A Sea of Glass Page 3
Elegant anemones (Anthopleura elegantissima) in a San Juan Island tide pool. The pale anemones contain no symbiotic algae. Photo by Drew Harvell.
Gosse’s peeking–into–tide pool lithographs of the British Isle anemones (page 22) inspired much of the Blaschkas’ fascination with these delicate creatures. An English naturalist, Gosse was credited with being the inventor of the aquarium after he created and stocked the first seawater exhibit at the London zoo. He was a passionate naturalist, prolific writer and illustrator, and an expert in ornithology, herpetology, and anemones. His Actinologia Britannica is a stunningly illustrated taxonomy of British sea anemones.
It’s clear from Leopold Blaschka’s early watercolors, which are almost identical in style and substance to Gosse’s lithographs, that the glassmaker was influenced by the artist’s passion for anemones. Employing his uncanny ability to create subtle shades of color in glass—pinks, teals, roses, and oranges—Blaschka replicated the beauty not only of Gosse’s lithographs but also of their living equals. The Blaschkas didn’t stop there; they juxtaposed these soft colors with finely spun details like eyespots, tentacles, and tubercles—often in contrasting colors—making the glass models even more appealing. Take, for example, the snakelocks anemone (Anemonia viridis), with its many extra-long aqua tentacles grading into fuchsia tips, or the beadlet anemone (Actinia equina), a rosecolored column set with blue-green eyespots (page 23). Both species are common in shallow coastal waters today, the snakelocks in the Mediterranean and the beadlet in Wales.
During their career, the Blaschkas created eighty-five glass models of sea anemones. In addition to being masters of color, they had a knack for re-creating the contours and textures of the body columns, like the lines of studs marching from tentacle to base on species like the Anthopleura ballii. And the glass triplet of the swimming anemone (Stomphia coccinea), with their peachstriped columns grading to bright-tipped tentacles, is evocative of the exact Blaschka match housed in aquaria and living on the walls of cliffs at the Friday Harbor Labs (below).
Lithographs of anemones in a tide pool, by Philip Henry Gosse. From Actinologia Britannica: A History of the British Sea-Anemones and Corals, 1860; courtesy of the Albert R. Mann Library, Cornell University.
Three anemones in glass (from top): snakelocks anemone (Anemonia viridis), beadlet anemone (Actinia equina), and Parantheopsis cruentata. The beadlet and snakelocks anemones are still common on European shores. Photos by Kent Loeffler.
Anemones are not only the first invertebrates that the Blaschkas molded in glass at the request of Heinrich Reichenbach, director of the Dresden Natural History Museum, they are also the first form of the entire cnidarian group, evolving in Precambrian oceans over 630 million years ago—long before even fish evolved. Although distinct in color and shape, all anemones evolved as variations on the same theme, one that is the most basic and primitive in the ocean: all have a short, wide base column that houses a stomach and ovaries, along with a ring of tentacles that surround a single opening where food goes in and waste comes out. Although their static lifestyle might suggest they’re easy prey, anemones are well defended; many can move by inching across the rocks, and of course Stomphia coccinea can even swim. Anemones are largely sit-and-wait predators, quietly reposing in the bottom of a rockweed- or eelgrass-shaded tide pool until a mussel or small crab blunders into their sticky, spring-loaded tentacles. Then zap!, hundreds of threadlike barbs called nematocysts fire, snagging and stunning their prey. Perhaps in the touch tank of a public aquarium, any person can safely experience the pull of an anemone’s nematocysts; the tentacle feels sticky and adheres to the skin but doesn’t break it.
The swimming anemone (Stomphia coccinea) alive in the San Juan Islands (left) and in glass. This anemone swims when threatened by predatory sea stars. Photos by Drew Harvell (left) and Claire Smith.
So how is this soft-bodied anemone related to calcified corals? It’s all about reproduction and renewable energy. They share the same polyp-form body, and when it comes to reproducing, each elegant anemone can single-handedly make his or her own family by simply splitting in half and then in half again. These kin are all genetically identical clones to the founding anemone and can continue splitting until a single sea anemone has parted into hundreds of versions of itself in one tide pool. Perhaps this has occurred for hundreds of years, with entire sections of coastline originating from one ancestral great-grandmother anemone, who may still be there. It should be no surprise that our great-grandmother anemone is a warrior, with weapons that can be used in territorial wars with other families. Some tide pools have two genetic stocks of anemone; when they find each other they can fight to the death. Teeth and claws are replaced by an armature of stinging capsules, each neatly packed with a coiled harpoon and poison that kills nerves, firing when the trigger is pulled by chemical or mechanical signals. This harpoon may be nature’s fastest cellular mechanism, firing with the speed of a bullet; it shoots in a billionth of a second, with an acceleration of over a million g’s, and injects a lethal neurotoxin upon contact. So in spite of being sedentary, our great-grandmother anemone has the firepower and the chemical sensors to capture fast-moving prey and defend the family tide pool.
With corals, the same dependable reproductive strategy transforms a single new baby coral into a massive cathedral housing millions of polyps. Though it might seem surprising to some, a coral reef is not a rocky ridge of inorganic substrate that’s been pushed up from the ocean floor by ancient volcanic action; it’s in fact a living colony of coral animals, formed by thousands of polyps budded from an initial parent polyp. The colony operates under one integrated nervous system that coordinates nutrient sharing and defensive behaviors. If you poke a polyp on one side of a coral colony, the tentacles on the other side will retract as a nervous impulse travels across the connected polyps. The essence of a coral or a hydroid colony is to be colonial, with each mouth connected to the next via subterranean channels. As with anemones, each monumental coral colony starts with a single swimming coral larva no larger than a sesame seed, which is tasked with the big job of picking the spot in which to settle and metamorphose into its adult polyp form. Then the magic of construction begins, with the unceasing budding of new polyps, seen beautifully in the Blaschka watercolor of soft corals, including sea pens, encrusting soft corals, and sea pansies (page 27).
Now imagine that each polyp in either a sea pansy or hard coral can catch its own small baby crabs, digest them, and share the remains with the others in the colony through stomach linkages that network through the tissue. In the reef-building hard corals, each polyp secretes a complex calcareous skeleton that acts like a hall of mirrors. Like some of their anemone cousins, these polyps are solar-powered animals housing tiny marine algae in their tissues that transform sunlight into energy to build more polyps and skeleton. Millions of years of evolution have optimized all aspects of their biology, including the shape of their skeletons and the size of their tentacles, to use solar power. This symbiosis is at once the great miracle that allows vast reefs to form and the Achilles heel that makes them vulnerable to climate change.
While the Blaschkas focused primarily on bringing anemones and soft corals to life through glass, some of their watercolors and a few models are breathtaking in their detail of reef-building corals, which so many of the Blaschka invertebrates depend on for food, habitat, and reproduction. These great cathedrals of calcium carbonate create habitats that allow coral reefs to be the richest marine ecosystems on earth. Studying the ecology, health, and status of these reef systems is my primary job, and one of my life’s quests is to understand how this most ancient of all immune systems functions in a changing climate.
Sea pens and sea pansies (Renilla muelleri) in a Blaschka watercolor. Courtesy of the Rakow Research Library, Corning Museum of Glass, BIB ID: 121319.
Scientists may disagree about many things, but there is consensus among coral reef scientists that reefs are highly endangered by the double whammy of w
arming sea temperatures and ocean acidification. We talk about climate change in terms like “business as usual,” meaning we project how much carbon dioxide will accumulate and contribute to increases in greenhouse gas warming if we do not cut our carbon emissions. In 2007, we predicted that under a business-as-usual scenario, most coral reefs would be functionally gone in fifty years (Hoegh-Guldberg et al. 2007). In 2057, I’ll be gone and my students will be as old as I am today, and tropical oceans will have warmed to the point where the symbiosis between most corals and their algal partners will break down. This is not argued: we have already witnessed the demise of many reefs due to “bleaching,” or the breakdown in this symbiosis from ocean warming. In 2013, I was part of a research team that contributed a chapter to the U.S. Climate Change Assessment for Oceans report showing evidence that the demise of coral reefs is one of the largest climate change impacts expected in the ocean (Doney et al. 2013). This transition of an entire ecosystem at risk is already under way. Saying “ecosystem at risk” is an understatement: more than one-third of the foundation species that build reefs are in immediate danger of extinction, twenty coral species were added to the endangered species list in 2014, and entire reef systems can die with a single warm event, as happened to some large tracts of reef in Palau and the Indian Ocean during the 1997–98 El Niño event (Burke et al. 2011). Also, by 2057 the average level of carbon dioxide in the tropical oceans may exceed 550 parts per million; that makes the oceans more acidic and is past the threshold at which most corals can build their carbonate skeletons. When the living corals that make up the reef die, then the anemones, sea stars, worms, fish, and turtles that depend on the reef for their home and food will also disappear.
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Long before there was any discussion about greenhouse gas–driven climate change impacts, I encountered the first evidence of their devastating influence on coral reefs. It was 1982, and I was a twenty-six-year-old PhD student from the University of Washington on a fellowship to study the fish and snails that were eating coral on the very low-diversity coral reefs of western Panama. We had steamed for thirty-six hours in the RV Benjamin, an old wooden coastal steamer with an all-Panamanian crew. We chugged out of Panama City, headed to the Uva Island Reefs in the Gulf of Chiriqui, a pristine, secluded place about eighty miles southeast of Corcovado.
It was our first day in this remote, uninhabited region of dense-jungled shores. We were headed to the fish-filled coral reefs that framed the island. As we buckled gear onto our dive tanks and loaded our small Zodiac, we talked about how many large bull sharks would see us and whether we would also be able to see them in these low-visibility waters. I knew the dangers: these waters were packed with bull sharks, which are considered one of the most dangerous sharks in the world, since they like very shallow coastal water and are very aggressive, prone to mistaking people for food in low-visibility waters. Peter Glynn, a staff scientist at the Smithsonian Tropical Research Institute, was the world’s leading coral reef biologist at the time, and I felt privileged to be diving his reefs with him. But he was also making me nervous with his talk about all the sharks we would see. As it turned out, the bull sharks were ever present, continually spooking us as they loomed out of the murk.
It was a still, early morning and the glass-surfaced ocean reflected the quiet green jungle as we headed to one of Peter’s long-term monitoring plots and my first dive in Chiriqui. I was not a very experienced diver at the time and I don’t mind saying my mind was split between the excitement of being there and my anxiety about big sharks. Once underwater, I forgot my fears and was surprised and confused—all the coral as far as I could see was white. I knew that living coral comes in all colors and shades of tan, brown, green, purple, and even magenta, but never white. I looked more closely and could see the coral’s delicate surface skin, with its living polyps covering the coral, so it was certainly a living reef, but it was eerie and ghostly and not right. To my eye, even the bright fish underwater appeared dazed and confused. These are very shallow reefs, and we were only in about fifteen feet of water, so we gestured to Peter and surfaced. “Why is the coral white, is it safe for us to be in the water?” we asked. He looked pretty shaken and said he’d never seen this before and didn’t know. I still remember the pulse of pure excitement that shot through me. Here I was, a brand new coral reef researcher, with the most respected, experienced coral reef scientist of our time, and he didn’t know why his reef was devoid of all pigments? At the time, none of us were aware of the import of our discovery. My excitement would have been tempered had I known that this was only the beginning of a horrific series of catastrophic coral bleaching and mortality events that by my mid-career would threaten the very sustainability of an entire ecosystem worldwide.
As we dove back down, we started to see more shades of pale—some corals were white, while other less common coral species, like Gardinoseris and Pavona, still retained their brown pigment. These reefs are like big canyons, and as we went deeper and rounded an outcropping, we saw a flash of movement. Chilled, I realized we had an escort of several bull sharks, larger than I, looming in and out of the limits of our vision. The combination of the ghostly conditions, murky water, and shark escort was enough to drive us out of the water. After a long day in the water, we gathered on the deck of the Benjamin over beer and dinner. Peter mulled over the possible causes of what he accurately reported was a coral stress response. Perhaps it was an unusual spike in warm or cold temperature, or perhaps low salinity had caused the symbiosis between coral and algae to break down. He was visibly excited to see a response on this scale and had worked hard all day on underwater surveys of his permanent transects to record the extent and different responses among the species—some of the coral had already died, while other species appeared unaffected. The papers Peter Glynn published about this event were the first scientific recordings of a coral bleaching that ultimately killed large tracts of reefs in Costa Rica, Panama, Colombia, and the Galapagos Islands (Glynn 1983, 1984). At the time, Peter estimated that this was the result of the most severe warming event in at least 190 years. Since then, this record has been smashed by the ever-quickening pace of deadly bleaching events from the Florida Keys to Mexico to Australia, Fiji, and Palau.
Although there was also a large Caribbean coral bleaching event in 1988, the next event I experienced was in 1997, in the Florida Keys. As an established associate professor at Cornell, I was prepared this time and understood what was happening when the scleractinian corals in the Florida Keys turned white. My postdoctoral fellow at the time, Kiho Kim, and I were working with Craig Quirolo of Reef Relief to record the impacts that a disease caused by the land-based fungus Aspergillus was having on vast stands of purple sea fans, a soft coral that was melting away Caribbean-wide (Kim and Harvell 1994). Kiho is now a gray-haired professor and chair of his department at American University, but at the time he was a newly minted PhD doing a postdoctoral residency in my lab. Together we launched a project that would be the focus of the next twenty years of my lab’s work: how climate and coastal stress were triggering new outbreaks of infectious disease on coral reefs. As an octocoral, soft-bodied and with eight tentacles, sea fans are closely related to some of the Blaschka models. One hypothesis for why these octocorals were sick with a land-based fungus was that warming was causing corals to be stressed, thus compromising their immunity and making them more susceptible to opportunistic diseases like the one the Aspergillus fungus was causing. Aspergillus can also be a human pathogen, and so there were many big questions we were trying to answer about emergent diseases in the ocean and their links with land. But our work with the sea fans was interrupted when we observed the reef turning white in Florida and another species of soft coral, Briareum asbestinum, not only turning white but suffering decaying tissue and dying in high numbers. The paper we published from that event demonstrated that some of the deaths we were attributing to bleaching and heat stress were actually caused by infectious disease (Harvell et al. 2001). A
s the winter of 1997–98 unfolded, we experienced the largest El Niño event in hundreds of years, and its impact stretched around the globe. This event elevated to 75 percent the proportion of the world’s coral reefs that were considered threatened. Corals died in bleaching events that included the Caribbean, the Indian Ocean, the Great Barrier Reef, and vast tracts of the Pacific (Burke et al. 2011). In 2004, we worked on the reefs of Palau, some of the most biodiverse in the world, and observed vast stretches, tens of kilometers in length, of completely dead reef that had still not recovered from the mass mortality of 1998. In chapter 8, I discuss the heat-related mass mortalities that are plaguing the Mediterranean and putting our Blaschka match, the orange cup coral, on the endangered species list (page 34).
In 2004, I received a call from Andy Hooten and Marea Hatziolos of the World Bank asking me to join a global project to improve the sustainability of coral reefs. The World Bank was worried about its investments: the economies of many developing countries are critically dependent on coral reef fisheries and other coral reef ecosystem services. Then, just as we were struggling to understand the consequences of severe warming impacts on coral reefs, the second bomb dropped at the annual meeting of our coral sustainability team in Mexico in 2006. In addition to warming caused by the accumulation of carbon dioxide in the atmosphere, the oceans were becoming detectably more acidic from the direct accumulation of carbon dioxide. The projections all showed clearly that this was going to be catastrophic. Nine years later, the beginnings of this ocean catastrophe can already be seen in the waters of the Pacific Northwest (see chapters 6 and 8).