Sorry for my absence, I have been away for quite some time with fieldwork, a long trip home to Hawaii, and a recent research cruise. I returned to KAUST in mid-January and had a few weeks to get back into the swing of things and work on some research papers, and then I started with my class for the semester, called Movement Ecology. It is taught by my advisor, Prof Berumen, and it is a very interesting and engaging class. The class is considered a “block course” so we meet every weekday from 9-4 for about a month. This year, the class also included a research cruise in the southern Red Sea.
The port that we departed for was a 5-hour drive south of KAUST (see the map below). Then we visited around three reefs per day for a week. I did quite a bit of diving, helping out on different projects. I wanted to summarize some of these projects and talk a bit about what we did.
The major project was called “Island Bioblitz” which was a multi-methods approach in investigating the biodiversity of fish (including sharks).
1.a. The most obvious way to do this is through visual fish surveys. To do this we lay out three 50m transects and have an observer record abundances of fishes. Lucia swam along the transect line, in one direction she recorded the large fish abundances that swam within 5 m of the transect tape. Once she turned around she recorded all of the small fishes within 2 m of the transect. Along the transect tape, one diver takes photos of the benthos in 1-meter intervals. Eventually, these photos will be analyzed (probably using coral point count) to assess the substrate (coral cover, sand, algae, etc). We also have another diver measuring rugosity. Rugosity helps assess the 3-d structure of the reef, as fish tend to prefer complex reefs as they have more places to hide. Measuring rugosity is pretty straight forward, we use a metal chain that is a known length, and we lay it near the transect and measure where it reaches on the transect. So if it is a sandy patch the chain will lay flat but if there is a lot of large branching coral the chain will measure shorter.
1.b. Another component of the bioblitz was using BRUVS (Baited Remote Underwater Video Systems). You can imagine that sometimes when we are scuba diving looking for fish we are scaring some away, and influencing their natural behaviors. BRUVS are a way to combat this. We set out a standard weight of frozen fish bait attached to a GoPro, which we set out at different depths for 90 minutes. We laid out four shallow BRUVS at 1.5 m depth around the islands, with another four BRUVS in deeper water. This was my task for most of the days, since I had to be on the islands anyway to look for nesting evidence. It was cool because we saw some baby sharks, barracuda, and other cool critters.
1.c. The last component of the island bioblitz was a method known as “eDNA” or environmental DNA. This technique is newish, and consists of taking sediment and water samples and analyzing the DNA. So if a fish or a shark swims by the reef and some of its scales or mucus are released into the water column we are able to identify that they were in the region. So in a simple sample we can get tons of positive hits indicating that this species was detected in the water. Unfortunately, eDNA can’t provide an abundance of an animal, and just say it was there are not. There are of course some limitations, and sometimes you get a false positive or false negative read.
1.d We were also using drone transects to film the island from above. This can help with counting turtle tracks and nests on the island, and we can also spot some larger fishes from above, like sharks, rays, and barracuda.
Due to all of these pros and cons, we used all three methods (fish surveys, BRUVs, drones, and eDNA) to assess the biodiversity on five islands in the southern Red Sea. The combine methods will be the best way to assess the total biodiversity of fishes.
In addition to biodiversity assessments, we also had days where we were diving some reefs and helping out on different projects.
- One project was simply assessing the biodiversity of fish using swimming transects at 30 m, and then they would get shallower until they were at the crest of the reef. I never was on this team because I am not very good and identifying fish.
- The coral team consists of three jobs. One was collecting some species of corals for genetic analysis and trying to find gall crabs (crabs that live within the coral skeleton). Another diver would take a quadrat underwater and take photos of the benthos (bottom of the ocean). And my task was usually to collect rhodoliths, which are crustose red algae that attach to reefs. I collected and photographed these for a research scientist from our lab.
- Another team was collecting feather duster worms, I also did this on my cruises last year. It is hard work to chisel out these worms who burrow very far into reefs. THis is for Shannon Brown’s master’s project looking at population genetics of these worms in the Red Sea and Arabian Gulf. She even thinks she has identified some new worm species which is cool. These seballae worms are very understudied, especially in the Red Sea.
The cruise went very smoothly, and I enjoyed being outside and underwater. I saw a grey reef shark, some turtles, and some beautiful coral reef ecosystems. I even saw a bunch of baby sharks while deploying the small BRUVs on the island. The cruise was only a week so it didn’t seem too long. Although the food wasn’t catered to vegetarians, I still survived and had a great time. My biggest issue was probably the lack of sleep I got, which usually happens when I sleep on boats. We returned from the cruise and had a week of class, and the week finished up with our final presentations (I talked about deep sea hydrothermal vents and larval connectivity) as well as a final exam yesterday. I am now finished with the class and now free to focus on my thesis! Hoping to do some field work within the next year and possibly finish up my PhD next year?
In other news, I was accepted to a conference in Colombia in March, and Germany in July, so if I can get funding I plan on going to both of these! Yay 2020 looks like I will be seeing some new countries!
Thanks for reading!