Crown-of-Thorns Seastar Surveys Soon to be Underway!

Anjali Arutchelvam • Oct 16, 2019

CCC will be assisting PENRMO in conducting surveys to identify Crown-of-Thorns Seastar outbreak areas!

Acanthaster spp ., more commonly known as the Crown-of-Thorns Seastar (CoTS), is the second largest Echinoderm with a maximum diameter of 50cm. CoTS are renowned for their ability to devastate coral reef ecosystems. However, despite more than 1200 research articles focusing on the Seastar’s biology and ecology, knowledge gaps exist that not only reduce the ability of resources to understand and manage the possible impact from CoTS outbreaks but also inhibit the understanding and quantifying the term “Outbreak”. As such, in recent years, there has been a resurgence of interest in the ecology and biology of CoTS and how this can be translated into practical solutions for resource management.

Acanthaster spp . hold a vast reproductive potential with large females producing up to 65 million eggs per season, of which is particularly relevant to large population fluctuations and possible ecological outbreaks. This fecundity, however, is found to be disproportionate to body size, with individuals less than 30cm producing 0.5 – 2.5 million eggs per year and those with a diameter of 40cm producing more than 46 million eggs per year. Male and female Acanthaster spp. must be within proximity and spawn simultaneously to increase chances of success, further identifying that a distance of 15m would result in a 30-50% chance of successful fertilisation.Post-spawning and successful fertilisation, the larval stage of Acanthaster spp . is typically 11 days but can decrease or increase from 9 to 42 days depending on environmental conditions, predominantly driven by phytoplankton abundance. CoTS juveniles and adults have strong preferences for consuming corals, albeit different types of corals.

CoTS are a highly successful predator of Scleractinian corals, often resulting in the death of an entire colony which can prove to be devastating to reef systems on both short- and long-term timescales. The Indo-Pacific, including Sogod Bay (Southern Leyte, The Philippines) and the Great Barrier Reef (GBR), Australia, are experiencing unprecedented outbreaks from Acanthaster spp . on a wide spatial scale which remains to be a major contributor to the declines observed in Scleractinian coral cover. There are great inconsistencies throughout the literature in defining an “Outbreak”, mainly due to the varying scales and localities where large increases in CoTS populations are recorded, despite the conspicuous differences in densities between ‘Outbreak populations’ and ‘non-Outbreak populations’. There are also great differences in the attempted criteria of an ‘Outbreak’ when considering CoTS population quantitively.

A rapid assessment was initiated in 2019 by the Southern Leyte State University to assess the potential for a CoTS outbreak in Sogod Bay. The aim was to identify and to quantify the extent of a CoTS outbreak in selected municipalities of Sogod Bay. Coral Cay Conservation (CCC) were invited by the honourable Ma’am Eva of the Provincial Environment and Natural Resources Management Office (PENRMO) to assist with this assessment. The aim of the report is to provide data on the densities of CoTS in the municipalities of Liloan and San Francisco, Sogod Bay. We will be surveying the reefs from our base in Napantao, San Francisco up to the town of Liloan. It is suggested, from previous CCC data and anecdotal observations, that CoTS densities in Southern Leyte are naturally (and sustainably) high.


The densities of CoTS were estimated in the municipalities of Liloan and San Francisco in Sogod Bay, Southern Leyte using data collected in 2019. Through anecdotal observations in 2019, it was observed that CoTS are present in large numbers around Sogod Bay, and a rapid snorkel assessment presented observations of more than 1 individual CoTS per hour. Data collected from 2013 to 2019 have demonstrated annual fluctuations with the highest density being in 2018. When recorded at the highest density in 2018, CoTS still remained under the various “Outbreak” criteria proposed from the literature, however, it must be noted that CoTS removal dives were conducted on an ad-hoc basis and therefore could have heavily influenced such abundances. This is supported through rapid visual assessments that have recorded much higher densities and large aggregations throughout the system.


In order to identify, manage and remediate possible CoTS outbreaks, two dives (assessment dive and removal dive) will be carried out. As CoTS present an ecological value in maintaining a healthy reef system through the predation of fast growing Acropora spp . and Montipora spp. , the sole purpose of the assessment dive is to provide clarity on whether the CoTS populations maintain or exceed a natural, sustainable level. The removal dive will only be conducted when an assessment dive has concluded an outbreak of CoTS is occurring on the assessed reef.


An assessment pattern that sees divers/snorkelers swimming across a reef in a straight line parallel to the shore whilst recording the number of CoTS observed will be used during the assessment dives with the intention of increasing efficiency and area covered. The surveys will be conducted at depths 4-10m and varied in straight-line distance which will depend on a number of factors, e.g. current strength, dive time, etc. An approximate width of 10m will be surveyed along these straight-line transects. For the removal dive, the CoTS removal team search in a free movement pattern that enables an efficient and targeted search. Whenever a CoTS is observed, a team of two snorkellers/divers will work together in collecting the individual; one person will remove the CoTS with a pair of tongs, and the other person will open the rice bag for the CoTS to be placed in. Prior to collecting the CoTS, one person will record the size of the individual, found at which depth and associated with which substrate. Any signs of immediate predation will also be noted.


The assessments will be carried out over the next few weeks and a follow up report with results from the assessments will be out following that so keep an eye out for that!


If you would like to get more information, you can check out PENRMO here or you can check out Southern Leyte State University here !

by Harriet Tyley 15 Dec, 2020
We would love to learn some more about you, how you found our Scholarship Programme and how it has helped you achieve your goals in the Philippines since graduating! 1) What year did you join the Scholarship Programme? I joined the Coral Cay team in Napantao, Southern Leyte from August to September 2016. In June 2017, I also came back to Coral Cay to help in survey dives for three weeks. Glad to have been given the chance to stay in the base twice with two different groups! 2) Could you please tell us a bit more about yourself? For example, what are your interests, where abouts in the Philippines are you from? etc. I am Carm, a development professional working in the intersection of environmental conservation and human development. I currently work for the Department of Agriculture, helping run projects that aim to improve protected area management in selected key biodiversity sites, at the same time, improve the socio-economic condition in the nearby coastal communities. Aggregation of whalesharks and manta rays are common in where I am currently based so it is a really exciting place to be! I am a Divemaster candidate looking to go “Pro” and I’m also in graduate school studying marine affairs. I love to cycle, hike, climb, fish, camp, discover new places, volunteer in causes, read non-fiction and watch silly rom-coms in my other time.
by Harriet Tyley 07 Dec, 2020
We would love to learn some more about you, how you found our Scholarship Programme and how it has helped you achieve your goals in the Philippines since graduating! What year did you join the Scholarship Programme? I was a Filipino scholar in August of 2013. Could you please tell us a bit more about yourself? For example, what are your interests, whereabouts in the Philippines are you from? etc. My name is Ara and I was born and raised in Manila. I grew up in a family of entrepreneurs and weekends would be spent in my grandparents house talking about business over lunch. The fast-paced life of the city was all I ever knew. In University, I took up Communication Technology Management and Minored in Marketing because I also wanted to start my own business someday. As I grew older, I had a constant need to get out of Manila and just travel. When I was not working, I would be exploring some remote island in the Philippines or visiting neighboring countries in Asia. In the past 15 years, I have held job titles like photographer, store manager, photo editor, production manager, operations manager, jewelry maker, mug maker, and now a business owner. Despite the frequent changes in job descriptions and careers, being a traveler, and now a scuba diver, are the only things that have remained constant in my life. What was it about Coral Cay Conservation that made you decide to apply for the scholarship programme? I learned about Coral Cay Conservation from one of my best friend and travel buddy, Jem. One day we were discussing where we could go next and she told me that she would not be available on certain dates because she got accepted as a dive scholar in Coral Cay Conservation. She told me that will be gone for a month doing reef surveys in Napantao, Southern Leyte. I had never heard of Coral Cay Conservation nor of a place called Napantao until that moment, so this peaked my interest even more. One month learning about the conservation and diving almost everyday for free? It seemed to good to be true! The more I read about the scholarship programme, the more I wanted to join. I have always wanted to learn scuba diving but kept pushing it down my bucket list. The idea of learning how to scuba dive for free in my own country was really a no-brainer for an ocean-lover like myself. I knew right away I couldn’t pass up on this opportunity.
by Harriet Tyley 01 Dec, 2020
Hi Daff, we would love to learn some more about you, how you found our Scholarship Programme and how it has helped you achieve your goals in the Philippines since graduating! 1) What year did you join the Scholarship Programme? I joined the CCC Scholarship Program in November of 2016. I learned about the program from a few acquaintances. It took me at least a year to finally apply and see where it takes me. During that time, I was working with the Department of Tourism. I had a good number of projects that involved eco-tourism, fisheries management, and marine conservation, which kind of made me decide to try and apply. It only took a couple of months for the head office to get me on board and informed me that I was accepted! It was a long trip to Napantao but I enjoyed it since it was my first time in that part of the country. When I arrived, I was met by Claire (field base manager), and of course, the ever-welcoming Coral and Shrimp! 2) Could you please tell us a bit more about yourself? For example, what are your interests, where in the Philippines are you from? etc. I grew up in a small town in Iloilo. We were living fairly in the middle of farmlands and the sea. As a result, most of the people in my place are either farmers or fishermen. My interest in the environment started way back when I was a kid and eventually became more involved as I got my education. I spent two years in a fisheries school where I studied during the first half of my high school. I eventually got into the outdoor movement, which brought me to mountain and cave explorations. It made me appreciate the world and the things around it more. It also gave me a better perspective on how we can help and do better in protecting the environment. During my professional career, I first got into research where I had the opportunity to work with fishing communities. There, I was able to experience first-hand how our oceans are under threat due to climate change and human activities.
by Harriet Tyley 24 Nov, 2020
We would love to learn some more about you, how you found our Scholarship Programme and how it has helped you achieve your goals in the Philippines since graduating! 1) What year did you join the Scholarship Programme? I joined Coral Cay Conservation’s Scholarship Program this year, 2020, specifically last March. And it’s probably the best thing that’s ever happened to me. I will forever thank myself for applying for it because it was such a beautiful opportunity. 2) Could you please tell us a bit more about yourself? For example, what are your interests, where abouts in the Philippines are you from? etc. Well, my name is Easter and that’s because I was born on Easter Sunday. I live in the small town of Hilongos Leyte, just two or more hours away from Southern Leyte. And just as how every other kid that grew up in a province with the beach just a walk away, I, too, grew up loving it. I remember just being in the water and finding comfort in it. I started taking swimming classes in Cebu City every summer I get the chance too, and I remember feeling so new to the feel of the pool, my swimming cap, and goggles. I never really wore these in the beach, my siblings and I would literally swim with or without goggles with our eyes wide open. I competed twice and didn’t do badly for a beginner. The city has a special spot in my heart because, before coming to Coral Cay, I worked at Turtle’s Nest Book Café & Gallery in Lahug. I worked behind the bar there and made cheap coffee while entertaining locals, regulars, and tourists. I guess I just love amusing people and learning about them. 3) What was it about Coral Cay Conservation that made you decide to apply for the scholarship programme? I found out about Coral Cay Conservation when I googled environmental conservation organizations near me. At the time, I was still in school but had already decided on taking a different path. I’ve always wanted to learn more about conservation, but the expenses in volunteering camps always hindered me until I saw Coral Cay Conservation’s Scholarship Program. I read what it included and what it did not and got excited about learning about corals! I’m not going to lie but during this time I didn’t know corals are animals, so, that got me so hooked and I just started reading about it! And since this was CCC’s specialty, I decided to apply. 4) What was the most exciting part of your scholarship placement? And what were your favourite moments? The most exciting part of the scholarship was scuba diving. I had only ever seen it in movies, the Discovery Channel or on National Geographic. I never thought I would be ever be learning about it and doing scuba diving myself. Also, because it made me see a part of the underwater world that I only ever hear in the news, see in movies, and read in books. And I have so many favorite moments with CCC, a few would be the pointy dives, dinner talks, Sundays when we’re supposed to be dry but we’d still choose to snorkel to see more of what’s under, and, honestly, just the whole of it! I have never been in a place with so much understanding and learning and good food and people! 5) What would you say to people thinking of applying to Coral Cay Conservations scholarship programme? Any words of wisdom or advice!? To anyone who’s planning to apply for Coral Cay Conservation’s Scholarship Program, please do. You’re going to learn a whole lot (more) about the ocean, the reefs, our planet, people and culture from different corners of the world, and butterflyfish! Do it. It’s going to be worth it! 6) Since finishing your scholarship with Coral Cay Conservation, where has life taken you? How have the skills and experience received from the scholarship benefited you since graduating? Given the current situation now, with COVID-19 and the halt to almost everything, I haven’t really done much since graduating. But I now have more confidence about the path I want to take and am in. With this, I revamped the organization—Kuntahay—that I started in September last year. Kuntahay is a Visayan term for “imagine” and with and through it, I want people to see the beauty of both under and above water. It also follows the conscious and careful lifestyle, hoping to encourage more people to be in the fight against climate change and systemic oppression. And the skills and experience that I have acquired in CCC have truly benefited me in some ways. I can now identify fishes, corals, coral bleaching and diseases! And when my friends and I go snorkeling in the neighboring town that has a dying/growing reef in it, I would share with them the exciting parts! But right now, I’m looking forward to enrolling to Marine Biology next school year, and it’s such a relief to be looking forward to something I know I actually want to pursue because I’ve been in and out of school for a while now, due to not having a clear idea of where I really want to go. But ever since my time in CCC, I’ve been introduced to new things and re-introduced to, what I believe I have nearly forgotten about in my years of being in the city, the ocean and its importance.
by Harriet Tyley 03 Nov, 2020
Biodiversity Restoration David Attenborough: A Life On Our Planet, opens our eyes to truths many of us have tried to ignore. Our planet is changing at an accelerated and unprecedented rate, and it is up to us to try and change this uncertain trajectory. Biodiversity loss is considered to be one of the severest threats to our environment, and without action, over half the world’s marine species could be nearing extinction by 2100. The ocean is home to over 90% of the habitable space on our planet, but only about 5% of the worlds ocean and adjacent seas are protected, compared to 12% of the worlds land . 50% of the oxygen on our planet is created in the ocean , by microscopic phytoplankton, which forms the very base of the marine food chain and enables life. The ocean is a critical carbon sink, and the blue carbon locked in our marine habitats may be up to 5 times the amount of carbon stored in tropical forests . And unfortunately, it is thought that between 3 0-35% of global critical marine habitats (seagrass, coral reefs and mangroves) have been destroyed.
by Harriet Tyley 27 Oct, 2020
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