acidification increases concentrations of bicarbonate ions while decreasing concentrations of carbonate ions — and these animals need calcium carbonate to produce their protective body parts.

Fish, meanwhile, are thought to be suffering neurological effects of acidifying oceans, while vast mats of algae are expected to flourish.

The good news is that populations of animals naturally adapt to changes in their environments — and evolutionary changes to help some species cope with ocean acidification are already underway. The bad news is that changes in oceanic pH levels might be happening too quickly for animals to adapt, threatening scores of marine species with extinction.

I asked Ryan Kelly, an assistant professor at the University of Washington’s School of Marine and Environmental Affairs, and a coauthor of a recent BioScience paper about acidification that I wrote about for Pacific Standard, whether we could do anything to help species accelerate the rate with which they evolve needed adaptations.

“‘Accelerating’ species’ evolutionary adaptations to acidification would mean either tweaking the heritability of traits — and it’s unclear whether this is desirable, or how to do it; or increasing the strength of selection — which would mean making the selective impacts of acidification worse than they already are,” Kelly said. “So I’m thinking that, in an evolutionary sense, you don’t want to accelerate adaptation.”

Is there anything that we can do?

“What you do want to do, in order to protect marine ecosystems as we know them, is to preserve the adaptive capacity of the species that make up those ecosystems. That means preserving the genetic diversity that exists within those species, so that when the selective pressures of acidification happen, there will be some variability in those species’ responses. When there’s no genetic diversity, you get no variability in response to selective pressure, and natural selection and evolution doesn’t really work.”

Which means that we need to expand and improve the globe’s network of marine reserves, banning fishing in some places, and giving species the best possible shot of surviving the storm of acidity that’s building around them.

“From a conservation perspective, measures that preserve existing genetic diversity safeguard the adaptive capacity of species and ecosystems. This means working to maintain large population sizes and not fragmenting habitats, which are common conservation measures.”

As U.S. Secretary of State John Kerry led workshops last month dealing with ocean acidification and other ocean health issues, President Barack Obama’s administration proposed sweeping expansions of marine reserves surrounding remote Pacific Ocean atolls. The move would limit fishing for tuna and other species, helping to protect top predators that are critical for ecosystem health, while also protecting smaller species that are killed as bycatch.

“This is an important step in trying to maintain the health of this region and, as a result, the surrounding areas in the Pacific,” said Lance Morgan, president of Marine Conservation Institute. “It will give us more resilience into the future. We’ll have to replicate this and do more work in other areas as well, but it is an important step.”

Meanwhile, the National Oceanic and Atmospheric Administration is planning to expand the boundaries of Gulf of the Farallones National Marine Sanctuary and Cordell Bank National Marine Sanctuary, both of which lie off the West Coast, where strong upwelling leads to especially severe rates of ocean acidification. Meanwhile, Kiribati recently announced that it would close an area the size of California to fishing to help wildlife recover.

Ocean acidification is not a major consideration in the creation of marine reserves, but it’s a growing threat against which the reserves can help populations of wildlife evolve natural defenses.

Western Australia to use “archaic” method to cull sharks

By John Upton

Great white sharks are among Earth’s most formidable predators. They are apex predators. They prey on fish, mammals and birds — but nothing preys on them.

Except humans.

And in Western Australia, the state government, tired of losing surfers and other beach-goers to the toothy jaws of these ferocious elasmobranchs, has become a predator.

“The preservation of human life is our number one priority,” said Troy Buswell, the state’s fisheries minister, in announcing new policies that will see white sharks killed if they venture within a kilometer of popular beaches. The state’s decision to cull sharks has sparked a global controversy, and polling suggests that even West Australians are overwhelmingly opposed.

Illustrated by Perry Shirley.
Illustrated by Perry Shirley.

“The decision by Western Australia officials to cull sharks off the coast is alarming,” said Ashley Blacow, a policy and communications official with nonprofit Oceana. “Sharks play a critical role in keeping ocean ecosystems healthy. The presence of sharks ultimately increases species stability and diversity of the overall ecosystem. White sharks in particular are a vulnerable species and they should be protected, not killed.”

One of Western Australia’s most controversial approaches to culling sharks will see floating drums placed around beaches, attached to baited hooks. The trapping equipment are known as “drum lines” — and conservationists regard them as appallingly cruel. Drum lines are illegal in many parts of the world, including in the U.S. One shark expert described the killing method as “archaic” in an interview with Nature.

“Drum lines are 55-gallon steel drums with heavy tackle-like chains or large lines connected to bait,” David McGuire, director of Shark Stewards, told us. “They’re usually anchored to the bottom or they can be linked in chains. I’ve seen them used illegally in Mexico to catch sharks. Essentially, the shark bites the bait, is hooked, and drowns.”

Perhaps most troublingly, there is a lack of scientific evidence that such culling actually protects humans from shark attacks. It might feel satisfying to kill a member of a species that has been killing humans, but that sense of satisfaction might be more of the revenge variety than anything else. Hawaii culled nearly 5,000 sharks between 1959 to 1976, yet there was no change in the rate at which sharks attacked humans in those same waters.

Unfortunately, it may take years of shark culling and shark attacks before the West Australian government can determine whether its new policies are having the effect that it desires.

“True effectiveness cannot be assessed by simply counting the number of sharks captured and killed,” writes University of Hawaii researcher Carl Mayer in an article published by The Conversation. “Demonstrable effectiveness means a measurable decrease in shark bite incidents in response to culling activities.”

Dutch gulls eat their young on Sundays

By John Upton

The durations of days and years are calibrated by celestial turntables: The spinning of the Earth and its arcing around the sun. Humans and wildlife alike live out rituals according to daily and annual schedules.

But the seven-day week is a human construct. It’s an arbitrary chunk of time that cocoons timetables of work and rest, of television programming and soccer practice. Whenever you see wildlife falling into a weekly routine, you can be confident it’s the result of a human influence.

A weekly schedule plays out among European herring gulls and lesser black-backed gulls nesting in the dunes of the Dutch island of Texel. And it’s a macabre one.

Illustrated by Perry Shirley.
Illustrated by Perry Shirley.

A chick being reared in these dunes may dread Sunday more than a young atheist dreads their mandatory church outings. It’s on Sundays that adult gulls are most likely to cannibalize the young. Saturdays are also popular chick-eating days among the Texel gulls, though not to the same extent as is the case on Sundays.

Sometimes the gulls eat their own chicks — or their own eggs. But more often they steal the unattended young of other birds, in some instances to be shared with their own hungry broods.

That’s not the only weekly pattern that marine ornithologist Kees Camphuysen has discovered during his studies on the island. Chicks tend to grow in spurts during the week, then their growth slows down over the weekends.

The Royal Netherlands Institute for Sea Research scientist thinks he knows what’s going on. He contends that it’s the weekly patterns of the region’s beamtrawlers and shrimpers that are driving the hebdomadal trends.

“[A] very strong weekly pattern in fleet size occurred, with high numbers of boats at sea Monday through Thursday, a much reduced number (mostly homeward bound) on Friday, and near to nothing on Saturdays and Sundays,” he wrote in his Ph.D. thesis.

The Texel Dunes gulls feast on the by-caught scraps of the fishing fleet, trailing the boats to scavenge protein for themselves and for their growing chicks. But when this supply of human surplus dries up over the weekends, the chicks’ growth rates slow, and hunger can drive the birds to cannibalism.

“Only commercial fisheries have a periodicity that can explain the strong, cyclic synchronisation in chick growth,” Camphuysen wrote. “Chick cannibalism rates were a mirror image of the rhythmic cycle in growth increments.”

The following series of photographs was published in Camphuysen’s Ph.D. thesis, showing an attack on an unattended chick by a bird from a nearby nest. The attacking gull can be seen sharing the kill with its own chick. If you would prefer to not see an adorable lesser black-backed gull chick being pecked to death and gutted by its own kind, then stop scrolling now.

cannibal-gull-in-action

A hungry red tide is a dangerous red tide

By John Upton

When fertilizer or sewage runs into a waterway, or when phosphorous and nitrogen rise up from the ocean depths, algae can converge and feast and mushroom on the buffet of growth-inducing nutrients.

But scientists have discovered that starving a poisonous red tide of its nutrient supply can trigger a very dangerous and counterintuitive response.

Red tides are freaky types of algae blooms. They often occur in the ocean or in salty bays, and they frequently produce poisons. Scientists prefer the term “harmful algal bloom,” since a red tide isn’t always red and it is most certainly not a tide.

Illustrated by Perry Shirley
Illustrated by Perry Shirley

The most common type of algae in Gulf of Mexico red tides is a dinoflagellate called Karenia brevis. The neurotoxin produced by these single-celled creatures help protect them from predation: Would-be hunters can die if they take a mouthful. But as the red tides break down, the poison escapes from the plankton cells and it can drift through the marine environment, poisoning it. The toxin can even spray into the air, aerosolized by crashing waves, where it can get into lungs and trigger serious ailments in people and other animals. The Floridian West Coast is often the worst affected.

Concentrations of the poison in each of the algae cells varies widely — from a mild 1 picogram per cell to a treacherous 68 picograms per cell. Needless to say, figuring out what causes a bloom to be especially poisonous would be valuable for public health officials.

Since Karenia brevis uses nutrients to grow, one may assume that starving them of phosphorous and nitrogen, such as by preventing fertilizer or sewage runoff into the Gulf, would protect the environment from their poisons.

But that’s only true up to a point. If you can keep nutrients out of the water, a bloom will not materialize, so there will be no danger of the waterway being poisoned by it. But if the nutrient supplies suddenly dry up, an existing bloom will switch into a defensive mode, stop growing and become very toxic.

The ecological theory to describe this response comes to us from botany. It is called the carbon:nutrient balance hypothesis.

North Carolina scientists grew samples of the dinoflagellate in water taken from the Gulf in a laboratory. Some samples were fed plenty of phosphorous, but others received very little. The scientists found that K. brevis strains living with limited phosphorous supplies produced 2.3 to 7.3 times more poison than did those that had plenty of phosphorous available.

“Because PbTxs [K. brevis brevetoxins] are potent anti-grazing compounds, this increased investment in PbTxs should enhance cellular survival during periods of nutrient-limited growth,” the scientists wrote in their paper, published last month in PLoS ONE.

The algae samples living without much phosphorous put their carbon to a defensive use, since it couldn’t be used as effectively for growth. The proportion of carbon that each cell used to produce poison as much as doubled when phosphorous was limited.

This is consistent with the carbon:nutrient balance hypothesis. When vegetation has lots of carbon and lots of nutrients available, it invests those building blocks of life into fast growth. But when nutrients, be they phosphorous or nitrogen, are in short supply, the carbon is put to a different use: Defense against predators.

It also helps explain some of the late season bursts in toxicity noticed in the red tides: They become poisonous after they have greedily slurped down the last of the available nutrients.

This research was limited to phosphorous. But previous research uncovered a similar red tide response when nitrogen was limited.

The discovery could help public health managers predict the potency of red tides in the Gulf of Mexico. By measuring the amount of phosphorous in the ecosystem, it could become possible to determine how dangerous the red tides will become.

New island, same old ecological succession theory

Norderoogsand / Illustration by Perry Shirley

By John Upton

It’s easy to think of the earth’s lands as static. But shorelines are constantly shifting as sea levels and land masses rise and fall. New islands can appear, and old ones can be engulfed by the tides.

Sandbanks appear frequently in the  Wadden Sea National Park, off the coast of Germany, as tides and waves push particles of sand around. These are normally ephemeral features that wax and wane like an erratic moon.

But during the past decade, scientists have watched with interest as one particular sandbank has weathered the storms and grown into a full blown island.

Norderoogsand, as it is named, is sheltered by nearby islands and has benefited from rare occurrences of high storm surges during its short life. As reported by The Telegraph, some of the dunes on  the 34 acre island have reached four meters.

Norderoogsand is already home to grasses and seabirds. These are among the wildlife that typically first occupy a new island. According to ecological succession theory, pioneer species such as these are the first to colonize a new or recently scorched land mass. Pioneer species travel easily and they are generally hardy.

Once pioneer species have been established, the environment becomes more accommodating for other species, such as mammals and slow-growing trees.

“Birds are usually first to arrive naturally, and they can often bring in plant seeds or other species in their feathers or droppings,” Dan Grout, a scientist at the nonprofit Island Conservation, told me. “The rate of colonization will depend on the few usual factors such as distances to other land masses, likely migration routes and, not insignificantly, whether human visitation will assist in any directed or inadvertent release of organisms.”

Scientists are looking forward to watching as ecological succession plays itself out on the young island, where gulls, geese, plovers, terns and peregrine falcons have been spotted. “It is to be hoped that the rare sandwich tern will also discover these dunes as a breeding place,” a conservationist told Die Welt newspaper.

But the ecological extravaganza could be fleeting, the experts warn. The entire island could yet be wiped out by a strong tide surge.

Rare bluefin sells for $1.8 million

sushi
Illustrated by Perry Shirley.

By John Upton

Couple quick facts about Pacific bluefin tuna, a fish that’s sold as sushi, mostly in Japan:

1. A 490-pound specimen caught off northeastern Japan sold during a fish market auction for ¥155 million. That’s nearly $US1.8 million. For a single fish. The winning bidder, Kiyoshi Kimura, president a sushi restaurant chain, broke the record for the highest price paid for a single bluefin tuna. Kimura set the previous record of ¥65 million one year earlier. Read all about it.

2. The Pacific bluefin population has plummeted 96.4 percent because of decades of overfishing, scientists reported in a recent stock assessment. Pew Environment Group’s Amanda Nickson warned that the species “is in danger of all but disappearing.”

So get your bluefin sushi on while you can. Or don’t.