International Sea Turtle Symposium 2024

Pattaya, Thailand, 24 – 29 March 2023

Session: Nesting Biology (Ecology, Behaviour, and Reproductive Success)

ASSESSING THE IMPACT OF CLIMATE CHANGE ON GREEN TURTLE HATCHLINGS AT TURTLE ISLANDS PARK, MALAYSIA: A MORPHOMETRIC, HATCHING SUCCESS AND SEX RATIO ANALYSIS

Giorgia Colombo¹ and Juanita Joseph¹

¹Borneo Marine Research Institute, Universiti Malaysia Sabah, Jalan UMS, 88400 Kota Kinabalu, Sabah, Malaysia

Email: GIORGIA_COLOMBO_MY22@iluv.ums.edu.my

Global warming as a consequence of climate change, affects various characteristics of sea turtle hatchlings. In this study, we analyze how temperature influences sex ratio, hatching success, incubation period, and size of green sea turtle hatchlings (Chelonia mydas) from nests incubated at Turtle Islands Park (TIP), Sabah, Malaysia. Additionally, we predicted the sex ratio of green sea turtle hatchlings in 2050 and 2100, considering both conservative (Ssp2-4.5) and extreme (Ssp5-8.5) climate change scenarios in TIP's hatcheries. All sea turtle nests at TIP are relocated to hatcheries on the island, which include shaded and unshaded hatcheries. Data were collected from 69 nests in unshaded hatchery and 44 nests in shaded hatchery between August 2023 and January 2024, comprising 71 nests during the dry season and 42 nests during the wet season. To determine whether significant differences exist, Student's t-test was used with p-value=0.05. Results indicate that the mean hatching success is similar between hatcheries (57%, p>0.05) but it is slightly higher during wet season (60%) compared to dry season (52%). Hatchlings incubated under shading conditions exhibit larger body sizes, but no significant differences are recorded in hatchling sizes between seasons. The incubation period is significantly longer during the wet season (58 ± 2.36 days) compared to the dry season (53 ± 2.79 days) for nests incubated in unshaded conditions. Furthermore, sand temperature was collected using temperature data loggers placed in both hatcheries (from December 2019 to August 2023) at a depth of 70cm within the sand, to which 0.5°C was added to replicate metabolic heating and thus nest temperature. The obtained nest temperature was fitted into the Hill equation thermal reaction norm for sex ratio, best suited for this population with parameters obtained from embryogrowth, a package in R. Results showed that the mean percentage of females produced at TIP hatcheries during the dry season in shaded and unshaded hatcheries was 44.3% and 91.3%, respectively, while during the wet season, it was 41.6% and 68.5%, respectively. Statistical projections obtained using KNMI Climate Explorer of air temperature and subsequently nest temperature via linear regression show that by 2050, the percentage of females will be 96.8% and 98.7% according to scenarios Ssp2-4.5 and Ssp5-8.5, respectively. By 2100, it will be 99.3% and 100%, respectively. Furthermore, the nest temperatures throughout all months of the year 2100, according to the most extreme scenario, exceed the upper threshold limit for hatching success (35°C). Our results revealed a higher percentage of females being produced in the TIP hatcheries. Further investigation into the structure and design of hatcheries is recommended, particularly due to the anticipated increase in female hatchlings resulting from rising temperatures.

Sea turtles exhibit environmental sex determination and face concerns of over-feminization and increased heat-induced embryonic failure and hatchling mortality due to rising global temperatures. Mitigating the impact of climate change may necessitate interventions to reduce sand temperature. One proposed strategy is irrigation with seawater, but uncertainties persist regarding turtle egg tolerance to saline nest sand. To test the hypothesis that sea turtle embryos can tolerate a regimen of irrigation with seawater at a management-relevant scale, I investigated the impact of two levels of large-scale irrigation with cooled seawater on green turtle nests and embryos, assessing the effects on important nest environmental factors and developmental success. Irrigation reduced the temperature in clutches by up to 5.6 °C (1.34 ± 0.10 °C, mean ± SD) at the high level of irrigation without adversely affecting clutch oxygen levels, sand water (matric) potential, or sand moisture content. While hatching success of irrigated clutches was notably low (1.5%) compared with unirrigated clutches (82%), late-stage embryonic mortality predominated, suggesting an unexpected tolerance of early embryos to saline sand and increasing our understanding of sea turtle resilience to irrigation with seawater. The observation that younger clutches may be less susceptible to seawater-associated mortality than mature clutches near hatching further informs the limitations and potential applications of irrigation with seawater as a management strategy.

The beach in Panadura provides nesting habitat mainly for Lepidochelys olivacea (Olive Ridley). In addition, Chelonia mydas (Green turtles) and the Dermochelys coriacea (Leatherback turtles) have been recorded previously. Panadura is a coastal town located in the Kalutara District of the Western Province, Sri Lanka. The nesting season in Panadura beach begins in late November and continues until the end of April every year. Local poachers used to harvest turtle eggs if they are not relocated in a safe place. The Coast Guard officers has been recruited as lifesaving guards who involved in collecting turtle eggs and incubating them. The project intends to evaluate the efficacy of exsitu conservation of turtles in recently created hatchery enclosure at Panadura beach.

The square-shaped hatchery enclosure encircled by a wire mesh made to protect the incubating nests and hatchlings from predators like stray dogs and land monitors was used as the sampling site. The potential issues impacted to turtle nesting in the beach were identified. The eggs laid by Lepidochelys olivacea were recorded monthly basis. The beach is patrolled at night by volunteers, TCP employees, and Coast Guard officials, to gather eggs and to keep for incubation. Consequently, all resulting hatchlings were released to the sea and counted the hatchlings.

During the 2022 nesting season, all together 5638 eggs of Lepidochelys olivacea have been collected and incubated. Out of the 5638 eggs, 4366 eggs were successfully hatched giving a 77.4% of hatching success. The highest average number of eggs (326/day) recorded in month of March while the lowest average number of eggs (125/day) recorded in January. Average number of eggs laid was 115/turtle. Vehicle use on the beach has the potential to harm emerging hatchlings, and light can disorient the hatchlings and disturb the nesting turtles. As a public beach, a lot of residents spent there for leisure time day and night with at beach. The beach features a kids' park, and the municipality allows individuals to rent it out for various events. Littering on the beach by visitors is also a considerable environmental issue. Noises of all these activities can potentially disturb the arriving of nesting females.

In contrary cleaning events conduct by TCP at regular basis at the beach is supportive for the turtle nesting habitat improvement and the established education center is well functioning to inform visitors about the value of protecting sea turtles and their ecosystems.

Regardless of the disturbance, the beach stretch is a highly promising site for turtle nesting, particularly for the Lepidochelys olivacea species. Eliminating obstacles will undoubtedly increase the number of species and turtle nesting sites in beach area.

It recommended to implement a beach usage policy based on the findings, for the implementation by the Panadura Urban Council regards to protect the nesting beach. Findings of the study will be helpful for further strengthen the ex-situ sea turtle conservation.

One of the most pressing environmental concerns of our era is the decline in biodiversity, and the preservation of biodiversity has emerged as a major global issue. New methods are now accessible to complement, or even substitute, conventional monitoring techniques. Citizen science approaches are poised to bolster biodiversity monitoring initiatives, conserving both human and natural resources. Marine turtles are endangered globally, and their survival depends on national conservation efforts, scientific research, and community involvement. To support conservation efforts, most Mediterranean countries have established monitoring and conservation programs aimed at identifying areas of concentration, nesting, and feeding grounds, as well as the causes of mortality.

Between August 2020 and August 2023, two citizen science tools were used to collect data on sea turtles stranded on Tunisian coasts: "e-Turtle," an Android mobile application downloaded by 5,000 users and developed as part of the Life MedTurtles project, and "TunSea," a Facebook group with 53,000 members founded by young researchers to facilitate communication between the public and the scientific community, organizations, fishermen, and individuals involved with sea turtles.

The two methods intersect in the types of data required from the user, including the date and the location of the stranding, the measurements, the physical condition of stranded turtles and the likely causes of stranding.

The total number of turtles stranded on the Tunisian coast, collected by the two approaches, was 1302 (1265 Caretta caretta, 12 Dermochelys coriacea, 8 Chelonia mydas and 17 unknown species). Out of this total, 60% were collected via the "e-turtle" mobile application, while the remaining 40% were collected through the "TunSea" Facebook group.

We were able to estimate the spatio-temporal distribution of stranding events using the data acquired using these methods which enables us to examine the potential reasons of stranding in relation with the fishing activity along the Tunisian coast, which appear to be the primary cause of this phenomena.

The utilization of both citizen science tools during the same time frame converges and does not contradict one another in collecting data on sea turtle strandings. However, the disparity and variety of data acquired are influenced by the choices made by citizens who opt for either of these two approaches.

Key words: Citizen Sciences, Life Medturtles, Marine turtles, Stranding, Facebook, TunSea, e-turtles, Mobile App,

Programmes such as school lectures on a particular subject or area to increase students’ knowledge, so that they know what are sea turtles and how to identify them. These programmes provide structured lessons, identifying and refreshing the knowledge and can greatly improve student knowledge on sea turtles. Schools are the ideal places to initiate significant change in the society. This study aims to show the effectiveness of school awareness programmes among students. The main objective of the school lectures is to inspire the younger generation to protect sea turtles from extinction in the future by creating a passion for sea turtles on them. The lecture of the sea turtles includes Introducing species, their behavior and habitats, their ecological importance, threats and their conservation and management. Ten selected schools were evaluated from both provinces and the series of awareness programmes started in March 2023. The evaluated schools are from North Western Province and Western Province in Sri Lanka. Five schools were evaluated from each province. The evaluation process was done by administering pre and post-questionnaires. The questionnaire includes ten questions of basic knowledge of sea turtles and both have same questions. Both male and female students from the age of 9 to 12 participated in this. Here, ten students who participated in the lecture were selected and before the lecture, they were given a pre-questionnaire to be completed in ten minutes and the post-questionnaire also to be completed by the same students in ten minutes after the lecture. Accordingly, the effectiveness of the programme was evaluated before and after the lecture. The effectiveness was estimated by the difference between post and pre questionnaires.The mean values of estimated effectiveness data were calculated for the each province. The mean value of the North Western Province is 40.8% while it was 51.6% for the Western Province. The null hypothesis is there is no significance difference between in programmes of two provinces. The P value is 0.002 (Two sample T test: p < 0.05). According to the results, the effectiveness values between North Western Province and the Western Province are significantly different. This could be due to facts that variations of the distance of the capital city which belongs to the Western province, proximity to the beach, the age difference among students, the lack of interest in the topic and the method of delivering the lecture. To get the optimal knowledge gain, the delivering method can be changed provincially. Hence, the proximity to the beach could be taken as a factor to the tailor the content of the future programme. In addition, the assessment tests can be done after 6 months to check long-term knowledge retention. However, it is concluded that school awareness campaigns are an appropriate way to develop awareness about sea turtles among school students and inspire them to protect them.