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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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Longcore, T., Duriscoe, D., Aubé, M., Jechow, A., Kyba, C. C. M., & Pendoley, K. L. (2020). Commentary: Brightness of the Night Sky Affects Loggerhead (Caretta caretta) Sea Turtle Hatchling Misorientation but Not Nest Site Selection. Front. Mar. Sci., 7.
Abstract: A Commentary on “Brightness of the Night Sky Affects Loggerhead (Caretta caretta) Sea Turtle Hatchling Misorientation but Not Nest Site Selection” by Stanley, T. R., White, J. M., Teel, S., and Nicholas, M. (2020). Front. Mar. Sci. 7:221. doi: 10.3389/fmars.2020.00221
Keywords: Commentary; light pollution; sea turtles; light measurement; photometry; glare; sky quality meter
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Rivas, M. L., Santidrián Tomillo, P., Diéguez Uribeondo, J., & Marco, A. (2015). Leatherback hatchling sea-finding in response to artificial lighting: Interaction between wavelength and moonlight. J of Experim Marine Biol & Ecol, 463, 143–149.
Abstract: Over the last decades, growing human populations have led to the rising occupation of coastal areas over the globe causing light pollution. For this reason, it is important to assess how this impact threatens endangered wildlife. Leatherback turtles (Dermochelys coriacea) face many threats of anthropogenic origin including light pollution on nesting beaches. However, little is known about the specific effects. In this study we studied the effect of different light wavelengths (orange, red, blue, green, yellow and white lights) on hatchling orientation under the presence and absence of moonlight by analyzing: (i) the mean angle of orientation, (ii) crawling duration, and (iii) track patterns.
Hatchling orientation towards the sea was always better under controlled conditions. In the absence of moonlight, leatherback hatchlings were phototaxically attracted to the experimental focus of light (misoriented) for the colours blue, green, yellow and white lights. Orange and red lights caused a lower misorientation than other colors, and orange lights produced the lowest disrupted orientation (disorientation). On nights when moonlight was present, hatchlings were misorientated under blue and white artificial lights. Crawling duration was low for misoriented hatchlings and high for the disoriented individuals. Our conclusion to this is that hatchlings can detect and be impacted by a wide range of the light spectrum and we recommend avoiding the presence of artificial lights on nesting beaches. Additionally, actions to control and mitigate artificial lighting are especially important during dark nights when moonlight is absent. |
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Stanley, T. R., White, J. M., Teel, S., & Nicholas, M. (2020). Brightness of the Night Sky Affects Loggerhead (Caretta caretta) Sea Turtle Hatchling Misorientation but Not Nest Site Selection. Front. Mar. Sci., 7.
Abstract: Sea turtles in the Gulf of Mexico, which are listed as either threatened or endangered under the US Endangered Species Act, face numerous threats but are particularly susceptible to the negative effects of light pollution on nesting beaches. Light pollution affects the distribution, density, and placement of nests on beaches, and disrupts seafinding in hatchlings emerging from nests; often leading to their death. Rapid urban growth near Gulf Islands National Seashore (GUIS), FL, United States, over the last century has contributed to increased light pollution on its beaches. There is concern that light pollution is causing females to build nests in at-risk locations subject to erosion and flooding, and is causing the observed high rates of hatchling misorientation. From 2015 to 2016, we measured brightness of the night sky, horizon profile, and lunar variables at GUIS at loggerhead (Caretta caretta) nests to assess the effects of brightness on building of at-risk nests and hatchling misorientation. In addition, we quantified the effects of relocating at-risk nests on nest success. We found that contrast in brightness between the landward and seaward directions at GUIS was partially responsible for high rates of hatchling misorientation, and there was a strong moderating influence of lunar fraction and lunar altitude on hatchling misorientation: larger lunar fractions and lower lunar altitudes reduced misorientation. We did not find an effect of artificial light, horizon profile, or lunar fraction on the propensity of loggerheads to build nests in at-risk locations, and found no evidence that relocating nests at GUIS reduced loggerhead nest success. In fact, we found that nest success was improved and hatchling misorientation rates were reduced for relocated loggerhead nests.
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