Phytoplankton response to experimental thermocline deepening: a mesocosm experiment

A number of modelling results suggested thermocline shifts as a consequence of global climate change in stratifying lakes. Abundance and composition of the phytoplankton assemblage is strongly affected by the stratification patterns, therefore, change in the thermocline position might have a substantial effect on this community or even on the whole lake ecosystem. In this study, thermocline depths in large mesocosms installed in Lake Stechlin (Germany) were deepened by 2 meters and phytoplankton changes were analysed by comparing changes to untreated mesocosms. Higher amounts of SRP were registered in the hypolimnion of treatment mesocosms than in the controls, and there were no differences in the epilimnion. Small but significant changes were observed on the phytoplankton community composition related to the effect of deepening the thermocline; however, it was weaker than the yearly successional changes. The most remarkable differences were caused by Planktothrix rubescens and by chlorophytes. P. rubescens became strongly dominant at the end of the experiment in the mesocosms, and in the open lake as well. The results of the experiment cannot clearly support the proliferation of cyanobacteria in general; however, the deepened thermocline can modify the behaviour of some species, as was observed in case of P. rubescens

Mi történik a vízbe hulló avarral?

Az évenkénti lombhullás biztosítja az erdei patakok külső szervesanyag-igényét, mely fontos energiaforrás a kisvízfolyásokban. A behulló avar mennyisége jelentősen eltérhet attól függően, hogy milyen a patak menti növényzet. A lehulló növényi részek legnagyobb részét a levelek teszik ki, ezért az avarlebomlás fontos része az ökoszisztéma1 összefüggéseinek. A folyamat vizsgálata segít a biodiverzitás2 megismerésében. A biológiai sokféleség3 napjainkban csökken, melynek okai lehetnek az erős emberi behatás, valamint a klímaváltozás, mely a különböző ökoszisztémákat éri. Erdei patakokban és az egyéb vizes élőhelyeken az avar lebomlása központi folyamat, melynek lefolyása függ a biológiai sokféleségtől. Így az avarlebomlás folyamatának vizsgálata fontos információkat szolgáltathat számunkra az adott víztest állapotáról

Ecosystem services provided by freshwater and marine diatoms

Diatoms, a unique group of algae colonising a wide range of aquatic habitats and contributing to human well-being in many ways. We list and summarise these services using the classification of the Millennium Ecosystem Assessment (MEA), i.e. supporting, regulating, provisioning and cultural services. The most relevant supporting services are photosynthesis and primary production, as well as sediment formation. They also play a key role in nutrient cycling and habitat provisioning and serve as food for many organisms. Regulating services as oxygen production, climate control or sediment stabilisation are difficult to discuss without diatoms. Many provisioning services, directly used by humans, can be obtained from diatoms. These are tangible products such as medicines and immunostimulants but direct technologies such as wastewater treatment, micro- and nanotechnologies were also developed using diatoms. Studying of the past, present, and future linked to diatoms as a tool for palaeolimnology, ecological status assessment of waters and climate modelling is essential. Finally, the impressive morphology and ornaments of diatom frustules make them one of the most spectacular microorganisms, inspiring artists or providing a number of educational opportunities. Therefore, protecting aquatic habitats they inhabit is not simply a nature conservation issue but the key for human well-being in the future

Corso di aggiornamento in batteriologia anaerobia

SIGLEITItal