"New insights on sources and sinks of organic matter in the oligotrophic coastal and open ocean".
Start: 22/09/2017 11:30 - End: 22/09/2017 13:00Place: Sala de Seminarios, IMEDEA
"Oligotrophic systems cover approximately 70% of the ocean surface and, due to their low concentrations of nutrient salts and chlorophyll, are essentially known as ocean deserts. However, their huge extension makes them playing an important role in the carbon cycle. While the primary production in the subtropical gyres of the open ocean is dominated by phytoplankton, in the oligotrophic coastal systems of the Mediterranean Sea Posidonia oceanica is the dominant primary benthic producer.
This Ph.D. thesis is focused on investigating two key compartments within the organic matter continuum of the coastal and oceanic oligotrophic ecosystems: the chromophoric dissolved organic matter (CDOM), and the transparent exopolymer particles (TEP). CDOM represents the optically active fraction of the dissolved organic matter (DOM) and it plays a key role in the photochemical and photobiological processes occurring in marine ecosystems.
TEP are organic particles of adhesive nature, formed via abiotic as well as biotic processes and are especially important for the biological carbon pump. Although in the last years the scientific community has increased its knowledge regarding the distribution of CDOM and TEP in the oceans, as well as about their roles in biogeochemical cycles, the current level of comprehension on the sources and sinks that control their dynamics in oligotrophic systems remains elusive. In this context, the identification of new sources of CDOM and TEP, and the deeper exploration of the biogeochemical processes governing them in oligotrophic systems – until now poorly explored – is the leitmotiv of this thesis.
In order to address these questions, we used a combination of field observation and laboratory experimentation.
On one hand, I participated in the Malaspina 2010 Expedition, which crossed 15 tropical and subtropical biogeographic provinces of the global ocean. On the other hand, the marine research station of Cap Ses Salines (Majorca) was used as reference of the oligotrophic coastal system and it was additionally compared with Es Caragol beach, characterized by its extensive P. oceanica meadows. At the global scale this thesis has evaluated, by means of the analysis of the absorption spectra of CDOM in the photic layer of the Atlantic, Indian and Pacific Oceans, the biogeochemical variables that mainly dictate the distribution of the optical properties of CDOM. Chlorophyll and apparent oxygen utilization have been shown to be the most relevant drivers, denoting the catabolic processes within the microbial food web as the main source of colour in the oligotrophic ocean. Moreover, this thesis has allowed the identification of Prochlorococcus as a potentially relevant source of TEP
in the oligotrophic ocean.
At the local scale, the time series results derived from the coastal observations have tested the hypothesis that P. oceanica is an important source of both CDOM and TEP, although the estimations of its contributions to the carbon cycle in the Mediterranean Sea and the biogeochemical processes require additional studies.
The original and novel results presented and discussed in this Ph.D. thesis propel new hypotheses to develop future research lines aimed at deeply comprehend the biotic and abiotic processes that control the dynamics of these components in the oligotrophic systems and its implications in the efficiency of the carbon pumps
in future global change scenarios."
Respuestas del genero Viola a los gradientes altitudinales y vulnerabilidad a las especies exóticas in sistemas de montaña
Start: 25/09/2017 11:30 - End: 25/09/2017 13:00Place: Sala de Seminarios, Imedea
Los ecosistemas de montaña son centros de biodiversidad mundial, debido a su aislamiento geográfico, a su papel como refugio de especies durante los cambios climáticos del pasado y a la gran variedad de condiciones ambientales que presentan a lo largo de sus gradientes altitudinales. Los gradientes ambientales que presentan los sistemas alpinos permiten testar respuestas ecológicas de las plantas a diferentes condiciones ambientales a través de distancias cortas, por lo que pueden funcionar como laboratorios al aire libre, especialmente útiles para entender las respuestas de las plantas al cambio global. Por ejemplo, la presencia de especies invasoras en estos sistemas puede crear efectos sinérgicos con los del cambio climático, creando consecuencias dramáticas para especies nativas ya amenazadas, o para ecosistemas frágiles, como los presentes en la alta montaña de islas oceánicas.
El principal objetivo de esta tesis es explorar las respuestas fisiológicas, reproductivas y fenotípicas de diversas especies de plantas entomófilas de montaña del género Viola a las distintas condiciones bióticas y abióticas que se encuentran a lo largo de sus gradientes altitudinales de distribución.
21/09/2017 Whale behaviour inspires new way forward for reef protection
20/09/2017 PhD thesis: Diversification patterns and phylogeography in a genus subterranean amphipod (Pseudoniphargus melitidae)
Welcome to the Mediterranean Institute for Advanced Studies (IMEDEA),
a research center jointly governed by the Spanish National Research Council (CSIC) and
the University of the Balearic Islands (UIB).