Human germ attacks already declining coral reefs

Plague, rabies, Lyme disease, bird flu and swine flu—people seem much more at risk for diseases from animals than the other way around. But it does go the other way too, and it has been discovered that such a case is responsible for a disease that has devastated coral reefs in the Caribbean.

“White pox disease” in coral is caused by a human strain of the common intestinal bacterium Serratia marcescens, which causes the hospital infection serratiosis. (Hospital infections, or nosocomial infections, happen because individuals already in poor health are exposed to pathogens by poor sanitary practices and invasive procedures such as surgery or catheterization.) [Etymological notes on scientific names are at the end of the post.]

The only coral known to be affected is Elkhorn coral (Acropora palmata), a major reef-bulding species in the Caribbean. Healthy Elkhorn coral looks like this.

Healthy Elkhorn coral (Acropora palmata).jpg

Here’s an example of Elkhorn coral infected with White pox disease.

White Pox Disease (Serratia marcescens) on Elkhorn Coral.jpg

A research team at the University of Georgia was recently awarded a $5M grant to investigate the disease in coral, which is “the first known case of such a ‘reverse zoonosis’ that involves the transmission of a human pathogen to a marine invertebrate”. Even more remarkable, in the words of James W. Porter, associate dean of the Odum School of Ecology and the team’s leader, “This bacterium has jumped from vertebrate to invertebrate, from terrestrial to marine, and from anaerobic to aerobic environments. Triple jumps like this are rare.”

In addition, according to the report in ProMED (partly drawn from this source),

The scope of the team’s research will extend beyond gaining an
understanding of the impact of white pox disease on elkhorn coral and
how to counter it. The most likely source of the pathogen for coral
reefs is under-treated human sewage, so the study will also explore
the intersection of public health practices and environmental health

“This investigation addresses not only environmental protection, but
also the socio-ecological determinants of coastal zone protection,”
said Porter. “This includes the cost of wastewater treatment
infrastructure. Given a reliance on tourism by most Caribbean
countries, this study addresses a disease system that is of great
economic importance and public health concern to developing nations.”

“This is science in action to save an endangered species and a threatened ecosystem,” said team leader Porter. “We are linking good public health practices to effective environmental protection.”

Elkhorn and Staghorn coral (Acroporis cervicornis) are both on the US Federal list of threatened species, and in 2008 the National Oceanic and Atmospheric Administration extended additional protection rules usually reserved for endangered species. The new rule will “prohibit the importing, exporting and taking of elkhorn and staghorn corals. Additionally, the rule prohibits any activities that result in the corals’ mortality or injury. Anchoring, grounding a vessel or dragging gear on the species is prohibited. Additionally, damaging the species’ habitat and discharging any pollutant or contaminant that harms the species violates NOAA’s new rule. The rule applies to elkhorn and staghorn coral in the Virgin Islands, Puerto Rico and Florida.” Of course the enforcement will be difficult, but it appears that it’s none too soon to reverse the decline of these reef-building species.

A recent analysis of 500 surveys of 200 reefs showed the most complex types of reef had been virtually wiped out across the entire Caribbean. What survives are mostly “flattened” reefs which provide poor habitat for fish including commercial species, and are less “effective in protecting coastal homes and villages from storm swells and tidal surges”.

Healthy reef of staghorn coral in the Caribbean, below.

Healthy Staghorn coral (Acropora cervicornis).jpg


When the branched corals are killed off, low-growing corals may take their place but don’t create the rich three-dimensional habitat that the branched ones do. Algae also may increase and blanket surfaces, preventing coral growth.

Flattened coral reef, degraded by loss of branching coral).jpg

Source. Photo by Jennifer E. Smith.

Other threats to coral reefs

Coral-building animals live symbiotically with algae. Influenced by water that is too warm or cold, the corals will “expel the algae (zooxanthellae) living in their tissues causing the coral to turn completely white. This is called coral bleaching. When a coral bleaches, it is not dead. Corals can survive a bleaching event, but they are under more stress and are subject to mortality.” Rising ocean temperatures have caused wide-spread bleaching events. Warm waters also absorb more CO2, causing the water to become more acidic and that makes it more difficult for reef-building organisms to form the calcium carbon skeletons that serve as their structural basis.

Overfishing, pollution including sewage and agricultural runoff, dredging,hurricanes, and development have all damaged coral reefs. Each new injury reduces the ability of living organisms to reproduce and to withstand further assaults.

Coral reefs are among the world’s richest ecosystems, second only to tropical rain forests in plant and animal diversity. They arfe essential to fisheries, tourism, and protecting beaches from erosion. Yet “nearly two-thirds of the Caribbean’s coral reefs are threatened by human activities. Agricultural runoff, overfishing, dredging, sewage discharge (a factor in White pox disease), and the growing pace of coastal development have already degraded important reef systems, resulting not only in a tremendous loss of biodiversity but also lost revenue from declining tourism and fishing, and increased coastal erosion.” This last statement comes from the World Resources Institute, which is active many environmental fronts and is currently sponsoring a country-by-country survey of the economic values of Caribbean coral reefs and mangroves: “Supporting the sustainable management of coral reefs and mangroves by quantifying their economic value”.

Elkhorn coral & research robot.jpg

Source. Some breakage from hurricanes can be seen. Also shown is Fetch1, an autonomous underwater vehicle for research that was developed by NASA.

More about coral reefs

Global Coral Reef Alliance
EPA, Coral Reefs and your Coastal Watershed
University of Florida, Overview with photos

Etymological notes

Serratia marcescens was discovered in 1819 by Venetian pharmacist Bartolomeo Bizio, as the cause of an episode of blood-red discoloration of polenta in the city of Padua.[7] Bizio named the organism four years later in honor of Serafino Serrati, a physicist who developed an early steamboat; the epithet marcescens (Latin for “decaying”) was chosen because of the pigment’s rapid deterioration. [Wikipedia]

Acropora palmata: Acropora from the Greek, akros (high) and poros (opening, pore); palmata handlike, from Greek palma (a palm, flat hand; palm branch).

Acropora cervicornis: Acropora as above; cervicornis from the Latin cervus (deer) and cornu (horn, antler)

Sea Snail Trail in Sand


Sea Snail Trail in Sand, Shi Shi Beach, Olympic National Park

A while back I posted some of our photos from a low-tide explore near Gold Beach, Oregon, and that got me interested in the marks and tracks left in the sand. I found this great photo on the flickr account livingwilderness. This photographer has an eye for patterns and forms in nature as well as spectacular scenes, in the American Southwest, Pacific Northwest, and New Zealand. Take a look!

Low tide at the Oregon Coast


There was an unusually low tide last week, minus 2 to 2.5 feet, and we went over June 22nd to go tidepooling. Our destination was Gold Beach, on the rocky southern coast of Oregon, and our tidepooling was at Myers Rocks about 7 miles south of Gold Beach. We hoped to see nudibranchs, commonly called sea slugs––a canard, since many are so elegant and beautiful. [See Oregon nudibranch photos by others: 1, 2, 3, 4, several species, video.] But those are mostly found further north. We did see lots of sea stars, anemones, and smaller creatures, as well as a dead sea lion that had been washed up.


I posted a set of about 50 photos to a gallery on but was frustrated in being unable to add long enough captions, so I am using some of the photos, in smaller form, here with comments, our best efforts at identification, and a few photos found online. On mobileme I recommend using the “mosaic” viewing option from among those at the bottom of the screen; this will show thumbnails at the right, and you can click on any one to see it full-size, then either return to the mosaic view or continue in slideshow form.

Traces in the sand

The receding tide left most stretches of sand flat and smooth as can be; other places, where the water swirled out past rocks, had wonderful ripple patterns. And then there was this odd thing sticking up like a soft-serve “ice cream” serving.

UFO sand castle1.jpg

UFO sand castle2.jpg

It was about about 10 inches tall, surrounded only by flat sand. Must have been an alien sand castle, and the builders left no tracks.

Other tracks were seen.


A few of the barnacle-covered rocks bore odd sandy structures, sometimes in a ring shape.


Something held this together, but what?


I did come across (but took no photos of) one that had crumbled a bit and when I examined a chunk it was still puzzling; mostly sand, with occasional fragile vertical rootlike things, connected to one another minimally if at all. Drawn away by things my naked eye could better appreciate, I didn’t examine this more closely but I hope someone may tell me more. There are some questions google can’t answer: googling “odd clumps of sand with rootlike things” doesn’t get much result. But of course a marine biologist, hearing that vague description, could immediately give me some likely candidates, and by asking a few more questions, probably identify it decisively. Score one for the human brain.

Sea Roaches, Barnacles, and Sea Stars

On another barnacled rock we found a scuttling little creature that made me think of a cockroach, and indeed turns out to be a Sea Roach or Rock Louse (perhaps the species Western Sea Roach, Ligia occidentalis). [Our identifications are the best we could do in a couple of hours at home, comparing our memories and photos with our field guides, including Ricketts & Hedgepeth, and also searching online, but they are open to revision. Leave a comment if you have suggestions or more information, please.]


There were Acorn Barnacles (a large group of species, barnacles without stalks)


and Gooseneck Barnacles, among Blue Mussels


The most numerous creatures were Sea Stars, Pisaster ochraceus, generally known as the purple ochre star or ochre star (comes in brown, orange, and purple) and anemones, mostly Giant Green Anemones, Anthopleura xanthogrammica, which get their bright coloration from symbiotic, single-celled algae living within them.


Sea Stars get stiff and hard when the tide goes out, but their flexibility is evident from how they shape themselves to the rock.


The mouth of the Sea Star is in the center, on the underside (oral side); it eats by everting its stomach through the mouth, enveloping and digesting its prey; it can pry open shellfish like clams with the hydraulically powered “suckers” or tube feet on its strong arms. The creatures inside the whelk shells being held next to the mouth, below, may be today’s lunch. Sea Stars themselves are a preferred food for sea otters.


Closer view of the tube feet.


Below, a closeup of the top side of a Sea Star; this is the aboral side, “away from the mouth”. (Not a typo for “arboreal”!) The white things are the so-called spines though they are just little nubbins really. More about Sea Stars, 1, 2.


Mollusks and others

Here’s a chiton, perhaps Katharina tunicata (Black leather chiton), about 1.5 inches long. Its familiars, whoever they may be, have nicknamed it “Black Katy”; knowing this, you too can be on casual terms with a mollusk!


These are primitive creatures, protected by overlapping segments of shell that flex enough so that they can move over uneven rocks and even curl up into a ball. Most eat algae that they scrape off the rocks beneath them using a radula, a hard sawtoothed band also found in predatory marine snails and squid. The Pacific Northwest is home to the world’s largest chiton, the Gumboot Chiton, up to 13 inches long and red as a brick. Wikipedia tells us that chitons were eaten by Native Americans, prepared like abalone: beat the large “foot” part until it is somewhat tenderized.

The wormlike thing (above and to the left of the chiton) is unidentified; our research turned up lots of possibilities, including some types that run 90 feet in length and maybe twice that (thus perhaps being longer than a blue whale!), but no way to tell for sure.

Another more familiar mollusk is the whelk. When you find whelk shells not firmly attached to rocks, they usually are empty ones that have been taken over by hermit crabs, but we found this one that had come loose but still had its original inhabitant. The visible part is the foot that mollusks use to attach themselves.


The bright red-orange creature below (we saw only one) is, we think, Ophlitaspongia pennata (Red encrusting sponge). Sometimes found with it is “a well-camouflaged little red nudibranch (Rostangea pulchra) on it or Rostangea’s red spiral eggcase”. But we didn’t see those.

Ophlitaspongia pennata (Red encrusting sponge).jpg

Plant life revealed by the low tide

Sea Grass,


Kelp (actually not plants but algae, see below)


an unidentified vining sand plant,


and Sea Palms (Potelsia palmaeformis).


These Sea Palms, enlarged here, actually looked like silhouetted seabirds when I took the picture. Only when I enlarged it on the computer did I see what they really were. Wikipedia tells more: “Potelsia is a genus of kelp. There is only one species, P. palmaeformis. It is found along the western coast of North America, on rocky shores with constant waves. It is one of the few algae that can survive and remain erect out of the water; in fact it spends most of its life cycle exposed to the air. It is an annual, and edible, though harvesting of the alga is discouraged.” This made me look further, since if I ever knew that seaweeds were algae, I had forgotten. On algae, the Big W says “Algae, singular alga, (Latin for “seaweeds”), are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms. The largest and most complex marine forms are called seaweeds. They are photosynthetic, like plants, and “simple” because they lack the many distinct organs found in land plants. For that reason they are currently excluded from being considered plants.” So, all that explains why these seaweedy things were up so high––the tide was low, but not so low that these seapalms would have been normally submerged, and I wondered about that. And now you know that if you want to call somebody really simple, you’d better liken him to an alga rather than a potato.

Birds and mammals

The bigger offshore rocks are nesting grounds for various sea birds, but none came near us. We were passed by a group of enthusiastic sea bird researchers in chest-high waders and rubber boots, off to climb one of the rocks and poke into nest burrows,


and later that afternoon we saw many Brown Pelicans, either on their way along the shoreline, or actually circling and diving for fish. Cormorants came for the fish too, riding the swells farther out than the diving pelicans, until they saw what they wanted. Also in the afternoon, as we walked and looked for agates (pretty rocks collected, many; agates, 3), we watched two seals close inshore, looked like a mother and youngster. All of these were beyond range of our cameras, but wonderful to see. It was sunny, hardly windy at all, and pleasurable to alternate between having warm bare feet above the surf line, and then chasing the churn of retreating sea-polished rocks and getting caught by knee-high icy waves.

WARNING: Next are several scenic photos, then a section of pictures I took of the dead sea lion we found on the beach as we left. If you do not want to see these, stop at the picture of the sunset.


Gravity has its way with an anemone, when the water is not there to support it.


Another thing I learned while writing this, and as a logophile I found my ignorance embarrassing, is that there is no such word as anenome. I thought maybe anenomes were the flowers and anemones were the sea animals with toxic stingers, but anenome is as non-existent a word as George W.’s “nucular”. These,


and these,


are anemones too, land plants rather than marine animals: Anemone coronaria (top) and Anemone narcissiflora (bottom) Photos from Wikimedia Commons.


Steller Sea Lion, Eumetopias jubatus, dead on the beach


This sea lion bore several wounds that could have been the result of shotgun slugs––ocean fishermen resent the voracious consumption of salmon and other species by sea lions. In recent years, both this species and the California sea lion (Zalophus californianus) have gotten lots of bad ink and acrimony for their opportunistic predation on salmon when the fish bunch up at the dams on the Columbia River, on their way to reproduce and die. Of course the losses to sea lions are miniscule compared to the damage caused over the past century by overfishing, dams blocking rivers, and habitat destruction from logging (which damages fish breeding habitat in various ways including erosion that silts up rivers and streams).

We also thought these might be wounds made by sea gulls pecking their way in to eat what is, for a bird, a huge miraculous mountain of meat. But a fish and wildlife guy that we talked to later said the carcasses must be “pretty ripe” and rotten before a gull can pierce the thick skin. We wanted the f & w people to know, partly in case these were bullet wounds, and the man we talked to said they would send someone down with a metal detector. Both species of sea lion are protected by law.

This was a sad thing to see, especially if the death was caused by humans. If the animal had been alive we would of course have gotten it whatever help and protection we could. But it was too late for that, and what we were left with was an unusual opportunity for a close look. So what follows is not ghoulish or callous, though it may be unpleasant viewing for some.

The Steller Sea Lion is quite different in appearance from the California Sea Lion. The former has a blocky head and thick neck. The latter is sleeker, more gracile, with a slender muzzle, and is the model of what we think of when we hear the phrase “trained seal” although of course “true” seals––such as harbor seals––don’t have the ability to rotate their hind legs forward and “walk on all fours” that a “trained seal” demonstrates. True seals have to lunge and wriggle, on land; sea lions actually walk. Steller Sea Lion males may reach lengths of 11 feet and weigh 600-1100 kg (1300-2500 lbs). This specimen (sex unknown) was only about 6 feet long. The photo below shows the small external ear which is a distinguishing feature of the group of species known variously as eared seals, fur seals, or sea lions (Otariidae).


The closed eye, the lid of which appears swollen and damaged, is at left; the little comma-shaped ear is in the upper right.


Above, a view from the back shows one of the large holes. There were 5 holes visible. It seemed to us that none were close enough together to be wounds from the teeth of some big sea-lion-eating predator, such as an orca. Large areas of orange-ish skin are visible where the fur is gone, perhaps worn off by rubbing against the sandy bottom. The animal’s tiny tail can be seen between the two rear flippers. I took some close-ups of the claws visible on these flippers:


and here, on the other rear flipper, which was more damaged .


I found it hard to appreciate what they might have looked like in life, but was able to find a great photo online taken through the glass at the Sea Life Center in Seward, Alaska.


It was still hard for me to visualize the use of these claws, since they do not stick out past the end of the flippers, nowhere near. But here’s another great photo of an aquarium sea lion scratching, from flickr, and you can see how the flexible flipper can fold to allow the claws to stick out and scratch that itch. I cropped the photo to zoom in on the flipper. I think this is a California Sea Lion, based on the narrower snout.


Finally, the front flipper of the Steller Sea Lion found dead near Myers Rocks.


To end on a less somber note, there is a protected set of offshore rocks, called Rogue Reef Rocky Shore Area, about ten miles north of where we were: “More than 1,800 threatened Steller sea lions (45% of Oregon state total) use this reef, forming the largest pupping site for this species in the U.S., south of Alaska. Over 300 harbor seals are also found here. Approximately 4,000 common murres and more than 500 Brandt’s cormorants nest here” too.

In fact,

These rocks are part of the Oregon Islands National Wildlife Refuge which includes all of the state’s coastal rocks, reefs and islands (a total of 1,853) and two headland areas and spans 320 miles of the Oregon coast. All of the island acreage is designated National Wilderness, with the exception of 1-acre Tillamook Rock and Lighthouse, and public access is closed, to protect the birds and marine mammals.

Thirteen species of seabirds nest on this refuge [along the length of the state], including Common Murres, Tufted Puffins, Leach’s and Fork-tailed Storm-petrels, Rhinoceros Auklets, Brandt’s, Pelagic and Double-crested cormorants, and Pigeon guillemots. Harbor seals, California sea lions, Steller sea lions and Northern elephant seals use refuge lands for breeding and haulout areas. [Source]