Diferencias tróficas entre Engraulis ringens (Jenyns, 1842) y Strangomera bentincki (Norman, 1936), en dos zonas de la corriente de Humboldt.
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Date
2025
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Universidad de Concepción
Abstract
El Sistema de la Corriente de Humboldt (SCH) es uno de los ambientes marinos más productivos del mundo, que sustentado por el ascenso de aguas subsuperficiales ricas en nutrientes que ascienden hasta la capa fótica, sostiene una de las actividades pesqueras más productivas del mundo. Engraulis ringens y Strangomera bentincki representan dos especies de importancia comercial para la flota artesanal e industrial de Chile. Especies con un amplio rango de distribución latitudinal como la anchoveta, se ven expuestas a condiciones ambientales diversas, a cambios en la disponibilidad de alimento y a cambios en la estructura trófica de los ecosistemas. La Zona Sur del SCH se caracteriza por presentar una marcada estacionalidad de las condiciones ambientales y oceanográficas, con un aporte estacional variable de nutrientes a través de los ríos, lo cual contrasta con la Zona Centro del SCH, donde los efluentes de agua dulce son escasos, y las condiciones ambientales de surgencia costera son persistentes a lo largo de todo el año. Cómo estas variaciones ambientales (latitudinales y estacionales) afectan la ecología trófica de estos peces pelágicos pequeños, es todavía poco conocido.
De manera reciente los isótopos estables (IE) de carbono y nitrógeno se han aplicado para estudiar la estructura de las tramas tróficas en los ecosistemas marinos. Las señales de nitrógeno (δ15N) son indicadoras del nivel trófico de los organismos, mientras que señales de carbono (δ13C) se emplean para identificar las fuentes de carbono orgánico que sustenta los consumidores, permitiendo identificar posibles variaciones estacionales en el uso del hábitat. Ambos IE pueden proporcionar información clave sobre la estructura trófica del ecosistema, las interacciones entre especies, y la asimilación de presas.
Empleando análisis de isótopos estables de δ13C y δ15N se analizó la variabilidad estacional en la ecología trófica de E. ringens y S. bentincki de dos zonas latitudinalmente distantes del Sistema de la Corriente de Humboldt: (Iquique 20°S, SCH Centro) y (Talcahuano 36°S, SCH Sur). El patrón de las condiciones ambientales estuvo acorde a lo descrito para ambas zonas, se observó un patrón más estable en el SCH Centro, mientras que en el SCH Sur las condiciones ambientales variaron estacionalmente. Las señales isotópicas de δ13C y δ15N variaron estacionalmente en los diferentes grupos funcionales muestreados (POM, Copépodos y Peces) de ambas zonas del estudio. Los resultados muestran que la anchoveta de ambas zonas ostró rangos estrechos de variaciones estacionales de δ13C (SCH central: 17,5‰ a -17,85‰; SCH sur: -15,53‰ a -15,85‰) pero marcadas diferencias entre zonas. Las anchovetas del SCH centro mostraron un rango inter estacional más amplio en los valores de δ15N (SCH central: 16,68‰ a 20,72 ‰; SCH sur: 16,70‰ -17,59‰), así como una amplitud trófica más amplia, donde el tamaño del Nicho Isotópico de anchoveta en la zona SCH centro fue alrededor de 3 veces superior al tamaño del nicho de la anchoveta en el SCH sur.
El solapamiento del nicho en la zona sur del SCH varió estacionalmente entre E. ringens y S. bentincki (mayor en verano (68,87% anchoveta, 97,69% S. común) y menor en invierno (30,62% anchoveta, 85,67% S. común)) acorde con la disponibilidad de alimento. Los valores del TP fueron mayores y más estables durante el año en la zona sur (excepto verano). El TP de E. ringens fue superior al TP de S. bentincki durante todas las estaciones del año.
Los resultados sugieren que aspectos tróficos asociados a variaciones ambientales pueden constituir mecanismos que impulsan la dinámica entre poblaciones de una misma especie en diferentes zonas latitudinalmente distantes. Este es el primer trabajo que considera la componente estacional en la ecología trófica de E. ringens y S. bentincki en el SCH. Resulta interesante comprender el rol de los peces pelágicos pequeños en el ambiente marino, las relaciones tróficas interespecíficas y su relación con las condiciones ambientales, ya que entregan información complementaria sobre la dinámica costera, el flujo de energía entre los niveles tróficos y aporta conocimiento fundamental para mejorar la gestión integrada de las pesquerías, cada vez más relevante en un contexto cambiante actual (debido a las modificaciones ambientales de distintas escalas espaciales y temporales (e.g cambio climático) o variaciones directas de origen antropogénico (presión pesquera)).
The Humboldt Current System (HCS) is one of the most productive marine environments in the world, sustained by the upwelling of nutrient-rich subsurface waters that ascend to the photic layer, sustaining one of the most productive fishing activities in the world. Engraulis ringens and Strangomera bentincki represent two species of commercial importance for Chile's artisanal and industrial fleet. Species with a wide latitudinal distribution range, such as anchoveta, are exposed to diverse environmental conditions, changes in food availability and changes in the trophic structure of ecosystems. The South Zone of the HCS is characterized by a marked seasonality of environmental and oceanographic conditions, with a variable seasonal input of nutrients through rivers, which contrasts with the Central Zone of the HCS, where freshwater effluents are scarce, and coastal upwelling environmental conditions are persistent throughout the year. How these environmental variations (latitudinal and seasonal) affect the trophic ecology of these small pelagic fishes is still poorly understood. Recently, stable isotopes (SI) of carbon and nitrogen have been applied to study the structure of trophic webs in marine ecosystems. Nitrogen signals (δ15N) are indicators of the trophic level of organisms, while carbon signals (δ13C) are used to identify the sources of organic carbon supported by consumers, allowing the identification of possible seasonal variations in habitat use. Both SI can provide key information on the trophic structure of the ecosystem, species interactions, and prey assimilation. Using stable isotope analysis of δ13C and δ15N, the seasonal variability in the trophic ecology of E. ringens and S. bentincki from two latitudinally distant areas of the Humboldt Current System were analyzed: (Iquique 20°S, HCS Central Zone) and (Talcahuano 36°S, HCS South Zone). The pattern of environmental conditions was in accordance with what was described for both zones, a more stable pattern was observed in the Central HCS, while in the South HCS the environmental conditions varied seasonally. The δ13C and δ15N isotopic signals varied seasonally in the different functional groups sampled (POM, Copepods and Fish) from both zones of the study. The results show that anchovy from both zones showed narrow ranges of seasonal variations of δ13C (central HCS: -17.5‰ to -17.85‰; south HCS: 15.53‰ to -15.85‰) but marked differences between zones. The anchovy in the central HCS showed a wider inter-seasonal range in δ15N values (central HCS: 16.68‰ to 20.72 ‰; south HCS: 16.70‰ -17.59‰), as well as a wider trophic breadth, where the anchovy Isotopic Niche size in the central HCS zone was about 3 times larger than the anchovy niche size in the south HCS. Niche overlap in the southern zone of the HCS varied seasonally between E. ringens and S. bentincki (higher in summer (68.87% anchovy, 97.69% S. común) and lower in winter (30.62% anchovy, 85.67% S. común)) according to food availability. TP values were higher and more stable during the year in the southern zone (except summer). The TP of E. ringens was higher than that of S. bentincki during all seasons. The results suggest that trophic aspects associated with environmental variations may constitute mechanisms that drive the dynamics between populations of the same species in different latitudinally distant areas. This is the first work that considers the seasonal component in the trophic ecology of E. ringens and S. bentincki in the HCS. It is interesting to understand the role of small pelagic fishes in the marine environment, the interspecific trophic relationships and their relationship with environmental conditions, since they provide complementary information on coastal dynamics, energy flow between trophic levels and contribute fundamental knowledge to improve integrated fisheries management, increasingly relevant in the current changing context (due to environmental modifications of different spatial and temporal scales (e.g. climate change) or direct variations of anthropogenic origin (fishing pressure)).
The Humboldt Current System (HCS) is one of the most productive marine environments in the world, sustained by the upwelling of nutrient-rich subsurface waters that ascend to the photic layer, sustaining one of the most productive fishing activities in the world. Engraulis ringens and Strangomera bentincki represent two species of commercial importance for Chile's artisanal and industrial fleet. Species with a wide latitudinal distribution range, such as anchoveta, are exposed to diverse environmental conditions, changes in food availability and changes in the trophic structure of ecosystems. The South Zone of the HCS is characterized by a marked seasonality of environmental and oceanographic conditions, with a variable seasonal input of nutrients through rivers, which contrasts with the Central Zone of the HCS, where freshwater effluents are scarce, and coastal upwelling environmental conditions are persistent throughout the year. How these environmental variations (latitudinal and seasonal) affect the trophic ecology of these small pelagic fishes is still poorly understood. Recently, stable isotopes (SI) of carbon and nitrogen have been applied to study the structure of trophic webs in marine ecosystems. Nitrogen signals (δ15N) are indicators of the trophic level of organisms, while carbon signals (δ13C) are used to identify the sources of organic carbon supported by consumers, allowing the identification of possible seasonal variations in habitat use. Both SI can provide key information on the trophic structure of the ecosystem, species interactions, and prey assimilation. Using stable isotope analysis of δ13C and δ15N, the seasonal variability in the trophic ecology of E. ringens and S. bentincki from two latitudinally distant areas of the Humboldt Current System were analyzed: (Iquique 20°S, HCS Central Zone) and (Talcahuano 36°S, HCS South Zone). The pattern of environmental conditions was in accordance with what was described for both zones, a more stable pattern was observed in the Central HCS, while in the South HCS the environmental conditions varied seasonally. The δ13C and δ15N isotopic signals varied seasonally in the different functional groups sampled (POM, Copepods and Fish) from both zones of the study. The results show that anchovy from both zones showed narrow ranges of seasonal variations of δ13C (central HCS: -17.5‰ to -17.85‰; south HCS: 15.53‰ to -15.85‰) but marked differences between zones. The anchovy in the central HCS showed a wider inter-seasonal range in δ15N values (central HCS: 16.68‰ to 20.72 ‰; south HCS: 16.70‰ -17.59‰), as well as a wider trophic breadth, where the anchovy Isotopic Niche size in the central HCS zone was about 3 times larger than the anchovy niche size in the south HCS. Niche overlap in the southern zone of the HCS varied seasonally between E. ringens and S. bentincki (higher in summer (68.87% anchovy, 97.69% S. común) and lower in winter (30.62% anchovy, 85.67% S. común)) according to food availability. TP values were higher and more stable during the year in the southern zone (except summer). The TP of E. ringens was higher than that of S. bentincki during all seasons. The results suggest that trophic aspects associated with environmental variations may constitute mechanisms that drive the dynamics between populations of the same species in different latitudinally distant areas. This is the first work that considers the seasonal component in the trophic ecology of E. ringens and S. bentincki in the HCS. It is interesting to understand the role of small pelagic fishes in the marine environment, the interspecific trophic relationships and their relationship with environmental conditions, since they provide complementary information on coastal dynamics, energy flow between trophic levels and contribute fundamental knowledge to improve integrated fisheries management, increasingly relevant in the current changing context (due to environmental modifications of different spatial and temporal scales (e.g. climate change) or direct variations of anthropogenic origin (fishing pressure)).
Description
Tesis presentada para optar al Grado de Magíster en Ciencias con Mención en Pesquerías
Keywords
Anchoveta Chile Zona Norte, Sardinas Chile Zona Norte, Corriente de Humboldt