Factors controlling plankton community production, export flux, and particulate matter stoichiometry in the coastal upwelling system off Peru

Eastern boundary upwelling systems (EBUS) are among the most productive marine ecosystems on Earth. The production of organic material is fueled by upwelling of nutrient-rich deep waters and high incident light at the sea surface. However, biotic and abiotic factors can modify surface production and related biogeochemical processes. Determining these factors is important because EBUS are considered hotspots of climate change, and reliable predictions of their future functioning requires understanding of the mechanisms driving the biogeochemical cycles therein. In this field experiment, we used in situ mesocosms as tools to improve our mechanistic understanding of processes controlling organic matter cycling in the coastal Peruvian upwelling system. Eight mesocosms, each with a volume of ∼55 m3, were deployed for 50 d ∼6 km off Callao (12∘ S) during austral summer 2017, coinciding with a coastal El Niño phase. After mesocosm deployment, we collected subsurface waters at two different locations in the regional oxygen minimum zone (OMZ) and injected these into four mesocosms (mixing ratio ≈1.5 : 1 mesocosm: OMZ water). The focus of this paper is on temporal developments of organic matter production, export, and stoichiometry in the individual mesocosms. The mesocosm phytoplankton communities were initially dominated by diatoms but shifted towards a pronounced dominance of the mixotrophic dinoflagellate (Akashiwo sanguinea) when inorganic nitrogen was exhausted in surface layers. The community shift coincided with a short-term increase in production during the A. sanguinea bloom, which left a pronounced imprint on organic matter C : N : P stoichiometry. However, C, N, and P export fluxes did not increase because A. sanguinea persisted in the water column and did not sink out during the experiment. Accordingly, export fluxes during the study were decoupled from surface production and sustained by the remaining plankton community. Overall, biogeochemical pools and fluxes were surprisingly constant for most of the experiment. We explain this constancy by light limitation through self-shading by phytoplankton and by inorganic nitrogen limitation which constrained phytoplankton growth. Thus, gain and loss processes remained balanced and there were few opportunities for blooms, which represents an event where the system becomes unbalanced. Overall, our mesocosm study revealed some key links between ecological and biogeochemical processes for one of the most economically important regions in the oceans

Arte, técnica y arquitectura globalizada

El mundo globalizado actual está promoviendo en nuestra sociedad cambios que nos impulsan a un mundo de consumismo y frivolidad. La arquitectura no se ha escapado, promoviéndose la idea de arquitectura-mercancía-moda. Hay una tendencia global que promueve la separación de técnica y arte, desalojando al hombre del centro de la escena. Para contribuir a recuperar el equilibrio en nuestras sociedades, los arquitectos debemos preocuparnos por incorporar objetos arquitectónicos sanos, y para ello se propone retornar a lo nuestro, a nuestras raíces: al patrimonio vernáculo y purificar desde ahí nuestras acciones

Arte, técnica y arquitectura globalizada

El mundo globalizado actual está promoviendo en nuestra sociedad cambios que nos impulsan a un mundo de consumismo y frivolidad. La arquitectura no se ha escapado, promoviéndose la idea de arquitectura-mercancía-moda. Hay una tendencia global que promueve la separación de técnica y arte, desalojando al hombre del centro de la escena. Para contribuir a recuperar el equilibrio en nuestras sociedades, los arquitectos debemos preocuparnos por incorporar objetos arquitectónicos “sanos”, y para ello se propone retornar a lo nuestro, a nuestras raíces: al patrimonio vernáculo y purificar desde ahí nuestras acciones.The globalized world of today is promoting changes in our society, which encourages a world of consumism and frivolousness. The world of architecture has not been left untouched by this trend and finds itself promoting the idea of architecture-merchandizefashion. There is a global tendency to separate the technical aspect from the artistic one, which removes the person from center stage. As architects, we should attempt to recover the balance in society by incorporating “sound” architectonical objects and thereby bring back our true values, the values of our roots: the vernacular heritage, and through that purify our actions

Arte, técnica y arquitectura globalizada

The globalized world of today is promoting changes in our society, which encourages a world of consumism and frivolousness. The world of architecture has not been left untouched by this trend and finds itself promoting the idea of architecture-merchandizefashion. There is a global tendency to separate the technical aspect from the artistic one, which removes the person from center stage. As architects, we should attempt to recover the balance in society by incorporating “sound” architectonical objects and thereby bring back our true values, the values of our roots: the vernacular heritage, and through that purify our actions.El mundo globalizado actual está promoviendo en nuestra sociedad cambios que nos impulsan a un mundo de consumismo y frivolidad. La arquitectura no se ha escapado, promoviéndose la idea de arquitectura-mercancía-moda. Hay una tendencia global que promueve la separación de técnica y arte, desalojando al hombre del centro de la escena. Para contribuir a recuperar el equilibrio en nuestras sociedades, los arquitectos debemos preocuparnos por incorporar objetos arquitectónicos sanos, y para ello se propone retornar a lo nuestro, a nuestras raíces: al patrimonio vernáculo y purificar desde ahí nuestras acciones

The carbonate system in coastal waters off the northern region of the Baja California Peninsula under La Niña conditions

In the North Pacific, variations in isopycnal depth influence the biogeochemical characteristics of the water column and the aragonite saturation horizon (ZΩa) during interannual events. The objective of this study was to assess the effect of the 2011 La Niña conditions on ZΩa in Todos Santos Bay (Baja California, Mexico) and surrounding waters. The results showed that ZΩa variability was modulated by the intensity of interannual conditions and by the water masses that were present in the region. Subarctic Water predominated in the upper 200 m with anomalous characteristics, such as low temperature and low salinity. Also, isopycnals shoaled toward the coast and ZΩa was thus ~30 m in the nearshore area, in contrast with the oceanic region, where ZΩa was ~150 m. Prior to this study, there were no records of ZΩa in Todos Santos Bay, nor were there any records of its shallowness

Revista esencia y espacio

Arquitectur