3 Nov. 2014 - Laura Marziali

Seminar Laura Marziali

Effect-based tools - Risposta delle comunità a macroinvertebrati acquatici alla contaminazione

Presenta: Laura Marziali -  CNR-IRSA, Brugherio (MB)

L’analisi delle comunità macrobentoniche è ampiamente utilizzata nel monitoraggio della qualità ecologica degli ecosistemi d’acqua dolce, come previsto dalla Direttiva 2000/60/EC. Tuttavia il limite degli indici biotici utilizzati è che non rispondono a specifiche pressioni, pertanto difficilmente possono guidare nell’individuazione delle cause di alterazione. In questo seminario vengono presentati alcuni recenti studi, focalizzati sullo sviluppo di nuove metriche stressor-specifiche che rispondono alla presenza di sostanze microinquinanti. L’approccio, a cavallo tra ecologia ed ecotossicologia, mira a sviluppare deglieffect-based tools con importanti risvolti applicativi: la prioritizzazione degli interventi di mitigazione degli impatti in presenza di multistress e la valutazione della loro efficacia nel recupero della qualità ecologica degli ecosistemi. A questo proposito saranno presentati alcuni casi di studio, che illustrano il nuovo approccio e le sue potenzialità.

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25 Sett. 2014 - Norman Yan

Seminar Norman Yan

Impacts on zooplankton of ongoing changes in the physics,
chemistry and biota of South-central Canadian lakes

Presenta: Norman Yan - (York University, Department of Biology, Toronto, ON, Canada)

New environmental issues are arising, even for the relatively remote, visually pristine, soft-water lakes of Canada. Using large scale (300 lakes) and long-term (35 year) data sets, Yan will show that while progress has been made on past environmental issues (eg. lake acidification and shoreline development), there are new widespread challenges, including rising temperatures, Natural Organic Matter (NOM) and Cl levels, falling Ca levels, and the spread of new predators including Bythotrephes. Yan will demonstrate that Canadian zooplankton: i) are threatened by Bythotrephes, Ca decline and road salt; ii) that native species differ enormously in their sensitivity to these threats; iii) that interactions of the stressors worsen the threat, eg., interactions of Bythotrephes with Ca decline, and oligotrophication with road salt; iv) and that rising levels of NOM have real but poorly understood effects on daphniid growth rates. We have made enormous strides in solving past environmental problems, but will likely not solve the current ones without understanding interactions of these emerging stressors.

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19 Sett. 2014 - Norman Yan

Seminar Norman Yan

Local vs. regional regulation of recovery of zooplankton of Sudbury lakes from acidification and metal pollution: lessons for Lake Orta

Presenta: Norman Yan - (York University, Department of Biology, Toronto, ON, Canada)

The largest number of historically acidified and metal-contaminated lakes in the world are near the mining and smelting complexes in Sudbury, Canada. Yan examines the 40 year pattern of recovery of the chemistry and zooplankton in 4 Sudbury lakes, three of which were limed in the 1970s. Zooplankton biodiversity is recovering in these lakes, but the rate of recovery varies by 150% among lakes. The temporal dynamics of species occurrence patterns suggests that recovery is not determined by meta-community processes, i.e. not by propagule pressure. Rather the key processes appear to be local, especially post-colonization persistence and population growth. Biotic ligand model results and toxicity bioassays using natural lake waters suggest that, despite 10 to 100-fold reductions in metal levels, metal toxicity remains the local factor that is regulating recovery of zooplankton. For managers wishing to promote ecological recovery, our work suggests that stocking is not required, a good thing given that historical emissions from smelters damaged about 7000 lakes.
Despite the widespread, historical extirpation of local populations, propagule delivery does not limit recovery. Rather lake managers should focus on in-lake processes, ensuring that waters are not toxic to, and can adequately support colonists.

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29 Ago. 2014 - Mustafa Sari

Seminar Mustafa Sari

Pearl Mullet Fisheries and Management in Lake Van, Eastern Turkey

Presenta: Mustafa Sari - (Fisheries Faculty, Yuzuncu Yil University, Van, Turkey)

The pearl mullet is the endemic fish species that can survive in the salty and alkaline waters of Lake Van. Lake Van is overing an area of 3712 km , with mean depth of 171 m, maximum depth of 451 m, and 1648 m above sea level, this is Turkey’s largest lake. Its waters are extremely alkaline and salty. The lake’s biological diversity is significantly different from both fresh and salt waters. Its phytoplankton resources consist of 103 species belonging to the Diatome, Bacteriophyta, Cynophyta, Chlorophyta, Flagellate and Phaeophyta groups, and its zooplankton resources include 36 species from the Rotatoria, Cladocera and Copepod groups. The pearl mullet (Chalcalburnus tarichi, Pallas 1811), a species belonging to the Cyprinidae family, is the only fish that can survive in Lake Van. The pearl mullet is a migrating species. Although it generally lives in the lake, it immigrates to the surrounding freshwater rivers for reproduction purposes and returns to Lake Van after the reproduction period.

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17 Lug. 2014 - Ruth Rawcliffe

Seminar Ruth Rawcliffe

Palaeo-webs: integrating the past and present to inform the future

Presenta: Ruth Rawcliffe - (CNR-ISE, Verbania)

Shallow lakes are often cited as classic examples of systems that exhibit trophic cascades, providing good model systems with which to test general ecological theory and to assess long-term community change. Preserving a rich biological record in their sediments, they are also important models for inferring long-term intergenerational dynamics. By integrating palaeolimnological and contemporary data using a spatio-temporal ‘analogue’ approach, we can reconstruct not just past assemblages (i.e. nodes within a food web), but also past interactions (i.e. links within a food web). This addition of a temporal dimension offers potential for reconstructing food webs over intergenerational timescales that are more appropriate to community response to long-term perturbations, such as eutrophication, acidification and climate change.

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