Begoña Bautista

Patterns in the size structure of the phytoplankton community in the deep fluorescence maximum of the Alboran Sea (southwestern mediterranean)

The Alboran Sea (southwestern Mediterranean) exhibits strong horizontal and vertical gradients associated with macroscale and mesoscale physical structures due to the input of surface Atlantic waters into the Mediterranean basin. During the summer of 1992, two anticyclonic and two cyclonic areas were found with fluorescence maxima (DFM) below the seasonal thermocline (ST). Although the depth of the ST is fairly constant, the position and intensity of the DFM is more variable, with a tendency to deepening and smoothing in the anticyclonic gyres. The position of the Atlantic–Mediterranean interface (AMI) can be used as a tracer for cyclonic or anticyclonic dynamics and their potential biological effects. A shallow AMI indicates divergence or upwelling dynamics and coincides with the highest fluorescence intensity, chlorophyll concentration and phytoplankton biovolume in the DFM. Under the conditions typical of the two anticyclonic gyres, the contrary is found. The size structure of phytoplankton shows significant differences between cyclonic and anticyclonic structures. Log-transformed size-abundance spectra can be adequately described by linear models with slopes of −0.78 for cyclonic and −0.93 for anticyclonic structures. The integration of size-abundance spectra indicates that picoplankton biovolume in the DFM is independent of the type of circulation or dynamics, whereas nanoplankton and, particularly, microplankton increase their absolute and relative presence in the DFM under cyclonic or upwelling dynamics.

Relations between chlorophyll, phytoplankton cell abundance and biovolume during a winter bloom in Mediterranean coastal waters

Abstract The relationships between three descriptors of phytoplankton biomass (chlorophyll, cell abundance and biovolume) during a winter bloom in the Mediterranean coastal waters of the Bay of Malaga (Southern Spain) were investigated. The relations observed are non-linear and imply that chlorophyll per cell, average cell volume and chlorophyll per unit cell volume are negative power functions of cell abundance. Non-linearity seems to be the result of time-delays in the initiation of the exponential growth phase for the three variables. The interplay of ontogenetic versus phylogenetic adaptations during that phase is discussed. Biovolume, obtained by image analysis from the integration of both numerical abundance and the size structure of the population, seems to be an ideal way of describing changes in phytoplankton biomass. The need for a transformation of image-analysis volumes to organic content is pointed out.

Fertilization and connectivity in the Garrucha Canyon (SE-Spain) implications for Marine Spatial Planning

Marine Spatial Planning is usually based on benthic georeferenced information or GPS tracked human activities, whereas the pelagic ecosystem is often ignored because of scarce and limited surface information. However, the 3-D pelagic ecosystem plays a key role connecting all the other ecosystems by physical (currents) and biological (migration) processes. According to remote sensing the Garrucha Canyon is oligotrophic, but 3-D sampling reveals subsurface upwelling, and converts it into the richest area around the Cape of Gata. Vertical connectivity by means of zooplankton migration, measured at two sampling stations, is 40 and 220 times faster than microphytoplankton settling and vertical water velocities respectively. Thus coupled physical-biological connectivity models are necessary to estimate the ecosystem connection and the fate of carbon, but also other substances (e.g. radioactivity), that might accumulate throughout the food-web. This is especially important in the Garrucha Canyon and the Coastal Areas Management Programme Levante de Almería where natural heritage and extractive fishery are important for the local economy.

EL PLANCTON DE LAS LAGUNAS DE SIERRA NEVADA: NECESIDAD DE ESTUDIOS TRANSDISCIPLINARES

La correcta valoracion de los procesos ecologicos, como base para el mantenimiento de la integridad ecologica del ecosistema, se ha convertido en una de las tareas de mas dificil cumplimiento en las labores de conservacion de los ecosistemas mediterraneos. La busqueda y desarrollo de herramientas en la deteccion y prevencion de alteraciones ambientales nos ha llevado a centrar la atencion en las lagunas de alta montana del Parque Nacional de Sierra Nevada, ecosistemas que presentan un singular valor ecologico dentro del ambiente mediterraneo, por su caracter oligotrofico, por su situacion a gran altitud y por la adaptacion de sus comunidades a condiciones ambientales extremas. El presente texto describe una propuesta de estudio integral en estos ecosistemas con una aproximacion basada en el analisis de las estructuras de tamano de las comunidades del plancton como herramienta descriptora y predictiva de las respuestas de esas comunidades a los cambios ambientales.