Efectos de la contaminación luminica nocturna (ALAN) sobre estadios tempranos de desarrollo larval de invertebrados intermareales y organismos planctónicos pelágicos
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2022
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es
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Universidad Andrés Bello
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La contaminación lumínica artificial nocturna (ALAN por su sigla en inglés) producida
por la iluminación urbana e industrial, así como otras fuentes, ha aumentado drásticamente en
las últimas décadas, especialmente en entornos costeros que albergan densas poblaciones
humanas. El 22% de la línea de costa a nivel mundial está actualmente intervenida y afectada
por contaminación lumínica, y se predice que este valor aumentara, a medida que la población
humana asociada a la costa se duplique para el año 2060; en efecto, se estima que ALAN se
expande en aproximadamente un 6% anual. La organización y estructura biológica y ecológica,
asociada a la costa, presentan un orden establecido, caracterizado a través de patrones espaciales
y temporales, y una intervención como es la “luz artificial” podrían alterar los patrones naturales
de luz y oscuridad con consecuencias en todos los niveles de organización biológica. A nivel
individual, ALAN puede provocar un conjunto de respuestas fisiológicas y de comportamiento
asociadas con procesos mediados por la luz, como los patrones de actividad diaria y las
interacciones depredador-presa. También se ha demostrado que ALAN modifica la composición
de la comunidad y la estructura trófica, con implicaciones para los procesos a nivel de
ecosistema, incluida la productividad primaria, el ciclo de nutrientes, y los vínculos energéticos
entre los sistemas acuáticos y terrestres. A pesar del conocido incremento de ALAN, sus efectos
sobre hábitats costeros han recibido menor atención en comparación a hábitats terrestres. Existe
evidencia, que ha demostrado como ALAN genera efecto en la migración vertical del
zooplancton, en la conducta en peces frente a depredadores visuales, desincronización del
desove en corales, reducción en la actividad, consumo de alimento y crecimiento en distintas
especies, cambios en la abundancia y ritmo circadiano, disminución en el rendimiento
fisiológico (consumo de oxígeno), y cambios en la conducta y fisiología de especies
depredadoras de invertebrados claves en el intermareal rocoso. Aun existiendo evidencia de lo
que provoca ALAN en organismos marinos, todavía se desconoce el real efecto que podría tener
este fenómeno en especies que exhiben distintas etapas en su ciclo de vida y en sus procesos
ecológicos, lo que son claves para la sobrevivencia y éxito reproductivo de especies de
invertebrados marinos, ya que los escasos estudios que existen solo se han centrado en una etapa
del ciclo de vida. Dentro de los invertebrados marinos, encontramos un grupo relevante, el cual es el
plancton, cuya función radica en transferir energía a los distintos niveles tróficos superiores. El
plancton es un grupo clave en la determinación de procesos adversos que están ocurriendo en el
medio marino y costero, ya que son susceptibles a cambios ambientales naturales y por ende a
cambios antrópicos. Siendo este grupo tan relevante en el medio marino, resulta interesante
entender cómo puede afectar un estresor antrópico como ALAN, en las distintas etapas de sus
ciclos de vida y en los diferentes grupos que se encuentran clasificados dentro del plancton
marino.
El objetivo de esta investigación fue evaluar el efecto de ALAN sobre la abundancia y
distribución del plancton de zonas costeras. Para esto se plantearon tres hipótesis de trabajo, las
cuales son abordadas en el Capítulo I, el cual se dividió en A y B y en el Capítulo II. Cada
Capítulo abordó problemáticas distintas asociadas al efecto de ALAN en invertebrados marinos
y de esta manera poder responder a las preguntas de investigación planteadas.
El Capítulo I se enfocó en evaluar el efecto de ALAN sobre las tasas de asentamiento de distintas
especies de cirripedos intermareales de importancia ecológica. El Capítulo I A utilizo como
modelo de estudio los cirrípedios intermareales Notochthamalus scabrosus y Jehlius cirratus,
los cuales son especies muy comunes en la costa de Chile. Para llevar a cabo esta investigación
se diseñó una metodología acorde para poder estudiar tasas de asentamiento de invertebrados
marinos. Los estudios se realizaron en distintos periodos del ciclo de vida (1) larva cypris (pre
metamorfosis) y (2) Spat (post metamorfosis). Para determinar el efecto de ALAN sobre larvas
cypris y spat, se diseñaron experimentos en terreno, utilizando placas de acrílico de 5*5 cm a la
cual se le añadió un sustrato artificial (Safety walk ®) con un sistema de luz artificial (LED)
adicionado a las placas y así poder determinar las tasas de asentamiento en presencia/ausencia
de condiciones ALAN. Tanto las placas con luz (ALAN) como las sin luz (control) se colocaron
en la zona intermareal del norte de Chile. Al cabo de un tiempo fueron contabilizados los
distintos estadios en placas con luz (ALAN) y sin luz (control). El Capítulo I B, utilizo como
modelo de estudio el cirrípedo intermareal Semibalanus balanoides, muy común en la costa de
Canadá. Se realizó exactamente la misma metodología que la realizada en Chile (Capítulo I A),
estudiando los mismos periodos del ciclo de vida larva cypris (pre metamorfosis) y Spat (post
metamorfosis y las placas de acrílico fueron instaladas en la costa norte de Canadá en el
Atlántico. La única diferencia entre ambos experimentos, fue que en Chile se instalaron las placas en un sustrato natural (rocas) y en Canadá fueron instaladas en sustrato artificial
(concreto). Los resultados encontrados en ambos capítulos I A y B, tuvieron la misma tendencia
tanto en Chile como en Canadá, encontrando que tanto en las placas con luz (ALAN) como las
sin luz (control) se asentaron larvas cypris como Spat de las tres especies en estudio, N.
scabrosus, J. cirratus y S. balanoides. Las larvas Cypris de las tres especies no se vieron
afectadas por ALAN. Por el contrario, la tasa de sentamiento de los Spat fue significativamente
menor en las placas con luz (ALAN) que en las sin luz (control) en las tres especies, lo que
sugiere impactos perjudiciales de ALAN en el proceso de asentamiento. Por lo tanto, del
hallazgo registrado en ambos trabajos (Capítulo I A y B), se pudo establecer que este tipo de
estrés antrópico (ALAN) está siendo perjudicial en lugares tan distantes como la costa del
Pacifico sur (Chile) y la costa del Atlántico norte (Canadá), en el continente Americano, las que
incluso presentan distintas condiciones oceanográficas (físicas, químicas y biológicas) pudiendo
establecer que ALAN genera un efecto negativo en la tasa de asentamientos de cirrípedios, lo
que se puede extrapolar a otras especies de invertebrados, que habitan otras zonas costeras del
mundo.
El Capítulo II de esta tesis doctoral, siguió la línea de investigación del Capitulo anterior,
y de esta manera poder complementar y ampliar el estudio del efecto de ALAN sobre
organismos planctónicos. El objetivo de este capítulo se centró en evaluar el daño colateral que
puede ejercer una actividad de origen antrópico como es la salmonicultura, a la comunidad
planctónica que coexisten en los ambientes, donde se desarrollan estas actividades. En el sur de
Chile se encuentran ubicados muchos centros de cultivo, principalmente de salmones. En estos
centros masivos de cultivo se utilizan luces LED que permiten generar fotoperiodos, con
objetivos claves que se relacionan con la fase de engorda y disminución del porcentaje de
madurez precoz de salmones. Sin embargo, no ha sido considerado el daño colateral que puedan
tener este tipo de actividad para especies no objetivo que se encuentran en la columna de agua
y que pertenecen a la comunidad plantónica. Para poder responder el objetivo planteado se
diseñó un muestreo en un centro de cultivo ubicado en la Reserva las Guaitecas, Puerto Melinka
(XI) región, donde se utilizaron módulos usados para el cultivo de salmones expuestos y no
expuestos a luz artificial. En cada módulo, se obtuvieron muestras de la columna de agua a
distintas profundidades (0, 1, 2, 5 y 10m) obteniéndose en paralelo las intensidades de luz (lux).
Se compararon los atributos comunitarios de abundancia, diversidad y riqueza de las especies encontradas. Los resultados mostraron que los atributos comunitarios fueron mayores en control
(sin luz). Otro resultado relevante fue al considerar las profundidades muestreadas, ya que se
registró una disminución en la abundancia de especies en la columna de agua en los primeros
metros 0, 2 y 5 a diferencia de los 10 m de profundidad en ALAN (con luz). Estos resultados
sugieren que la contaminación lumínica influiría significativa y negativamente sobre la
distribución vertical y estructura comunitaria del zooplancton. Estos efectos podrían alterar la
trama trófica de este y otros ambientes expuestos a este estresor.
Todos los resultados obtenidos de esta tesis doctoral demuestran que ALAN influye
negativamente en la comunidad planctónica, desde las tasas de asentamiento como en la
distribución vertical y estructura comunitaria del plancton marino, por lo que podemos concluir
que, ALAN es una amenaza emergente para la biodiversidad tanto en Chile, como a nivel
mundial, perturbando los ecosistemas al alterar patrones de actividad diurna/nocturna
(migración vertical), procesos de asentamiento y reclutamiento (en etapas larvales), generando
cambios en la estructura y las funciones de las comunidades de invertebrados y se expande
rápidamente en los hábitats costeros debido a la rápida urbanización. Los resultados de esta
investigación doctoral pueden tener aplicaciones directas para las políticas públicas nacionales
y locales de planificación espacial costera en Chile, que deberían considerar los efectos de
ALAN en las especies costeras. La estabilidad económica de un país es esencial y una actividad
como es la acuicultura es relevante en términos de producción, sin embargo, es necesario revisar
y estudiar, el daño colateral que se está generando a especies no objetivos, que coexisten en
estos ambientes marinos, recomendando nuevas normativas para aplicar el uso de nuevas
tecnologías lumínicas (lámparas ecológicas) en la acuicultura y en las zonas urbanas asociadas
a la costa.
Artificial light pollution at night (ALAN) from urban and industrial lighting, as well as other sources, has increased dramatically in recent decades, especially in coastal environments that are home to dense human populations. Twenty-two percent of the world's coastline is currently disturbed and affected by light pollution, and this value is predicted to increase as the human population associated with the coast doubles by 2060; indeed, ALAN is estimated to expand by approximately 6% per year. The biological and ecological organization and structure associated with the coastline has an established order, characterized by spatial and temporal patterns, and an intervention such as "artificial light" could alter the natural patterns of light and darkness with consequences at all levels of biological organization. At the individual level, ALAN can elicit an array of physiological and behavioral responses associated with light-mediated processes, such as daily activity patterns and predator-prey interactions. ALAN has also been shown to modify community composition and trophic structure, with implications for ecosystem-level processes, including primary productivity, nutrient cycling, and energetic linkages between aquatic and terrestrial systems. Despite the known increase in ALAN, its effects on coastal habitats have received less attention compared to terrestrial habitats. There is evidence that has shown how ALAN has an effect on the vertical migration of zooplankton, on fish behavior towards visual predators, desynchronization of spawning in corals, reduction in activity, food consumption and growth in different species, changes in abundance and circadian rhythm, decrease in physiological performance (oxygen consumption), and changes in the behavior and physiology of key invertebrate predatory species in the rocky intertidal. Although there is evidence of what causes ALAN in marine organisms, the real effect that this phenomenon could have on species that exhibit different stages in their life cycle and ecological processes, which are key to the survival and reproductive success of marine invertebrate species, is still unknown, since the few studies that exist have only focused on one stage of the life cycle. Within the marine invertebrates, we find a relevant group, which is the plankton, whose function is to transfer energy to the different higher trophic levels. Plankton is a key group in the determination of adverse processes that are occurring in the marine and coastal environment, since they are susceptible to natural environmental changes and therefore to anthropogenic changes. Being this group so relevant in the marine environment, it is interesting to understand how an anthropogenic stressor such as ALAN can affect the different stages of their life cycles and the different groups that are classified within the marine plankton. The objective of this research was to evaluate the effect of ALAN on the abundance and distribution of plankton in coastal areas. For this purpose, three working hypotheses were proposed, which are addressed in Chapter I, which was divided into A and B, and Chapter II. Each Chapter addressed different problems associated with the effect of ALAN on marine invertebrates, and in this way was able to answer the research questions posed. Chapter I focused on evaluating the effect of ALAN on the settlement rates of different ecologically important intertidal cirripedes. Chapter I A used as a study model the intertidal cirripedes Notochthamalus scabrosus and Jehlius cirratus, which are very common species in the coast of Chile. In order to carry out this research, a methodology was designed to study settlement rates of marine invertebrates. The studies were carried out in different periods of the life cycle (1) cypris larva (pre metamorphosis) and (2) Spat (post metamorphosis). To determine the effect of ALAN on cypris and spat larvae, field experiments were designed using 5*5 cm acrylic plates to which an artificial substrate (Safety walk ®) was added with an artificial light system (LED) added to the plates in order to determine settlement rates in the presence/absence of ALAN conditions. Both the plates with light (ALAN) and without light (control) were placed in the intertidal zone of northern Chile. After a period of time, the different stages were counted in plates with light (ALAN) and without light (control). Chapter I B, used as a study model the intertidal barnacle Semibalanus balanoides, very common on the coast of Canada. Exactly the same methodology was used as in Chile (Chapter I A), studying the same periods of the larval life cycle cypris (pre metamorphosis) and Spat (post metamorphosis) and the acrylic plates were installed on the north coast of Canada in the Atlantic. The only difference between the two experiments was that in Chile the plates were installed on a natural substrate (rocks) and in Canada they were installed on artificial substrate (concrete). The results found in both chapters I A and B, had the same tendency both in Chile and Canada, finding that both in the plates with light (ALAN) and without light (control) cypris larvae settled as Spat of the three species under study, N. scabrosus, J. cirratus and S. balanoides. Cypris larvae of the three species were not affected by ALAN. On the contrary, the settling rate of Spat was significantly lower on plates with light (ALAN) than on those without light (control) in all three species, suggesting detrimental impacts of ALAN on the settling process. Therefore, from the findings recorded in both works (Chapter I A and B), it can be established that this type of anthropogenic stress (ALAN) is being detrimental in places as far apart as the South Pacific coast (Chile) and the North Atlantic coast (Canadá), in the American continent, which even present different oceanographic conditions (physical, chemical and biological) that can (physical, chemical and biological) of the coast, so it can be established that ALAN generates a negative effect on the settlement rate of barnacles, which can be extrapolated to other invertebrate species that inhabit other coastal areas of the world. Chapter II of this doctoral thesis followed the line of research of the previous chapter, and in this way was able to complement and expand the study of the effect of ALAN on planktonic organisms. The objective of this chapter focused on evaluating the collateral damage that an anthropogenic activity such as salmon farming can cause to the planktonic community that coexist in the environments where these activities are developed. In the south of Chile there are many farming centers, mainly for salmon. In these massive farming centers LED lights are used to generate photoperiods, with key objectives related to the fattening phase and reduction of the percentage of early maturity of salmon. However, the collateral damage that this type of activity may have on non-target species found in the water column and belonging to the planktonic community has not been considered. In order to respond to this objective, a sampling was designed in a culture center located in the Guaitecas Reserve, Puerto Melinka (XI) region, where modules used for the culture of salmon exposed and not exposed to artificial light were used. In each module, samples were taken from the water column at different depths (0, 1, 1, 2, 5 and 10m) and light intensities (lux) were obtained in parallel. The community attributes of abundance, diversity and richness of the species found were compared. The results showed that the community attributes were higher in the control (without light). Another relevant result was when considering the depths sampled, since there was a decrease in the abundance of species in the water column in the first meters 0, 2 and 5 as opposed to the 10 m depth in ALAN (with light). These results suggest that light pollution would significantly and negatively influence the vertical distribution and community structure of zooplankton. These effects could alter the trophic web of this and other environments exposed to this stressor. All the results obtained from this doctoral thesis demonstrate that ALAN negatively influences the planktonic community, from the settlement rates to the vertical distribution and community structure of marine plankton, so we can conclude that ALAN is an emerging threat to biodiversity both in Chile and worldwide, disturbing ecosystems by altering patterns of diurnal/nocturnal activity (vertical migration), settlement and recruitment processes (in larval stages), generating changes in the structure and functions of invertebrate communities and rapidly expanding in coastal habitats due to rapid urbanization, fishing and aquaculture. The results of this doctoral research may have direct applications for national and local public policies for coastal spatial planning in Chile, which should consider the effects of ALAN on coastal species. The economic stability of a country is essential and an activity such as aquaculture is relevant in terms of production, however, it is necessary to review and study the collateral damage that is being generated to non-target species that coexist in these marine environments, recommending new regulations to implement the use of new lighting technologies (ecological lamps) in aquaculture and in urban areas associated with the coast.
Artificial light pollution at night (ALAN) from urban and industrial lighting, as well as other sources, has increased dramatically in recent decades, especially in coastal environments that are home to dense human populations. Twenty-two percent of the world's coastline is currently disturbed and affected by light pollution, and this value is predicted to increase as the human population associated with the coast doubles by 2060; indeed, ALAN is estimated to expand by approximately 6% per year. The biological and ecological organization and structure associated with the coastline has an established order, characterized by spatial and temporal patterns, and an intervention such as "artificial light" could alter the natural patterns of light and darkness with consequences at all levels of biological organization. At the individual level, ALAN can elicit an array of physiological and behavioral responses associated with light-mediated processes, such as daily activity patterns and predator-prey interactions. ALAN has also been shown to modify community composition and trophic structure, with implications for ecosystem-level processes, including primary productivity, nutrient cycling, and energetic linkages between aquatic and terrestrial systems. Despite the known increase in ALAN, its effects on coastal habitats have received less attention compared to terrestrial habitats. There is evidence that has shown how ALAN has an effect on the vertical migration of zooplankton, on fish behavior towards visual predators, desynchronization of spawning in corals, reduction in activity, food consumption and growth in different species, changes in abundance and circadian rhythm, decrease in physiological performance (oxygen consumption), and changes in the behavior and physiology of key invertebrate predatory species in the rocky intertidal. Although there is evidence of what causes ALAN in marine organisms, the real effect that this phenomenon could have on species that exhibit different stages in their life cycle and ecological processes, which are key to the survival and reproductive success of marine invertebrate species, is still unknown, since the few studies that exist have only focused on one stage of the life cycle. Within the marine invertebrates, we find a relevant group, which is the plankton, whose function is to transfer energy to the different higher trophic levels. Plankton is a key group in the determination of adverse processes that are occurring in the marine and coastal environment, since they are susceptible to natural environmental changes and therefore to anthropogenic changes. Being this group so relevant in the marine environment, it is interesting to understand how an anthropogenic stressor such as ALAN can affect the different stages of their life cycles and the different groups that are classified within the marine plankton. The objective of this research was to evaluate the effect of ALAN on the abundance and distribution of plankton in coastal areas. For this purpose, three working hypotheses were proposed, which are addressed in Chapter I, which was divided into A and B, and Chapter II. Each Chapter addressed different problems associated with the effect of ALAN on marine invertebrates, and in this way was able to answer the research questions posed. Chapter I focused on evaluating the effect of ALAN on the settlement rates of different ecologically important intertidal cirripedes. Chapter I A used as a study model the intertidal cirripedes Notochthamalus scabrosus and Jehlius cirratus, which are very common species in the coast of Chile. In order to carry out this research, a methodology was designed to study settlement rates of marine invertebrates. The studies were carried out in different periods of the life cycle (1) cypris larva (pre metamorphosis) and (2) Spat (post metamorphosis). To determine the effect of ALAN on cypris and spat larvae, field experiments were designed using 5*5 cm acrylic plates to which an artificial substrate (Safety walk ®) was added with an artificial light system (LED) added to the plates in order to determine settlement rates in the presence/absence of ALAN conditions. Both the plates with light (ALAN) and without light (control) were placed in the intertidal zone of northern Chile. After a period of time, the different stages were counted in plates with light (ALAN) and without light (control). Chapter I B, used as a study model the intertidal barnacle Semibalanus balanoides, very common on the coast of Canada. Exactly the same methodology was used as in Chile (Chapter I A), studying the same periods of the larval life cycle cypris (pre metamorphosis) and Spat (post metamorphosis) and the acrylic plates were installed on the north coast of Canada in the Atlantic. The only difference between the two experiments was that in Chile the plates were installed on a natural substrate (rocks) and in Canada they were installed on artificial substrate (concrete). The results found in both chapters I A and B, had the same tendency both in Chile and Canada, finding that both in the plates with light (ALAN) and without light (control) cypris larvae settled as Spat of the three species under study, N. scabrosus, J. cirratus and S. balanoides. Cypris larvae of the three species were not affected by ALAN. On the contrary, the settling rate of Spat was significantly lower on plates with light (ALAN) than on those without light (control) in all three species, suggesting detrimental impacts of ALAN on the settling process. Therefore, from the findings recorded in both works (Chapter I A and B), it can be established that this type of anthropogenic stress (ALAN) is being detrimental in places as far apart as the South Pacific coast (Chile) and the North Atlantic coast (Canadá), in the American continent, which even present different oceanographic conditions (physical, chemical and biological) that can (physical, chemical and biological) of the coast, so it can be established that ALAN generates a negative effect on the settlement rate of barnacles, which can be extrapolated to other invertebrate species that inhabit other coastal areas of the world. Chapter II of this doctoral thesis followed the line of research of the previous chapter, and in this way was able to complement and expand the study of the effect of ALAN on planktonic organisms. The objective of this chapter focused on evaluating the collateral damage that an anthropogenic activity such as salmon farming can cause to the planktonic community that coexist in the environments where these activities are developed. In the south of Chile there are many farming centers, mainly for salmon. In these massive farming centers LED lights are used to generate photoperiods, with key objectives related to the fattening phase and reduction of the percentage of early maturity of salmon. However, the collateral damage that this type of activity may have on non-target species found in the water column and belonging to the planktonic community has not been considered. In order to respond to this objective, a sampling was designed in a culture center located in the Guaitecas Reserve, Puerto Melinka (XI) region, where modules used for the culture of salmon exposed and not exposed to artificial light were used. In each module, samples were taken from the water column at different depths (0, 1, 1, 2, 5 and 10m) and light intensities (lux) were obtained in parallel. The community attributes of abundance, diversity and richness of the species found were compared. The results showed that the community attributes were higher in the control (without light). Another relevant result was when considering the depths sampled, since there was a decrease in the abundance of species in the water column in the first meters 0, 2 and 5 as opposed to the 10 m depth in ALAN (with light). These results suggest that light pollution would significantly and negatively influence the vertical distribution and community structure of zooplankton. These effects could alter the trophic web of this and other environments exposed to this stressor. All the results obtained from this doctoral thesis demonstrate that ALAN negatively influences the planktonic community, from the settlement rates to the vertical distribution and community structure of marine plankton, so we can conclude that ALAN is an emerging threat to biodiversity both in Chile and worldwide, disturbing ecosystems by altering patterns of diurnal/nocturnal activity (vertical migration), settlement and recruitment processes (in larval stages), generating changes in the structure and functions of invertebrate communities and rapidly expanding in coastal habitats due to rapid urbanization, fishing and aquaculture. The results of this doctoral research may have direct applications for national and local public policies for coastal spatial planning in Chile, which should consider the effects of ALAN on coastal species. The economic stability of a country is essential and an activity such as aquaculture is relevant in terms of production, however, it is necessary to review and study the collateral damage that is being generated to non-target species that coexist in these marine environments, recommending new regulations to implement the use of new lighting technologies (ecological lamps) in aquaculture and in urban areas associated with the coast.
Notas
Tesis (Doctora en Medicina de la Conservación)
Proyecto Fondecy N° 1171056 “Direct and indirect effects of artificial light pollution on a sandy beach arthropod guild” y Fondecyt N°1200794 “Multiple characteristics of artificial light pollution at night (ALAN) as drivers of change in sandy beach organisms” ambos del PI Dr. Cristian Duarte.
Proyecto Fondecy N° 1171056 “Direct and indirect effects of artificial light pollution on a sandy beach arthropod guild” y Fondecyt N°1200794 “Multiple characteristics of artificial light pollution at night (ALAN) as drivers of change in sandy beach organisms” ambos del PI Dr. Cristian Duarte.
Palabras clave
Contaminación Lumínica, Plancton Marino, Cirripedios, Larvas, Desarrollo, Investigaciones