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Day 13: MPAs and coral health

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Today, we ran another experiment. We wanted to identify and analyze the impacts of Marine Protected Areas (MPAs) on coral health. In MPAs, human activity is limited. This should theoretically lead to healthier and more stable coral populations. Glover’s Reef is one of seven MPAs in Belize, and we wanted to see whether that intention was actually working. In order to do this, we went to four locations—two in the MPA and two in unprotected areas—and looked at the coral there, analyzing the biodiversity and algae coverage. Each snorkel team looked at three sites per location. We took pictures of the coral with square quadrats to have evenly sized regions with which we could do our calculations. In total, each group would analyze 12 photos, and then we would come together and draw broader conclusions.

We set out later in morning. The snorkeling was fun and it didn’t take that long to lay down the quadrats—we were only at each location for maybe 20 minutes. I’m getting very used to the reefs—I feel like I know exactly what I’ll find beneath the surface. One exciting surprise was that we saw a dolphin near one of our locations in the MPA. It was tough to make out because it was far off, but what a cool experience. We got back around lunch and took a break to change and eat.

After lunch, we analyzed our data. Although we had limited sites, there seemed to be higher biodiversity on average in the MPA. Algae coverage is another metric of reef health, as fish populations will keep algae from smothering the reef. We were not in full agreement about whether there was more in the non-MPA sites, so we decided that aspect was inconclusive. Still, it did look like the MPA corals were healthier overall. We presented the poster—which is our fourth!—and then had some free time.

After dinner, we closed out the day with taxon & topic presentations. I had my last one today, on cryptobenthic fish. I think it went well! I’m glad that I’ve gotten to see some, and I feel like my classmates were interested in it as well.

Working on the poster
Snorkeling outside the MPA
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Day 11: Parrotfish Diet Exploration

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Today we did our first experiment out on the reef. After breakfast, we got together and designed the experiment. First, we formulated our question by brainstorming the things we had been curious about from our previous day out on the reef. We settled on parrotfish partially because we had been seeing a lot of them and partially because they seem particularly interesting. We decided to do fish follow surveys in which we pick an individual and observe them for a period of time, recording what they do in that interval. We were looking at their eating habits in particular, which are a bit hard to pin down. We ended up deciding to watch the fish for a total of 45 minutes, following individuals for five minutes at a time. Our first location in the morning was the patch reef and sea grass beds just off the docks, and in the afternoon we looked at patch reefs further out.

With our experimental designed, we had to pick our subjects to narrow down our focus. We opted to look at four species in particular and divided them up among the different groups. My group was looking at their redtail parrotfish, which we understood predominantly ate sea grass. We set out, staked out the sea grass beds by the dock, and started our time. We had trouble finding parrotfish close to the dock, so we kept swimming further out. As we got further from the dock (and closer to the reef), we started seeing more parrotfish, but not the ones we were looking for. We primarily saw striped parrotfish

In order to have replicates, in the afternoon, we went on the boat to a new patch reef. As an aside, we learned today that Glover’s has over 900 patch reefs, so I ill be saying ‘we visited a new patch reef’ quite a lot. We visited two patch reefs and they both seemed even more vibrant than the reef by the dock at Glover’s. We saw plenty more striped parrotfish in decently sized schools and were also able to see some of the redtail parrotfish as well. They seemed more concentrated on the margin of the reef, but they definitely were eating the sea grass. We also saw a fair number predatory fish, including a handful of barracudas. I think we started to see more species once we figured out not to swim so aggressively and instead to sort fo drift. We weren’t seeing the redtail parrotfish before because they were so skittish, but once we started drifting we saw all kinds of fish. I was also fairly impressed by the massive conchs.

In the evening, we were treated to presentations by representatives from the Wildlife Conservation Society, the Belizean fisheries service, and the coast guard, all of which operate out of this island. We learned about what each group does on the island and how the protected area is maintained. It was a nice compliment to the similar presentation we had at Las Cuevas. That might be one of the most valuable aspects of this trip, to me—learning all about how research stations operate and what researchers do there.

Overall, a hugely successful day! We’ll start tomorrow with data analysis and poster making from our fish follow surveys, and then move on to more activities. Apparently we’re not doing as much snorkeling tomorrow, but I’m excited to see what activities are in store on land.

Parrotfish swimming along coral and sea grass
Initial-stage parrotfish! Can you spot them?
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Day 4: Pitfall traps and cecropia trees

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Today was our second full day at Las Cuevas and we set up two more experiments. In the morning, we were testing nutrient limitations in the different layers of the forest. Nitrogen is the primary limiting nutrient that we wanted to focus on. In order to see just how limiting it was in the forest floor and the canopy, we set up multiple pitfall traps, evenly spaced along a trail. Some of these traps had a source of nitrogen in them (coming from the most readily-available source we had, urine) and some just had water. In theory, the traps with the nitrogen source should attract more insects, and the ones in the region which is more nitrogen limited—the canopy—should have a bigger difference between the water traps and the traps with nitrogen. The traps were a bit tough to set up, because we had to wire them to the trunks and dig them into holes at the vase, but we ended up managing to set them all up with a bit of group coordination and ingenuity. 

I set up the pitfall traps on a tree.
Setting up pitfall traps

That wasn’t our only experiment of the day. In the afternoon, we were looking into mutualistic relationships between ants and Trumpet trees, AKA cecropia trees. The ant colonies live inside the trunks and protect the trees from other insects and animals which might graze on them. We wanted to see if young specimens, without any colonies to protect them, had other defenses. In order to do this, we planned to capture some herbivorous insects — grasshoppers and katydids— and keep them in a container with cecropia leaves to see if there was a difference in how much they chose (or were able) to eat. These trees live along disturbed areas, so we ventured out along the road leading to Las Cuevas. It wasn’t long before we encountered a small mature tree, and we chopped it down to access the leaves, which are concentrated near the top, and to inspect the ant colonies inside. The ant colonies were so interesting—they live in these flat layered chambers and feed on nutrients that the plant supplies. When we opened up the tree, the ants were swarming all over, and it took a little while for them to calm down. There was also a tarantula den in the base of the tree. Amazing how one tree can host so much life.

It took us significantly longer to find a young tree. We walked pretty far along the main road, until we realized that, because it was maintained, young cecropia trees might have been removed. We walked back to the unmaintained San Pastor road, which we had walked along yesterday, and almost immediately found a young cecropia. We noticed a hole in it, but no ants came out when we disturbed it. We cut it at the hole and realized that there was an ant queen inside with larvae but no workers yet. we had caught it just in time! No colony had established itself yet. We got back just before dinner and set up the mini habitats. Tomorrow we’ll inspect them to see how much of the leaves the insects ate and perform some simple data analysis. I can’t wait!

A tree cut open to reveal chambers in the trunk swarming with ants.
The more mature cecropia, with an ant colony inside.
A small cecropia tree cut open to reveal a lone ant.
The young cecropia with an ant queen inside.

 

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Day 3: Watching the forest

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Today we set up our first field experiment of the trip. We were presented with motion-activated camera traps and challenged to come up with a research question we wanted to investigate over the next five days. These camera traps would take photos whenever they detected movement, allowing us to look at animals when there aren’t any humans around. With these cameras, we were challenged to design a simple pilot study that we could carry out. We decided to look into the differences in biodiversity between areas with manmade trails and areas that hadn’t been disturbed. We had 14 camera traps, so we determined 7 different locations along trails and roads of different widths, and then decided to associate each trail camera with one deeper into the underbrush. By 9:45, we had designed our experiment and were ready to head out into the forest around Las Cuevas.

In the morning, we set up six of the cameras. It was a bit slow-going at first as we perfected the method, but by the end of the morning we were experts. We each took turns setting them up—I went third. It took some bushwhacking to set up the traps in the undisturbed areas, but that allowed us to see some impressive wildlife and trees. One of the earliest things we saw was a big cat scratch on the trail. Hopefully, with cameras nearby, we’ll be able to see some actual big cats by the end of the week. I also saw some massive leaves among the leaf litter, which I think belong to the Bigleaf Grape. We also saw the large, spiny outer shell of a seed pod of a palm tree as well as a bird of paradise plant.

Students head into a dense thicket in a single-file line.

Bushwhacking to place off-trail camera traps
A camera trap on a tree
A fully set up camera trap

After lunch, we did a different loop and placed the eight remaining cameras, including on the road leading to the research station. We were much more exposed in the afternoon, and as it grew hotter and hotter, I started to notice that my sweaty hands were partially erasing and smudging my field notebook. It’s a bit annoying, but now that I know about it I can mitigate the issue. It was also the first full day of field work, which was punishing but manageable. I’m staying hydrated and getting rest when I can and I think I’m managing it just fine.

The day isn’t quite over yet—this evening, I’m giving my topic lecture. I get to share what I learned about the biological history of the region. I got a preview of it today, when we saw trees adapted to fending off giant ground sloths, which are extinct now. I think it’ll go well. I’m interested to see what our cameras will pick up—I’ll be sure to update when we collect them again at the end of the week.

Protrusions with small thorns spaced out on the trunk of a tree.
These unusual thorns would have protected the tree from the now-extinct giant ground sloth.