This morning we spent an hour on the back reef on the northeast side of Middle Caye. We had visited the area on May 28th, but this time we went to collect all of the biodiversity of the zone that we could. Most of what we were able to collect was algae because it is usually stationary and safe to touch. We also collected some mollusks and crustaceans. A lot of the hermit crabs that we found in the water were occupying old conch shells, which shows how large they were. It was interesting to compare how the live conchs and hermit crabs in conch shells looked when they were retracted. Our jellyfish expert, Sam, found dead box jellyfish floating near the shoreline and collected them even though their tentacles are very dangerous to touch.
We collected a lot of the species of algae that I had already seen last time we visited the back reef, but it was good to consolidate the data. Overall we collected samples of Halimeda incrassata, H. opuntia, Dictyosphaeria cavernosa, Penicillus capitatus, Rhipocephalus phoenix, Udotea conglutinata, U. flabellum, Caulerpa cuppressoides, C. racemosa, and possibly Chaetomorpha linum. It was difficult to tell the difference between the Penicillus species because some seemed to have a slightly flat top or a slightly bigger top than the descriptions of P. capitatus that I was able to find in the literature. I am not sure that the filamentous algae that we collected were C. linum. They seemed similar to the description, but I couldn’t completely rule out other species.
In the afternoon we dissected lionfish to record their dimensions and what they were eating. We had caught 4 lionfish, and the individual that my group dissected had puncture wounds in its face from the spear. The most difficult part of the dissection was attempting to sex the fish. Ultimately my group was not able to determine where the gonads were, so we couldn’t tell whether it was a female or a male. We opened up the lionfish’s stomach and found a much smaller fish that was barely digested. The lionfish was 19cm from mouth to the tip of the tail, and the ingested fish was 2cm long. Lionfish stomachs can expand to 30 times their empty size, which made the stomach of our individual comparatively empty.
By this time tomorrow we will all be back in the United States. Tomorrow promises to be a crazy day, and I’m looking forward to end the trip with the same spirit that we have had throughout our time here.
The project of the morning consisted of quantifying the marine debris that was washed up on the windward side of Middle Caye. At four sites we measured the amount of trash that the 14 of us could collect in 15 minutes. By weight, 50% of the debris that we gathered was plastic and another 21% was Styrofoam. 14% was rope and 15% was glass, rubber, or other materials. Overall we collected 41.22 kg of debris in one hour, which is especially significant because the shore gets cleaned every week. The amount of debris that we collected on a small portion of this small island far away from the shore was staggering.
In the afternoon we ventured through a stand of mangroves to the leeward side of the island to the back reef. We were there to collect data on coral colonies that the EBIO 319 students measured last year, but we were also able to explore the area. The large quantity of sand on the back reef made it a good place to find green algae. Most of the Caulerpa that I saw were either Caulerpa cupressoides (cactus tree algae) or C. urvilleana. The Caulerpa were often found near Penicillus capitatus and Udotea flabellum. I also saw a few examples of Dictyosphaeria cavernosa (green bubble algae) on corals and in sea grass.
While we were collecting debris I noticed a fair amount of filamentous algae on the rocks along the shore. I’m not sure whether they were from the Cladophoraceae or Derbesiaceae family. Some of them might have been Rhizoclonium riparium.
I forgot to mention yesterday that I found Caulerpa racemosa (green grape algae) on the windward back reef that we visited. The algae were in very shallow water right behind the reef crest. I also have seen examples of Acetabularia calyculus (mermaid’s wine glass) in the shallow water off of the dock.
To start off this morning we ventured outside of the atoll’s lagoon to the fore reef. The fore reef is the outer edge of the reef and has the highest diversity of any reef zone. However, the fore reef also has the highest wave energy and is much deeper than the lagoon or back reef. The boat ride to the drop zones was pretty choppy, which was a bit of a challenge for some people, but most people were able to enjoy the reef once they got off the boat, and we didn’t have any vomiting.
I found it harder to see details on the fore reef because it was deeper and I couldn’t dive far enough down, but I was still able to see interesting aspects of the fore reef. There were bigger fish than in the lagoon, and I believe that the diversity of fish species may have been greater as well. The coral on the fore reef was also amazing because it had more space to grow, so the colonies were much larger. We even saw some Acropora palmata colonies, which is a species of coral that used to be a dominant reef builder but recently saw enough colony death to make it endangered. I also enjoyed seeing Acropora cervicornis because it has distinct white tips with an apical polyp that is much larger than the rest of the coral’s polyps. I learned about A. cervicornis in a class that I took last semester, so it was cool to be able to see it in person.
While we were on the fore reef we also saw a huge ray swimming across a sandy area and a nurse shark that followed our group for a while as we snorkeled alongside the reef crest.
In the afternoon we were able to go out on the back reef by Middle Caye. The water was around three feet deep, making it difficult to navigate, but we were able to get closer to the sea floor than we had been able to before. This was especially beneficial for viewing green algae, as they flourish in areas with high sun and sand. I saw a number of species of Udotea, Caulerpa, and Penicillus all in close proximity. These three species were all found on the sea floor in sandy areas or on dead corals that had accumulated a large amount of sediments. Some species of Halimeda were also found in sandy areas on the sea floor, but some were growing in crevices found on corals. The Halimeda on the floor were taller and had smaller segments, whereas the species on corals were more clumped and had larger segments
The back reef had the first lionfish that we were able to spear. While on Middle Caye, we aren’t permitted to eat any fish that we catch other than lionfish, because they are invasive. Tomorrow we will be taking measurements of the four lionfish that we caught and then we’ve been promised lionfish ceviche, which sounds delicious!