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Temporal variability of bottom hypoxia in open and semi-enclosed coastal areas in an upwelling region
Indexado
WoS WOS:001430329600001
Scopus SCOPUS_ID:85217947752
DOI 10.1016/J.POCEAN.2025.103435
Año 2025
Tipo revisión

Citas Totales

Autores Afiliación Chile

Instituciones Chile

% Participación
Internacional

Autores
Afiliación Extranjera

Instituciones
Extranjeras


Abstract



Hypoxia events driven by the onshore advection of oxygen-poor upwelling waters have become increasingly common along Eastern Boundary Upwelling Systems (EBUS). More frequent or intense drops in nearshore oxygen concentrations can impact the behavior, population dynamics, and geographic distribution of many coastal species. To better understand these effects, it is necessary to determine the periodicity of hypoxia in the inner shelf, its response to upwelling-favorable winds, and the local factors that may modify its intensity and duration. Here, we used a two-year record (March 2017-February 2019) of near-bottom dissolved oxygen (DO) and water temperature from seven sites spanning 260 km of the upwelling coast of Central Chile to characterize the local variability in oxygen concentration and its association with coastal winds. The temporal patterns observed in the inner shelf were compared with 13.5 years of monthly hydrographic profiles (2002- 2015) from a mid-shelf station located ca. 30 km offshore. The spatial structure of nearshore hypoxia was inferred from hydrographic data gathered during two surveys conducted in winter 2018 and late summer 2019. Inner-shelf hypoxia (DO<2.0 mg/L) occurred predominantly in the austral summer and exhibited substantial among-site differences in its persistence and timing relative to wind-driven upwelling. The mean duration of summertime hypoxia events ranged between 1 and 9 days, except for a site at the innermost section of the Gulf of Arauco, where events could be as long as 62 days. Hypoxic waters appeared at the inner shelf after 1-2 days of sustained upwelling-favorable winds (59% of the hypoxia events occurred after <= 2 days of persistent wind). The seasonality and vertical structure of hypoxia were apparent in the mid-shelf monthly time series, with the hypoxic layer's upper limit ascending to 20-30 m depths during spring-summer (October-March) and receding to 45-60 m in autumn-winter (May-September). Hydrographic properties of the hypoxic layer pointed to Equatorial Subsurface Water (ESSW) as the source water mass for mid-shelf hypoxia throughout the year. These properties were consistent with those observed on the inner shelf. Among the seven inner- shelf sites, Arauco showed the most persistent (70% of the time spanned by our records) and severe hypoxia, with DO levels below those observed at the mid-shelf during active upwelling. We hypothesize that these conditions respond to a combination of physical phenomena and coastal eutrophication that locally enhance thermal stratification, productivity, and benthic oxygen consumption, thus amplifying the severity of hypoxia and physiological stress for marine organisms inside the Gulf of Arauco.

Revista



Revista ISSN
Progress In Oceanography 0079-6611

Métricas Externas



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Disciplinas de Investigación



WOS
Oceanography
Scopus
Geology
Aquatic Science
SciELO
Sin Disciplinas

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Publicaciones WoS (Ediciones: ISSHP, ISTP, AHCI, SSCI, SCI), Scopus, SciELO Chile.

Colaboración Institucional



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Autores - Afiliación



Ord. Autor Género Institución - País
1 Munoz, Richard - Universidad de Concepción - Chile
Universidad Católica de la Santísima Concepción - Chile
2 Tapia, Fabian J. - Universidad de Concepción - Chile
3 Sobarzo, Marcus - Universidad de Concepción - Chile

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Financiamiento



Fuente
Universidad de Concepción
FONDECYT
Fondo Nacional de Desarrollo Científico y Tecnológico
COPAS
Interdisciplinary Center for Aquaculture Research
Agencia Nacional de Investigación y Desarrollo
ANID BECAS/Doctorado Nacional
INCAR (FONDAP-ANID)
COPAS COASTAL (ANID)
Programa de Investigacion sobre Ecosistemas del Golfo de Arauco (PREGA)
ANID for the FONDECYT grant
Programa de Investigación sobre Ecosistemas del Golfo de Arauco

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Agradecimientos



Agradecimiento
RM was supported by ANID BECAS/Doctorado Nacional 21231834 and by FONDECYT grant 1161512 awarded to FT. RM also thanks the Laboratory of Coastal Physical Oceanography, Universidad de Concepcion for the computer equipment to analyze the data set. FT thanks ANID for the FONDECYT grant (1161512) that made it possible to collect the DO and temperature data series. FT and MS have been partially supported by COPAS Coastal (ANID FB210021) and by INCAR (FONDAP-ANID 1523A0007) . MS was also partially supported by the Programa de Investigacion sobre Ecosistemas del Golfo de Arauco (PREGA) . The COPAS time series program (Departamento de Oceanografia, Universidad de Concepcion) provided the monthly hydrographic data from Station 18 (2002-2015) .
RM was supported by ANID BECAS/Doctorado Nacional 21231834 and by FONDECYT grant 1161512 awarded to FT. RM also thanks the Laboratory of Coastal Physical Oceanography, Universidad de Concepci\u00F3n for the computer equipment to analyze the data set. FT thanks ANID for the FONDECYT grant (1161512) that made it possible to collect the DO and temperature data series. FT and MS have been partially supported by COPAS Coastal (ANID FB210021) and by INCAR (FONDAP-ANID 1523A0007). MS was also partially supported by the Programa de Investigaci\u00F3n sobre Ecosistemas del Golfo de Arauco (PREGA) . The COPAS time series program (Departamento de Oceanograf\u00EDa, Universidad de Concepci\u00F3n) provided the monthly hydrographic data from Station 18 (2002\u20132015).

Muestra la fuente de financiamiento declarada en la publicación.