A Sea of Glass Read online

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  As we are carried fast now with the current in the growing dark, we see that the feather stars aren’t the only echinoderms that creep from the safety of the reef. Brittle stars are a favorite food for fish and spend their days hidden under corals or rocks or tightly furled in the branches of soft corals. As daylight wanes, the long-armed brittle stars also wind their way to the highest points and reach stiff, filtering arms into the current. Sea cucumbers are easier to miss, but one barrel sponge we pass is covered with tiny, apodous Synapta lamperti. “Apodous” means without feet; this family of sea cucumbers does not have tube feet. The Blaschkas re-created nine different species in the Synapta genus alone. On the reef edge, I spot a huge foot-long black-spotted cucumber, slowly dredging through the sediment one tentacled arm at a time. It’s striking, with its spots and large, jet-black arms, but what I really want to see is the juvenile of this species, because the youngster has orange spots on a mottled black and white background; it’s a dead ringer for an unusually colored species of toxic, brightly colored nudibranch. This is a spectacular example of using the warning coloration of the nudibranch for its own protection, exactly like the Batesian mimicry of butterflies, played out across whole phyla of invertebrates. After the trauma of our recent star outbreak, I am happy to reflect on this display of echinoderm biodiversity, out to greet the advancing dark.

  8.

  THE VOYAGE OF OUR BLASCHKA BIODIVERSITY

  The Mediterranean coral Dendrophyllia ramea in glass. This is a nonphotosynthesizing coral endangered by warming-related mass mortality in the Mediterranean. Photo by Guido Motofico, courtesy of the Natural History Museum of Ireland.

  THE UNDERWATER CLIFF FACE loomed beside me as I struggled to catch up to the other divers. I had stopped in mid-breath when I saw the hamster-sized brown-spotted nudibranch Discodoris atromaculata, popularly known as the sea cow. A somewhat undignified name for a predatory mollusk, but the big brown and white blotches are definitely Guernsey-like. I am alone now, way behind the group, but it is oddly pleasant having the seascape all to myself. We are two-thirds of the way through our dive in the marine reserve at Portofino, Italy, and I’m happy, having been lucky enough to find four species of nudibranchs, including a tiny zebra slug, small as a yellow jacket wasp, glittering bright blue with yellow stripes (page 154). The current zooms me along, and sixty feet ahead I see a cliff edge carpeted with bright purple and gold sea whips and colonies of red precious coral, Corallium rubrum. It’s a happy place, a protected corner of the ocean, with zooming big fish, foundation species like the sea whips and corals, and bright gems of biodiversity like the nudibranchs.

  I have shared a global voyage of discovery with the Blaschkas, exploring the tree of invertebrate life, following the trail of these soft-bodied creatures from the coast of Washington to the heart of the Indo-Pacific, with several stops in between. The most satisfying news is that I have observed Blaschka matches at all these sites, but especially in the Mediterranean. We find them in every habitat we explore. Along the Ligurian coast, there were rafts of by-the-wind sailors washed up on the beaches, and we were surrounded by flotillas of the mauve stinger jellyfish during one dive. The fish markets were packed with cephalopod matches, probably as they were during the Blaschkas’ time: the common octopus, the curly tentacle octopus, the bobtail squid, and the common cuttlefish. Two species of the tiny sepiolid squid turned up on our dinner plates. Underneath the docks and attached to wrecks are nudibranchs, anemones, bright feather duster worms, brittle stars, octopuses, and cuttlefish. Inside the no-fishing preserve at Portofino, the sheer rock walls are carpeted with sea whips, precious corals, sponges, and sea squirts. Predatory nudibranchs and red sea stars prowl these same rock walls. Having seen them previously as Blaschka glass masterpieces, I find their natural splendor elevated by translation into art forms. We still have within our reach the fragile legacy of the Blaschkas.

  A zebra slug (Felimare picta) on an underwater cliff in the Mediterranean. Photo by David O. Brown.

  Although it is clear from the mastery of their glass pieces that Leopold and Rudolf loved the natural world to the point of obsession, I enjoy hearing it in Rudolf’s own words. Rudolf writes in a letter to an American colleague, Walter Deane (a founding member of the New England Botanical Club), “I think I belong to that same order of men as you, to the true lovers of nature. On every walk I take, there must be something to study of nature, it may be a plant or insect or bird or whatever. I think a man can never finish these studies and is never too old to learn from nature” (Rossi-Wilcox and Whitehouse 2007). In another letter, to Mary Ware at Harvard in 1908, Rudolf reflects back on his time making and observing sea creatures in his aquarium: “In thinking of Marine Zoology I am getting quite young again, so much is this science amalgamated with my own development. I remember of the time of 28 years ago when we had established for our studies an Aquarium-room filled with seawater-tanks, and of the eagerness and pleasure in observing the life of the wonderful delicate beings from the sea” (Reiling 2007).

  When Leopold and Rudolf Blaschka crafted their first marine masterpieces in 1863, the oceans were healthy and sea animals plentiful. There were six billion fewer humans alive, and the planet still held many wild places yet to be discovered—and exploited—by man. The combustion engine was still in its nascent stages, having been created in 1859, and the first fuel-powered automobile was still two decades away. The Wright brothers wouldn’t launch the world’s first airplane for another forty years. People communicated by telegraph and only a few owned personal radio sets. Much has changed since then.

  It would have been impossible for the Blaschkas to comprehend the world of today. They never could have imagined that the world’s population would surpass seven billion, nor could they have imagined the technological achievements of our era, from autos to iPhones. Certainly, they might have begun to see the early signs of industrial pollution, but it’s unlikely that they could have imagined the eventual toll it would take on their beloved ocean environment: first acid rain and then the wholesale change in the global ocean’s pH, creating a hot acid soup that dissolves the very skeletons of its lifeblood. To the Blaschkas, the ocean was a vast, immeasurable realm, not even fully charted and abundant with magical creatures that most of the world had no idea existed—which is what inspired them to spin these glass creatures in the first place. What would they make of today’s despoiled oceans—the millions of tons of plastic waste floating in endless gyres, bigger even than small countries; dead zones that span full hundreds of miles in once species-rich regions; the precious corals and tide pools evoked by Gosse bleached out and dead? It would be the stuff of nightmares, to be sure. In writing this book, I occasionally imagine myself sitting, especially with Leopold, and explaining all that has happened and how it affects the ocean biodiversity he loved so much. This is what I would say.

  I share with you a passion for the artistry of the ocean’s diverse invertebrates. It is painful to describe how, in our quest for improved life and material goods, humans have squandered the riches of our planet, including the ocean. Some of the 800 invertebrates you have created to teach my students are at risk in today’s oceans. In the past 160 years, the world’s population has grown from one to seven billion and over-fishing, coastal pollution, and habitat destruction have taken a big toll on the diversity of all marine animals. We still have lots of jellyfish, anemones, nudibranchs, and even some cephalopods in our oceans, but we cannot easily find as many different kinds as you had at your fingertips. It turns out to be surprisingly hard to track the fate of the many animals you saw so easily. You could have gone to the shore at Naples and found twenty species of nudibranchs and five species of octopus in a single day. Even with equipment to breathe underwater, our team spent nearly a week diving in Spain and Italy and found only six species of nudibranchs, a single octopus, and a single cuttlefish. If you had dived in the night ocean at Naples in 1868, you might have seen an ocean alive with five times as
many squid, octopus, and cuttlefish species as today. If you were stationed beside a tide pool, perhaps fifteen anemone species would be at hand. I’m sorry to tell you that industrialization has filled our skies and oceans with a gaseous pollutant, carbon dioxide, which is changing our climate and rapidly warming the entire planet. The oceans are doing their job of absorbing almost 30 percent of the pollutant, but in so doing they have become 30 percent more acidic globally. Some spots are already so acidic that sea butterflies and oysters are dissolving and the fertilization of new eggs fails. Perhaps the worst of the news is that messing with the atmosphere on this planetary scale has set a change in motion that will continue for fifty years even if we reduce the emissions today. Climate change, which has caused all the world’s oceans to warm, is taking a huge and continuing toll on your brilliant undersea beds of precious corals, soft corals, and sponges. The impact that warming and rising seas will have on humans living near the sea in countries like Indonesia is too sad to even tell you about.

  No matter how I describe the changes of the last 160 years to Leopold, it sounds more like science fiction than fact. We are living near a vastly different ocean that puts our living biodiversity at risk.

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  Although our data are poor, what undeniable changes have we seen in the species that were common in Leopold and Rudolf’s day and that are part of our collection? The Blaschkas selected many invertebrates that were easy to collect, abundant, and found throughout the world, but a full 25 percent of them are not widespread; they are endemic to the Mediterranean and found nowhere else on the planet. Some of these species are among the rare or unconfirmed on my list. Although we found healthy ones in northern Italy, the gorgeous orange cup coral, Astroides calycularis, is an endemic species and is listed as endangered in the Mediterranean. The solitary cup coral, Balanophyllia europaea, has been endangered by repeated warming events in the north Adriatic, with over 80 percent killed at some sites in the 2012 warming (Kružić and Popijač 2015). I also had hoped the different octopus and squid species would be more common. I’m concerned about the jeweled squid and the paper nautilus. The paper nautilus, Argonauta argo, lives in tropical and subtropical seas, including the Mediterranean, and is reported to be susceptible to mass mortalities in California, these being possibly associated with red tides (caused by toxic algae called dinoflagellates). Interestingly, the baby nautilus, in its early life, resides in salps and some jellyfish and so is reliant on their populations being healthy (Orenstein and Wood n.d.). Chiroteuthis veranyi, the long-tentacled squid, and Histioteuthis bonnellii, the jeweled umbrella squid, are present in deep Pacific waters off Monterey, California, but rarely seen directly by cephalopod expert Maurizio Wurtz (University of Genova) in the Mediterranean. He knows they are still present because both turn up as prey in the stomachs of dolphins and sharks. Although it was always possible to find a nudibranch or two, there were many we could not find, and many were quite rare.

  In the Mediterranean today, important foundation species that create habitat, many of them Blaschka matches, are at risk. Matches at risk include the precious coral (Corallium rubrum), sea whip (Eunicella verrucosa), solitary coral (Balanophyllia europaea), endemic cup coral (Astroides calycularis), and sponge (Axinella sp.). They continue to be heavily impacted in the series of mass mortalities that has rocked Mediterranean biodiversity (Garrabou et al. 2009). Perhaps the most well-studied impacts have been recorded for the precious red coral, since it has been commercially harvested since the Blaschkas created their models in the 1860s. A recent study around the Bay of Naples, using remote operated vehicles to resurvey many of the historical red coral banks, shows huge declines relative to historical surveys from a hundred years ago, even in very deep waters (Bavestrello et al. 2014). This series of shallow- and deeper-water mass mortalities in the Mediterranean, the seat of Blaschka biodiversity, alerts us to climate-linked impacts on ocean life. A 2014 study confirmed that warming events that started in 1983 and have increased in frequency have caused large-scale mass mortality of Mediterranean invertebrates (Rivetti et al. 2014), largely affecting precious and gorgonian corals and sponges, with fourteen events recorded between 1983 and 2011. In some years, over a third of the biomass of habitat-forming species died. A look at the species affected shows there are quite a few Blaschka animals in this group. No one has even tried to detect the impact of these mortality events on the mobile animals such as the cephalopods, worms, and nudibranchs. These animals are also likely diminished in these events through direct heat stress, new outbreaks of disease, and loss of habitat or prey. As discussed in chapter 6, when we look up the twenty-five currently accepted species of cephalopods in Cornell’s collection in the IUCN checklist, eleven are not assessed, six are classified as “data deficient,” and the remaining eight are considered of “least concern.” That tells us nothing except that we do not have good numbers. So I cannot say yet how many of our Blaschka animals are endangered or even extinct. We do know that a few are considered endangered and that Mediterranean biodiversity has been seriously impacted in the past two decades.

  Our invertebrates are not the only animals at risk. The Mediterranean is considered a world hot spot of marine biodiversity, with over 17,000 reported marine species, a fifth of which are found nowhere else (Coll et al. 2010). However, Mediterranean marine life is among the most endangered in the world, due to increasing human threats that affect all levels of biodiversity (Costello et al. 2010; Coll et al. 2012), severe impacts from climate change, and biological invasions ( Katsanevakis et al. 2014).

  We know far more about the fate of our backboned ocean biodiversity than we do about the fate of invertebrates. For instance, the IUCN reports that over 40 percent of Mediterranean fish are endangered, including popular commercial fish such as bluefin tuna, sea bass, and hake (www.iucnredlist.org). The IUCN cites overfishing, marine habitat degradation, and pollution as the drivers, all stresses that impact our Blaschka matches as well. IUCN records indicate that almost half the species of Mediterranean sharks and rays and over half the species of Mediterranean dolphins and whales are threatened with extinction, as are a third of all crabs and crayfish.

  What is the prospect for our oceans? We have just passed 400 parts per million (ppm) of carbon dioxide in our atmosphere. It was 280 ppm in 1860, while the Blaschkas were creating our collection. In 2000, it was 370. This huge change in CO2 has contributed to significant climate warming, which is already endangering all the world’s coral reefs and the non-reef corals of the Mediterranean. We are also experiencing a more than 30 percent increase in the acidity of our oceans. In considering what levels of CO2 are dangerous for invertebrate biodiversity, I have my eye on 500 ppm because it is a tipping point for the ability of animals like snails and corals and brittle stars to make their skeletons. Big change happens quickly once you pass that point. At what point will our calcified animals not make skeletons? At what point will reproduction and fertilization be impaired for our ocean biota? Our job as scientists is to go and find out.

  Israeli researchers grew corals at different levels of CO2 and found that above 700 ppm CO2, they grow as small, disconnected anemones and do not calcify into reefs (Fine and Tchernov 2007). The complete failure to calcify is an extreme tipping point. Long before this is reached, we expect to see many calcified animals with thinning skeletons, such as the almost transparent limpets observed in the high-CO2 seeps near Naples, Italy. This is already happening. Even though we know that there will be variation among species in their sensitivity to changing levels of CO2, we can be confident that waters in excess of 500 ppm CO2 will present big problems for many animals with calcareous skeletons. Despite not having enough survey data on our Blaschka invertebrate biodiversity, we do have warning signs. In spring 2014, sea butterflies made headlines and were shown on the cover of Science magazine along with the news that they were actively dissolving in the oceans off Washington State (Bednaršek et al. 2014).

  The 2013 report from the Intergovernmenta
l Panel on Climate Change, which is comprised of the world’s leading climate scientists, put it this way:

  Human influence has been detected in warming of the atmosphere and the ocean, in changes in the global water cycle, in reductions in snow and ice, in global mean sea level rise, and in changes in some climate extremes. . . . It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century. . . . The consistency of these observations demonstrates that the pH of surface waters has decreased as a result of ocean uptake of anthropogenic [human-caused] CO2 from the atmosphere. (IPCC 2013)

  Once the pH shifts to the point that a species cannot reproduce, as discussed in chapter 7, it’s merely a matter of time until it goes extinct. It is sobering to imagine that many sea animals may experience halved reproductive success in the next fifty years; the results would be catastrophic.

  We know that successful fertilization of sperm and egg is very pH dependent. We know that many invertebrates and fish in the ocean free-spawn; that means they release their eggs and sperm into the ocean water and rely on the correct acidity to facilitate fertilization. Experiments with sea urchins (Stronglylocentrotus nudus) have shown that fertilization success decreased to 45 percent even at 450 parts per million of carbon dioxide (Sung et al. 2014). Other studies confirm that an increase in CO2 can cause pH to drop and reduce fertilization success. Jon Havenhand (2008) has shown that at a pH of 7.7, 24 percent fewer eggs of urchins were successfully fertilized, because sperm stop swimming and do poorly in low-pH water.