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Abd Mutalib, A. H., Fadzly, N., Ahmad, A., & Nasir, N. (2014). Understanding nesting ecology and behaviour of green marine turtles at Setiu, Terengganu, Malaysia. Mar Ecol, 36(4), 1003–1012.
Abstract: In this paper, we emphasize the importance of understanding the nesting ecology and nesting behaviour of green marine turtles (Chelonia mydas). Data were collected from 2007 until 2012 from nesting beaches at Setiu Terengganu, Malaysia. We focused on one of the beaches, Telaga Papan, based on data collected in 2012. We recorded the distribution of nesting areas, the emergence hour and the correlation between successful nesting attempts and false crawls. Telaga Papan had a significantly higher distribution of green marine turtle nesting compared with the other five beaches (ANOVA, F5,42 = 8.874, P < 0.01, mean = 36.750 ± 3.727). The highest number of successful nesting attempts was recorded in 2012 (mean = 28.714). A majority of the species landed between 22:00 and 23:59 h (25%). There was a strong correlation between successful nesting attempts and false crawls (rs = 0.883, P = 0.02). Based on these findings on the nesting ecology and nesting behaviour of green marine turtles, we suggest that scientific research, strict monitoring, awareness programs and policy implementation should be carried out proactively. Such activities are necessary to reduce the anthropogenic pressures at the nesting beaches as well as to ensure more successful nesting attempts of green marine turtles in Setiu.
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Constant, N. (2015). Geospatial assessment of artificial lighting impacts on sea turtles in Tortuguero, Costa Rica. Master's thesis, Duke University, Durham, NC.
Abstract: Between June and August 2014, I conducted walking surveys to map the nesting beach
and light sources using a Trimble Juno SB GPS unit, and I developed a GIS database that formed the basis for subsequent analyses and data visualization. I built STC’s monitoring data from 2004 through 2014 into a polygon layer of the beach subdivided into mile sections defined by mile markers erected by STC. During the new moon in June and July 2014, I conducted brightness surveys in concert with STC’s light surveys and measured brightness in units of luminance at 50-meter intervals along the beach using a Unihedron Sky Quality Meter. Using spatial data of the beach and light sources, luminance data from brightness assessments, and monitoring data from STC, I determined a mean luminance value for each mile section, examined the relationship between luminance and nesting activity, and mapped light pollution on the beach. I found that mean luminance and the total number of green turtle emergences per mile section were significantly negatively correlated. Mean luminance exceeded the minimum threshold for light pollution in 6 of the 43 mile sections, and there were significantly fewer emergences in mile sections experiencing light pollution. Mean luminance was highest in mile sections adjacent to Tortuguero Village, where sources of artificial light were concentrated. These findings were consistent with STC’s light survey data, and mean light count and the total number of green turtle emergences per mile section from 2004 to 2014 were also significantly negatively correlated. Cumulatively, these results suggest that artificial lighting from adjacent development impacts green turtle utilization of nesting habitat and changes the spatial distribution of green turtle nesting activity on Tortuguero Beach. These results were consistent with the findings of previous studies conducted on sea turtle nesting beaches and support the need for a turtle-friendly lighting initiative in Tortuguero. Keywords: Animals; sea turtles; light pollution; GIS; Tortuguero; Costa Rica
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Fritsches, K. A. (2012). Australian Loggerhead sea turtle hatchlings do not avoid yellow. Marine and Freshwater Behaviour and Physiology, 45(2), 79–89.
Abstract: When emerging from the nest, sea turtle hatchlings primarily orient using visual stimuli, with light pollution known to disrupt effective sea localization behavior. Previous studies have shown that sea turtle hatchlings respond differently to different wavelengths of light but Loggerhead hatchlings, exclusively among species tested, have a strong aversion to yellow light (at 600 nm). This study repeats these experiments with an Australian population of Loggerhead hatchlings (Caretta caretta) and Flatback hatchlings (Natator depressus). The orientation preference was measured using a modified y-maze set-up with the animals response observed using an infrared camera. This study showed that both Loggerhead and Flatback hatchlings can see and are attracted to light in the ultraviolet waveband (365 nm) and, to a lesser extent to longer wavelengths of 600 nm and above. The surprising finding was that the Loggerhead hatchlings tested here, unlike their conspecifics in Florida, do not show any avoidance to yellow but are attracted to bright lights of wavelength between 365 nm (UV) and 600 nm. This suggests potential differences in the visual behavior among different populations of sea turtles of the same species. No difference was detected in the response of Loggerhead hatchlings to flickering or steady light stimuli.
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Kamrowski, R., Limpus, C., Moloney, J., & Hamann, M. (2012). Coastal light pollution and marine turtles: assessing the magnitude of the problem. Endang. Species. Res., 19(1), 85–98.
Abstract: Globally significant numbers of marine turtles nest on Australian beaches; however, the human population of Australia is also heavily concentrated around coastal areas. Coastal development brings with it increases in artificial light. Since turtles are vulnerable to disorientation from artificial light adjacent to nesting areas, the mitigation of disruption caused by light pollution has become an important component of marine turtle conservation strategies in Australia. However, marine turtles are faced with a multitude of anthropogenic threats and managers need to prioritise impacts to ensure limited conservation resources can result in adequate protection of turtles. Knowledge of the extent to which nesting areas may be vulnerable to light pollution is essential to guide management strategies. We use geographical information system analysis to over-lay turtle nesting data onto night-time lights data produced by the NOAA National Geophysical Data Center, to assess the proportion of marine turtles in Australia potentially at risk from light pollution. We also identify the Australian nesting sites which may face the greatest threat from artificial light. Our assessment indicates that the majority of nesting turtles appear to be at low risk, but population management units in Western Australia and Queensland are vulnerable to light pollution. The risk to turtles from light generated by industrial developments appears significantly higher than at any other location. Consequently, managers of turtle management units in regions of proposed or on-going industrial development should anticipate potentially disrupted turtle behaviour due to light pollution. Our methodology will be useful to managers of turtles elsewhere.
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Kamrowski, R. L., Limpus, C., Jones, R., Anderson, S., & Hamann, M. (2013). Temporal changes in artificial light exposure of marine turtle nesting areas. Glob Chang Biol, 20(8), 2437–2449.
Abstract: Artificial light at night poses a significant threat to multiple taxa across the globe. In coastal regions, artificial lighting close to marine turtle nesting beaches is disruptive to their breeding success. Prioritizing effective management of light pollution requires an understanding of how the light exposure of nesting areas changes over time in response to changing temporal and spatial distributions of coastal development. We analyzed multitemporal, satellite night-light data, in combination with linear mixed model analysis, to determine broadscale changes in artificial light exposure at Australian marine turtle nesting areas between 1993 and 2010. We found seven marine turtle management units (MU), from five species, have experienced significant increases in light exposure over time, with flatback turtles nesting in east Australia experiencing the fastest increases. The remaining 12 MUs showed no significant change in light exposure. Unchanging MUs included those previously identified as having high exposure to light pollution (located in western Australia and southern Queensland), indicating that turtles in these areas have been potentially exposed to high light levels since at least the early nineties. At a finer geographic scale (within-MU), nine MUs contained nesting areas with significant increases in light exposure. These nesting areas predominantly occurred close to heavily industrialized coastal areas, thus emphasizing the importance of rigorous light management in industry. Within all MUs, nesting areas existed where light levels were extremely low and/or had not significantly increased since 1993. With continued coastal development, nesting females may shift to these darker/unchanging 'buffer' areas in the future. This is valuable information that informs our understanding of the capacity and resilience of marine turtles faced with coastal development: an understanding that is essential for effective marine turtle conservation.
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