Coastal light pollution in Australia: insights and implications for marine turtle conservation

Kamrowski, Ruth Lisa Elaine (2014) Coastal light pollution in Australia: insights and implications for marine turtle conservation. PhD thesis, James Cook University.

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Increases in artificial light which occur as coastlines are developed pose a significant threat to marine turtles at the nesting beach because of the importance of light for their natural orientation. Globally significant numbers of marine turtles nest on Australian beaches; however the human population of Australia is also heavily concentrated along the coast, and coastal regions are undergoing rapid urbanisation and industrialisation. As a result, the mitigation of disruption caused by increasing levels of light pollution has become an important component of marine turtle conservation strategies within Australia.

The formulation of effective light mitigation strategies is hampered by several important knowledge gaps: 1) We lack understanding of the potential light pollution impact on marine turtles at ecologically-relevant scales. This knowledge is important for management prioritisation, but also to assess species' and population resilience in the face of coastal change. 2) We have little knowledge of the orientation behaviour of endemic flatback turtle hatchlings, which are being increasingly exposed to large scale development. This information is necessary to prevent management measures being based on behavioural knowledge extrapolated from different species and populations with possible behavioural differences. 3) Little attention has been paid to the human dimension of managing light close to nesting beaches. Effective lighting management will require widespread stakeholder support and participation; however, gaining support for lighting management initiatives is difficult because light at night is an integral aspect of modern society. My thesis addresses these knowledge gaps and aims to provide a scientific basis to inform and guide more effective marine turtle conservation strategies related to mitigation of light pollution. Given the disparate nature of the knowledge gaps, to meet this aim necessitated an interdisciplinary approach.

I began by overlaying nesting data onto remotely-sensed nighttime lights data. First, I assessed the proportion of marine turtles potentially exposed to light pollution, and identified the Australian nesting areas which have the highest exposure (Chapter 2). I found that all species of marine turtle reliably nesting in Australia were exposed to light pollution, demonstrating the management value of this thesis. Management units (MU) of turtles which nest at higher latitudes in Western Australia and Queensland were found to be the most vulnerable to light pollution. The risk to turtles from light generated by industrial developments, and to a lesser extent large urban areas, was also identified as significant.

Second, I used linear mixed model analysis to examine broad scale trends in light exposure at nesting areas between 1993 and 2010 (Chapter 3). All five species had at least one MU with a significant increase in light exposure, and east Australian flatback turtles experienced the fastest increase. MUs identified as the most light-exposed in Australia in Chapter 2 did not change, indicating those turtles have been potentially exposed to high light levels for at least two decades. Finer scale analysis indicated that significant light increases predominantly occurred for nesting areas located close to heavily industrialised coastal areas.

The detrimental impact of industrial light for Australian marine turtles was confirmed with a subsequent examination of flatback hatchling sea-finding ability at two nesting beaches located in regions of proposed or ongoing industrial development (Chapter 4). I assessed sea-finding using a combination and comparison of commonly-used methods for measuring hatchling orientation, and I recorded relative light levels at each site using a stellar photometer. Flatback hatchlings at a nesting beach with highly modified light horizons showed markedly reduced seafinding ability compared to hatchlings in a region which is currently dark but earmarked for future development. My comparison and evaluation of methods suggested that explicitly described fan-based methods, in addition to strategically-placed arenas, would provide the best data for accurately assessing hatchling sea-finding ability in future studies.

These chapters demonstrate that management effort in Australia should be prioritised to focus on mitigation of lighting in existing or proposed developments occurring close to marine turtle nesting areas at high latitudes along both the east and west coasts. The broad scale methods I developed in the former analyses, and the evaluation of methods I conducted in the latter, will also collectively benefit managers of marine turtles impacted by artificial lighting in other parts of the world.

My remaining data chapters (5, 6 and 7) examined the human dimension of effective lighting management in the nesting regions I had identified as vulnerable to light pollution. I first examined resident engagement with light reduction in a Queensland coastal community exposed to four years of light reduction campaigning (Chapter 5). Semi-structured questionnaires guided by an existing theoretical constraints framework determined that despite high levels of cognitive and affective engagement (knowledge and concern), community behavioural engagement (action) with light reduction was limited. I went on to explore specific community beliefs regarding light reduction for turtle conservation, using persuasive communication techniques based on the Theory of Planned Behaviour (Chapter 6). Despite limited behavioural engagement, I found residents had moderate-strong intentions to reduce light. Personal norms (morals) were a strong predictor of behavioural intention, and I found significant differences in the strength of salient beliefs held by campaign compliers and non-compliers. I therefore suggest that the strongest persuasion potential for future communications, as a means of increasing community behavioural engagement with light reduction, may result from targeting specific identified salient beliefs, in combination with an appeal to personal norms.

Next, I focused on industrial lighting in Western Australia. I conducted a qualitative, exploratory case study to examine the lighting management of a large industrial development located adjacent to flatback turtle nesting beaches (Chapter 7). Semi-structured interviews and annual reports were used to evaluate the ‗success' of the lighting management. No conclusive lighting impacts on turtles had been found to date, and relevant stakeholder judgements of the lighting management were either positive or neutral. Overall I judged the lighting management to be successful, and thus recommend that current and future industrial developments emulate the lighting management in this example to minimise disruptive impacts. Based on emergent themes in the data, I went on to develop a conceptual framework to understand drivers behind the successful light management. The importance of effective and comprehensive regulation was highlighted; however this was determined to be dependent upon the existence of adequate scientific knowledge. Effective future management of light pollution impacts will therefore require increased management and regulatory focus on lighting impacts for marine turtles and other species.

Overall, my interdisciplinary thesis demonstrates the value of combining and synthesising several research methods for informing management of a complex environmental issue. Effective management of light pollution for marine turtles requires an understanding of how and where marine turtles are impacted, using ecological, biological, spatial and temporal information. Yet factors influencing human behaviour and motivations are extremely complex, and the methods required to effectively manage light-use in one instance may not achieve the same outcomes elsewhere. My findings have been incorporated into Government documents and should help direct future management of marine turtles in Australia by highlighting the areas where turtles face the greatest potential exposure to artificial light, whilst also providing managers with a better understanding of potential methods for tackling relevant human behaviour to reduce impacts.

Item ID: 40148
Item Type: Thesis (PhD)
Keywords: artificial light; Australia; behavior; behaviour biodiversity; coastal development; community engagement; conservation planning; conservation; constraints; environment; GIS analysis; habitat management; hatchlings; industrial development; light pollution; light; marine biodiversity; marine turtles; Natator depressus; nesting; orientation; persuasive communication; population resilience; population; Port Curtis; public engagement; sea turtles; temporal change; theory of planned behavior; vulnerability assessment
Related URLs:
Additional Information:

For this thesis, Ruth Kamrowski received the Dean's Award for Excellence 2015.

Publications arising from this thesis are available from the Related URLs field. The publications are:

Chapter 2: Kamrowski, Ruth L., Limpus, Col, Moloney, James, and Hamann, Mark (2012) Coastal light pollution and marine turtles: assessing the magnitude of the problem. Endangered Species Research, 19 (1). pp. 85-98.

Chapter 3: Kamrowski, Ruth L., Limpus, Colin, Jones, Rhondda, Anderson, Sharolyn, and Hamann, Mark (2014) Temporal changes in artificial light exposure of marine turtle nesting areas. Global Change Biology, 20. pp. 2437-2449.

Chapter 4: 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.

Chapter 5: Kamrowski, Ruth L., Sutton, Stephen G., Tobin, Renae C., and Hamann, Mark (2014) Balancing artificial light at night with turtle conservation? Coastal community engagement with light-glow reduction. Environmental Conservation, 42 (2). pp. 171-181.

Chapter 6: Kamrowski, Ruth L., Sutton, Stephen G., Tobin, Renae C., and Hamann, Mark (2014) Potential applicability of persuasive communication to light-glow reduction efforts: a case study of marine turtle conservation. Environmental Management, 54 (3). pp. 583-595.

Other publications:

Limpus, Col, and Kamrowski, Ruth L. (2013) Ocean-finding in marine turtles: the importance of low horizon elevation as an orientation cue. Behaviour, 150 (8). pp. 863-893.

Date Deposited: 20 Aug 2015 03:49
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050211 Wildlife and Habitat Management @ 40%
05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050202 Conservation and Biodiversity @ 40%
17 PSYCHOLOGY AND COGNITIVE SCIENCES > 1799 Other Psychology and Cognitive Sciences > 179999 Psychology and Cognitive Sciences not elsewhere classified @ 20%
SEO Codes: 96 ENVIRONMENT > 9607 Environmental Policy, Legislation and Standards > 960702 Consumption Patterns, Population Issues and the Environment @ 33%
96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960808 Marine Flora, Fauna and Biodiversity @ 33%
97 EXPANDING KNOWLEDGE > 970105 Expanding Knowledge in the Environmental Sciences @ 34%
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