Gonzalo Saldías

University of Bío-Bío | UBB · Department of Physics

The Columbia River (CR) is the largest source of freshwater along the U.S. Pacific coast. The resultant plume is often transported southward and offshore forming a large buoyant feature off Oregon and northern California in spring-summer - the offshore CR plume. Observations from autonomous underwater gliders and Moderate Resolution Imaging Spectro...

Climatological hydrographic data for the southeastern Pacific from the World Ocean Atlas show an extended low-salinity region associated with high rainfall/river runoff along the Chilean Patagonia coast. However, the structure and variability of this extensive freshwater area is poorly understood due to the lack of periodic hydrographic observation...

The response of a coastal ocean numerical model, typical of eastern boundaries, is investigated under upwelling-favorable wind forcing and with/without the presence of a submarine canyon. Experiments were run over three contrasting shelf depth/slope bathymetries, and forced by an upwelling favorable alongshore wind. Random noise in the wind stress...

The influence of climate variability on the Northeast Pacific (NEP) ocean is mainly linked to the impact of El Niño Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO), and North Pacific Gyre Oscillation (NPGO) on the modulation of coastal circulation, coastal upwelling, and ecosystem response. The impact of climate variability on th...

Plain Language Summary There are several ways in which deep water can reach the shallower coastal ecosystem near shore. Recent observations show evidence that coastal trapped waves, which are a special type of wave that travels close to the coast always keeping the land on its right (left) side in the northern (southern) hemisphere, can bring this...

The response of a coastal ocean model, simulating a typical Eastern Boundary system, to downwelling-favorable winds with and without the presence of a submarine canyon is studied. Three contrasting bathymetric configurations, considering shelves with different depth and slopes, are evaluated. Experiments without a submarine canyon represent the wel...

RESUMEN El golfo de Arauco, situado en Chile centro-sur, es una de las zonas con las tasas más altas de producción biológica en el Sistema de Corrientes de Humboldt Sur. En este golfo, donde la actividad urbano-industrial convive con comunidades pesqueras y concesiones acuícolas, son múltiples los forzantes físicos que influyen en la variabilidad e...

Changes in phytoplankton composition and abundance are controlled by multiple factors, including physical forcing and nutrient stoichiometry. This study seeks to assess the interplay between the environmental and biogeochemical conditions in shaping the phytoplankton community structure in open ocean waters off western Patagonia. For this purpose,...

The variability of phytoplankton dynamics is a crucial component of coastal biogeochemical cycles at various spatial-temporal scales. A key geophysical parameter that advances our understanding of phytoplankton dynamics in coastal zones is the remote sensing reflectance (Rrs), which can be used as a proxy for the concentrations of colored dissolved...

The influence of Biobio Canyon on the circulation and coastal upwelling and downwelling was evaluated by using high-resolution hydrodynamic simulations of the coastal ocean off central Chile, a highly productive zone of the Southern Humboldt Current System that supports important coastal ecosystem services. The model bathymetry was GEBCO 2020 with...

Over the recent decades, an apparent worldwide rise in Harmful Algae Blooms (HABs) has been observed due to the growing exploitation of the coastal environment, the exponential growth of monitoring programs, and growing global maritime transport. HAB species like Alexandrium catenella—responsible for paralytic shellfish poisoning (PSP)—Protoceratiu...

The response of a coastal ocean model, simulating a typical Eastern Boundary system, to downwelling-favorable winds with and without the presence of a submarine canyon is studied. Three contrasting bathymetric configurations, considering shelves with different depth and slopes, are evaluated. Experiments without a submarine canyon represent the wel...

Colored dissolved organic matter (CDOM) is an indicator and optical proxy of terrestrial processes such as land use with allochthonous material fluxes, biogeochemical cycles, and water quality in coastal zones influenced by rivers. However, the role of land use changes on the spatial and temporal availability of CDOM has been poorly explored in Chi...

Concepción Bay is a socio-economic and ecologically important embayment, whose hydrographic variability has been historically regulated by wind-modulated seasonal upwelling events during spring-summer and by freshwater from precipitation and river discharges during fall-winter. This system is subject to several anthropogenic and environmental strai...

Green algae blooms of the genus Ulva are occurring globally and are primarily attributed to anthropogenic factors. At Los Tubos beach in Algarrobo Bay along the central Chilean coast, there have been blooms of these algae that persist almost year-round over the past 20 years, leading to environmental, economic, and social issues that affect the loc...

The coastal ocean off western Patagonia is one of the main coastal regions with high freshwater inputs from rivers, rain, and glaciers in the Southern Hemisphere. This study conducts an analysis of the seasonal and interannual variations in sea surface salinity and meridional geostrophic transports, specifically focusing on the Cape Horn Current, u...

Small coastal rivers often discharge directly into the surfzone, where the fate of freshwater and river-borne materials (e.g., sediment, nutrients and contaminants) is primarily determined by interactions between buoyant plume processes and the nearshore wave forcing. Understanding river-wave interactions in the surfzone is essential to assess coas...

Submarine canyons are topographic discontinuities where non-linear complex dynamics modify the flow along the isobaths, causing strong cross-shelf transport and topographic upwelling. Within canyons, advective transport can retain organisms and particles, especially when organisms modify their vertical distribution by vertical migrations. These pro...

River plumes have a direct influence on coastal environments, impacting coastal planktonic and benthic communities, including fishery resources. In general, the main drivers of river plume dynamics are the river discharge and the alongshore wind stress, whereas the tides and topography play a secondary role. In central Chile, rivers flowing into th...

In recent decades, global dissolved oxygen (DO) measurements have registered a decrease of ∼1%–2% in oxygen content, raising concerns regarding the negative impacts of ocean deoxygenation on marine life and the greenhouse gas cycle. By combining in situ data from 2016 to 2022, satellite remote sensing, and outputs from a physical‐biogeochemical mod...

Spatial synchrony occurs when geographically separated time series exhibit correlated temporal variability. Studies of synchrony between different environmental variables within marine ecosystems worldwide have highlighted the extent of system responses to exogenous large-scale forcing. However, these spatial connections remain largely unstudied in...

The coast of central Chile has multiple rivers with a marked seasonal discharge variability. Few studies have addressed primarily the seasonal variability of river plume extension and vertical structure. Here, we have analyzed the effects of multiple river outflows on the hydrography (salinity and density) and meridional transports off central Chil...

Mass stranding events of different taxonomic groups are periodic in certain coastal regions worldwide, but the underlying causes for these occurrences are not yet fully understood. In the Eastern Pacific Ocean (EPO), the most frequent and documented mass strandings correspond to the jumbo squid Dosidicus gigas, but the different hypotheses proposed...

The methylation of DNA is an environmentally inducible epigenetic mechanism reflecting the short‐term ecological and environmental background of populations. Marine invertebrate populations, which spread along a latitudinal cline, are particularly suitable for profiling DNA methylation, due to the heterogenous environmental conditions experienced....

Euphausiids (hereafter “krill”) are one of the main components of the pelagic communities of the Humboldt Current System (HCS). Their community dynamics have been well studied in central-southern Chile where upwelling is strongly seasonal, but little is known about the permanent-upwelling area of the HCS, which yields the largest fishery in the wor...

Harmful Algal Blooms (HAB) pose a severe socio-economic problem worldwide. The dinoflagellate species Alexandrium catenella produces potent neurotoxins called saxitoxins (STXs) and its blooms are associated with the human intoxication named Paralytic Shellfish Poisoning (PSP). Knowing where and how these blooms originate is crucial to predict bloom...

The biogeochemical dynamics of fjords in the southeastern Pacific Ocean are strongly influenced by hydrological and oceanographic processes occurring at a seasonal scale. In this study, we describe the role of hydrographic forcing on the seasonal variability of the carbonate system of the Sub-Antarctic glacial fjord, Seno Ballena, in the Strait of...

Ciclo diario de las variables oceanográficas en el Seno Reloncaví para el período estival 2021: una mirada en alta resolución temporal al paso de un frente termohalino Introducción El seno Reloncaví (SR) es un sistema semicerrado rodeado de una línea de costa casi circular que se conecta por el este con el estuario de Reloncaví (ER) y al sur con el...

The response of inner shelf circulation and bottom temperature variability to synoptic wind forcing and freshwater outflow is evaluated in an area with a wide continental shelf off central Chile. This forced circulation, with a strong seasonal evolution from upwelling- to downwelling-favorable conditions, is a key process modulating the exchange of...

Northern Patagonia is characterized by multiple rivers that discharge considerable amounts of freshwater into the coastal ocean, forming large river plumes that influence hydrographic and ecological processes. In this study, we use satellite ocean color data from MODIS (Moderate Resolution Imaging Spectroradiometer) to characterize the seasonal and...

A shortage of dissolved oxygen in seawater can adversely impact marine life and ecosystems. Low oxygen conditions at depth occur in many coastal regions, driven by both local productivity and remote changes in the source waters. A low‐oxygen dense pool of water is observed every summer over the mid‐shelf off southwest Vancouver Island in the Juan d...

Coastal upwelling ecosystems support some of the most productive fisheries of the planet together with a large shellfish aquaculture sector that depends on oceanographic processes to deliver planktonic larvae to replenish and feed the farmed stock. Coastal shellfish aquaculture operations in Chile and Perú have experienced large interannual fluctua...

Human activities have led to an increase in land use change, with effects on the structure and functioning of ecosystems. The impact of contrasting land uses along river basins on the concentration of colored dissolved organic matter (CDOM) reaching the coastal zone, and its relationship with the carbonate system of the adjacent coastal ocean, is p...

Euphausiids are crustaceans with a complex life cycle that play a significant role in the trophic pathways of the highly productive Humboldt Upwelling System. We studied the effect of upwelling and climate variability on the austral spring distribution and abundance of krill life stages using 8 years of physical and biological sampling off northern...

The coastal region off Chilean Patagonia has been poorly studied due to the lack of available observations. Here we analyzed, by the very first time, biogeochemical (BGC) data to elucidate the role that biological and physical processes play on nitrate, oxygen, pH and hydrographic variables, along a salinity gradient off central Patagonia. Argo flo...

Using 19 years of remotely sensed Enhanced Vegetation Index (EVI), we examined the effects of climatic variability on terrestrial vegetation of six protected areas along southwestern South America, from the semiarid edge of the Atacama desert to southern Patagonia (30°S-51°S). The relationship between satellite phenology and climate indices, namely...

Estuaries and saltmarshes represent a fundamental component in the life cycle of many crab species. Diverse studies show that temperature and salinity may modulate abundance, size fre- quency distribution (SFD), sex ratio and growth in crustaceans. These population parameters are usually challenging to estimate due to the high environmental variabi...

The upwelling shadow in the Gulf of Arauco (GA) is studied using 15 years of daily satellite images of Sea Surface Temperature (SST) from Geostationary Operational Environmental Satellites (GOES), as well as heat flux and wind data from the ERA5 reanalysis product. An Upwelling Shadow Index (USI) is developed based on the SST differences between th...

Northern Patagonia is one of the largest estuarine systems worldwide. It is characterized by complex geography, including islands, peninsulas, channels, and fjords. Here, the Inner Sea of Chiloé (ISC) is the largest estuarine system extending about 230 km in the meridional direction.Phytoplankton’s long-term dynamics and the main physical drivers o...

The vast spatial extent of the ocean presents a major challenge for monitoring changes in marine biodiversity and connecting those changes to management practices. Remote-sensing offers promise for overcoming this problem in a cost-effective, tractable way, but requires interdisciplinary expertise to identify robust approaches. In this study, we us...

This study assessed natural variation in the macroinvertebrate assemblages (MIB) and water quality in one of the main basins with the largest agricultural activities in Chile (Aconcagua River Basin). We sampled throughout the annual cycle; nine sampling sites were established along the basin, classifying according to agricultural area coverage as l...

Surface oceanic fronts are regions characterized by high biological activity. Here, Sea Surface Temperature (SST) fronts are analyzed for the period 2003-2019 using the Multi-scale Ultra-high Resolution (MUR) SST product in northern Patagonia, a coastal region with high environmental variability through river discharges and coastal upwelling events...

The increasing shellfish aquaculture requires knowledge about nearshore environmental variability to manage sustainably and create climate change adaptation strategies. We used data from mooring time series and in situ sampling to characterize oceanographic and carbonate system variability in three bivalve aquaculture areas located along a latitudi...

The analysis of synoptic satellite data of total chlorophyll-a (Chl-a) and the environmental drivers that influence nutrient and light availability for phytoplankton growth allows us to understand the spatio-temporal variability of phytoplankton biomass. In the Panama Bight Tropical region (PB; 1–9ºN, 79–84ºW), the spatial distribution of Chl-a is...

• The spatial variation in community structure among 30 areas for the management and exploitation of benthic resources (AMEBRs) in central Chile was assessed from surveys conducted during the same spring–summer season. One hundred taxa identified in the subtidal surveys were grouped into 10 functional groups. • The influence and relative importance...

The variability of thermal fronts in eastern ocean boundaries has received increased attention because of being active regions of vertical fluxes of tracers and biological activity. Sea Surface Temperature (SST) images from three distinct satellite products are used to identify areas with enhanced surface thermal gradients (i.e. thermal fronts) in...

Coastal upwelling regions represent less than 2% of the marine biosphere's volume. Nonetheless, local biogeochemical processes have a considerable impact on the structure and functioning of the global oceans. In this study we characterize the evolution of biogeochemical properties during the upwelling seasons of 2009 and 2010 in the coastal ecosyst...

Over the last century climate change has impacted the physiology, distribution and phenology of marine and terrestrial primary producers worldwide. The study of these fluctuations has been hindered due to the complex response of plants to environmental forcing over large spatial and temporal scales. To bridge this gap, we investigated the synchrony...

Aim: We assess the spatial distribution of a suite of coastal biophysical characteristics and how their variability is related to the distribution and geographic range of a diverse assemblage of coastal benthic species with different larval dispersal strategies. Location: South-eastern Pacific (SEP) coast between 18°20’S and 42°35’S. Methods: Bioph...

Western Patagonia harbors unique and sparsely studied terrestrial ecosystems that are threatened by land use changes and exposure to basin-scale climatic variability. We assessed the performance of two satellite vegetation indices derived from MODIS — Terra, EVI (Enhanced Vegetation Index) and NDVI (Normalized Difference Vegetation Index), over the...

The coastal margin of the Pacific Northwest of the United States is a highly dynamic and productive region. Here, we use satellite, high-frequency mooring, and glider estimates of biologically relevant physical and optical variables to characterize seasonal patterns and latitudinal and cross-shore gradients in particle concentrations between the Wa...

The upwelling system off central Chile (36.5∘ S) is seasonally subjected to oxygen (O2)-deficient waters, with a strong vertical gradient in O2 (from oxic to anoxic conditions) that spans a few metres (30–50 m interval) over the shelf. This condition inhibits and/or stimulates processes involved in nitrogen (N) removal (e.g. anammox, denitrificatio...

The use of remote sensing has allowed enormous progress in our understanding of biophysical processes worldwide. Despite their importance, the use of satellite bio-optical products is still limited due to their optical complexity. In this study we assess the performance of the Moderate Resolution Imaging Spectroradiometer algorithm for chlorophyll-...

The Columbia River delivers the greatest amount of freshwater to the coastal ocean along the U.S. Pacific coast. This freshwater forms the Columbia River plume, a mesoscale plume with significant implications on coastal ocean physical, biological, chemical, and geological processes. The plume is transported south and offshore during the upwelling s...

The Douro River represents the major freshwater input into the coastal ocean of the northwestern Iberian Peninsula. The seasonal and interannual variability of its turbid plume is investigated using ocean color composites from MODIS (Moderate Resolution Imaging Spectroradiometer) sensor aboard the Aqua and Terra satellites (2000-2014) and long-term...

The upwelling system off central Chile (36.5&degree: S) is seasonally subjected to oxygen (O2) deficient waters, with a strong vertical gradient in O2 varying from oxic to anoxic conditions on a scale of a few meters (30–50 m interval) over the shelf. This condition inhibits and/or stimulates processes involved in nitrogen (N) removal (e.g., anammo...

Geographically widespread species must cope with environmental differences between habitats. Information concerning geographic variations in response to climate variability is critical because many morphological, life-history and physiological traits show variation across space. Reciprocal transplant experiments have shown to be relevant to evaluat...