Two weeks after crisscrossing the Dominican Republic from one compass extreme to another, the Baseline Caribbean team delivered their collection of reef fossils and modern reef sediments — all 800kg of it — to Santo Domingo’s Las Américas International Airport for shipping to Panama.

In all, the expedition logged about 1,500km on the road, three full field days exploring fossil reefs, 14 dives on modern reefs, two birthdays (Aaron had his b-day, too) — and only a couple of upset tummies from the mystery meat dishes and/or the choppy seas.

The 18 crates of samples include 65 large bulk bags and 130 small ones. “There are a lot of steps you have to go through to get them shipped,” said Erin. “Filling out papers with customs, checking the permits, waiting around, sending the samples through customs where some get randomly opened, and then packing them up nicely.”

If all goes as planned, the samples should arrive for analysis at the lab of STRI staff scientists Aaron O’Dea in the next few days. Then the “real” work begins — finding and identifying all the corals, dermal denticles and other traces of past and modern Caribbean reef in those bulk bags will take many months. But let’s not remind the team of that until everyone gets a much deserved rest after two nonstop weeks on the road!

 

After three days of sampling in Samaná Bay, it’s time to pack up and head back to Santo Domingo with another 90 sediment samples. It was neat to see the differences between the fossil reefs of the Enriquillo Valley and their modern counterparts in Samaná, a bay with a similar form and comparable sheltered fringing reef environment.

While one of our study sites was home to a large thicket of living staghorn coral (Acropora cervicornis), most of the reefs we visited were devoid of this IUCN critically endangered species. All that remained were eroded fragments of their branches covered in algae and encrusting organisms. Instead, algae, sponges, the occasional coral head, soft coral, or gorgonian (sea fan) populated the sandy bottom. Starfish and urchins patrolled the substrate, but we saw few fish.

In contrast, fish were much more abundant at the reef with healthy staghorn coral. We spotted small parrotfish, wrasses, surgeonfish, lizardfish, and territorial damselfish tending their algal gardens amongst the branches of the staghorn coral. We even saw an octopus crawling along a crevice between coral heads. In this shallow habitat, we collected sediment between the living staghorn colonies or in areas containing its rubble. While we encountered large waves and wind during our visit, the bay is normally more quiet. As such, we found the sediment to be fine and silty — exactly what we were looking for.

Deeper on the reefs, the corals were more densely distributed than I had originally expected them to be. As on the fossil reefs, we collected sediment samples between the thickets of coral heads, including brain coral (Diploria), star coral (Orbicella), lettuce coral (Agaricia), and starlet coral (Siderastrea). We even observed some of the same coral species that we had identified a week earlier on the fossil reefs.

While our qualitative observations suggest differences between the mid-Holocene and modern reef communities, the next step is processing the sediment we collected to characterize the microfossils left behind by the inhabitants of these reefs — both common and cryptic. Now we just need to get the samples back to Panama!

—Erin Dillon

 

If one photo could sum up the strangeness of the Enriquillo basin it would be this one of a cow walking through a desert being flooded by the hypersaline lake 42m below modern day sea level.

Erin Dillon gives an introduction to Samana Bay on a very choppy sea before diving down into the thickets of staghorn coral (Acropora cervicornis) with algal-gardening threespot damselfish, as we search for the modern counterparts to our fossil samples…

We reached Samana, in the very northeast of the island of Hispañola. This natural bay was a 17th century pirate hangout. We are here because the site is very similar in geography to how the Enriquillo bay would have looked 7,000 years ago — open to the ocean to the east, very sheltered, flanked on either side by mountains, with high run-off and sedimentation. It is critical we make our fossil and modern samples as comparable as possible in order to measure changes over time. We are therefore sampling the sediments in the reef crests and the fore-reef of fringing reefs around the Bay — just as we did in the Enriquillo basin. We were very surprised to see healthy-looking staghorn coral (Acropora cervicornis) in this region. Four years ago it did not look like this.

How much work do you cram into a two-week expedition? As much as possible. But there’s always time to celebrate something important, even on the highway. Happy birthday, Erin Dillon!

STRI pre-doctoral fellow Erin Dillon talks about the start of the sampling day at Punta Cana and how she hopes to discover shark dermal denticles in the reef sediments.

This region is massively developed tourist destination with its own private airport. Few sharks are officially reported on the reefs here but fisherman claim to catch hammerheads. If there are many hammerheads that are avoiding surveys the sediments in the reef should preserve their denticles…

Photos to follow soon

Erin Dillon and Mauro Lepore take bulk samples from two degraded reefs at La Caleta in Dominican Republic. These samples will be used as a direct comparison with the Holocene fossil samples to determine how much coral, fish and sponge communities have changed in 7000 years.