Data from: Crustacean photoreceptor damage and recovery: Applying a novel scanning electronic microscopy protocol in artificial light at night studies

As sources of artificial light at night (ALAN) expand worldwide, research
on their impacts has also increased. Most of these studies, including
those in coastal habitats, have focused on behavioral and ecological
responses to ALAN, overlooking impacts on the photoreceptor, the basic
functional structure of animals to absorb light. Examining structural
changes in the photoreceptor is essential to understand the mechanisms by
which ALAN may be impacting species, particularly those adapted to
different light backgrounds. This study examined the photoreceptor
(rhabdom) of two sandy beach crustaceans exhibiting different light
tolerances at night: the amphipod Orchestoidea tuberculata and the isopod
Tylos spinulosus. We developed a novel protocol to measure these species’
photoreceptor areas and quantify the damage caused by ALAN using
histological sections and scanning electron microscopy (SEM). Our results
showed that in the isopod, a species naturally adapted to lower light
intensities at night than the amphipod, the rhabdom surface was 20-times
larger, and presented a tapetum, an adaptive feature found in species
living in low light conditions. This confirmed that this species is
potentially more sensitive to ALAN than the amphipod. Consistently, a
brief period of exposure to ALAN (1 h, 20 lux) caused 3-6 times more
damage in the isopod’ rhabdom. In fact, ALAN caused structural damage in
the isopod’ but not in the amphipod’ rhabdom, a damage that did not show
signs of recovery from ALAN after 1 and 24 h. Thus, the damage caused by
ALAN on an organism’s photoreceptors is likely to be more severe and
persistent in species naturally adapted to lower light levels at night.
Installation of permanent ALAN sources nearby the burrowing area of these
light sensitive species may have differential effects on their activity
and interactions at night. ALAN may also become a new selection pressure
on these species, a concern with wide implications given the ubiquity
among animals of the photoreceptor structure and its response to light.