Influence of industrial light pollution on the sea-finding behaviour of flatback turtle hatchlings

Kamrowski, Ruth L., Limpus, Col, Pendoley, Kellie, and Hamann, Mark (2014) Influence of industrial light pollution on the sea-finding behaviour of flatback turtle hatchlings. Wildlife Research, 41 (5). pp. 421-434.

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Context: Numerous studies show that artificial light disrupts the sea-finding ability of marine turtle hatchlings. Yet very little has been published regarding sea-finding for flatback turtles. Given the current industrialisation of Australia's coastline, and the large potential for disruption posed by industrial light, this study is a timely investigation into sea-finding behaviour of flatback turtle hatchlings.

Aims: We investigate sea-finding by flatback turtle hatchlings in relation to ambient light present in areas of planned or ongoing industrial development, and evaluate the fan and arena-based methods that are frequently used for quantifying hatchling dispersion.

Methods: Using a combination of methods, we assessed the angular range and directional preference of sea-finding hatchlings at two key flatback turtle rookeries, Peak and Curtis Islands, during January–February 2012 and 2013, and at Curtis Island in January 2014. Relative light levels at each site were measured using an Optec SSP-3 stellar photometer, and moon phase, moon stage and cloud cover were also recorded.

Key results: We found no evidence of impaired hatchling orientation, and observed very low levels of light at Peak Island. However, at Curtis Island, hatchlings displayed reduced sea-finding ability, with light horizons from the direction of nearby industry significantly brighter than from other directions. The sea-finding disruption observed at Curtis Island was less pronounced in the presence of moonlight.

Conclusions: The reduced sea-finding ability of Curtis Island hatchlings was likely due to both altered light horizons from nearby industry, as well as beach topography. Both methods of assessing hatchling orientation have benefits and limitations. We suggest that fan-based methods, combined with strategically placed arenas, would provide the best data for accurately assessing hatchling sea-finding.

Implications: Sky glow produced by large-scale industrial development appears detrimental to sea-finding by flatback turtle hatchlings. As development continues around Australia's coastline, we strongly recommend continued monitoring of lighting impacts at adjacent turtle nesting beaches. We also advise rigorous management of industrial lighting, which considers cumulative light levels in regions of multiple light producers, as well as moon phase, moon-stage, cloud cover and time of hatchling emergence. All these factors affect the likelihood of disrupted hatchling sea-finding behaviour at nesting beaches exposed to artificial light-glow, industrial or otherwise.

Item ID: 37694
Item Type: Article (Research - C1)
ISSN: 1448-5494
Keywords: industrial development, marine turtle, Natator depressus, orientation, Port Curtis
Funders: School of Earth and Environmental Sciences, James Cook University, Australian Geographic Society, Wildlife Preservation Society of Queensland, Pendoley Environmental
Date Deposited: 12 Mar 2015 02:48
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050202 Conservation and Biodiversity @ 20%
05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050211 Wildlife and Habitat Management @ 40%
06 BIOLOGICAL SCIENCES > 0602 Ecology > 060201 Behavioural Ecology @ 40%
SEO Codes: 96 ENVIRONMENT > 9607 Environmental Policy, Legislation and Standards > 960701 Coastal and Marine Management Policy @ 50%
96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960808 Marine Flora, Fauna and Biodiversity @ 50%
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