Samuel Hormazabal

Pontifical Catholic University of Valparaíso | PUCV · School of Ocean Sciences

The vertical variability in the oxygen minimum zone (OMZ) in the eastern South Pacific (ESP; 0–40°S) is characterized by the influence of anticyclonic intrathermocline eddies (ITEs), which are subsurface‐intensified mesoscale features that are frequently generated in the coastal upwelling zone off Peru and Chile. The unique lens‐shaped signatures t...

Mesoscale and submesoscale processes that contribute to localized increases in nutrients in the sunlit layer can stimulate phytoplankton growth and community changes, but the mechanisms involved remain sparsely documented with in situ data in the case of Eastern Boundary Upwelling Systems (EBUSs) and of most ocean regions. The role of diapycnal mix...

Understanding the influence of mesoscale and submesoscale features on the structure of phytoplankton is a key aspect in the assessment of their influence on marine biogeochemical cycling and cross-shore exchanges of plankton in Eastern Boundary Current Systems (EBCS). In this study, the spatio-temporal evolution of phytoplankton size classes (PSC)...

In Eastern Boundary Upwelling Systems, cold coastal waters are separated from offshore by a strong cross-shore Sea Surface Temperature (SST) gradient zone. This upwelling front plays a major role for the coastal ecosystem. This paper proposes a method to automatically identify the front and define its main characteristics (position, width, and inte...

An approach that improves the spectral-based PHYSAT method for identifying phytoplankton functional types (PFT) in satellite ocean-color imagery is developed and applied to one study case. This new approach, called PHYSTWO, relies on the assumption that the dominant effect of chlorophyll-a (Chl-a) in the normalized water-leaving radiance (nLw) spec...

Seamounts in the Juan Fernandez Ridge, as well as in other seamount regions in the eastern South Pacific and in the world oceans, remain poorly studied ecosystems in terms of structure and functioning. Here, community respiration by epipelagic mesozooplankton in three seamounts of the Juan Fernandez Ridge, including the O`Higgins Seamount close to...

In recent years, quasi-zonal mesoscale jet-like features or striations have been ubiquitously detected in the time-mean circulation of the world ocean using satellite altimetry and in situ data. Most likely the result of some organization of the mesoscale eddy field such as preferred eddy tracks, these striations may be able to advect and mix physi...

In eastern boundary current systems (EBCSs), submesoscale to mesocale variability contributes to cross-shore exchanges of water properties, nutrients, and plankton. Data from a short-term summer survey and satellite time series (January-February 2014) were used to characterize submesoscale variability in oceanographic conditions and phytoplankton d...

An intensification of upwelling-favorable winds in recent decades has been detected in some of the main eastern boundary current systems, especially at higher latitudes, but the response of coastal phytoplankton communities in the Humboldt Current System (HCS) remains unknown. At higher latitudes in the HCS (35-40°S), strong seasonality in wind-dri...

The effects of climate change on ocean conditions will have impacts on fish stocks, primarily through physiological and behavioural effects, such as changes in growth, reproduction, mortality and distribution. Habitat and distribution predictions for marine fishery species under climate change scenarios are important for understanding the overall i...

The Southeast Pacific, which encompasses the coasts of Peru and Chile, is one of the world's most productive regions resulting principally from the upwelling of subsurface nutrient-rich waters. Over the satellite altimetry era, there have been numerous evidence that surface mesoscale eddies play an important role in the offshore transport of rich c...

Mesoscale eddies are prominent structures in the world's oceans generating a high degree of spatial and temporal heterogeneity that influences zooplankton distribution. Euphausiids (krill) are a key zooplankton group mainly inhabiting coastal upwelling areas where high productivity, advection and eddy kinetic energy (EKE) play pivotal roles in the...

The annual cycle and phenology of phytoplankton (satellite-derived chlorophyll-a, Chl-a) in the coastal upwelling region off central-southern Chile, their time-space variation, and the extent of their coupling with those of wind-driven upwelling (as Zonal Ekman Transport, ZET), Sea Surface Temperature (SST), and Photosynthetically Active Radiation...

Regional Ocean Modeling System (ROMS) results, combined with chlorophyll-a (Chl-a) and satellite altimetry information as well as information from oceanographic cruises were analyzed to identify interactions between intrathermocline eddies (ITEs) and the Juan Fernandez Archipelago (JFA), and discuss their potential impact on surface Chl-a concentra...

The Easter Island Province (EIP) encompasses Easter Island (EI) and Salas y Gomez Island (SGI), which are located in the eastern boundary of the south Pacific subtropical gyre. This province is one of the most oligotrophic region in the world ocean with a high degree of endemism and distinguished by having the clearest waters in the world. Issues r...

Escuela de Ciencias del Mar, Pontificia Universidad Catolica de ValparaisoP.O. Box 1020, Valparaiso, Chile The Chilean oceanic islands have been received little attention, both scientifically and in terms of conservation. In fact, the first marine protected areas around these islands were created in the last two years, 10 years behind those establi...

Spatial and temporal variability of the island mass effect (IME; defined as local increases of phytoplankton associated with the presence of islands) at the Juan Fernández Archipelago (JFA) is analyzed using chlorophyll-a (Chl-a) satellite data, altimetry, sea surface temperature, wind, geostrophic currents and net heat flux over a ten year period...

Thee goal of the Pacific Ocean Boundary Ecosystem Climate Study (POBEX) was to diagnose the large-scale climate controls on regional transport dynamics and lower-trophic marine ecosystem variability in Pacific Ocean boundary systems. An international team of collaborators shared observational and eddy-resolving modeling datasets in the Northeast Pa...

The goal of the Pacific Ocean Boundary Ecosystem and Climate Study (POBEX) was to diagnose the large-scale climate controls on regional transport dynamics and lower trophic marine ecosystem variability in Pacific Ocean boundary systems. An international team of collaborators shared observational and eddyresolving modeling data sets collected in the...

The three-dimensional structure and the origin of mesoscale anticyclonic intrathermocline eddies (ITEs) in the coastal transition zone (CTZ) off central Chile (31-41°S) were analyzed through the combination of data from oceanographic cruises and satellite altimetry, and the application of an eddy-resolving primitive equation ocean model coupled wit...

Time-space fluctuations of chlorophyll-a (Chl-a) within the region off central-southern Chile (33-42 degrees S), and their association with meteorological-oceanographic conditions, were analyzed using satellite time series data (2002-2012). The mean distribution of moderate values of Chl-a (approximate to 0.5 mgm(-3)) in the northern section (33-38...

Las fluctuaciones en abundancia, biomasa, estructura de edad y patrones de distribución de los recursos pesqueros responden, entre otros, a la variabilidad ambiental. Estas respuestas son consecuencia tanto de efectos climáticos directos sobre los recursos como indirectos actuando sobre niveles tróficos relacionados. En este estudio se revisa: i) e...

Cape Ghir (similar to 31 degrees N), in the Canary Current System, is an area of permanent coastal upwelling with maximum intensity in summer-autumn, when a strong across-shore thermal gradient and increased mesoscale activity are present. The effects of spatial (cross-shore transect with 7 stations) and temporal (5 dates: from December 2008 to Oct...

Fluctuations in abundance, biomass, age structure and distribution patterns of fisheries often respond to environmental variability. These responses are a result of both direct climatic effects on resources and indirect action on related trophic levels. In this study we review: i) the state of knowledge about the physical mechanisms associated with...

Eighteen years of satellite data on sea level and wind stress in the southeastern Pacific region, were used to show the capabilities of Multitaper Method - Singular Value Decomposition (MTM-SVD) as a valuable method to analyze multiple time series distributed over a large area on the ocean. Here we performed a comprehensive review of the MTM-SVD me...

Off southern‐central Chile, the impact of spring upwelling variability on common sardine (Strangomera bentincki) recruitment was examined by analyzing satellite and coastal station winds, satellite chlorophyll, and common sardine recruitment from a stock assessment model. In austral spring, the intensity of wind‐driven upwelling is related to sea s...

Eighteen years of satellite data on sea level and wind stress in the southeastern Pacific region, were used to show the capabilities of Multitaper Method - Singular Value Decomposition (MTM-SVD) as a valuable method to analyze multiple time series distributed over a large area on the ocean. Here we performed a comprehensive review of the MTM-SVD me...

Mesoscale features are recurrently found in the Coastal Transition Zone (CTZ) off central-southern Chile (∼35–40°S), a region characterized by seasonal wind-driven coastal upwelling. In this study, oceanographic data from two consecutive cruises carried out during the upwelling season (January 2009) were combined with satellite time series data in...

Located approximately 360 nm off the coast of Chile there is a disjoint realm of two small oceanic islands systems, the Juan Fernández and the Desventuradas archipelago. Currently the local economy of the islands is almost exclusively supported by the harvest and trade of marine resources, focusing mainly on the exploitation of the rock lobster (Ja...

La variabilidad espacial y temporal del ciclo anual de la clorofila-α en el archipiélago de Juan Fernández se analiza usando ocho anos de datos satelitales de clorofila-α, viento, corrientes y nivel del mar. Este archipiélago está conformado por tres islas: Robinson Crusoe-Santa Clara (RC-SC) y Alejandro Selkirk (AS). Las islas RC-SC se encuentran...

Observations of surface drifters launched over the continental slope of Portugal (Bay of Setúbal) are analyzed with the Rotary Wavelet Spectrum Method to study the contribution of mesoscale activity to near-inertial variability. Drifter data used here are part of the MREA04 (Maritime Rapid Environmental Assessment 2004) sea trial carried out by the...

Eleven years of satellite data on surface chlorophyll-a, wind, and altimetry were used to analyze the spatial and temporal variability of the phytoplankton biomass in the Peru–Chile Current System (PCCS; 10–40°S) and to examine the main mechanisms determining this variability. Multitaper Method–Singular Value Decomposition was used to identify stat...

Located approximately 360 nm off the coast of Chile there is a disjoint realm of two small oceanic islands systems, the Juan Fernandez and the Desventuradas archipelago. Currently the local economy of the islands is almost exclusively supported by the harvest and trade of marine resources, focusing mainly on the exploitation of the rock lobster (Ja...

The spatial and temporal variability of the annual cycle of chlorophyll-a in the Juan Fernandez archipelago is analyzed through eight years of satellite data of chlorophyll-a, wind, currents and sea level. This archipelago consists of three islands: Robinson Crusoe-Santa Clara (RC-SC) and Alexander Selkirk (AS). The RC-SC islands are in a region of...

Abstract As part of their efforts to improve the national fisheries management system, Chilean fisheries authorities have identified the need to develop a fisheries research program based on state-of-the-art fisheries knowledge and information systems. To meet this challenge, a structural matrix analysis of the existing cognitive system and a liter...

As part of their efforts to improve the national fisheries management system, Chilean fisheries authorities have identified the need to develop a fisheries research program based on state-of-the-art fisheries knowledge and information systems. To meet this challenge, a structural matrix analysis of the existing cognitive system and a literature rev...

The possible effects of climate change on Chilean marine ecosystems are considered. Relationships between the abundance of exploited species, fishing effort and environmental variables are elucidated, and conceptual models for an ecosystemic management of fisheries are proposed. A projection for anchovy fisheries in northern Chile is carried out, c...

El objetivo General de Este Documento es determinar las unidades poblacionales de jurel (Trachurus murphyi) existentes en el Pacifico Sur y estudiar los procesos migratorios de este recurso.

In the Humboldt Current System, the region off central-southern Chile has relatively high eddy kinetic energy, generating an extensive coastal transition zone (∼600 km offshore) in which coastally derived eddies are recurrent features. This energy might promote strong exchanges of water, biogeochemical properties, and plankton between the coastal u...

The eastern boundary of the Chile-Peru Current System constitutes one of the most biologically productive ecosystems in the world, due largely to coastal upwelling and the horizontal advection of nutrients. In this ecosystem, El Nino events are of great importance in the interannual variability of the environment. A change was observed in the envir...

The eastern boundary of the Chile-Peru Current System constitutes one of the most biologically productive ecosystems in the world, due largely to coastal upwelling and the horizontal advection of nutrients. In this ecosystem, El Niño events are of great importance in the interannual variability of the environment. A change was observed in the envir...

The oceanographic setting and the planktonic distribution in the coastal transition zone off Concepción (∼35–38°S, ∼73–77°W), an area characterized by its high biological production, were assessed during two different seasons: austral spring with equatorward upwelling favorable winds and austral winter with predominately northerly winds. Oceanograp...

The offshore propagation of mesoscale eddies contributes significantly to expanding the area of high chlorophyll concentration beyond the coastal upwelling center as shown by satellite data of chlorophyll, wind stress, sea level anomalies between (1997–2003) off central Chile. Mesoscale eddies (∼6.45 × 103 km2) formed near the coastal zone in sprin...

Ten years of continuous current meter recordings near the core of the Peru-Chile Undercurrent (PCU) over the continen- tal slope at 30°S off Chile, local and equatorial wind stress data, and monthly oceanographic sections off Valparaíso (33°S) are used to study the variability of the PCU and the Oxygen Minimum Zone (OMZ) off Chile. The physics that...

Ten years of continuous current meter recordings near the core of the Peru-Chile Undercurrent (PCU) over the continental slope at 30°S off Chile, local and equatorial wind stress data, and monthly oceanographic sections off Valparaíso (33°S) are used to study the variability of the PCU and the Oxygen Minimum Zone (OMZ) off Chile. The physics that g...

1] High resolution SeaWiFS (Sea-viewing Wide Field-of-view Sensor) chlorophyll and satellite wind data (1997 – 2004) are used to analyze the coastal and oceanic behavior of sea surface chlorophyll (CHL) concentration in the eastern boundary current system off Chile (18°– 40°S). Two contrasting regimes are evident; a coastal regime, where CHL maximu...

DATA REPORT SERIES DE TIEMPO OCEANOGRAFICAS Y METEOROLOGICAS CAMPAÑA DE VERANO Proyecto de Modelación Hidrológica y Control de la Contaminación en las Bahías de Concepción y San Vicente Por Marcel Ramos Q. Oscar Pizarro A. Winston Rojas E. Aldo Montecinos G. Samuel Hormazabal F. Eduardo Navarro V. Concepción, Abril 2005

DATA REPORT MEDICIONES OCEANOGRÁFICAS EN LAS BAHÍAS CONCEPCIÓN Y SAN VICENTE CAMPAÑA DE VERANO Diciembre 2004- Febrero 2005 Proyecto de Modelación Hidrológica y Control de la Contaminación en las Bahías de Concepción y San Vicente

Current observations at several depths between 250 and 3750 m are reported from a 30°S, deep sea site 150 km off the Chile coast for the period July 1993–June 2001. These results are used with current observations from a nearby slope site, satellite altimeter data, and hydrographic and Acoustic Doppler Current Profiler data from the WOCE P6E sectio...

Satellite-derived along-shore windstress variability off subtropical Chile at intraseasonal periods has been recently associated with the corresponding wind variability over the tropical Pacific. Along the coastal strip in which satellite winds can not be resolved, wind-driven upwelling might be in principle modulated through large-scale intraseaso...

We present geostrophic velocities obtained using hydrographic-altimeter data and direct measurements of currents from 11 cruises offshore of Baja California from January 2000 to July 2002. The study area was dominated by meanders and eddies in geostrophic balance. Two mechanisms of eddy generation were observed; the first associated with the geomet...

Seven years of subsurface current observations at deep-sea and continental slope moorings off Chile (30°S), satellite sea surface anomaly, and satellite wind stress are used to examine space, time, and propagation characteristics of the mesoscale eddy activity in the coastal transition zone off Chile. This zone off Chile extends from the coast to ∼...

The rich biological productivity within the Peru-Chile current system depends mainly on wind-driven coastal upwelling, which brings colder, nutrient-rich, subsurface waters into the illuminated upper layer, promoting high phytoplankton productivity whish is available for zooplankton and ultimately for fish. Off central Chile (29-39°S), where strong...

En la primavera de 1995, se instaló un anclaje con dos correntómetros sobre el umbral de la constricción de Meninea para un análisis inicial de corrientes. El experimento fue parte del programa multidisciplinario Cimar 1 Fiordos. Durante 61 días se obtuvo las mediciones cada 30 minutos. Los correntómetros estaban instalados a 25 m y 40 m bajo la su...