Functional diversity of living benthic foraminifera of the Southeastern Pacific Ocean and their relationship with environmental variables.
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Date
2026
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Universidad de Concepción
Abstract
Los foraminíferos bentónicos son indicadores clave que proporcionan información sobre el funcionamiento de los ecosistemas a través de sus adaptaciones a los gradientes ambientales. En el presente estudio se evalúa la diversidad taxonómica y funcional de las comunidades de foraminíferos bentónicos vivos a lo largo del margen continental occidental de América del Sur (1°-50°S) y a profundidades de entre 79 y 4500 m. Se identificaron un total de 365 especies, siendo Rotalida, Lituolida y Astrorhizida los órdenes más frecuentes.
La riqueza y diversidad de especies mostraron una pronunciada variabilidad espacial estructurada no por un gradiente latitudinal continuo, sino por umbrales ambientales discretos, asociados principalmente a la disponibilidad de oxígeno. Los análisis de diversidad funcional revelaron que las comunidades más ricas desde el punto de vista taxonómico ocupaban un espacio de rasgos funcionales más amplio, aunque de forma desigual en toda la zona de estudio, lo que indica una redundancia funcional considerable. Este patrón se asocia a un fuerte proceso de selección ambiental de especies (filtrado ambiental), junto con asociaciones de alta diversidad taxonómica en los que se observó una saturación parcial del espacio funcional.
Por el contrario, los sectores heterogéneos promovieron una mayor diferenciación de nichos y diversificación funcional. Los rasgos medios ponderados por la comunidad respaldaron cambios latitudinales consistentes en la morfología, las estrategias tróficas y la tolerancia al oxígeno. Los modelos aditivos generalizados identificaron la temperatura, la salinidad, el oxígeno, las concentraciones de fosfato y silicato y las características de los sedimentos como factores determinantes de la diversidad taxonómica y funcional, siendo el oxígeno el factor estructurante dominante. Los análisis de nicho confirmaron un fuerte efecto de este filtrado ambiental en condiciones de bajo oxígeno, donde las comunidades estuvieron dominadas por especialistas que ocupaban nichos marginales.
Nuestros resultados demuestran que la disponibilidad de oxígeno regula la distribución de las especies, la configuración de los nichos y la organización funcional, modulando el equilibrio entre la redundancia y la diferenciación en los ecosistemas bentónicos del Pacífico sudoriental. Este estudio establece una base de referencia regional para evaluar las consecuencias ecológicas de la continua expansión de la OMZ en el Pacífico sudoriental.
Benthic foraminifera are key indicators that provide insights into ecosystem functioning through their adaptations to environmental gradients. This study assesses the taxonomic and functional diversity of living benthic foraminiferal communities along the western South American continental margin (1°–50°S) and water depths from 79 to 4500 m. A total of 365 species were identified, with Rotalida, Lituolida, and Astrorhizida as the most frequent orders. Species richness and diversity exhibited pronounced spatial variability structured not by a continuous latitudinal gradient, but by discrete environmental thresholds, primarily associated with oxygen availability. Functional diversity analyses revealed that taxonomically richer communities occupied broader functional trait space, though unevenly across the study area, indicating substantial functional redundancy. This pattern emerged under environmental filtering, particularly in highly diverse assemblages where partial saturation of trait space occurred. In contrast, heterogeneous sectors promoted greater niche differentiation and functional diversification. Community-weighted mean traits revealed consistent latitudinal shifts in morphology, trophic strategies, and oxygen tolerance. Generalized additive models identified temperature, salinity, oxygen, phosphate, silicate concentrations, and sediment characteristics as drivers of taxonomic and functional diversity, with oxygen emerging as the dominant structuring factor. Niche analyses were consistent with environmental filtering under oxygen-depleted conditions, where communities were dominated by specialists occupying marginal niches. Our results demonstrate that oxygen availability regulates species distributions, niche configuration, and functional organization, modulating the balance between redundancy and differentiation in benthic ecosystems of the Southeastern Pacific. This study establishes a regional baseline to assess ecological consequences of continued OMZ expansion in the Southeastern Pacific.
Benthic foraminifera are key indicators that provide insights into ecosystem functioning through their adaptations to environmental gradients. This study assesses the taxonomic and functional diversity of living benthic foraminiferal communities along the western South American continental margin (1°–50°S) and water depths from 79 to 4500 m. A total of 365 species were identified, with Rotalida, Lituolida, and Astrorhizida as the most frequent orders. Species richness and diversity exhibited pronounced spatial variability structured not by a continuous latitudinal gradient, but by discrete environmental thresholds, primarily associated with oxygen availability. Functional diversity analyses revealed that taxonomically richer communities occupied broader functional trait space, though unevenly across the study area, indicating substantial functional redundancy. This pattern emerged under environmental filtering, particularly in highly diverse assemblages where partial saturation of trait space occurred. In contrast, heterogeneous sectors promoted greater niche differentiation and functional diversification. Community-weighted mean traits revealed consistent latitudinal shifts in morphology, trophic strategies, and oxygen tolerance. Generalized additive models identified temperature, salinity, oxygen, phosphate, silicate concentrations, and sediment characteristics as drivers of taxonomic and functional diversity, with oxygen emerging as the dominant structuring factor. Niche analyses were consistent with environmental filtering under oxygen-depleted conditions, where communities were dominated by specialists occupying marginal niches. Our results demonstrate that oxygen availability regulates species distributions, niche configuration, and functional organization, modulating the balance between redundancy and differentiation in benthic ecosystems of the Southeastern Pacific. This study establishes a regional baseline to assess ecological consequences of continued OMZ expansion in the Southeastern Pacific.
Description
Tesis presentada para optar al grado de Magíster en Ciencias con mención en Zoología.
Keywords
Foraminifera, Ecosystem, Diversity, Aquatic biological, Niche (Ecology)