IMPACTS OF ARTIFICIAL LIGHT AT NIGHT ON BENTHIC
AUTOTROPHS IN FRESHWATERS
Maja Grubisic
Worldwide, freshwaters are more and more illuminated by artificial lights
coming from urban areas. Light is a driver of many biological processes,
including autotroph production of oxygen and organic matter. With better
understanding of biological consequences of increased illumination at
night, we can adapt existing lighting strategies to minimize negative
environmental impacts and light pollution.
Artificial nighttime illumination can alter community composition of
benthic biofilms: diatoms tend to become more abundant under
illuminated conditions
Autotrophs in younger biofilms at earlier colonization stages tend to
respond more sensitively to artificial light at night, compared to older,
established biofilms
The sensitivity of benthic autotrophs to artificial nighttime illumination
largely depends on the season
Grubisic et al. Does light pollution affect benthic primary producers in shallow streams? Results from flume
experiments. In prep.
Grubisic et al. Effects of artificial nighttime illumination in lowland agricultural ditch system. In prep.
Benthic autotrophs - diatoms, green algae
and cyanobacteria – grow attached to
underwater surfaces, where they form a
substantial part of biofilm communities,
together with other aquatic flora and
microfauna.
Light is one of the main regulators of
biofilm dynamics (Figure 1).
Figure 1
In all shallow, clear waters, where artificial
nighttime illumination reaches the bottom, it
can potentially affect benthic autotrophs:
Directly – by increasing photosynthesis
Indirectly – by increasing their
consumption by herbivores
(Figure 2)
Figure 2