The 2015 season continued to drive the NHRCP as an institute of research as well as conservation. During the season, eight manuscripts in particular were completed that are highlighted below. The research topics range from new discoveries in feeding of corals, to assessment of health and threats to the coral reefs of Koh Tao, and even an analysis of isotope prevalence that provided some very interesting results. Below you can see a summary of those papers, and also click on the links for more information or to download the PDF of the paper.
1) An update to the list of coral reef fishes from Koh Tao, Gulf of Thailand, Scaps and Scott 2014
After spending a long time in the works, an updated inventory of fish species for Koh Tao was published in the journal Checklist a couple of months before the start of the 2015 season. This inventory identified 223 species of coral reef fishes belonging to 53 families for the island, including 21 species that were new records for the island and a further seven species that were novel records for the Gulf of Thailand region. The species found in this paper highlights the rich biodiversity and ecological importance of Koh Tao, and adds further importance in the need to conserve the habitat that supports such a breadth of life.
2) Resilience-based assessment for targeting coral reef management strategies in Koh Tao, Thailand. Cabral 2014
In late 2014, one of our long term interns for the 2014 season, Madalena Cabral, finished her Masters thesis for the University of Lisbon. Her paper looked at the resilience level of fourteen coral reef sites on Koh Tao, to a range of ecological disturbances. Her findings suggested that the majority of reefs on the island had a resilience level of ‘medium’ to ‘high’ based on an adapted protocol on resilience by the International Union for the Conservation of Nature (IUCN). However, disturbances due to development and nutrient input were highlighted, and conservation focus on these areas recommended.
3) Spawning Observation of Acanthaster planci in the Gulf of Thailand. Scott, Mehrotra and Urgell 2014
Just before the New Year, the team published the record of its novel observation for Koh Tao in the journal Marine Biodiversity. In September 2014, during a Crown of Thorns survey, the team witnessed a mass, multi species spawning event that included sea cucumbers and sea stars, in particular, the Crown of Thorns (Acanthaster planci). This voracious coral predator has been found to cause sporadic outbreaks on Koh Tao, and on coral reefs around the world. This is the first record of spawning of the species on the island and the Gulf of Thailand, and adds to a very limited global dataset on such events.
4) Tracing Anthropogenic Nutrient Inputs Using δ15N Levels in Algae Tissue Koh Tao, Thailand. Romeo 2015
Lawrence Romeo completed his Master’s thesis for the Scripps Institution of Oceanography with the program earlier in 2015. His incredibly interesting investigation looked at the use of macro-algal tissue as an indicator for source of nutrient input at two sites on Koh Tao. By measuring the abundance and ratio of two isotopes of nitrogen in the algal tissue, he was able to deduce that the dominant source of nutrients being used by the algae was terrestrial in origin, more specifically from under-treated sewage material. Nutrient inputs in coral reef ecosystems are a key factor in the prevalence of competing fouling organisms, with wide variety of potential sources. This study provided the incredibly valuable insight and hard evidence for one of the leading threats to coral reef ecosystems on the island.
5) Predation on a sacoglossan gastropod by a mushroom coral. Mehrotra et al. 2015
During an EMP transect at the start of the season, an observation of a sea slug being ingested by a mushroom coral was made. This observation proved to be novel due to rarity of interaction by both predator and prey, and was published in the journal Coral Reefs in March 2015. Sacoglossan sea slugs have a limited selection of predators making this abundant coral a significant potential predator. Additionally, Mushroom corals have thus far only been known to feed on zooplankton, and recently found to feed on salps and jellyfish, making sea slugs the first non-planktonic prey species to be recorded for mushroom corals on reefs worldwide.
6) A large gape facilitates predation on salps by Heteropsammia corals. Mehrotra, Scott, and Hoeksema 2015
In mid-2015, the team published records of another novel coral feeding observation, in the journal Marine Biodiversity. This time, the small solitary corals of the genus Heteropsammia were observed consuming salps, gelatinous planktonic individuals, and chains, significantly larger than the coral itself. These corals are commonly found in the ‘muck’ habitat in a number of locations around Koh Tao. This finding contributed to the growing understanding of prey plasticity displayed by solitary corals and the importance of having a mouth large enough to ingest such organisms.
7) Direct impacts of diving on Koh Tao. Treffers 2015
After a successful internship at the program, Sjors Treffers completed his project investigating influences and impacts of dive related tourism on the health of coral reefs around the island. His study involved the use of questionnaires to diveschools around the island and additional observational monitoring techniques to assess the impacts. The study concluded that dive pressure was largely linked the dive management and the ratio of divers to dive leaders. Additionally the study isolated forms of contact and direct pressure from divers on the reefs. The study was part of his degree at the Van Hall Institute in Leeuwarden, Netherlands.
8) The dietary preferences, depth range and size of the Crown of Thorns Starfish (Acanthaster spp.) on the coral reefs of Koh Tao, Thailand. Haines 2015
Another key intern project completed this year was the investigation into dietary preferences and distribution (among other things) of the Crown of Thorns (COTs) sea star on Koh Tao, by Leon Haines. The study analyzed the past and novel data of COTs observations via transects and roving surveys around the island, and crucially, what the dominant prey species of coral are. The data suggested that the preferred prey species were those in the genera Fungia, Pavona and Porites, and that over three quarters of all observations of the sea star observed feeding with only 22% of observations showing a non-feeding sea star. The study was part of his degree at the Van Hall Institute in Leeuwarden, Netherlands.