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Remipedes and cave diving: Field notes from Joey Pakes

By UCMP grad student Joey Pakes, July 1–7, 2008

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Joey is a graduate student at UCMP currently doing research on remipedes, crustaceans that live in underwater caves and look a bit like centipedes. Her research requires SCUBA diving in these caves. Check out an introduction to Joey's research or her first field report.

July 1, 2008: Sad morning
This morning I awoke to find someone digging at a nest of newly hatched sea turtles on the beach directly outside of our condo. It wasn't completely clear whether someone had tampered with the nest or what, but several of the hatchlings had been unable to dig themselves out of the sand. How sad! As the man dug, he found a few struggling hatchlings that seemed too weak to survive for long. Baby sea turtles don't have it easy — once they burrow out of the sand, they have to race across the beach to the water, then swim off and catch their own food, avoiding predators the whole time. A hard enough task for fit turtles, let alone those exhausted from trying to dig through a thick layer of sand. For a variety of reasons, few hatchling turtles actually survive to adulthood. On a positive note, many of the baby turtles from this nest clearly had managed to dig through the sand over the course of the night, judging from the number of empty cracked eggs. I hope some of them make it to adulthood since sea turtle populations are at dangerously low levels.

An exposed clutch of mostly hatched sea turtle eggs One of the hatchling turtles that was unable to dig itself out of the sand A healthy adult sea turtle sighted offshore near Akumal
Click on any photo to see enlargements. Left: An exposed clutch of mostly hatched sea turtle eggs. Center: One of the hatchling turtles that was unable to dig itself out of the sand. Right: A healthy adult sea turtle sighted offshore near Akumal.

Later in the day we went for a dive in Casa Cenote which connects with the ocean via a cave. It was only a three-minute dive from the lagoon to the open ocean with the brisk oceanbound current. Afterwards, we explored the mangroves (which grow around the perimeter of the cenote) and the caves underneath their prop roots. Different kinds of mangroves have different methods of dealing with salt water — some have roots that efficiently filter out salt and others take up the salt and later secrete it through their leaves. After this fun day of recreational diving, the group sat down at the nearby beachfront restaurant for a feast of fresh seafood.

Shane prepares to explore some of the caves amongst the mangrove roots at Casa Cenote Brett tackles a student as she emerges from a shallow cave made by mangrove roots After emerging from the cave that connects Casa Cenote to the ocean, this is what one sees when looking back toward shore: a typical Mexican palapa, an open-sided restaurant with a thatched roof Okay, dinner time!
Far left: Shane, a Texas A&M undergrad, prepares to explore some of the caves amongst the mangrove roots at Casa Cenote. Second from left: Surprise attack! Brett tackles a student as she emerges from a shallow cave made by mangrove roots. Second from right: After emerging from the cave that connects Casa Cenote to the ocean, this is what one sees when looking back toward shore: a typical Mexican palapa, an open-sided restaurant with a thatched roof. Hmmm … a restaurant. Far right: Okay, dinner time!

July 2, 2008: Crocodile?
Today, Brett and I dove Aak Kimin Cenote — just across the street from our condo — to recover a sonde, a device that records the abiotic (non-biological) characteristics of the water over time. These characteristics include salinity, temperature, conductivity, pH, depth, and dissolved oxygen content. Professor Iliffe and Brett had placed the sonde there four days earlier. This expensive piece of equipment is on loan to their lab from the manufacturers and I was really hoping that it functioned properly so that I, too, could benefit from it. The data collected by the sonde in each of my cave sites will help me later when I look at correlations between environment and differences in foodwebs and abundance.

I joined Brett on this dive out of curiosity and my vested interest in the sonde — I tried not to think about the eight-foot crocodile that inhabits this cenote and the reports of two other crocs recently sighted in the vicinity. So, we jumped into the smelly, algae-filled water, which hid us from the crocodiles … and vice versa. Fortunately, we saw no large reptiles this day.

We swam down to the guideline and squeezed through a muddy crack in the cenote floor. Several feet in, the water became surprisingly clear, revealing a gorgeous, jagged fracture that was six-feet wide and three-stories tall. This fracture descends to a depth of about 220 feet, making it one of the deepest cenotes in the state of Quintana Roo. Upon reaching the sonde, Brett unclipped it from the line to which it was fastened and I offered to hold it as he reeled up the rest of the line. I gripped the expensive device tightly, not wanting to see it fall through some crack in the cave wall. All went smoothly and we ascended to the cave entrance. Mission completed! Hopefully, the data will turn out well and I can trust that the sonde will perform reliably at my sites later in the week.

July 4, 2008: Remipede sighting!
I have just had the best Fourth of July ever thanks to my first remipede sighting at Taj Mahal Cenote! Although I was not planning to collect today, inspired by the diversity of life here, I put an isopod (one of a diverse group of crustaceans that includes the common pillbug) into a plastic tube during our morning dive. Needing more collecting tubes, I made a trip back to the condo before the second dive. After distributing some of the tubes to Brett and two other students, we set off to find the remipede and other crustaceans we had seen earlier.

A beautifully landscaped path leads down to the Taj Mahal Cenote entrance

One of the entry points to Taj Mahal
Julie and Joey surface in one of Taj Mahal's air-filled rooms

Julie and Brett in Taj Mahal
One of the rooms in Taj Mahal is known for its great light shows. When the sun is overhead, beams of light enter through holes in the ceiling

Top left: A beautifully landscaped path leads down to the Taj Mahal Cenote entrance. Bottom left: One of the entry points to Taj Mahal. Top center: Julie and Joey surface in one of Taj Mahal's air-filled rooms. Bottom center: Julie and Brett in Taj Mahal. Notice that their regulators are on long hoses (seven feet long) and wrapped around their necks. Should another diver run out of air, he/she can use this long-hosed regulator. The diver who's sharing will then use a regulator on a shorter hose that is strapped to the base of the neck. Then both divers can swim to safety. Far right: One of the rooms in Taj Mahal is known for its great light shows. When the sun is overhead, beams of light enter through holes in the ceiling.

The mysids (shrimp-like crustaceans) and isopods proved easy to catch, but the quick-swimming shrimp were very elusive. Between the four of us and Professor Iliffe, who was collecting on another dive, we returned to the condo with 12 mysids, four large isopods (plus the one I caught in the morning), one small isopod, and three shrimp. Unfortunately, we did not see another remipede on the dive, but after the students leave, I'll return to Taj Mahal to get sediment and water samples, take measurements with the sonde, and collect more animals … which I hope will include a remipede or two. I was up until after midnight identifying and photographing the specimens and so missed the holiday fireworks, but it was all well worth it. It is quite exciting to have found my first site. My research is finally underway!

July 7, 2008: Turtle sighting
Yesterday, we dove both the Mayan Blue and Naharon Cenotes. Naharon is an interesting cave with walls that are so black they seem to absorb all of your light. Even the use of several high-intensity dive lights fails to clearly reveal a room's dimensions, resulting in quite an unusual diving experience. At the end of my second dive, I found an old pair of Oakley sunglasses at the bottom of the cenote pool. Wanting to do my part to lessen the pollution of these unique environments, I (ahem) took them with me. Finding the sunglasses proved to be a nice bonus, but it was trivial compared to the evening's excitement.

The entrance to Naharon Cenote Dr. Iliffe briefs us before our Naharon dive
Left: The entrance to Naharon Cenote. Right: Dr. Iliffe briefs us before our Naharon dive. These briefs are necessary so that each diver knows the configuration and specific dangers (e.g., water currents) of a cave system. It is also important that each diver knows the route they will follow.
 

Around midnight I noticed a number of people huddled outside our condo on the beach. When I went down to investigate, I found a silent group of turtle conservationists hovering over something. Only after my eyes had adjusted to the dark did I realize that the object of interest was a female turtle digging in the sand. Her shell was at least three feet long and her paddle-like arms were moving around in the sand as she laid her eggs. Every once in a while, the conservationists would bring over red lights (less disruptive than white) to inspect the progress of the nesting. After about 45 minutes, the turtle completed its business and made its way back to the ocean — only then did I have a chance to ask some questions about what I had just seen. The turtle was a Loggerhead and had probably laid about 120 eggs. The conservationists covered up the nest with more sand, surrounded it with coral rubble, and marked it with a sign dating the nesting. Hopefully, in about 60 days, most of the hatchlings will make their way out to the water. Conservation programs like Centro Ecologico Akumal, the Akumal Ecological Center, are helping to replenish the world's dwindling sea turtle populations by protecting beaches used annually by nesting sea turtles. Go to www.ceakumal.org to see what you can do to help. For a small fee, you can even become a Turtle Watch Volunteer.

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Photo of Taj Mahal entrance by Sara Collar; Taj Mahal light show by Brett Gonzalez; Shane, palapa, Taj Mahal path, and Julie and Joey by Ryan Morales; Julie and Brett by Joey Pakes; turtle eggs, hatchling turtle, sea turtle, Brett tackling another diver, dinner, Naharon entrance, and Dr. Iliffe by Aimy Thorsen.