Artificial Light Impacts on Coastal Ecosystems (ALICE)

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Coastlines are illuminated with artificial light at night (ALAN) from piers, promenades, ports harbours, and dockyards. Artificial sky glow created by lighting from coastal settlements can now be detected above 22% of the world's coasts nightly, and will dramatically increase as coastal human populations more than double by year 2060. Life history adaptations to the moon and sun are near ubiquitous in the upper 200m of the sea, such that cycle's and gradients of light intensity and colour are major structuring factors in marine ecosystems. The potential for ALAN to reshape the ecology of coastal habitats by interfering with natural light cycles and the biological processes they inform is increasingly recognised.Marine invertebrates are extremely sensitive to natural light throughout their life cycle. Examples include synchronised broadcast spawning in reef corals informed by moonlight cycles, zooplankton sensitivity to moonlight at >100m depth, and phototaxis of larvae under light equivalent to moonless overcast nights. The reproductive, larval and adult phases of marine invertebrates are all affected by night-time lighting of equivalent illuminances to those found in ports and harbours. Further, direct impacts on organism behaviour can indirectly affect other species in coastal food web's, changing ecosystem structure. The potential for coastal ALAN to disrupt marine organisms, species interactions, population dynamics, and organism distributions is clear.The growing use of white Light Emitting Diodes (LEDs) (69% of global lighting by 2020) will exacerbate ALAN's impacts. LEDs emit more blue wavelength light that: i) penetrates deeper into seawater compared to older lighting technologies; and ii) many marine organism responses are most sensitive to. Tailoring LEDs to avoid blue wavelengths represents one mitigation option trialled on land that can be improved by investigating the spectral dependence of biological responses.ALICE will tackle fundamental gaps in our understanding of marine ecosystem responses to ALAN, by carrying out the following research: -1. Laboratory experiments to determine the impacts of ALAN on coastal organisms: Parallel experiments will quantify the impacts of ALAN interference with natural light cycles on the life history responses of marine invertebrates. These relationships will be used to model the growth rate of marine invertebrate populations exposed to different intensities of cool white LED light assuming optimal conditions with no predators or competitors.2. Laboratory experiments to determine the impact of ALAN on species interactions: The relationships between white LED light intensity, and species interactions (predation,competition and mutualism) will be simultaneously quantified during the above experiments, and used to model the impacts of ALAN on marine invertebrate populations accounting for their relationships with one another in nature.3. Mapping and modelling the distribution of ALAN in coastal marine habitats: The intensity of colour composition of ALAN in coastal waters will be mapped across three contrastingly urbanised UK estuaries. These data, and associated optical modelling, will be used with satellite data to globally map ALAN intensity from the sea surface to a depth of 100m.4. Modelling ALAN impacts on species distributions: The population models (1,2) and the ALAN distribution model (3), will allow a synthesis assessment of long term changes in species distributions that may result from ALAN impacts. 5. Quantifying the benefits of avoiding ALAN wavelengths: we will quantify the ecological benefits of: i) removing blue light form LEDs blue using optical filters; ii) replacing white, with longer wavelength Amber LEDs. In addition we will quantify the responses of marine invertebrate larvae to different colours of light, so that the design of ecologically friendly LED lighting can be better informed.