Science

Contrary to appearances in this blog, I do spend some time working in Palau. Since PICRC hasn't had any field projects for the past few months, I've been working primarily with two postdocs from the University of the Ryukyus in Okinawa, Japan. One, Julien Lorien, is conducting a study of invertebrate biodiversity, for which we've been collecting specimens at sites all over Palau. Most coral reef biodiversity studies focus on fishes and corals, so, as I've mentioned before, invertebrates are poorly understood, and many species haven't yet been described. 

I've been helping Julien collect crustaceans (crabs and shrimp), molluscs (mussels, snails, nudibranchs), and echinoderms (starfish, sea urchins, sea cucumbers), which he'll later use for DNA analysis (unfortunately the shipment of needed chemicals won't come in until after I leave). Specimen collecting consists of looking for fun critters and then snatching them from the reef and stuffing them in vials: contrary to all my values as a diver and nature lover but admittedly fun as a scientist. The vials and jars are all slightly buoyant and invariably come tumbling out of my bag whenever I open it, so the bonus fun part of collecting is feeling like an astronaut as they float past my face and I have to grab for them in slow motion. 

Picking up a specimen, being careful not to injure any coral. Photo by Yuen Shyan. 

Trapping above specimen in a vial. Photo by Yuen Shyan. 

Julien secures a specimen on a dive in Peleliu. 

 Another part of his project involves collecting dead coral rubble, which is full of nooks and crannies and therefore invertebrates. We fill baskets with rubble and bring them to the surface with lift bags: like hot air balloons that we fill with air from our tanks. 

PICRC researcher Lincoln Rehm and I fill a basket. I've partially inflated the lift bag so we can move the basket around. Photo by Yuen Shyan. 

Descending with a basket in Nikko Bay. Photo by Susy Gritsch.

Julien and I tote our balloons back to the boat. Photo by Susy Gritsch. 

Science is SO FUN! Photo by Susy Gritsch. 

The baskets are extremely heavy (they're essentially full of rocks), so getting them back on the boat is a challenge. Photo by Susy Gritsch. 

The ever photogenic collection team: my skeptical self, PICRC volunteer Martin Gritsch, and Julien. Photo by Susy Gritsch. 

We keep the rubble submerged in seawater while we stare contemplatively into the distance. Photo by Susy Gritsch. 

Back on land, we process the rubble by breaking it into tiny pieces with hammers and chisels and removing any animals hiding inside. Smelly, spattery work, this is fun for maybe the first five hours. Luckily a new crop of high school volunteers has appeared who are more enthusiastic, or at least more coercible. 

Martin and I process a basket. Photo by Yuen Shyan. 

Some animals we found inside the rubble, which will be photographed and then preserved in ethanol.

All the specimens we collect by hand or in baskets are given a unique number, preserved in ethanol, and entered into a database with as specific a taxonomic identification as we can manage just by looking at them (often not very specific at all!). Filling and labeling these 400+ jars was how I spent a few weeks before Christmas, before I foisted the job on a hapless high schooler. 

The other project is with Yuen Shyan, who is conducting a long term coral monitoring study. First we had to set up permanent monitoring quadrats by pounding rebar into the coral with sledgehammers in a 4mx4m square (I hope I can put "Underwater Sledgehammering" as a skill on my resume). We're now returning to those sites so Yuen can take pictures of all the corals in the quadrats. Martin and I stretch a rope square across the rebar and then clip smaller ropes at 1m intervals to create a grid, which helps Yuen orient the pictures when she stitches them together for analysis. She takes photos of the whole quadrat, using the PVC structure shown below to maintain a standard height, and when she's done, Martin and I quickly take apart the ropes and set them up again at the next quadrat (there are three per site). Wrangling long dangly ropes around fragile coral isn't easy, but Martin and I have developed a finely choreographed routine, and are extremely proud of our underwater teamwork. 

I secure a rope as Yuen takes quadrat photos. Photo by Susy Gritsch. 

Martin and I disassemble the grid. Photo by Susy Gritsch. 

Ascending with the pipes we use to cover the rebar. Photo by Susy Gritsch. 

 After the photo quadrats, we do a second dive at each site and collect data on the benthic habitat and fish populations along five linear transects. My job is to swim slowly along the transect tape and take a video. All the fishes that swim into the frame will be identified and recorded.

Between these two projects I've been diving almost every day of the past few weeks! I couldn't be more glad that Julien and Yuen are here and in need of volunteers to carry their sledgehammers.

Fish video transect. Photo by Susy Gritsch. 

Science is STILL FUN! But sometimes a little chilly (less than 80 degrees). Photo by Susy Gritsch. 

Bumphead spawning

Last Tuesday, a few days before the new moon, I went on another spawning dive, this time for bumphead parrotfish (Bolbometopon muricatum). Researcher Paul Collins picked me up at 4:45am and we joined the rest of the bleary-eyed but enthusiastic group for a dark and rainy ride out to the aggregation site near Ulong Channel.  Weaker currents at the new moon and fewer big sharks meant that this dive was less of an adrenaline rush than the snapper spawning, but it was still spectacular to see thousands and thousands of huge fish assembling for this monthly spawning event. 

Paul jumped in first to check the progress of the aggregation. He invited the rest of the group in as droves of bumpheads started heading purposefully toward the spawning site. 

As they started milling around in the sand, we stayed well above them to avoid disturbing them. Paul compared this stage of the aggregation process to so many cockroaches congregating in a dark kitchen. 

As with the snapper, spawning begins as a female darts toward the surface and several males follow, releasing a cloud of gametes. 

Visibility was shot within a few minutes; it was best not to think about it too much. 

Males assume this white-faced, banded mating coloration only during spawning. 

Paul and his colleague Richard Barnden have been studying these spawning events for several years, and although there's still much that's poorly understood, Paul has some theories about how spawning patterns change over the fishes' life histories. "For bumpheads, older terminal phase males tend to have a harem mating structure with maybe ten females, and follow a separate spawning schedule," Paul explained to me after the dive. "We think what we're seeing here is more like a rave."

We finished the day with a wonderfully sharky dive at Siaes Corner and a colorful wreck in the otherwise muted and murky Lighthouse Channel. 

Gray reef sharks at Siaes Corner

Lighthouse Channel