One of our recent interns, Andre Wax, completed and presented a research study on a topic of his choosing! Read about Andre’s work below.
Trapezia Bidentata, also known as the Rusty Guard Crab, are the local species of guard crabs found on Pocillopora corals near Quepos – Manuel Antonio region of the Eastern Tropical Pacific in Costa Rica. They are a species of smaller guard crab, maxing out at around 2.5 cm in length, and provide protection against smaller corallivores. The Pocillopora corals that they inhabit are species of branching corals, which provide shelter for the guard crabs. T. Bidentata will also stimulate the coral to release mucus by massaging the coral with their legs and collect the mucus the coral excretes and will consume this as their food source.
This study aims to discover if there is a relationship between the health of Pocillopora corals in the Quepos – Manuel Antonio area and the number of Trapezia Bidentata crabs found living in the coral. A null and alternative hypothesis were generated, where the null stated that there would be no relationship found while the alternative hypothesis stated that the number of T. Bidentata crabs found on the corals would depend on the health of the coral. If the alternative was true, it could be found that on healthier corals there are more guard crabs. Furthermore, larger corals likely have more crabs due to there being more space available.
Initial findings
The depth, length, number of T. Bidentata present, and coral health were recorded. Coral health was recorded using a scale from zero to four, representing dead and healthy respectively. Initially, depth was compared with the number of crabs and the length of the coral, and no correlation was found (Figure 1.1 and 1.2).
When coral length and number of crabs were compared with each other a strong correlation was found. The trendline generated from this data allowed for the data to be analyzed for the corals that had more crabs than expected (data points above the trendline) and corals that had less crabs than expected (data points below the trendline). Samples that had more crabs than expected had health ratings of 3.5 or 4 most frequently, with a few data points with a health rating of 3 and only one data point that was below a health rating of 3 (see figure 1.3).
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With all of the projects we work hard on throughout the year, we are always looking for help. You can get involved with one of our internship or volunteer programs.
When coral length and number of crabs were compared with each other a strong correlation was found. The trendline generated from this data allowed for the data to be analyzed for the corals that had more crabs than expected (data points above the trendline) and corals that had less crabs than expected (data points below the trendline). Samples that had more crabs than expected had health ratings of 3.5 or 4 most frequently, with a few data points with a health rating of 3 and only one data point that was below a health rating of 3 (see figure 1.3). Corals with less crabs than expected were generally corals that we unhealthy. When the frequency of finding different numbers of crabs on the corals was compared, it was revealed that as the corals get healthier, crabs would be found in higher numbers more often than compared to the corals that are unhealthy, and high numbers of crabs are only found on corals that are the healthiest (see figure 2.1).
Finally, based analysis of the data, the corals were separated into two categories, healthy corals (3-4 health rating), and unhealthy corals (0-2.5). Box and whisker plots were utilized to remove outliers and ensure normal distribution before conducting a two-variable t-test assuming unequal variances (see figure 3.1 and 3.2). This test was selected due to the possibility of unequal standard deviation among data sets and due to the large sample size. Using α = 0.05, the two hypotheses were H0 (T. Bidentata number is different when comparing health of Pocillopora corals): p ≥ 0.05 and HA (T. Bidentata number is different when comparing health of Pocillopora corals): p<0.05. When conducted, a p-value of 4.175*10-8 was obtained. 4.175*10-8 < α = 0.05 so the null hypothesis is rejected.
Analysis of the data reveals that T. Bidentata were found in larger quantities on the healthier corals. The coral length vs. crab number data reveals that very few unhealthy corals can have more crabs than expected, and this is supported by the t-test which resulted in an incredibly low p-value, suggesting a very strong significant difference between the number of T. Bidentata on healthy vs. unhealthy corals.
One possible reason for this could be that unhealthy corals are unable to sustain higher numbers of T. Bidentata. Since dead coral could not be able to produce mucus for the guard crabs to feed on, it would not be possible for guard crabs to survive on the coral.
The feeding strategy of crabs could also better prepare the immune system of the corals for future stressors. When corals release mucus, it is part of their immune response to stressors in their environment.
There are several reasons that this could be occurring. Since guard crabs feed on the mucus from the corals, unhealthy corals would supply guard crabs with less food so a lower number of guard crabs would be found. Another possibility is that a higher number of crabs would allow the coral to be more resistant to stressors in the environment. Corals with higher numbers of crabs would have more crabs to protect against corallivores. This would keep the corals healthier because predator attacks would be less successful in consuming the coral. The feeding strategy of Trapezia crabs could also keep corals healthier. When they feed, they stimulate the immune response of corals causing them to release mucus. Keeping the immune response stimulated could keep the coral more prepared for stressors that would cause this immune response.
Guard crabs such as T. Bidentata can be used in the future as an effective indicator species. Due to the strong relationship the number of guard crabs found on Pocillopora corals can be used to quantify the health of the corals. The benefits that this can provide is another way to determine coral health besides visual examination.
When fragmenting corals, it is important to ensure that guard crabs can remain on the corals. Guard crabs need to be on corals to survive, so if they are removed from corals during the fragmenting process, it is essential to reattach them to a fragment and attempt to keep the crabs on the fragments through the out-planting process. When fragmenting, cutting slowly allows the crabs time to move out of the way of the blade.
Trapezia Bidentata crabs play an important role in the reefs in the Quepos – Manuel Antonio area. With invasive species such as the Crown of Thorns seastar entering Costa Rica, the protection guard crabs provide is going to be essential in ensuring the survival of the reefs. Further research on this subject could include examining the coral health and guard crabs in a controlled setting, examining the size and number of crabs found depending on the shape and structure of corals, and comparing the health of corals and the number of guard crabs in coral nurseries.
Here at Marine Conservation Costa Rica, we have a number of opportunities available for those looking to make a difference to Marine wildlife. Hear about the experiences of two of our previous interns, Andre and Mary-Grace below.
What is the sea life like?
Andre
It’s a lot of fish. The visibility is not that good, so it is hard to see other animals. A lot of damsels farm and eat algae and surgeonfish. Occasionally you’ll see octopus, sharks and turtles but it is much rarer than the other common reef fish.
Mary-Grace
At Quepos it is very interesting. The diving is amazing and there are more surges, which makes it harder to dive. I feel like this makes you a more experienced diver because it is a challenge. In Caño the water is much more still and calm.
How would you describe the variety of sea life? Do they seem healthy and diverse?
Andre
The sea life is very diverse with a lot of different types of fish!
Mary-Grace
The animals here are quite diverse, we have seen a bunch of different fish like the butterfly fish and sergeant majors, sea slugs, and some crabs on the nursery corals.
How would you describe the Coral you see?
Andre
There is not a lot of reef building coral so generally, it’s pretty sparse. We see some of the branching coral and some of the bouldering coral which are big and look like boulders.
Mary-Grace
We have two types of corals: the branching and boulder corals. The branching coral grows like a tree, and the boulder coral grows on the ground.
Do you encounter Coral bleaching more than healthy reefs?
Andre
You definitely see a lot of both. At Caño Island there is definitely a lot of bleached coral but here in Quepos there is less bleached coral. A lot of the coral is fairly young, but you see a fair share of both.
Mary-Grace
Here in Quepos, we have some coral bleaching and coral disease, but we can’t tell which it is without doing research on it. We definitely do see coral bleaching, more at Caño Island than here in Quepos.
As a diver do you practice a marine conservation lifestyle? If so, what does this look like for you?
Andre
Yes, mostly using reusable plastics and bottles. I would also say making conscious choices of where you are throwing things away, so pollutants don’t end up in the ocean.
Mary-Grace
Personally, I try to be conservative about what I use such as avoiding single-use plastics. If I do I try to reuse them as much as possible. I will keep my trash collected until I am near a trash can to avoid it getting to the ocean.
Describe the process of new Coral colonies being planted.
Andre
I haven’t done much with the coral because I am with the marine conservation side but most of the coral are very small.
Mary-Grace
In the restoration program we find coral of opportunity which is coral floating around, and not breaking off coral from a healthy reef. From there we pull it out and fragment it (cut it a little) to help the growth accelerate. We let them grow in the nursery for a few months before planting them back onto the larger coral structure.
Describe the process of new Coral colonies being planted.
Andre
I haven’t done much with the coral because I am with the marine conservation side but most of the coral are very small.
Mary-Grace
In the restoration program we find coral of opportunity which is coral floating around, and not breaking off coral from a healthy reef. From there we pull it out and fragment it (cut it a little) to help the growth accelerate. We let them grow in the nursery for a few months before planting them back onto the larger coral structure.
What inspired you to be a diver?
Andre
I have always really liked the ocean since I was a kid so it is my plan to enter marine biology. Diving is very helpful for researching the ocean and its’ biology and is a big interest of mine.
Mary-Grace
For me, I have wanted to dive since I was young. I did a discovery course and realized I was too scared. With it being on my mind this past year, I finally decided to face my fears and did it. I quickly realized there was nothing to be scared of at all.
What inspired you to take action with Marine conservation?
Andre
I care about conservation in general, but diving is a part of it. Being out in nature and the environment is important because we as humans are a part of nature. It’s important because without it we would die too.
Mary-Grace
When I was little, my sister showed me the movie Blue Ocean and it showed me that our oceans need help with restoration. Corals are extremely important for the health of our oceans and that is why I want to take action and help build a healthy ocean.
Has anything surprised you?
Andre
The visibility was a little surprising at first. I’m always surprised when I see a lot of garbage at the dive sites. A lot of plastics are seen.
Mary-Grace
Yes, when diving in Quepos I was expecting a coral reef with lots of animals and abundant life. Instead, I saw a lot of emptiness which I wasn’t expecting. I was expecting more Great Barrier Reef style but that just isn’t the reality for most coral reefs.
During your time here, what was your most memorable experience?
Andre
Last week we saw a turtle that was swimming around us and as I swam back to my group it started chasing me out of its territory, so that was pretty cool.
Mary-Grace
My most memorable experience was last week when I found my first nudibranch. They’re barely an inch big and very hard to find. I was super excited to find my first one.
Like what you hear and Interested in taking part yourself? Just click the button below to read more about the Internships available to you!
One of our recent interns, Joe came and joined us for a month, assisting with our environmental education program. This is about his experience with us.
In my time working with Marine Conservation Costa Rica (MCCR) I have experienced growth and bonding, and learned exceedingly. Working in the Environmental Education internship, I have helped to organize lessons, learn new teaching skills, and about the importance and intricacies of conservation. Not to mention, I have hugely improved on my Spanish.
I had the unique opportunity to go into a primary school and teach in Spanish about marine conservation. While this sounded daunting to me at first, the experience was invaluable. Teaching gave me confidence and a better understanding of how to help people learn in a productive and educational way. It was great because not only was I teaching others, but I was also learning too. I went from knowing limited Spanish to far more competent very quickly and felt comfortable speaking, answering and understanding Spanish. I was also helped every step of the way by the fantastic team at MCCR who allowed me to feel optimistic in the face of a big task.
First things first…
First, my teaching at the school consisted of prep work. I created a powerpoint in English then in Spanish about my chosen topic for the children. After creating the powerpoint and speaker notes, I went over them a few times with the team to make sure I felt comfortable with the pronunciation and was ready to speak it to the kids. Jointly, I worked to prepare an activity for the children, to create a more fun and interactive setting. Finally, I was ready.
I went in and was greeted by the staff and set up my presentation. Once I was up there, all of my nerves suddenly vanished and my head cleared, I was prepared and excited now. I thoroughly enjoyed doing my presentation and was able to answer and understand the kids’ questions, which was neat. I proceeded smoothly to the activity in which we helped the kids paint their own sharks and then play a game using the sharks they had made.
An enjoyable experience
The children seemed to really enjoy the whole day which made it even more of a fulfilling experience. I also had the fantastic opportunity to help teach about coral conservation and fragmentation to an older group of teenagers at the event. This involved speaking to multiple different groups about the complexities of coral reefs and helping with hands-on activities on fragmenting coral to help replant the reefs. This not only granted further confidence but really helped to teach me about the work people do for conservation, the importance of it and the intricacies of the marine fauna we are trying to protect. On top of all of this, there are other activities all interns and supporters can participate in.
MCCR often organizes group activities that provide unforgettable experiences, such as a trip to the mangroves to see crocodiles. The fantastic team, other interns and general positive and friendly people around it all means super fun group trips to beautiful waterfalls, beaches or other fun activities such as football are a commonplace to why I always felt involved and like my time was being spent well, making the most, of the beautiful country of Costa Rica and Quepos.
Want to get involved ?
With all of the projects we work hard on throughout the year, we are always looking for help. You can get involved with one of our internship or volunteer programs.
We recently joined forces with a awesome bunch of like-minded environmentally conscious folk in Quepos. Together we built this beautiful Sailfish made of reused plastic bottles. The entire construction process took more than 180 hours, so working over 15 days. The sculpture consists of over 3500 bottles, 3000 caps, and is an impressive 13 meter in length and weighs 200 kilos.
All this plastic for the art project was collected from our region around Quepos. Much of it is recyclable plastic…however, did you know that plastic cannot be recycled in Costa Rica? In fact, Costa Rica only has the capacity to recycle glass.
All other collected recyclables like plastic, aluminum and paper, have to be exported for recycling with current figures showing that only 9% of plastic collected for recycling is actually recycled. Much of our recycling ends up in landfills in far corners of the globe or burnt, so releasing toxic gases. This is why recycling is no longer the solution for our plastic world..we find alternatives to plastics.
REDUCE, REUSE and REFUSE!
This beautiful sailfish represents a hope for the future of Quepos. Many hands joined together to make it a reality, working together under the blazing sun and the occasional rain storm. Art projects like this are a way to reuse plastics and raise awareness of the plastic problem. Thank you to the Comite Ambiental de Quepos and to the artist, Alban Corrales for letting us work on this amazing project.
Coral Coral Coral! We have been really busy working in our coral nurseries these last couple of weeks. Kat and our new intern Anni have cleaned and measured all our current coral fragments; we can report some great growth since the last data collection a month ago!
Tool fundraiser update
We are thrilled that our “Tool Fundraiser” has allowed us to purchase a Gryphon AquaSaw! Thank you so much to our generous donors that made this purchase possible! The Aquasaw is a diamond blade bandsaw, and is ideal for precision fragmenting of hard corals. This is going to totally change the way we can process corals to go out to the nurseries.
Tuesday was for fragmenting!
On Tuesday we collected corals from wild donor colonies and brought them back to the Marina for processing. We used the new saw to “micro-fragment” the corals into smaller pieces to grow in the nurseries. The saw makes it much easier to cut the fragments into the perfect size and causes less stress to the corals. The coral fragments were then attached to concrete discs on which they will grow in our ocean nurseries for the next 6 month to a year. Cutting the corals into small fragments stimulates growth, we will also be monitoring and cleaning to give them and even better chance of survival.
Coral planting here we come
On Wednesday, we are excited to announce that we took over 100 fragments of 3 coral species and planted them in our nurseries!! If you would like to help fund our coral reef restoration work, our tool fundraiser is still going! We have several more tools that we need including an underwater drill, that will use for attaching the coral colonies grown in our nurseries back onto our local reef.
November to me, always brings a sense of anticipation. You can feel the summer coming to Costa Rica. In October, businesses take their annual vacation and boats get their bottoms painted November though is the start of the new season. Here at Marine Conservation Costa Rica we are also really excited to get back in the water!
Starting this season, we welcome John Reinbott to our crew. John is a marine biologist and is fresh from a year long internship at the Coral Restoration FoundationTM in Florida. John and I are going to be working closely together on our coral restoration project. This last week we have been looking at the nurseries. We have also been brainstorming lots of ways we can improve on our current methods…and it’s been fun!
Welcome Coral intern – Anna
We also welcome Anna, our new coral intern from Ecuador. She will be helping us with data collection, maintenance and cleaning. Also building new structures and community education. Looks like it’s going to be an amazing season!
If you are interested about what we get up to, you can see on our daily goings on on our Instagram stories @marineconservationcostarica
