Planktonic potential CO2 emission calculation: preliminary results by applying an adapted enzymatic methodology to marine ecosystems

[EN]Isocitrate Dehydrogenase (IDH) is a key enzyme in the Krebs cycle, being responsible for the production of one of the three CO2 molecules related to cellular respiration. In order to measure the potential CO2 production linked to the marine planktonic community we have adapted an enzymatic methodology. Preliminary results show that different proportions of autotrophs, heterotrophs and mixotrophs and their metabolic pathways, lead to different relationships between potential CO2 emission and potential O2 consumption during cellular respiration. Although more experiments need to be made, this methodology is leading to a better understanding of cellular respiration in marine samples and their impact on the food chain, vertical Carbon flux and the current sequestering capacity for anthropogenic CO2.

Understanding the zooplankton ammonium excretion: from biogeochemical implications to intracellular regulatory mechanisms

[EN] This thesis focuses on the zooplankton NH4+ regeneration that supports about the 80% of the phytoplankton requirements. In its more oceanographic facet, it elucidates the control that the mesozooplankton community exerts on the primary productivity in the northern Benguela, and models the N-fluxes from zooplankton NH4+ excretion. At the physiological level, it examines the relationship between the NH4+ excretion and its associated biochemistry. Assuming the substrate availability as the critical factor in regulating the velocity of NH4+ production, a bisubstrate model was developed to predict its actual rate in zooplankton. Overall, this research provides knowledge about the implications of zooplankton NH4+ excretion on the biogeochemical cycles, and introduces new insights into the study of this process from enzymatic measurements.

On the respiratory metabolism of marine plankton: its application in assessing carbon fluxes and the role of substrates in its biochemical control

Programa de doctorado en Oceanografía. La fecha de publicación es la fecha de lectura

Lagrangian evolution of a mid ocean anticyclonic eddy

[EN]The lagrangian evolution of 4 months old anticyclonic intrathermocline eddy of the Canary Eddy Corridor is investigated from the trajectories of 5 satellites tracked drifting buoys. Buoys were drogued below and above the Ekman depth at 15 m and 100 m, respectively. One buoy remained inside the eddy during almost 4 months being thus a long lived coherent feature with a life span of at least 8 months. The eddy consisted in a central core rotating in solid body rotation with a rather constant periodicity of 4 days and in an outer ring rotating much more slowly with periodicities between 8 and 12 days…

Okeanos : un proyecto de divulgación al servicio de las ciencias marinas y la protección de los océanos

[ES]Presentación de la revista Okeanos

Impact of increasing pCO2 on marine potential respiratory activity

[EN]Due to the increasing atmospheric CO2, several on-going research programs, including the German-led KOSMOS GC14 experiment, are evaluating the impact of acidification on marine organisms, intent to predict their future. In the KOSMOS GC14 mesocosm experiment we assessed the effect of different CO2 concentrations on metabolism in microplankton (0.7-50µm size) and in biogenic particles harvested by sediment traps.

Understanding the zooplankton ammonium excretion : from biogeochemical implications to intracellular regulatory mechanisms

[EN]Zooplankton play a key role in marine ecosystems and their biogeochemical cycles. They exert control over the primary productivity through the consumption of organic matter and, at the same time, the release of nutrients that sustains the phytoplankton growth. This thesis focuses on the NH+ 4 excretion processes related to these heterotrophic organisms that support, at a global scale, about the 80% of the phytoplankton requirements. However, thereisno clear constant pattern in the zooplankton contribution to theNH+ 4 regeneration throughout thedifferent pelagic ecosystems, so continuousmonitoring of thismetabolic processisessential at widetemporal and spatial scales...

New insights into POC dynamics in the subtropical northeast Atlantic Ocean

[EN]The capacity of the ocean to sequester atmospheric carbon (CO2) depends to a large extent on the dynamics of biogenic carbon in the water column. However, most current global and regional estimates of carbon balances are solely based on particles collected with drifting and moored sediment traps. As a consequence, construction of ocean carbon budgets has long been guided by the simplification introduced by sediment traps, which give a 1D vision of the whole picture. In this thesis we have assessed a quantitative analysis of the flux magnitude and the mechanisms of transport of the whole particle spectrum (suspended, slowly-sinking and sinking particles).

Upwelling in the Eastern Subtropical North Atlantic Ocean

[EN]Coastal upwelling in the eastern margin and offshore curl-driven upwelling in the southeastern margin, make the subtropical Northeast Atlantic a region of major primary productivity. When examining a broad zonal area, from the coast to 40_W, we find that the upward transport of nutrients due to offshore curl-driven upwelling becomes the main control on productivity. Nevertheless, despite its relatively small zonal extension of about 100 km, coastal upwelling extends its impact towards the open ocean through offshore Ekman transport and convergence of the meridional flow at Cape Blanc (21_N).

Uncovering diversity and structure of bacteroidetes populations in marine environments

[EN]One of the main questions in microbial ecology is to understand what are the processes that structure and govern the species composition of communities. Answering to this question implies the need to detect bacterial species in environmental samples or at least to define ecologically meaningful “units of differentiation”. The dynamics and distribution of different broad taxonomic groups that constitute the bacterioplankton (at the phylum or class level) has been widely studied. The different large groups are known to follow different spatial distributions and seasonal cycles, but important variations also occur at lower levels (i.e. species or ecologically distinct populations). In this thesis we aimed to study some of these aspects for an important group of marine bacteria: the phylum Bacteroidetes.

Capa de dispersión profunda en la zona económica exclusiva del noroeste de México

[ES]Se presenta un estudio realizado en la zona económica exclusiva del noroeste de México próxima a la region del Pacífico Norte de Baja California Sur, a bordo del barco de investigación “BIPO INAPESCA”. Como objetivo general se expondrá el estudio, sobre una campaña de prospección, la capa de dispersión profunda en el Noroeste de México, aplicando métodos de la acústica pesquera. Para ello, de la zona prospectada se mostrará el transecto que mejor describe la capa de dispersión profunda, cómo funciona el análisis e interpretación de los ecogramas indicando el tipo de ecos o agregaciones de los peces que componen la capa de dispersión profunda y finalmente se mencionarán los programas o software utilizados para el post-procesamiento de los datos

Can zooplankton secondary production models predict growth in the marine mysid Leptomysis lingvura (G.O. Sars, 1866)?

[EN]Zooplankton growth and secondary production are key input parameters in marine ecosystem models, but their direct measurement is difficult to make. Accordingly, zooplanktologists have developed several statistical-based secondary production models. Here, three of these secondary production models are tested in the marine mysid Leptomysis lingvura (Mysidacea, Crustacea). Mysid length was measured in two cultures twice a day, which were grown on two different food concentrations. Growth rates ranged from 0.11 to 0.64 day-1, while secondary production rates ranged from 1.77 to 12.23 mg dry- mass day-1. None of the three selected models were good predictors of growth and secondary production in this mysid species.

Abundance and diversity of marine microbial eukaryotes

[EN]Microeukaryotes are important ecological players in any kind of ecosystem, most notably in the ocean, and it is therefore essential to collect information about their abundance and diversity. To achieve this general goal this thesis was structured in two parts. The first part represents an effort to define our “diversity unit” from studies based on the well-known cloning and Sanger sequencing approach. Basically, we wanted to establish a solid baseline for the second part of the thesis. We started with data from one cruise (Chapter 1) and then continued with the analysis of the complete dataset of 18S DNA sequences available at that time (Chapter 2).

Respiratory electron transport activity in plankton: determinants and detection

[ES]La presente tesis, se centra en el estudio del Sistema de Transporte de Electrones (ETS) en organismos del plancton marino, los factores que lo influencian la interpretación de estas mediciones y su detección mediante espectrofotometría y espectrofluorometría, en muestras oceánicas naturales y en cultivos de organismos marinos. Se pudo establecer, la biomasa, la respiración (R) y la respiración potencial (ɸ), en tres transectos en los océanos Índico y Atlántico Norte Sur. A su vez, se determino el estado fisiológico, en tres tamaños del zooplancton, midiendo la relación R/ɸ. Se exploró los efectos de la inanición sobre la R y la variación con respecto a la ɸ en el zooplancton

Biomasa, distribución y metabolismo del zooplancton en aguas de la Península Antártica

[ES]El presente trabajo de tesis titulado "Biomasa, distribución y metabolismo del zooplancton en aguas de la Península Antártica" forma parte de un ambicioso proyecto que tiene como finalidad cuantificar, examinar y desentrañar las interacciones complejas de la cadena trófica en el Océano Sur. La primera parte describe la complejidad de la red trófica característica del Océano Sur. También, esta parte introductora se enfoca en la distribución de las especies zooplanctónicas y surelación con el ciclo del carbono y nitrógeno. En este mismo proyecto y como segunda parte, hemos desarrollado un método no destructivo a partir de imágenes digitales para una estimación precisa de la biomasa de cada grupo sistemático del mesozooplancton.