Inter-annual variability of oceanographic conditions and phytoplankton in Valparaíso Bay (~33°S), central Chile

Abstract

Variabilidad inter-anual de las condiciones oceanográficas y del fitoplancton en la bahía Valparaíso (~33°S), Chile centralResumen.-Se estudió la variabilidad inter-anual de las condiciones oceanográficas y de la abundancia y biomasa del fitoplancton en una estación fija ubicada en la bahía de Valparaíso (~33°S) usando 10 años (1986)(1987)(1988)(1989)(1990)(1991)(1992)(1993)(1994)(1995)(1996) de observaciones in situ. La serie temporal mostró vientos S-SO intensos y una cuasi-permanente actividad de surgencia que enriquecen de nutrientes la columna de agua y sustentan al fitoplancton en la bahía. El cambio más importante en las condiciones bio-oceanográficas fue observado durante el evento de El Niño 1987, con aumento de la temperatura, caída en la salinidad y en la concentración de nitrato y fosfato, así como en la biomasa del fitoplancton en comparación con La Niña 1988 cuando se detectó agua mas fría, salada y rica en nutrientes. Bajo condiciones El Niño (1987-1988 y 1993) se registraron altas descargas del río Aconcagua que precedieron la caída en la salinidad y el aumento en la abundancia de dinoflagelados. Se observaron dos periodos con diferencias en las condiciones oceanográficas; 1988-1992 presentó baja temperatura e incremento en los nutrientes (nitrato), la biomasa del fitoplancton y en la abundancia de diatomeas en comparación al periodo 1993-1996. A lo largo del periodo de estudio se registró una tendencia positiva en la surgencia, acompañada con una caída en la biomasa del fitoplancton y la abundancia de dinoflagelados. Este estudio proporciona nuevas evidencias sobre la influencia de El Niño Oscilación del Sur (ENOS) en el fitoplancton y las condiciones oceanográficas en la zona costera frente a Chile central.Abstract.-The inter-annual variability of oceanographic conditions and phytoplankton abundance and biomass was studied using 10 years (1986)(1987)(1988)(1989)(1990)(1991)(1992)(1993)(1994)(1995)(1996) of in situ observations at a fixed station in Valparaíso Bay (~33°S). The time series analysis revealed that strong S-SW winds drive a quasi-permanent upwelling activity that maintain the nutrients availability in the water column to fuel the phytoplankton in the bay. The most important changes in bio-oceanographic conditions were observed during 1987 El Niño event, which was characterized by higher temperatures but lower values for salinity, nitrate, and phosphate concentrations, together with a decrease of phytoplankton biomass compared to 1988 La Niña event when colder, saltier, and nutrient-rich upwelled water were observed. High Aconcagua River discharges were observed during the El Niño conditions (1987-1988 and 1993), which led to a decrease in surface salinity and a high abundance of dinoflagellates. Two periods with differences in bio-oceanographic conditions were observed; 1988-1992 showed lower temperatures but higher nutrients (nitrate), phytoplankton biomass and abundance of diatoms than 1993-1996 period. Throughout the study period, positive trends in upwelling activity was registe...

Influence of coastal upwelling on micro-phytoplankton variability at Valparaíso Bay (~33ºS), Central Chile

“…These changes are not related to river discharge as seen in other coastal upwelling systems, (e.g., California/Oregon, NW Iberian-Portugal coasts), or even in central-south Humboldt area. In those areas, freshwater input leads to changes in phytoplankton structure, biomass (Chl-a) and PP (Warrick et al 2005, Silva et al 2009, Iriarte et al 2012, Léniz et al 2012, Testa et al 2018, Aparicio-Rizzo & Masotti 2019.…”

“…These changes are related to wind-driven upwelling activity that promotes the arrival of nutrients to the surface. However, nutrients from rivers in Central Chile can also impact the phytoplankton (Iriarte et al 2012, Anabalón et al 2016, Aparicio-Rizzo & Masotti 2019. Seasonal freshwater discharge can impact coastal systems during weak upwelling activity periods when nutrient input from rivers can help maintain basal phytoplankton biomass (Chl-a) and PP (Léniz et al 2012, Testa et al 2018.…”

Spiractinospora alimapuensis gen. nov., sp. nov., isolated from marine sediment of Valparaíso Bay (Chile) and proposal for reclassification of two species of the genus Nocardiopsis

“…Valparaíso Bay is located between Punta Con-Con in the north and Punta Ángeles in the south, approximately at 33° latitude and 71° 5′ longitude, in the Valparaíso Region, Chile. The bay is oriented to the northwest and with a semicircular shape, presenting a coastal development of approximately 22.5 km () [29]. Ocean dynamics are determined by the presence of subantarctic waters of the Humboldt current, affected during the winter by continental contributions from the Aconcagua River, and in spring and summer by the influx of subsurface equatorial waters from upwelling processes [30, 31].…”