Tag Archives: quadrat

Quadrats, not quadrants!

Day 1 of Beach Days, 5/23.

My day began in the savanna cabanas of the tropical education center and it is about to end in a hammock on the Middle Caye of Glover’s Atoll. The view has changed drastically. Compared to the 100 meter visibility in the savanna, my view here at Glover’s is only cut short by the horizons. In this grand view, I see faraway lightning that may be associated with a brewing tropical storm. But because it is likely more than hundreds of miles away, I cannot hear the thunder.

This is our first day at the beach and it has mostly felt like vacation. We travelled to a marina in Belize City to catch a 3-hour boatride to Glover’s. On the way we saw the difference between deep and shallow water, and a myriad of other islands in the area. One constant object I observed was the availability of Sargassum on the ocean surface, some of which were cut up by the motors on our boat. Before I knew exactly what I was looking at, Scott and Jessica yelled out to me asking me to identify the green floating algae. With the amount of intensity and excitement they yelled at me, I understood it must have been something obvious: they are the Sargassum seaweed that has been infesting many coral reef areas, outcompeting many other species of corals and causing their decline. They are a group of brown algae that utilizes fouaxin to photosynthesize which gives them a slightly redder and browner color, although they also have the green pigments that come with chlorophyll. They are also the only species of red and brown algae that has air bladders, allowing them to trap air within the organism.

After arrival, we practiced snorkelling, a follow up to to first practice we had on campus in the recreational pools. This time we were surrounded by bone fish, nurse sharks, stingrays, corals, and jellyfish. The most difficult aspect of this practice was not touching things we should’t touch: corals, stingray and wildlife in general. Compared to the rainforest, where we were able to put our hands on almost anything that we were able to catch, the corals here are very fragile and many animals here are hidden and able to be aroused if touched, such as stingrays. With the construction of marine-use guadrats, we will be exploring and initiating contact with corals and perhaps a Echinoderm or two. The key is to not destroy the wildlife and no let the wildlife destroy us.

Stay tuned to find out how to best place quadrats on corals!



In Which Things Go As Planned

  Our first boat day was today! We measured live coral cover compared to macro algae and recently dead coral. We also collected sea urchins for 25 minutes and then measured them.

We actually did two boat trips today. One was to the south of the island in the marine protected area and the other was slightly further away in the same direction outside of the protected zone. We collected the same data at each site and we will compare it later when we analyze.

Pencil Urchin
Pencil Urchin

I saw a huge wall of queen conch at our second site, but all of them were dead. Apparently the huge eagle rays eat them. I also saw flamingo tongues on gorgonians. It’s satisfying when things behave like they’re supposed to.

After we got back from the boat trip I became the first 319 student to actually take a kayak out. I went down into the mangroves and explored a little with Ella and Stephanie. We saw the skeleton of a pelican hanging in a tree, an osprey, some crabs on logs, and a beautiful sunset.

Pelican skeleton
Pelican skeleton


After dinner we had free time, and we hung a light off the dock to see if we could attract anything to it. Mostly we got a bunch of tiny fish and some crustaceans (maybe shrimp?). People switched from looking at the light underwater to looking at the stars and some point. They were beautiful.

Day 11: Counting corals and urchins

The projects of the day consisted of comparing live stony coral cover and numbers of urchins between the Marine Protected Area (MPA) and a zone outside of the MPA at Glovers Reef. To measure coral cover, we laid down 7 transects that were each 100 ft long. Every 25 ft along the transect we measured two quadrats that were 2 ft by 2 ft. Each quadrat is fitted with twine to make 81 squares, or 64 intersection points. We looked at what was underneath each intersection and classified it as live stony coral, recently dead stony coral, macroalgae, other living organisms, or other dead/abiotic objects. Tomorrow we will analyze the data that we gathered, but we predicted that there would be a higher percent of live coral cover inside the MPA.

To count urchins, we timed how many urchins 18 people could collect in 25 minutes. Tomorrow we will compile all of the data and determine which urchin species were most common and quantify the difference between the MPA and the area outside the MPA.

Collected urchins (Photo credit: Scott)
Collected urchins (Photo credit: Scott)

We didn’t have very much time to explore the reef, but during data collection I was able to observe several species of parrotfish, including what I believe was a stoplight parrotfish. I also noted a large number of flamingo tongue snails, which are an interesting species of mollusk that is mostly an off-white shade with yellow spots that have a black outline. The snails are mostly found on sea fans.

As for green algae, I saw pinecone algae in the MPA. The pinecone algae are concentrated in sandy areas where they are able to attach their holdfast to the sand. The pinecone algae were smaller than I was expecting and were narrower, so they could be a slightly different species than I researched. There was also calcareous green algae that was growing on dead coral both in the MPA and outside of it. While the algae consisted of multiple species, I believe that most of them were species of Halimeda. Most of the green algae that I saw today was covered in sediment so it was difficult to identify the exact species.

Day 10: Quadrats and Transects

We started off this morning with a refreshing snorkel session at 8:30am. This time we brought out more gear, specifically a clipboard with waterproof paper to take notes of what we saw. There was a general feeling among all of us that the waterproof paper had to be some sort of black magic, but it worked so we stopped questioning it. Holding the clipboard and trying to take photos and write notes while avoiding being pushed into the coral by the currents took a long time to get used to, and I definitely haven’t mastered it.

Gathering data in sea grass beds

To make everything more confusing, we added more gear after lunch. We performed a short experiment to practice using transect tapes and quadrats. The question that we were trying to answer was whether Halimeda or Penicillus species had a higher abundance and density in the sea grass off of the pier at Middle Caye. We worked in 6 groups to run transects across the beds of sea grass and counted the number of individuals of each species in quadrats along the transects.

In the end, we found 153 Halimeda individuals and only 1 Penicillus individual in the 216 square feet that we measured. We noticed that even slight differences in the composition of the sea grass bed, such as the density or length of the grass, changed the likelihood of algae being found in the plot. To quantify these differences we would have to run another experiment that focused on the different zones in the sea grass bed. Our experiment was limited because of the small area that we covered and difficulty that we had counting the individuals. Even though we were in water that was 8 feet deep at most, it might have been easier to run the experiment using SCUBA so we wouldn’t have to keep surfacing, which made counting confusing when we had to see under blades of grass.

Halimeda and Penicillus are interesting green algae because they are calcareous. Halimeda incorporates calcium carbonate into its thallus in flat chips, whereas Penicillus has calcium carbonate in the brush-like filaments at the top of the algae. The different forms of calcium carbonate lead to different types of sand. Halimeda creates large, flat grains of sand. The sand from Penicillus is finer and muddier.

Day 10

Today was our first complete day on the reef. I can’t really put into words how lovely it is here. Sure I have sand on just about every surface of my body, but I am thoroughly enjoying my time here. The day was centered on two tools: the transect and quadrat.

First, we tried to quantify the percent cover of crab holes on the paths around the station (using the quadrats/transect on land). Honestly, my group did not get that much data (only one half of a square was covered over our entire transect).

This was then scaled up for our afternoon activity, transects searching for two geneses of green algae (Halimeda and Penicillus). We were trying to answer a similar question to the percent crab hole cover. We wanted to know if Halimeda or Penicillus would be more abundant in the sea grass bed.

Again, my groups struggled to find anything on our transect, with it being placed in some of the thickest grass. Either way, our data showed a significantly higher amount of Halimeda over Penicillus.

On the reef I continued to see Gorgonian sea fans, as well as whips and rods. I think that the future challenge that I will face is distinguishing between soft corals that are branching, yellow/brown, with them all being of similar morphology. Tomorrow on the more distant reef, I hope to see more.