Wavelength-dependent effects of artificial light at night on phytoplankton growth and community structure

Abstract

Artificial light at night (ALAN) is a disruptive form of pollution, impacting physiological and behavioural processes that may scale up to population and community levels. Evidence from terrestrial habitats show that the severity and type of impact depend on the wavelength and intensity of ALAN; however, research on marine organisms is still limited. Here, we experimentally investigated the effect of different ALAN colours on marine primary producers. We tested the effect of green (525 nm), red (624 nm) and broad-spectrum white LED ALAN, compared to a dark control, on the green microalgae Tetraselmis suesica and a diatom assemblage. We show that green ALAN boosted chlorophyll production and abundance in T. suesica . All ALAN wavelengths affected assemblage biomass and diversity, with red and green ALAN having the strongest effects, leading to higher overall abundance and selective dominance of specific diatom species, some known to cause harmful algal blooms. Our findings show that green and red ALAN should be used with caution as alternative LED colours in coastal areas, where there might be a need to strike a balance between the effects of green and red light on marine primary producers with the benefit they appear to bring to other organisms.

Quantity and Quality of Light on Growth and Pigment Content of <em>Dunaliella</em> sp. and <em>Anabaena</em> sp. Cultures and the Use of Their Absorption Spectra as a Proxy Method for Assessment

“…From an ecological and physiological perspective, the various pigments found in microalgae show differences in the capacity of algae to use light with various spectral compositions for photosynthesis and to adapt to various lighting regimes [14,[75][76][77][78][79]. As a result, the spectrum makeup of light is a crucial growth parameter for producing microalgae [80][81][82]. In the present study, substantial differences were recorded in maximum biomass, the content of pigments and pigment ratios among the intensities of white light and among the three light colors used in both microalgae examined.…”

The impacts of artificial light at night on the ecology of temperate and tropical reefs

“…Studies on terrestrial plants confirm that relatively low levels of short durations of ALAN can effectively influence the growth and reproduction of terrestrial autotrophs [ 20 ]. Similarly, ALAN from white LED lighting has been shown to significantly increase maximum photosynthetic efficiency and photosynthetic biomass of epilithic microphytobenthos on rocky intertidal shorelines [ 21 ], and increase biomass and alter assemblage diversity of phytoplankton communities [ 22 ]. Therefore, by increasing the availability of light for photosynthesis, ALAN probably enhances primary productivity on coral and temperate reefs.…”

Will “Air Eutrophication” Increase the Risk of Ecological Threat to Public Health?

“…Light availability is another key factor controlling the growth of algae in aquatic ecosystems . Urbanization has led to rapid expansion of ALAN in space at a rate of 2–6% per year. − With the advent of a wide range of lighting devices, both cool and warm white ALAN has become increasingly abundant. , For freshwater cyanobacteria, warmer white ALAN means a higher photosystem II:photosystem I ratio and hence stronger photosynthesis activities . A positive correlation was observed between photosynthetically active radiation and toxin production in Microcystis aeruginosa .…”