Scientist at Work Blog: Swift Diving in Bali

C. Drew Harvell is associate director for environment at the Atkinson Center for a Sustainable Future at Cornell University. She is studying the health of coral reefs and marine ecosystems in Indonesia, and is helping to plan a new project, Capturing Coral Reef Ecosystem Services. This is her final post.

Wed., Jan. 23

Our last stop is Bali. Once we were free from the crush of oppressive traffic and overt tourism in Denpasar, I did get lost in the rapture of my surroundings ? it seems like everything the Balinese touch turns beautiful. From the seductive Hindu temples of Uluwatu and roadside architecture, to the small inviting byways and richly turned fabrics, the back roads of Bali are enticing. But we were still on duty as scientists, with tasks to accomplish.

This beautiful culture is also over-loved in terms of tourism and development. My final dives were to some islands close to Denpasar with well-developed hotel-based tourism.

The dives on the reefs, in super-high currents, were on the list for our last trip a year ago, but one of the scientists on our team developed typhoid, and instead we spent the time watching over her in one of Denpasar?s excellent small clinics.

Many locations in Southeast Asia have a high incidence of typhoid. One of my areas of specialization is as a disease ecologist of marine organisms. It is a little different from being a doctor for people. However, it does mean that I am fascinated by the same viruses, bacteria and fungi that medical doctors deal with to help their human patients.

I am interested in the transmission routes these germs take in nature and the aspects of their biology that allow them to cross from one host to another. Examples of what we call zoonoses include the now-famous Kendra virus, transmitted from horse to human, or rabies, from dogs to humans. Then there are the bugs that are passed from humans to coral, in reverse zoonosis. My students and I are on the hunt for their reservoirs or hiding places in natural ecosystems, and want to know how environmental changes can affect disease risk for both humans and wildlife.

That brings me back to typhoid. It is caused by a bacterium, salmonella typhi. It is prevalent in places that do not have good septic treatment because its route of transmission is what we call fecal-oral, and I think that is all I have to say.

I am not a human doctor, so I do not have the best data on levels of typhoid transmission, but Craig Altier, a salmonella expert from the Cornell University College of Veterinary Medicine, tells me that places in Indonesia have some of the highest levels of typhoid in the world. And it made my friend very sick, very quickly, with what looked like a bad stomach flu, but included blood and heart complications.

Treatment involves large doses of antibiotics and is usually successful as long as you don?t happen to tangle with an antibiotic-resistant strain. Thankfully that didn?t happen in my colleague?s case, but there was another nasty complication. The typhoid was accompanied by another bug, called entamoeba histolytica ? also known as amoebic dysentery ? which also follows the same transmission routes. The typhoid and amoebic dysentery presented a double whammy, and without the extremely good health care she received, could easily have been fatal.

And here is why many of us are interested in a concept called ?One Health?: There is excellent evidence linking human health and environmental health. One goal in our work in Indonesia is to see if we can link high levels of human infections with adverse health in the ocean environment.

I work on the infectious diseases of corals, which live in near-shore coastal locations. Coral health is a good sentinel for the well being of reefs. When conditions in the water get bad, corals get sick. And since corals can?t move and wear their entire being on their surface, they get sick in very obvious, place-based ways.

For example, the black band disease I talked about in my first post reliably increases when temperatures increase, and it also increases when there is an overabundance of nutrients.

Another well-known example is a coral disease called white pox from the Florida Keys. White pox looks like coral measles ? its symptoms include ulcerative white spots all over the coral?s surface. The white spots eventually coalesce, causing lesions that eat all the living tissue away and kill the coral.

Some cases of white pox are caused by a fecal coliform bacterium, serratia marcescens. Katie Sutherland, a scientist in Florida, was able to link the disease-causing bacterium to fecal coliform strains cultured from human sewage treatment plants.

Earlier during our trip, in Sulawesi, I showed pictures of us collecting samples to test for the presence of a group of fecal coliforms, called enterococci. They are the same ones the Environmental Protection Agency in the United States uses as an indicator for the safety of our waters.

In the United States, the notifiable limit set by the E.P.A. is 35 counts per unit (C.P.U. means the number of bacteria cultured from a standard water sample of 100 milliliters). Our preliminary samples from some coral reef locations near heavily populated islands ranged from 3 to more than 200 C.P.U. That is not a healthy condition for people swimming in the water or eating fish from that water. We also found corals in this area with higher than background levels of disease.

Human pollution is hardly the only threat to our marine life. My lab, and a group of scientists linked through a research network I run, financed by the National Science Foundation Biological Oceanography, work on how climate change is making both animals and plants sicker in the world?s oceans.

Our work has shown that several diseases of corals increase during extreme warming, which we can anticipate in the coming decades.

So how does this relate to the spectacular and somewhat dangerous dive I am about to take? Climate-driven warming alone will likely cause many opportunistic infections in corals in the coming decades. As good stewards of this most precious of marine resources, we need to do the science that shows us how to make these reefs more resilient, so that they get through this rather tight bottleneck humans are imposing.

And so on to the dive: I am now in a spectacular location in Bali, notorious for extremely strong currents (think fast-flowing rivers), some of which have the dangerous property of sweeping downward, sort of like an undersea water-fall. The same colleague who became sick with typhoid cautioned me, ?Be very careful diving there, Drew, several people have died from being swept down too deep by those strong currents during the past year.? Great.

I made sure to pick a highly reputable and competent dive company. And I asked them to not only take me to their most beautiful sites with high coral cover, but also ones that are potentially affected by poor tourism practices, like discharging untreated sewage.

I am advising an international team of coral health biologists, including Indonesian scientists, to develop comprehensive identification of the predominant coral disease syndromes throughout Indonesia. Happily, in most locations of Indonesia, we are so far finding some of the lowest levels of coral disease in the world.

In most of our sites ? for example, Wakatobi National Park or Biak, Papua ? less than 1 percent of every coral colony is sick. This can be compared to some sites in the Caribbean, like Puerto Rico or the Mexican Yucatan, where we have found over 30 percent of the remaining corals to be sick. We are very interested to find out why the levels of coral disease are so low on the species-rich reefs of Indonesia, and what kinds of ecosystem services make these corals more resilient to disease.

Still, the area is not problem-free. We have seen locally high levels like those next to the tourist operations here, where sewage is released directly onto the reef.

How do I know they are discharging sewage? As we started our drift dive near a tourist pontoon, the relatively murky water and toilet paper floating by were good indicators.

And the ulcerative white spot diseases of this area?s corals are a good indicator that all is not well.

I saw these sick corals at the beginning of this dive and hadn?t seen them at other locations. And I saw a lot of reef on this dive, since it was a heck of a fast dive in very high currents, covering well over a kilometer.

It was, as I was warned, tricky; every time I grabbed hold to snap a picture, my dive buddy would be swept out of sight with the current. I didn?t run into any down currents, but we did hit a fast up current along one wall, like an elevator, that made it hard to keep at depth.

Happily we were quickly washed from the tainted reefs to a bright, clear, lovely rich reef filled with cool stuff like big sea snakes, tiny bright blue moray eels, a high diversity of corals, a high diversity of fish and of course, clown fish.

Locations like this depict the value of our plan to team with the Nature Conservancy to develop a Pacific-wide coral health survey ? to use coral health as a sentinel for reef-wide sustainability and a fast-changing indicator of declining environmental conditions.

The good news is that local environmental stressors like sewage discharge are relatively easy to fix, compared with the larger global issue of climate change.

All in all, this was a productive trip, where I was able to juggle work on two coral reef sustainability projects. We were able to advance the Capturing Coral Reef Ecosystems Services Project, by finding sites where the value of ecosystem services of marine protected areas, coral reefs and mangroves can be advanced, and we were able to identify firsthand some key issues in supporting new eco-businesses in the coral triangle.

I was also able to move forward our work with the National Science Foundation-supported One Health project, by developing with colleagues at Hasanuddin University in Sulawesi new assays for bacteria in the water and new sites for surveying coral health.

The rich and unique center of coral biodiversity that thrives in Indonesia provides an unusual opportunity as a study system for those lucky to be welcomed as partners. At the same time, it is a global commons that is in need of help through new partnerships that the Indonesians can use to steward their resources.

Financing for this expedition was provided by N.S.F. Biological Oceanography, International Programs and U.S.A.I.D. PEER.

Source: http://scientistatwork.blogs.nytimes.com/2013/02/19/swift-diving-in-bali/?partner=rss&emc=rss

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