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    Sea Turtles, Artificial Light at Night and What the Public Thinks

    March 2, 2024

    Artificial light at night—ALAN is its acronym—is something every beach community deals with. About a dozen North Carolina university students attending the Coastal Studies Institute on Roanoke Island just published a paper on the subject, and their findings were interesting.

    Every fall semester, the Coastal Studies Institute (CSI) hosts about a dozen students for an intensive study of a particular topic. The students look at environmental and social science aspects of their project, and the dual scrutiny of the topic can be very telling.

    At the end of the semester, the students present their findings to the public and publish a paper on their project.

    This past semester, the students looked at the effect of ALAN on sea turtle nesting on the northern Outer Banks. The study area was from Oregon Inlet to the North Carolina/Virginia state line at Carova.

    The study was somewhat inconclusive when it came to the effects of ALAN on nesting behavior in the study area. There were a number of reasons for that.

    Certainly the length of their study, approximately three months, was limited in time and scope. It is also known that the Outer Banks is at the northern end of where sea turtles nest, so the numbers they were dealing with were relatively small.

    There was some evidence that sea turtle activity has been increasing over a nine-year comparison time frame—2014-2022. That’s all beach activity for sea turtles, so information includes false crawls, which is when a sea turtle crawls onto the beach but does not lay eggs or nest. Since the only reason sea turtles come ashore is to lay eggs, a false crawl is considered abnormal behavior.

    The trend of increasing activity is clear, although it was not a straight-line increase in the nine years studied. As an example, 2017 saw a low of 25 reported activities, but since that time, there has been a steady increase.

    Sea Turtle Swimming off the Outer Banks Coastline
    Sea Turtle swimming around Oregon Inlet on the Outer Banks.

    ALAN has been shown to have an adverse effect on sea turtle nesting in longer-term studies and in other locations. The students acknowledged that there is considerable scientific literature pointing to an adverse effect on turtle behavior, but they noted that given the limited scope of their study, they could not say definitively that ALAN affected sea turtle behavior.

    But if their conclusions regarding nesting behavior were inconclusive, their findings about where the darkest areas of the Outer Banks were, and public perception of ALAN were compelling and somewhat surprising.

    The students used two sets of data to determine how dark the study area was. They used satellite data collected in 2022 from September through November, showing how much light was emitted from the Outer Banks. They compared that to a handheld light meter used to take readings during new moons in September, October, and November. There was a strong correlation between the satellite readings and the handheld device.

    Nags Head, Kill Devil Hills, and Kitty Hawk emitted the most light—they are the most built-up areas, and Kill Devil Hills, in particular, stood out as emitting the most ALAN.

    However, not all areas that have seen strong development emitted significant amounts of ALAN. Duck, for example, was noticeably darker than the towns to the south.

    That seems to be by design. Asked in an email whether the town of Duck had ordinances that made it one of the darker towns on the Outer Banks, Joe Heard, Director of Community Development, wrote, “The Town of Duck has adopted and enforces standards that limit the direction and intensity of exterior lighting.”

    Artificial light on the Outer Banks at night
    Comparison of ALAN as measured by satellite (L) and handheld light meter. The comparisons are remarkably similar. Satellite measurements (VIIRS) show the darkest areas as the lowest number. Handheld readings (SQM) show the darkest as the highest readings.

    Town ordinances mandate hoods or coverings for most lighting with the goal of the lights shining down. The ordinances also limit how bright lights can be.

    Another finding that was apparent and significant in the surveys is that the public is very aware of ALAN and that artificial light is something that can have an adverse affect on the environment.

    The students surveyed about 500 respondents asking them to rate their level of concern about artificial light at night. Almost 70 percent of the answers indicated they were concerned or very concerned about ALAN.

    There was some variation in how residents, seasonal residents, and visitors viewed the issue, and women tended to be a little more concerned than men, but across all categories, a significant majority of respondents felt ALAN was an issue that should be addressed.

    The findings led the students to note in their conclusion, “Based on our survey of Outer Banks residents and visitors, we came away with several conclusions. First and foremost, we found that the majority (~70%) of both residents and visitors were concerned about ALAN levels on the Outer Banks. Additionally, respondents perceived ALAN to negatively affect all the factors surveyed, with overwhelmingly negative perceptions of ALAN on star-gazing and sea turtles.”

    To view the presentation of their findings, click here.