Pinnipeds as new sentinel on plastic pollution
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Archivos
Fecha
2019
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Profesor/a Guía
Facultad/escuela
Idioma
en
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Universidad Andrés Bello
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Licencia CC
Licencia CC
Resumen
La acumulación plásticos se ha convertido en una problemática global, generando
efectos perjudiciales en los ambientes marinos. Estos son diferentes en función del tamaño
de los plásticos (Micro o Macroplásticos), ya que la exposición a los mismos es diferente.
Como ejemplos, se destaca para microplásticos su toxicidad por los químicos que los
componen o pueden transportar. Como para macroplásticos, la mortalidad causada por
enredos e inanición por ingesta. Actualmente, se calcula que los microplásticos, y en especial
las microfibras, son el tamaño predominante en los océanos. Convirtiéndose en un tema
ampliamente estudiado actualmente en diversas líneas de investigación.
Recientemente múltiples trabajos se han publicado respecto a la ingesta y los efectos
de los microplásticos como contaminantes bioacumulables en las tramas tróficas. Sin
embargo, esto no ha sido investigado en profundidad en mamíferos marinos hasta la fecha,
siendo los organismos topes en las tramas tróficas de distintos ecosistemas marinos.
Evidencia publicada hasta la fecha indica que los plásticos de menor tamaño, y entre ellos
las microfibras, tienen el mayor potencial para biomagnificarse a medida que ascendemos en
la trama trófica. A la fecha hay trabajos que sugieren una relación entre biomarcadores de
salud de mamíferos marinos en zonas con niveles elevados de contaminación ambiental por
microplásticos. No obastante, todavía existen vacíos en el conocimiento.
Dentro de los mamíferos marinos, el grupo más susceptible a sufrir enredos en
macroplásticos son los pinnípedos. Siendo especies ampliamente distribuidas y
representativas de un diverso grupo de ecosistemas marinos. No obstante, no se ha
encontrado un patrón definido a nivel mundial ni sus efectos sobre las poblaciones de
pinnípedos. Por ejemplo, ya se ha estudiado el efecto de los macroplásticos sobre tortugas y
aves marinas, demostrando el impacto de estos contaminantes sobre los distintos ambientes
marinos a nivel mundial. Aun así, en mamíferos es muy poco lo que se conoce.
Por estas razones, se hace necesario monitorizar cual es el daño que se está generando
en los distintos ecosistemas marinos y costeros altamente productivos para poder realizar
comparaciones y poder prevenir a tiempo posibles impactos no deseados como consecuencia
del aumento de este contaminante. Debido al amplio conocimiento sobre su
comportamientos, fisiología, inmunología, reproducción y dinámicas poblacionales, los
pinnípedos son considerados como útiles centinelas de la salud de los ecosistemas. Por ello,
este proyecto busca proponer a los pinnípedos como biomonitores de la contaminación tanto
de micro como macroplásticos sobre los ecosistemas marinos. Para ello se evaluaron tres
objetivos (uno para cada capítulo).
Para evaluar la contaminación microplástica, se examinaron 51 heces femeninas de
una población de la Patagonia Norte. Los resultados no mostraron presencia de partículas
microplásticas, sin embargo el 67% de ellas mostraron una notable abundancia de
microfibras, que hasta ahora sólo se habían reportado en animales alimentados en cautiverio.
Como resultado de este trabajo proponemos que el examen de las heces de la foca de piel de
Sudamérica y también de otros pinnípedos pueda ser una herramienta eficiente para
monitorear los niveles ambientales de microfibras y tal vez microplásticos en el medio
ambiente debido al fácil reconocimiento de los animales y sus heces. A partir de estos
resultados se generó una monitorización de la concentración de microplásticos (fragmentos
y fibras) en las escisiones (n=205) de cuatro especies/subespecies de pinnípedos, a través de
cinco localidades diferentes en el Océano Pacífico sur (Perú y Chile). Las muestras de todas
las colonias contenían microplásticos y, en general, el 68% de las muestras examinadas
contenían microplásticos. Las rookeries situadas fuera de la placa continental (rookeries
oceánicas) tienen una mayor concentración microplástica que las rookeries situadas en la
placa continental (rookeries costeras). Las diferentes dietas de cada especie, y las
distribuciones de las áreas de distribución en el hogar, probablemente explican nuestros
resultados. El estudio presenta una técnica no invasiva útil para rastrear la contaminación
plástica en las dietas de los principales depredadores como bioindicadores para futuros planes
de vigilancia y manejo.
Para evaluar los efectos macroplásticos sobre los pinnípedos, se registraron
parámetros poblacionales clave, así como las proporciones de enredo (es decir, la relación
entre el número de enredo y el número de población) de una colonia sudamericana de lobos
marinos en la isla de Guafo, Chile. Parametrizamos un modelo de población de matriz
estocástica estructurado por clases de etapa para predecir las tasas de crecimiento de la
población bajo cinco escenarios: A) sin enredos, B) proporciones de enredos observadas en
nuestra población de estudio (1.2x10-3); y aumentando las proporciones de enredos por la
literatura: C) 3.04x10-3, D) 4.42x10-2, y E) 8.39x10-2. La tasa de crecimiento de la
población fue menor en todos los escenarios con enredo (B-E) en comparación con el
escenario A, disminuyendo entre el 20,34% (escenario B) y el 91,38% (escenario E) del
número total proyectado en el escenario A (~2.950 individuos). Estos resultados sugieren que
incluso los niveles más bajos de proporción de enredo reportados en la literatura podrían
tener efectos significativos a nivel poblacional en los pinnípedos.
Finalmente, para identificar las áreas más vulnerables a la contaminación
macroplástica, se utilizaron dos Modelos Aditivos Generalizados (GAMs) que incluían
números de enredo reportados, covariables del esfuerzo pesquero (basadas en diferentes tipos
de artes) y desechos plásticos flotantes para cada distribución de especies por colonia de
estudio. Estos modelos nos permitieron desarrollar mapas de puntos calientes globales que
predicen las regiones más vulnerables donde los pinnípedos sufren enredos en redes
fantasma. Los cofactores más relevantes para ambos modelos fueron tanto las especies
encontradas como el tipo de arte de pesca (Trampa, Cerco, Cerco no atunero, Cerco atunero
y red de enmalle) fueron los factores más importantes para predecir los enredos de
pinnípedos. Se predice que las pesquerías estacionarias son la mayor amenaza para el enredo
de pinnípedos, lo cual es probable debido a que estas pesquerías están ampliamente
distribuidas y son propensas a la captura incidental. Este enfoque es útil para identificar
regiones geográficas de alta prioridad para reducir las interacciones entre los artes de pesca
y los pinnípedos.
Probando con estos resultados, que los pinnípedos podrían ser los adecuados para
evaluar la contaminación por plásticos en los ecosistemas marinos a nivel mundial.
The accumulation of plastics has become a global problem, generating harmful effects in marine environments. These are different depending on the size of the plastics (Micro or Macroplastics), as the exposure to them is different. As examples, microplastics stand out for their toxicity due to the chemicals that compose them or can transport them. As for macroplastics, mortality caused by entanglements and starvation by ingestion. Currently, it is estimated that microplastics, and especially microfibres, are the predominant size in the oceans. It has become a widely studied topic in several lines of research. Recently multiple papers have been published regarding the intake and effects of microplastics as bioaccumulative contaminants in trophic wefts. However, this has not been investigated in depth in marine mammals to date, the organisms being tops in the trophic wefts of different marine ecosystems. Published evidence to date indicates that smaller plastics, including microfibers, have the greatest potential to biomagnify as we ascend the trophic weft. To date, there are studies that suggest a relationship between health biomarkers of marine mammals in areas with high levels of environmental pollution by microplastics. However, there are still gaps in knowledge. Within marine mammals, the group most susceptible to macroplastic entanglements are pinnipeds. There is no definite pattern of the effect of these pollutants at a global level or their effects on pinniped populations. These species are widely distributed and representative of a diverse group of marine ecosystems. However, the effect of macroplastics on turtles and seabirds has already been studied, demonstrating the impact of these pollutants on different marine environments worldwide. Even so, little is known about mammals. For these reasons, it is necessary to monitor the damage that is being generated in different marine and coastal ecosystems in order to make comparisons and be able to prevent possible undesirable impacts in time as a result of the increase in this pollutant. Due to the wide knowledge about their behavior, physiology, immunology, reproduction and population dynamics, pinnipeds are considered as useful sentinels of ecosystem health. Therefore, this project seeks to propose pinnipeds as biomonitors of both micro and macroplastic pollution on marine ecosystems. In order to do this it were evaluated three objectives (one for each chapter). To evaluate the microplastic pollution, it were examined 51 female scats from a population in Northern Patagonia. The results showed no presence of microplastic particles, however 67% of them showed a remarkable abundance of microfibers, which until now had only been reported in animals fed in captivity. As a result of this work we propose that the examination of scats from South American Fur Seal and also other pinnipeds could be an efficient tool to monitor environmental levels of microfibres and maybe microplastics in the environment due to the easy recognition of the animals and their scats. Following these results was generated a monitorization of microplastics (fragments and fibers) concentration in the scats (n=205) of four pinniped species/subspecies, throughout five different locations in the southern Pacific Ocean (Peru and Chile). Samples from all rookeries contained microplastics, and overall, 68% of the examined scats contained microplastics. Scats from rookeries located outside the continental plate (oceanic rookeries) had a higher microplastic concentration than rookeries located on the continental plate (costal rookeries). The different diets of each species, and home range distributions, probably explain our results. The study presents a useful non-invasive technique to track plastic pollution in top predator diets as bioindicators for future surveillance/management plans. In order to evaluate macroplastic effects over pinnipeds, it was recorded key population parameters as well as entanglement ratios (i.e. the ratio between entanglement number and population number) of a South American fur seal colony at Guafo Island, Chile. We parametrized a stochastic matrix population model structured by stage classes in order to predict the population growth ratios under five scenarios: A) without entanglements, B) entanglements ratios observed in our study population (1.2x10-3 ); and increasing entanglements ratios by literature: C) 3.04x10-3 , D) 4.42x10-2 , and E) 8.39x10-2 . The population growth rate was lower in all the scenarios with entanglement (B-E) in comparison with scenario A, decreasing between 20.34% (scenario B) to 91.38% (scenario E) of the projected total number in the scenario A (~2,950 individuals). These results suggest that even the lowest levels of entanglement ratio reported in the literature might have significant effects at the population-level in pinnipeds. Finally, for identify areas most vulnerable to macroplastic contamination, it was used two Generalized Additive Models (GAMs) which included reported entanglement numbers, covariates of fishing effort (based on different gear type) and floating plastic debris for each species distribution per study colony. These models allowed us to develop global hotspots maps that predict the most vulnerable regions where pinnipeds suffer entanglements in ghost nets . The two best models both found species and fishing gear type (Trap, Seine, Purse seine Non-tuna, Purse seine Tuna and Gillnet) were the most important factors to predicted entanglements of pinnipeds. Stationary fisheries are predicted as the highest threat to pinniped entanglement, which is likely because such fisheries are widely distributed and prone to bycatch. This approach is useful to identify geographic regions of high priority to reduce interactions between fishing gear and pinnipeds. Proving with these results, that pinnipeds are goodare suitable to be selected as sentinels to evaluate plastic pollution in marine ecosystems worldwide
The accumulation of plastics has become a global problem, generating harmful effects in marine environments. These are different depending on the size of the plastics (Micro or Macroplastics), as the exposure to them is different. As examples, microplastics stand out for their toxicity due to the chemicals that compose them or can transport them. As for macroplastics, mortality caused by entanglements and starvation by ingestion. Currently, it is estimated that microplastics, and especially microfibres, are the predominant size in the oceans. It has become a widely studied topic in several lines of research. Recently multiple papers have been published regarding the intake and effects of microplastics as bioaccumulative contaminants in trophic wefts. However, this has not been investigated in depth in marine mammals to date, the organisms being tops in the trophic wefts of different marine ecosystems. Published evidence to date indicates that smaller plastics, including microfibers, have the greatest potential to biomagnify as we ascend the trophic weft. To date, there are studies that suggest a relationship between health biomarkers of marine mammals in areas with high levels of environmental pollution by microplastics. However, there are still gaps in knowledge. Within marine mammals, the group most susceptible to macroplastic entanglements are pinnipeds. There is no definite pattern of the effect of these pollutants at a global level or their effects on pinniped populations. These species are widely distributed and representative of a diverse group of marine ecosystems. However, the effect of macroplastics on turtles and seabirds has already been studied, demonstrating the impact of these pollutants on different marine environments worldwide. Even so, little is known about mammals. For these reasons, it is necessary to monitor the damage that is being generated in different marine and coastal ecosystems in order to make comparisons and be able to prevent possible undesirable impacts in time as a result of the increase in this pollutant. Due to the wide knowledge about their behavior, physiology, immunology, reproduction and population dynamics, pinnipeds are considered as useful sentinels of ecosystem health. Therefore, this project seeks to propose pinnipeds as biomonitors of both micro and macroplastic pollution on marine ecosystems. In order to do this it were evaluated three objectives (one for each chapter). To evaluate the microplastic pollution, it were examined 51 female scats from a population in Northern Patagonia. The results showed no presence of microplastic particles, however 67% of them showed a remarkable abundance of microfibers, which until now had only been reported in animals fed in captivity. As a result of this work we propose that the examination of scats from South American Fur Seal and also other pinnipeds could be an efficient tool to monitor environmental levels of microfibres and maybe microplastics in the environment due to the easy recognition of the animals and their scats. Following these results was generated a monitorization of microplastics (fragments and fibers) concentration in the scats (n=205) of four pinniped species/subspecies, throughout five different locations in the southern Pacific Ocean (Peru and Chile). Samples from all rookeries contained microplastics, and overall, 68% of the examined scats contained microplastics. Scats from rookeries located outside the continental plate (oceanic rookeries) had a higher microplastic concentration than rookeries located on the continental plate (costal rookeries). The different diets of each species, and home range distributions, probably explain our results. The study presents a useful non-invasive technique to track plastic pollution in top predator diets as bioindicators for future surveillance/management plans. In order to evaluate macroplastic effects over pinnipeds, it was recorded key population parameters as well as entanglement ratios (i.e. the ratio between entanglement number and population number) of a South American fur seal colony at Guafo Island, Chile. We parametrized a stochastic matrix population model structured by stage classes in order to predict the population growth ratios under five scenarios: A) without entanglements, B) entanglements ratios observed in our study population (1.2x10-3 ); and increasing entanglements ratios by literature: C) 3.04x10-3 , D) 4.42x10-2 , and E) 8.39x10-2 . The population growth rate was lower in all the scenarios with entanglement (B-E) in comparison with scenario A, decreasing between 20.34% (scenario B) to 91.38% (scenario E) of the projected total number in the scenario A (~2,950 individuals). These results suggest that even the lowest levels of entanglement ratio reported in the literature might have significant effects at the population-level in pinnipeds. Finally, for identify areas most vulnerable to macroplastic contamination, it was used two Generalized Additive Models (GAMs) which included reported entanglement numbers, covariates of fishing effort (based on different gear type) and floating plastic debris for each species distribution per study colony. These models allowed us to develop global hotspots maps that predict the most vulnerable regions where pinnipeds suffer entanglements in ghost nets . The two best models both found species and fishing gear type (Trap, Seine, Purse seine Non-tuna, Purse seine Tuna and Gillnet) were the most important factors to predicted entanglements of pinnipeds. Stationary fisheries are predicted as the highest threat to pinniped entanglement, which is likely because such fisheries are widely distributed and prone to bycatch. This approach is useful to identify geographic regions of high priority to reduce interactions between fishing gear and pinnipeds. Proving with these results, that pinnipeds are goodare suitable to be selected as sentinels to evaluate plastic pollution in marine ecosystems worldwide
Notas
Tesis (Doctor en Medicina de la Conservación)
Palabras clave
Pinnípedos, Investigaciones, Contaminación Marina, Chile