Time-series measurements of settling particulate matter in Alfonso Basin, La Paz Bay, southwestern Gulf of California

Silverberg, Norman; Aguirre-Bahena, Fernando; Mucci, Alfonso

doi:10.1016/j.csr.2014.05.005

Cited by 27 publications

(25 citation statements)

References 61 publications

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“…Reoxygenation need not indicate disappearance of the OMZ, as no proxy record indicates fully oxygenated water conditions (Tems et al, 2016), including the data produced in our studyspecifically, Mo, V, and U values are several times higher than their crustal average values (Wedepohl, 1995). The oxygenation chronology of the last millennium starts with the predominantly (Rodríguez-Castañeda, 2008;Choumiline, 2011;Silverberg et al, 2014). d Drill core (Ivanochko and Pedersen, 2004).…”

Section: Chronology Of Reoxygenation and Deoxygenation Events Over Thmentioning

confidence: 63%

“…The sill restricts the incursion of North Pacific Intermediate Water (NPIW) and North Pacific Deep Water (NPDW) (Figures 1A,B). Primary productivity is higher on the eastern side of the GC because it is nourished by nutrients upwelled predominantly during dry and cold seasons with strong northwesterly winds (Lavín et al, 2013;Silverberg et al, 2014). Mesoscale eddies together with wind-driven coastal upwelling (primarily along the mainland margin during winter) promote primary productivity in the region (Badan-Dangon et al, 1991;Trasviña-Castro et al, 2003;Deutsch et al, 2014).…”

Section: Depositional Settingmentioning

confidence: 99%

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Scenarios of Deoxygenation of the Eastern Tropical North Pacific During the Past Millennium as a Window Into the Future of Oxygen Minimum Zones

et al. 2019

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Diverse studies predict global expansion of Oxygen Minimum Zones (OMZs) as a consequence of anthropogenic global warming. While the observed dissolved oxygen concentrations in many coastal regions are slowly decreasing, sediment core paleorecords often show contradictory trends. This is the case for numerous high-resolution reconstructions of oxygenation in the Eastern Tropical North Pacific (ETNP). While major shifts in redox conditions of the ETNP are dominated by glacial-interglacial cycling, important fluctuations also occur in response to minor climatic and oceanographic perturbations. It is important to understand these scenarios of past redox variation, as they are the closest analog for near future climate and oceanographic change. We present recently collected sediment core proxy records from the Gulf of California in which we reproduce the variability of productivity and oxygenation of the ETNP OMZ during the past millennium. We emphasize paleoproductivity (C org , Ni, Ba excess ) and paleoredox indicators (Mo, Cd, V, U auth ) in sediment cores collected in Alfonso and La Paz basins and compare these OMZ records with other archives of the Eastern Pacific. Our findings indicate that the OMZ expanded in response to increased upwelling and productivity during cold intervals of the early 1400s, early 1500s, late 1600s, and early 1800s AD (evidenced by higher Ni, V, Cd, Mo, and U auth ). The most hypoxic times corresponded to the beginning of the Little Ice Age (expressed in elevated Mo). Significant OMZ contractions occurred around late 1300s, early 1700s, and late 1900s AD after reoxygenation events that were instigated by low productivity (lower Ni, V, Cd, Mo, and U auth ). The mechanisms that control decadal-to-centennial oxygen variability in the ETNP remain unidentified but are likely influenced by solar forcing not only driving migrations of the Intertropical Convergence Zone (ITCZ) but more importantly changes in the intensity of the Pacific Walker Circulation (PWC). During the Little Ice Age solar irradiance was at its lowest for the past millennium, which strengthened the PWC. This pattern contributed to more frequent La Niña-like conditions, which enhanced upwelling of nutrient-rich waters in the west coast of North America, driving productivity and reducing bottom oxygen levels, as seen in our ETNP records.

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Section: Chronology Of Reoxygenation and Deoxygenation Events Over Thmentioning

confidence: 63%

Section: Depositional Settingmentioning

confidence: 99%

Scenarios of Deoxygenation of the Eastern Tropical North Pacific During the Past Millennium as a Window Into the Future of Oxygen Minimum Zones

et al. 2019

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“…1a). The region is known to have very rich biodiversity, including endangered and endemic species, with high ecological relevance (Silverberg et al 2014). The bay interchanges water masses with the gulf through two openings, Boca Grande (wide and deep) to the north, and San Lorenzo Channel (shallow and narrow) to the south, which generates important matter and energy flows between both environments (Monreal-Gómez et al 2001).…”

Section: Introductionmentioning

confidence: 99%

Bio-optical characterization of the waters of the Bay of La Paz, southern Gulf of California, during late spring 2004

Coria-Monter

Monreal‐Gómez

Salas‐de‐León

et al. 2020

Rev. biol. mar. oceanogr.

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Information on selected bio-optical properties and primary production values of the waters of the Bay of La Paz, southern Gulf of California, is reported during June 2004, a region characterized to have very rich biodiversity, including endemic and endangered species, with high ecological relevance. In-situ measurements of natural fluorescence and photosynthetically available radiation (PAR) enabled the subsequent calculation of the incident irradiance (E0), the light extinction coefficient (k), compensation depth (Zc) and critical depth (Zcr). The results suggest the presence of light propitious conditions for phytoplankton community growth and net primary production, which are highly significant for the potential development of models of light penetration, ocean color, primary productivity, and analyses of organic carbon energy flow.

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“…Es la unidad con menor tamaño medio de grano (4.5 ± 0.6 Φ) y se puede atribuir a que la zona tiene la menor o nula influencia de la energía del oleaje. Por consiguiente, representa un área para el depósito de sedimentos terrígenos (Nava-Sánchez et al, 2001) o por hundimiento de partículas en suspensión en la columna de agua (Silverberg et al, 2014). La unidad 1a registra un contenido de CaCO 3 entre 20 y 40% influenciado por la proximidad de la unidad 4a, el aporte de bioclastos de foraminíferos, fragmentos de conchas de moluscos bentónicos y nanoplancton calcáreo (Urcádiz-Cázares, 2005).…”

Section: Discussionunclassified

“…La porción noroeste de la BLP es más profunda e incluye a la cuenca Alfonso, con 420 m de profundidad (Cruz-Orozco et al, 1996). La depresión recibe sedimentos terrígenos, eólicos y hemipelágicos (Silverberg et al, 2014). Hacia el sureste de la BLP la profundidad disminuye desde los 220 m hasta la línea de costa, configurando una plataforma con pendiente suave donde el fondo marino contiene arenas finas de origen terrígeno (Cruz-Orozco et al, 1996).…”

Section: Introductionunclassified

Classification of seafloor units based on the spatial distribution of superficial sediments in La Paz Bay, Gulf of California

Cázares¹

2017

Hidrobiológica

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2017. Clasificación de unidades del fondo marino a partir de la distribución espacial de los sedimentos superficiales de la Bahía de La Paz, Golfo de California. Hidrobiológica 27 (3): 399-409. DOI:10.24275/uam/izt/dcbs/hidro/2017v27n3/Urcadiz RESUMEN Antecedentes. El mapeo del fondo marino genera información útil para estudios ecológicos y de conservación en zonas marinas. Sin embargo, las metodologías para la delimitación de unidades en los fondos dominados por sedimentos no consolidados son escasas. Objetivos. Clasificar y caracterizar unidades en el fondo marino a partir de la distribución espacial de cuatro variables: el contenido de carbonato de calcio, el tamaño medio de grano, la clasificación del sedimento y la profundidad en la bahía de La Paz. Métodos. La distribución espacial de las cuatro variables mencionadas fue generada a partir de modelos de interpolación. Los modelos se elaboraron con base en los datos de 85 muestras de sedimento superficial y utilizando un sistema de información geográfica. La clasificación de unidades se determinó agrupando polígonos construidos a partir de los modelos e implementando un análisis de agrupamiento jerárquico. La caracterización se obtuvo con los valores predichos en los modelos. Resultados. Los modelos presentaron valores entre 2.7 a 95% de contenido de carbonato de calcio, -0.9 a 7.8 Φ de tamaño medio de grano (donde Φ es una transformación logarítmica del diámetro de sedimento), 0.1 a 4 Φ de clasificación y 0 a 680 m de profundidad. El análisis jerárquico determinó 14 unidades en el fondo marino. Cuatro unidades conforman el 91% del área de estudio. La unidad 4a se caracteriza por un alto contenido de CaCO 3 (72 ± 20%); la unidad 3a, por una mala clasificación (2.2 ± 0.7 Φ); la unidad 2a, por una clasificación moderada (1.1 ± 0.3 Φ), y la unidad 1a, por la presencia de sedimentos finos (4.5 ± 0.6 Φ). Conclusiones. Este estudio representa una de las primeras propuestas de clasificación de unidades del fondo marino sobre sedimentos no consolidados en la BLP. La metodología empleada permitió separar cuatro principales unidades que reflejan condiciones ambientales con características propias. También se establecen los primeros modelos de distribución por medio del cálculo de la media del error y la raíz cuadrada del error cuadrático medio, que contrasta un conjunto de observaciones independientes contra los valores modelados de las variables citadas. Esta propuesta se puede utilizar como línea base en estudios de zonas costeras y plataformas continentales del Golfo de California y otras regiones marinas, en tanto dicha distribución no se vea afectada por eventos hidrometeorológicos extremos, en cuyo caso se requeriría un estudio similar.Palabras clave: Carbonato de calcio, clasificación, fondo marino, interpolación, sedimentos, tamaño de grano. ABSTRACTBackground. Seafloor mapping provides valuable information for ecological studies and conservation of marine areas; however, the methods used to delimit seafloor units in areas dominated by unconsolidated sediments ...

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Time-series measurements of settling particulate matter in Alfonso Basin, La Paz Bay, southwestern Gulf of California

Cited by 27 publications

References 61 publications

Scenarios of Deoxygenation of the Eastern Tropical North Pacific During the Past Millennium as a Window Into the Future of Oxygen Minimum Zones

Scenarios of Deoxygenation of the Eastern Tropical North Pacific During the Past Millennium as a Window Into the Future of Oxygen Minimum Zones

Bio-optical characterization of the waters of the Bay of La Paz, southern Gulf of California, during late spring 2004

Classification of seafloor units based on the spatial distribution of superficial sediments in La Paz Bay, Gulf of California

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