Ecology and taxonomy of benthic diatoms in continental aquatic ecosystems

Resumo

Human activity and the changes that naturally occur in aquatic ecosystems affect their biological communities. Algal communities, in particular, are influenced by factors such as light, temperature, pH, current velocity, and nutrients. Benthic algae constitute the base of the predatory food chain, since they assimilate dissolved nutrients and use solar energy in the production of organic matter. Diatoms are eukaryotic, unicellular organisms and their main characteristic is the presence of an external silica wall (frustule), which is normally used to differentiate the different genera and species. The analysis of the structure of algae associations and their function in the ecosystem is of great interest for the interpretation of the energy balance, water quality and ecosystem management. The characteristics that make diatoms ideal organisms for use as ecological indicators are: 1) they are cosmopolitan and very diverse; 2) they have short life cycles, which allows them to colonize substrates in a short space of time; 3) react quickly and sensitively to changes in water chemistry; 4) they are easy to collect, handle and preserve, due to the resistance of their frustule and 5) the counting techniques are fast, obtaining comparable and reproducible results in the long term. The main objective of this work is to deepen in the taxonomy and ecology of the different diatom species, using all the databases available within the RE1 (Aquatic Ecology) research group, as well as new data from sampling and in situ experiments. These data include data on the composition and abundance of diatoms from areas with Atlantic climate (Galicia, Asturias, the Basque Country, Portugal, etc.), and with Mediterranean climate (Balearic Islands), which will allow the ecological profiles of communities and species to be studied in a broad manner in different environmental gradients. Likewise, the inclusion of databases taken over different years will allow the identification of the variation in their spatio-temporal distribution. These data will allow the comprehensive and comparative analysis of the diatom associations and the indication provided by the existing diatomological indices, to test their efficiency in detecting impacts to aquatic ecosystems through the ecological status based on diatoms; in urban aquatic ecosystems (urban lagoons), and in Atlantic and Mediterranean river basins. Thus, it is intended to evaluate the use of the different metrics and the optimization of their correct use in environmental monitoring campaigns in different regions. All this work will be accompanied by field work with different sample collections and different field and laboratory experiments, with the aim of studying those variables derived from human pressures that may influence diatom species; alterations in land uses derived from eucalyptus plantations, nutrient enrichment, light, etc