National and international researchers studied how artificial light affects the vision of two species of crustaceans that commonly inhabit the beaches of northern Chile. It was revealed that this type of lighting generates damage to its compound eyes, in addition to its levels of adaptation vary according to the level of light. The process was possible thanks to an electronic microscopy protocol developed by the equipment.
of coastal ecology and anthropogenic impacts)
The beach flea Orchestoidea tuberculata and the isopod Silence spinulosses They are species that live on sandy beaches. Between algae and sand, both They break down organic matter, helping to recirculate nutrients and balance these ecosystems.
Without the presence of these organisms on the beaches, “tourism in coastal areas could be affected, due to the accumulation of organic matter on the sand and whose withdrawal and cleanliness, for example in the US, has been estimated at more than 500 million dollars a yearwith the dollar at half the current price, ”says Dr. Patricio Manríquez, associate researcher at Ceaza.
They are also part of the feeding of other animals. “Research carried out in beaches of the Northern Hemisphere have evident the inclusion of isopods and amphipods of the family Talitridae, In the carnivorous diet, such as birds and mammals, ”he adds.
The objective of the scientific team was to answer: How does artificial night light (Alan) affect the visual photoreceptor structure of both species?
It should be noted that, although little visible during the day, night light pollution in coastal areas grows along with the urban and tourist sectors, affecting each living being exposed to it. Including small animals such as crustaceans, which depend on the dark to survive.
How to get to the eyes of a crustacean?
"The specimens of both species were obtained from Las Conchitas beach - Los Choros, commune of La Higuera. This beach was selected because both study models coexist and until the time of the experiment, it did not have light pollution or even close, being a pristine habitat of this pollutant and consequently, with study models completely oblivious to this," says Dr. Manríquez.
As for the way of studying it, it was through Electronic Scanning Microscopy and the evaluation of the photoreceptor area of a cross -section of the omátidas (Structural and functional vision units).
To observe these damages in detail, the researchers developed a simple but innovative method of Removingwhich allows to study the internal structure of the compound eyes.
-According to Dr. Manríquez, this technique “allowed the observation of histological cuts in MEB and opens a new path in the three -dimensional study of these visual structures, not only within the field of biology and/or in the context of light pollution, but also of biotechnology and engineering, where the generation of 3D models of compound eyes can now be corroborated by means of empirical analysis taken from the same models. Generation of artificial compound eyes, it is today an area in constant increase in countries such as Japan or Korea ”.
In this context, the crustaceans were exposed for an hour to light white LED (20 lux) in their natural habitat. Then changes were observed after 1 and 24 hours of recovery. The controls were in complete darkness (0.001 lux), separated by rock formations that avoided the dispersion of the light.
What they revealed
The team identified structural damage in the eyes of both species, but with notable differences.
The isopod Silence spinulossesadapted to very low luminosity environments, presented greater damage to its photoreceptors. This has structures such as the tapetum, which intensifies the light that enters the eye, but also makes it more vulnerable. Instead, the amphipod Orchestoidea tuberculata (Beach flea), accustomed to greater light exposure, showed greater tolerance.
"This can be particularly relevant in other environmental impact studies of light pollution as well as a Alan monitoring mechanism in areas of incipient pollution but in increase, such as the effects in the underwater area and the presence or absence of algae forests," says Dr. Manríquez.
Can a coastal isopod of night light pollution recover?
It is worth mentioning that Another study of the area He emphasized the crustacean most affected by artificial light: the isopod Silence spinulosses.
"The results showed that exposure to Alan had negative effects on its locomotive activity, consumption and absorption of food, and growth. Although some effects, such as consumption and growth, were reversed after removing the light source, others, such as activity and efficiency in food absorption did not show recovery in the short term," said Dr. Manríquez.
Finally, the researcher highlights that “this type of studies allows us to anticipate the ecological effects of a growing threat. The eyes of crustaceans can be a tool to monitor environments Before the damage is irreversible”.
The studies were developed in collaboration between researchers at the CEAZA-Laboratory Scientific Center for Ecology and Behavior of Early Ontogeny (LECOT), the Andrés Bello University (UNAB), Prince Edward Island University (Canada), the Catholic University of the North (UCN) and the University of Plymouth (United Kingdom).
