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Boiling Cold Water at Jarvis Island

By Jennifer Smith, head researcher on the Benthic Team

Before dawn yesterday we crossed the equator, arriving soon thereafter at Jarvis Island. This small, US-owned island, part of the new Pacific Remote Islands Marine National Monument, is about as far away from sizable human populations as one can get. Upon awakening, the first thing I noticed was that the water around the ship was boiling. There were some ridiculously strong currents with eddies swirling among whitecaps, but that was not the only source of the churning. The surface as far as I could see was alive with dolphins gracefully coming up for a breath of air. Clearly these waters must be productive. Sitting nearly on the equator, Jarvis lies in the flow of a number of strong currents that drive cold nutrient-rich water up from the depths, nutrients that feed the thriving food web we encounter on our first dive.

Jarvis Island: Clinching the Argument

The Hanse Explorer departed from Washington Island Tuesday evening and arrived Thursday morning at Jarvis Island. So doing it transported the researchers from heavily populated Washington to uninhabited Jarvis, from human-impacted reefs to reefs that are truly spectacular. The next few posts tell of the sharky-ness and of the importance of the reefs at Jarvis Island.

 
by Forest Rohwer, head researcher on the Microbe Team

Jarvis is about as cool as a coral reef gets. The diving is done on coral walls that plunge, literally, to the abyss. The water just off the reef is that striking deep blue of the open ocean. Everytime we get in the water, there are sharks everywhere. Schools of 50+ black jacks pass right next to us and there are thousands of anthais—those brilliant quintessential reef fish— darting up and down off the reef.

Jarvis is important to our research effort because one critisism of the first Line Islands Expedition (2005) was that local oceanographic conditions could be the cause of the observed coral decline at the inhabited islands. There are a large number of reasons why this critisism is unfounded, but the best airtight evidence is Jarvis and the other Southern Line Islands. Every one of these uninhabited coral reefs has large numbers of predators, low numbers of pathogenic microbes, and high coral cover. That is, they are most like the more northern but uninhabited Palmyra and Kingman, even though they are found over a very wide range of different oceanographic conditions. Conversely, all of the inhabited islands surveyed (Christmas, Fanning, and Washington) are characterized by an almost complete absence of sharks, more pathogenic microbes, and declining coral cover.

A Pleasant Find for this Particular Ocean

by Gareth Williams, member of the Benthic Team

Lionfish are a hot topic in coral reef conservation at present. They are an invasive predatory species in the Caribbean and are devastating fish populations on the reefs. However, in the Pacific they are native and a lucky find for a diver during the day. As we searched for cryptic species hiding among the coral heads this morning at Washington Island we came across a spotfin lionfish (Pterois antennata) resting upside down and motionless under a ledge. After much twisting and turning I managed to get my camera far enough into the reef crevice to capture a close-up image of this elusive predator. Their camouflage is truly spectacular.

Medical Report

by Craig Cook, MD

Life on a scientific vessel cruising tropical islands sounds exotic, but there is often a price to pay. The scientific work can be quite physically demanding. Almost everyone has bruises from banging into things, even from getting into and out of our dive boats. No matter how careful we are, we are at the mercy of unexpected movements of the boat. Today for instance, we had six foot seas to contend with which almost guarantees a collision with something.

On the bottom, these same conditions can result in a scrape from a piece of coral. As careful as we are, cuts and scrapes do occur. On land these may only require a Band-Aid, but in the tropics these same scrapes and cuts can turn into something serious. Even the tiniest abrasion can become infected and become much bigger. To make sure this does not occur, we diligently wash each wound and, if necessary, take antibiotics. Right now we have three members of the scientific team on antibiotics.

Other medical issues we have had to treat include an ear infection and a tooth abscess. We even had a minor surgery case. The good news is that none of these has become serious enough to prevent the affected person from continuing their research. While you may be surprised by this lengthy list, but this is pretty much routine for this size of an expedition.

Stuart Sandin Featured on NYT "Scientist at Work" Blog

Stuart Sandin, head researcher of the Fish Team and veteran of previous research expeditions, is sharing reports from the current Line Islands expedition with the followers of the Scientist at Work blog at the New York Times. That blog, described as "the modern version of a field journal, a place for reports on the daily progress of scientific expeditions — adventures, misadventures, discoveries," is an ideal venue for Stuart's observations from the Line Islands and his reflections on how humans might use and enjoy coral reefs, yet keep them healthy and productive. As he noted in his first post there: …in order to manage coral reefs in the presence of people, we have to understand how coral reefs work in the absence of people. The Line Islands give us a rare opportunity to do so.

More reports from him will be published on the Scientist at Work blog during these remaining days of the expedition. Between all the hours spent each day as reef researcher, team leader, and writing for two blogs, Stuart is truly a scientist hard at work.

The Underappreciated Reef Algae

by Jennifer Smith, head researcher on the Benthic Team

Coral reefs are known for their spectacular diversity and striking beauty. When most people think of coral reefs they think of the colorful coral animals themselves—the organisms that build the reef structure and provide habitat, shelter, and food for a number of other reef inhabitants. but much diversity and beauty are also to be found in a lesser known and certainly less appreciated group of organisms: the algae. The algae are incredibly important to reef ecology and productivity, but the very word algae often makes people cringe. Why, they typically ask, would you care about “pond scum” or “slime”? The answer is that in the tropics the reef algae (aka marine plants or seaweeds) represent a large number of species—in many places the total number greatly exceeds the number of coral species. These marine autotrophs get their energy directly from the sun. They capture this as chemical energy which they rapidly convert into usable “food” for the rest of the reef food web, making them essential for a healthy reef ecosystem. And they are fascinatingly diverse.

We scientists usually classify reef algae in three functional groups: the turf algae, the crustose coralline algae, and the larger macroalgae. Each of these major groupings contains hundreds of species worldwide and each group is unique and important in its own way.

Getting It at Kingman Reef

 
 
By Levi Lewis, a Ph.D. student in the Smith Lab, SIO

“Okay, I get it.” Dr. Sandin (head researcher on the Fish Team) was asking what I thought of my first dive on Kingman Reef, one of the most remote and pristine coral reef ecosystems in the world. As a new PhD student in the coral reef lab at SIO, being on the Hanse Explorer was an exciting opportunity for me to witness all that I’d heard and read regarding intact reef ecosystems.

Hatay Toys Unlimited: Our Source for the Best in Custom Coral Reef Research Equipment

by members of the Microbe Team

One of the main tasks for the Microbe Team is the harvesting of water from different sites along the reefs at each atoll visited. These water samples are our mainstay, the first step required for virtually all our work. When we later process and analyze the samples, we can get:

  1. The numbers of microbes and viruses per unit volume.
  2. Sufficient collected microbes and viruses for DNA analysis to characterize both communities.
  3. The concentrations of nutrients and dissolved organic carbon (DOC).
  4. Isotope data to determine if there is human-derived fertilizer (a pollution indicator).

Collecting water from specific locations underwater is not simple. We use special collectors devised by wizard and "toy" builder Mark Hatay who works with the Rohwer Lab at SDSU. We call these collectors Niskins because they are modifications of the Niskin bottle invented by Shale Niskin in 1966 (which in turn was a modification of the Nansen bottle invented by Fridtjof Nansen in 1910). They really should be known as Hatays, or maybe H-Niskins, but the Niskin name has stuck. The original Niskins were designed for remote use at great depths, provide only approximate control over location and position, and, worse yet, are made of materials that leech chemicals that are toxic to microbes. Mark's devices are designed to be used by SCUBA divers to collect clean water samples from precisely 1 meter above the coral surface. Each is a polycarbonate tube with caps at each end, materials that are compatible with the chemistry and the biology of seawater. When capped each holds 2 liters of seawater.

The Past, Present, and Future of the Reefs at Fanning Atoll

by the Paleo-Benthic Team

To a Paleo-Benthic, today's coral reefs are rich in clues about their past and offer hints as to their future. Atolls such as those that make up the Line Islands are built of the dead skeletons of corals, foraminifera, and calcifying algae. Beneath the deep layers of marine skeletal debris is the old, extinct volcano that gave rise to the island originally. As the volcanoes age and cool, they sink deeper. The islands keep up with this sinking by growing upwards thanks to the constant supply of new skeletons produced by living corals, foraminifera, and calcareous algae. If natural or human disturbances cause the die-off of these organisms, the supply of atoll-building materials will decrease. Coupled with sea-level rise, this could spell disaster for the marine, terrestrial, and human communities living on coral atolls like these. This is yet another reason healthy, living coral reef communities are so important.

Fanning (Tabuaeran) Atoll, a recent port of call, was an interesting study in contrasts. Its lagoon is huge (110 km2 compared to only 34 km2 of land), and most of the lagoon water is exchanged through a single passage on the western (leeward) side of the atoll. This creates amazingly strong currents—up to 3 or 4 knots—and huge standing waves during the peak incoming and outgoing tides. This jet of water seems to act as a barrier between the reefs on the northern and southern sides of the pass. South of the pass, the coral cover was spectacular, covering around 80% of the substrate. Gigantic plates of Acropora and multicolor whorls of Montipora blanketed the bottom.

Clocking the Microbes

by Forest Rohwer, head researcher on the Microbe Team

Microbes are major players in the health or decline of a coral reef. On the 2005 Line islands Expedition, we found that there were ten times as many microbes in each milliliter of reef water on the degraded, algae-covered reefs at Christmas Island as compared to pristine Kingman. Not only were there more, but they were more active and growing faster, and more of them were of the pathogenic kind. These observations combined with aquarium experiments indicated that what the microbes were doing was interrelated with other happenings on the benthos.

When a reef is not grazed, there is a lot more of the large fleshy algae that are commonly called seaweeds. Some of the sugars they make by photosynthesis are released into the seawater. These dissolved sugars make up a big part of the dissolved organic carbon pool—the DOC pool. Microbes eat DOC. More algae, more DOC, more microbes and more rapidly growing microbes. Too many microbes growing too fast are bad news for the corals. Normally there are the right numbers and the right kinds of microbes living in the coral's surface mucus. There they pay their rent by protecting the coral from invading pathogens and by supplying it with usable nitrogen compounds. But when overfed, they can grow so fast that they consume all the local oxygen, and suffocate the coral.

One of the goals on the 2010 expedition is to measure the growth rate of the microbes at different locations and determine how it relates to the productivity of the other main members of the reef community (the corals, the algae, and the fish) and to the health of the reef (the reef's CHI).

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