Variabilidad espacio temporal de la biomasa de los grupos funcionales del fitoplancton frente a la costa peruana (2000-2009)

El Norte del Ecosistema de la Corriente de Humboldt (NECH), localizado a lo largo del Sudeste del Océano Pacífico, frente a Perú, es considerado uno de los sistemas naturales más productivos en el mundo, por ello de gran relevancia el estudio del fitoplancton como base de la trama trófica marina. Basados en las relaciones entre la superficie celular, biovolumen y máxima dimensión lineal de las células de las especies del fitoplancton, se encontraron 140 especies en el grupo funcional ‘R’ (especies ruderales, adaptables a condiciones de alta mezcla); 133 especies en el grupo funcional ‘S’ (especies estrés-tolerantes, predominantes en condiciones oligotróficas y de alta luz) y 19 especies en el grupo funcional ‘C’ (especies competitivas, oportunistas, predominantes en condiciones mesotróficas y de alta luz). En el grupo funcional R destacaron las diatomeas elongadas, pennadas, dispuestas en cadenas; en el S se encontraron dinoflagelados, diatomeas centrales grandes y silicoflagelados; mientras que, en el grupo funcional C destacaron cocolitofóridos, algunos dinoflagelados mixotróficos y nanoflagelados. Los porcentajes de coincidencia entre la clasificación morfométrica de grupos funcionales del presente estudio y la clasificación ecológica, estuvieron entre 52 y 90 %. Se propone el uso de estos grupos para evaluar variaciones espacio-temporales del fitoplancton y su relación con condiciones ambientales en el NECH.The Northern Humboldt Current Ecosystem, located along the Southeastern Pacific off Peru, is considered as one of the most productive natural system in the world, being of great relevance the study of phytoplankton as the basis of the marine trophic web. Based on the relationships between the cell surface, biovolume and maximum linear dimension of the cells of the phytoplankton species, 140 species were found in the functional group 'R' (ruderal species, adaptable to high mixing conditions); 133 species in functional group 'S' (stress-tolerant species, predominant in oligotrophic and high light conditions) and 19 species in functional group 'C' (competitive, opportunistic species, predominant in mesotrophic and high light conditions). These three groups are respectively composed of elongated, pennate, and chain-forming diatoms (group R); dinoflagellates, large central diatoms and silicoflagellates (group S) and coccolithophores, some mixotrophic dinoflagellates and phytoflagellates (group C). Coincidence percentages between the functional groups classification of the present study and the ecological classification were between 52% and 90 %. The use of functional groups is proposed to evaluate the spatio-temporal variations of phytoplankton and its relation with environmental conditions in the Northern Humboldt Current Ecosystem

Procedure for maintaining order and cleanliness in the Phytoplankton and Primary Production Laboratory

En este Protocolo de Orden y Limpieza en el Laboratorio de Fitoplancton y Producción Primaria, se exponen los procedimientos de limpieza del material de laboratorio (vidrio, acrílico, entre otros), así como de los equipos utilizados dentro del mismo. Además, se incluyen algunas pautas que deben mantenerse durante el desarrollo del trabajo, para prevenir posibles incidentes que puedan ocurrir durante la ejecución de las diferentes actividades técnicas.ABSTRACT: This Protocol for Organization and Cleanliness in the Phytoplankton and Primary Production Laboratory outlines procedures for cleaning laboratory materials (glass, acrylic, among others) and the equipment used within. Additionally, it includes guidelines to be observed during work to prevent potential incidents during the execution of various technical activities

A bloom of Azadinium polongum in coastal waters off Peru

Species of the dinophycean genus Azadinium are known for their potential production of azaspiracids (AZAs), a group of microalgal toxins that can cause shellfish poisoning. Increase of global Azadinium records indicates a rather wide distribution, but quantitative abundance data of species of Amphidomataceae are hardly available. Within the Peruvian bio-oceanographic monitoring program we detected and sampled a dense bloom of Azadinium in Peruvian coastal waters off Chancay in February 2014 at a water temperature of about 20.5 °C and a salinity of 35. With water discoloration and cell densities of Azadinium up to 1 million cells per liter this is the first Azadinium bloom record for the Pacific. The causative taxon was determined using scanning electron microscopy as Azadinium polongum, a species previously recorded only from the type locality, the Shetland Islands (north Atlantic) and described as non-AZA producer. The field population conformed to the Shetland type culture in most morphological aspects. However, the first intercalary plate of the Pacific field population without exception was not in contact with the first precingular plate, which is different to the type culture of Az. polongum. Moreover, the size and shape of the median intercalary plate was slightly different and very variable in the Pacific population, and occurred in about equal abundance in quadra- (i.e., in contact with four other plates) or in penta-configuration (i.e., in contact with five other plates), a feature not reported for the type culture of Az. polongum. Liquid chromatography coupled with mass spectrometry revealed no AZA above detection level in the bloom sample, indicating that the Peruvian Az. polongum can be regarded as a non-AZA producer

Phytoplankton functional groups in the Northern Humboldt Current Ecosystem (NHCE)

El Norte del ecosistema de la Corriente de Humboldt, localizado a lo largo del Sudeste del Océano Pacífico, frente a Perú, es considerado uno de los más productivos sistemas naturales en el mundo, siendo de gran relevancia el estudio del fitoplancton como base de la trama trófica marina. Tomando en cuenta las relaciones entre la superficie celular, biovolumen y máxima dimensión lineal de las células de las especies del fitoplancton, se encontraron 140 especies en el grupo funcional ‘R‘ (especies ruderales, adaptables a condiciones altas de mezcla); 133 especies en el grupo funcional ‘S’ (especies Stress-tolerantes, predominantes en condiciones oligotróficas y de alta luz) y 19 en el grupo funcional ‘C’ (especies colonizadoras, oportunistas, predominantes en condiciones mesotróficas y de alta luz). En el grupo funcional R destacaron las diatomeas elongadas, pennadas, dispuestas en cadenas; en el grupo funcional S se encontraron dinoflagelados, diatomeas centrales grandes y silicoflagelados; mientras que, en el grupo funcional C destacaron cocolitofóridos, algunos dinoflagelados mixotróficos y fitoflagelados. Los porcentajes de coincidencia entre la clasificación morfométrica de grupos funcionales del presente estudio y la clasificación ecológica, estuvieron entre 52 y 90%. Se propone el uso de estos grupos para evaluar las variaciones espacio-temporales del fitoplancton y su relación con las condiciones ambientales en el Norte del ecosistema de la Corriente de Humboldt, cuyos niveles de turbulencia son menores al de los fiordos chilenos.ABSTRACT: The Northern Humboldt Current ecosystem (NHCE), located in the southeastern Pacific off Peru, is one of the most productive natural systems worldwide. This area is of great relevance for the study of phytoplankton as the basis of the marine trophic web. Based on the relationships between the cell surface area, biovolume, and maximum linear dimension of the cells of the phytoplankton species, we found 140 species in the functional group ‘R’ (ruderal species, which are adaptable to high mixing conditions); 133 species in functional group ‘S’ (Stress-tolerant species, predominant in oligotrophic and high light conditions), and 19 species in functional group ‘C’ (colonizing, opportunistic species, predominant in mesotrophic and high light conditions). These three functional groups (FGs) are respectively formed by elongated, pennate, and chain-forming diatoms (group R); dinoflagellates, large central diatoms, and silicoflagellates (group S), and coccolithophores, some mixotrophic dinoflagellates, and phytoflagellates (group C). The percentages of coincidence between the morphometric classification of the FGs of this study and the ecological classification were between 52% and 90%. We propose the use of FGs to evaluate the spatio-temporal variations of phytoplankton and its relation with environmental conditions in the NHCE, whose turbulence levels are lower than those recorded in Chilean fjords

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

KOSMOS 2017 Peru mesocosm study: overview data

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 mod- ify surface production and related biogeochemical processes. Determining these factors is important because EBUS are considered hotspots of climate change, and reliable predic- tions 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 con- trolling organic matter cycling in the coastal Peruvian up- welling 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 sub- surface waters at two different locations in the regional oxy- gen minimum zone (OMZ) and injected these into four meso- cosms (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 indi- vidual mesocosms. The mesocosm phytoplankton commu- nities were initially dominated by diatoms but shifted to- wards a pronounced dominance of the mixotrophic dinoflag- ellate (Akashiwo sanguinea) when inorganic nitrogen was exhausted in surface layers. The community shift coincided with a short-term increase in production during the A. san- guinea 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 decou- pled from surface production and sustained by the remain- ing 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 limita- tion which constrained phytoplankton growth. Thus, gain and loss processes remained balanced and there were few oppor- tunities for blooms, which represents an event where the sys- tem becomes unbalanced. Overall, our mesocosm study re- vealed some key links between ecological and biogeochem- ical processes for one of the most economically important regions in the oceans