This is a short report on the annual 37th international sea turtle symposium (ISTS) that took place in Las Vegas, USA, 15-20 April 2017. I am writing this on the way back home, while waiting in Las Vegas, Los Angeles and Reykjavik airports.
Every year the ISTS provides an excellent opportunity for all sorts of people to meet up and discuss ongoing issues with regards to local and global aspects of sea turtle research and conservation. I will try here to convey my impressions and pinpoint specific subjects that I found very interesting.
Every year the symposium has a different theme and this year’s theme was climate change. Climate change is a hot topic in sea turtle research (both literally and metaphorically) for many reasons. Temperature has many effects on the different life stages of sea turtles and it is of utmost importance to see how they will react on the global temperature rise (as well as interesting from an academic point of view).
One main issue here is that all species of sea turtles exhibit what is called temperature dependent sex determination. Roughly, (and this roughly is a subject of current research) higher egg incubation temperatures produce female hatchlings and lower produce male ones. However, as James Spotila noted in his speech – also addressed in this paper here and here – the problem with high temperatures is not so much the feminisation of the populations rather than the increased hatchling mortality in the nests. In other worlds, as Spotila said:
“High temperatures: loads of dead female hatchlings”
Marc Girondot, an expert on the mechanisms under which sea turtle sex is determined gave a very interesting talk with title “Thermal reaction norm for sexualisation: the missing link between nest temperature and ratio”. He stressed that under variable incubation temperatures it is not true that the sex is determined in the middle third of the incubation duration (as at least I thought) but the issue is rather more complicated. Moreover, he stated that incubation duration is not indicative of sex ratios. That is, even though someone would think that high incubation durations (which could be resulted by lower temperatures) should produce more males, this is not necessarily true. Moreover, he said that when examining sex ratios in a specific population, one should not rely on important values e.g. pivotal temperatures (temperature that produces 50% males and 50% females) that have been derived in other populations but each population should be examined separately. In any case the subject is more complicated than what one might initially think (at least I am lacking the technical knowledge to fully understand it). Remember though that the more we are learning about a subject the more we realise that we have yet to learn!
But what about turtles that are already live on very hot areas? Nicolas Pilcher, gave a talk about the hawksbills in the Arabian gulf, where air temperatures can reach 50 degrees during the summer. He noted the existence of, maybe unexpected, high proportions of males to females in the population there. He explained that this is due to the fact the hawksbills there nest quite early in the summer season. That is, turtles there have adapted to the warm conditions. In fact colonisation of northern (southern for the south hemisphere) beaches is an adaptation which could help mitigate the effect of climate change. Maybe this has started already: this year there was a loggerhead nest in the south part of France, near Saint-Tropez, the northmost point that has been recorded for the species ever. Sandra Hochscheid also presented some nest time series from Italy that suggests that a colonisation might be happening there as well. Pilcher finally noted in his talk that
“Sea turtles have survived large scale climatic changes over millennia. The question is how fast they are able to do that…”
which is the main message that one should keep in mind here.
There were many presentations regarding the use of drones in sea turtle research and in fact one entire workshop was dedicated to that technology which has been recently introduced to the sea turtle community. Among their main applications are: sea turtle abundance estimates in the sea, behavioural studies, estimates of operational sex ratios during mating season as well as sex ratios in foraging grounds, beach monitoring and constructions of 3D beach maps. The insights that they provide are numerous and no doubt they can be of great use. My feeling is that even though their use might not be groundbreaking (at least not yet), things might change soon, especially if their flight time, currently very restricted, becomes much longer. Regarding, general use of video footage, its usefulness was also highlighted in a talk by Alexandra Gulick, student of Karen Bjorndal, who studied green turtle foraging behaviour using static cameras in the sea floor.
The use of drones and static cameras had also a main role in my presentation about the cleaning stations of Zakynthos island, Greece. The talk was titled “Detection and use of seasonally ephemeral fish-cleaning stations by breeding sea turtles using drones and undewater cameras” and it was a joint work with Gail Schofield, Rebecca Haughey and Kostas Katselidis. It was accompanied by a video presented in the symposium’s video night, which entertained the crowd quite a bit! I am going to come back soon with a blog post exclusively dedicated to that subject.
Another talk that made me think a lot was the one by Ken Lohmann on “Magnetic navigation and geomagnetic imprinting in sea turtles” where some very convincing arguments were given in support of the fact that sea turtles use the earth’s magnetic field to locate their nesting beach. The corresponding paper is available here and further information can be also read in the 3rd volume of The Biology of Sea Turtles. Ken Lohmann is actually also the new president elect of the International Sea Turtle Society and he will be organising the 2019 symposium (I believe somewhere near Florida, USA).
Genetics play now a main role in sea turtle research substituting or accompanying the traditional flipper tagging methods. Researchers are able to assign to every nest the genetic profile of the mother – the corresponding SWOT article. A very nice example is the research that it is being done with hawksbills in Jumby Bay on Long Island, Antigua in the West Indies. This was presented in a form of a poster by Kathryn Levasseur. Through genetic studies, people in that project were able to verify the presence of mother-daughter as well as sibling pairs in the same nesting beach. In combination with saturation tagging they were also able to determine in a very good accuracy the sexual maturation age for this specific population (around 15 years). In fact the same result was also confirmed by another study presented by Jamie Clark et al. using skeletochronology (google that word) another very powerful technique which is able to estimate the age of a turtle using growth layers/rings in their bones.
A very nice message was given by Selina Heppell in a talk titled “Great, we saved them! Now what?”. She stressed that conservation successes should be addressed and celebrated and in many cases we should “switch from an emergency conservation mode to a larger horizon, more holistic picture”. In fact this rhetoric is strongly supported by many scientists. Brendan Goldley gave a similar message in the final part of his plenary talk in the previous ISTS in Lima, Peru, 2015. I will also come back to that in a future blog.
The new SWOT report (the State of the World’s sea Turtles) was also launched during the symposium. If you have never heard of SWOT, you should definitely have a look at the website of this high quality sea turtle magazine, which this year was dedicated to the sea turtles of Africa. This time, three photos of mine, two from Zakynthos and one from Ghana were included in the report. You can also have a look at last year’s report featuring an article of Gail Schofield and mine on how in-water turtle observations generate valuable new insights.
Finally, the usual ISTS festivities were adapted to match the spirit of Las vegas…
…and it was also announced that the next symposium will take place next year in Kobe, Japan:
Many thanks to all people who worked towards the organisation of this very successful symposium! I am also grateful to the International Sea Turtle Society for providing a travel grant which allowed me to take part in it!