26 Mag. 2014 - Edward Mitchell

Seminar Edward Mitchell

Testate amoebae in peatlands and lakes:
diversity, functional role and multiple uses as bioindicators of present and past ecosystem changes  

Presenta: Edward Mitchell ( Laboratory of Soil Biology, University of Neuchâtel )

Testate amoebae are a common group of shelled protozoa in terrestrial and aquatic habitats. They feed on bacteria as well as protists and micro-eukaryotes and thus play an important role in microbial food webs. They are abundant and diverse and their true diversity and biogeography is now being revealed by molecular taxonomy. Preserved shells in peat and lake sediments inform on past environmental changes while living communities can be used to monitor on-going changes in ecosystems including effects of restoration, climate change and other impacts.

In this talk I will give an overview of these relatively poorly known organisms and of some current research topics related to their use as bioindicators.

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20 Mag. 2014 - Paolo Montagna

Paolo Montagna

Geochemical signal in coral skeletons:
tool to understand the climate

Presenta: Paolo Montagna ( CNR-ISMAR, Bologna )

Scleractinian corals can provide multi-century, sub-annual resolution paleoceanographic records. They can be precisely dated by 230Th/U technique and they systematically incorporate isotopic and chemical tracers that reflect the environmental conditions of the ambient seawater. On the other hand, the chemical and isotopic signals encoded into coral skeletons can be used to investigate the biomineralization processes and model the coral calcification rate in the future. In particular, the boron isotopes extracted from the skeleton of zooxanthellate and azooxanthellate corals can effectively be used to quantify the internal pH and the response of calcification to ocean acidification and rising seawater temperature (McCulloch et al., 2012). With the recent advances in analytical techniques, non-traditional stable and radiogenic isotopes can now be measured in relatively small coral portions and the results can be combined with established tracers in a unique multi-proxy approach. I will present geochemical results from shallow- and deep-water corals from the Mediterranean Sea and the Atlantic Ocean. In particular I will discuss the use of Li/Mg ratio, boron and neodymium isotopes as reliable proxies for seawater temperature, pH and water-mass circulation, with examples based on long-lived specimens and coral fragments from sediment cores.

McCulloch M., Falter J., Trotter J., Montagna P. (2012). Coral resilience to ocean acidification and global warming through pH up-regulation. Nature Climate Change, 2, 623-627.

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13 Mag. 2014 - Isabella Bertani

Seminar Bertani

Regime shift triggered by an extreme climatic event in an oligotrophic mountain lake

Presenta: Isabella Bertani ( LifeWatch-Ita, Centro Tematico Interazioni, CNR-IBAF, Monterotondo Scalo )

Climatic extremes, especially heatwaves and droughts, have increased in frequency, duration and magnitude in many regions of the world as a result of climate change, and this trend is predicted to continue, thereby raising urgent questions regarding their ecosystem-scale consequences on freshwater systems. We explored the impacts of a summer heatwave on a small, stratifying lake that is part of the Italian LTER Network. A sudden transition from a phytoplankton- to a macrophyte-dominated regime occurred during the heatwave. We investigated candidate mechanisms driving the switch from pelagic to benthic control of primary production, and we examined physico-chemical and biological time series to identify the major ecosystem-level consequences of the switch. Our results provide evidence of abrupt and extensive ecological changes that are indicative of a regime shift. We show that ecological implications of the shift propagate across multiple trophic levels and determine marked changes in community structure that persist long after the climatic anomaly.

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29 Apr. 2014 - Mattia Cesa

Seminar Mattia Cesa

Moss bags per il monitoraggio dei micro-inquinanti nelle acque continentali

Presenta: Mattia Cesa (Università di Trieste)

Disporre di bio-accumulatori per il monitoraggio chimico dei corpi idrici e per l'analisi delle tendenze temporali è un'esigenza ormai pressante nell'attuale contesto normativo. I muschi acquatici offrono una sorprendente combinazione di sensibilità, resistenza e versatilità nell'implementazione di monitoraggi ed indagini ambientali.
L'Università di Trieste ha investito 10 anni di studio, sperimentazione ed applicazione della tecnica dei 'moss bags' per il monitoraggio degli elementi in tracce in svariati contesti. Presto saranno pubblicate dall'ISPRA le linee guida per l'utilizzo di questo metodo, che potrebbe essere impiegato anche per il monitoraggio di sostanze prioritarie e contaminanti emergenti.

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15 Apr. 2014 - Giulia Poma

Giulia Poma

Evaluation of bioaccumulation processes of
Brominated Flame Retardants (BFRs) in biotic matrices

Presenta: Giulia Poma ( CNR-IRSA, Brugherio )

The global reduction in the use of PBDEs and HBCD as flame retardants has opened the way for the introduction of “novel” BFRs (nBFRs) in place of the banned formulations, indicating those BFRs that are new in the market or newly/recently observed in the environment in respect to PBDEs and HBCD. Consequently, consumption and production of these nBFRs will keep rising, and increasing environmental levels of these chemicals are expected in the near future.
In Italy, previous studies showed high concentrations of PBDEs in the Varese province due to the presence of a great number of textile and plastic industries, and particularly in the sediments of Lake Maggiore. For these reasons, the present work aimed to evaluate the presence, and the potential bioaccumulation and biomagnification processes of six different classes of BFRs (PBDEs, HBCD, DBDPE, BTBPE, HBB and PBEB) in the Lake Maggiore ecosystem, with particular regard to abiotic (lake and river sediments) and biotic (zebra mussels, zooplankton, and three fish species) matrices.

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