25.02.2015

2 марта 2015г. пройдет очередной научный семинар кафедры прикладной экологии СПбГУ

Дорогие коллеги и друзья!

Приглашаем вас принять участие в работе научного семинара кафедры прикладной экологии СПбГУ.

Ближайшее заседание семинара состоится в понедельник, 2.03.2015, в 17-30 на кафедре прикладной экологии по адресу 16-я линия В.О., дом 29, п.5.

С докладами выступят Элизабет Эхарке Гонсалес и Эстер Мас Марти,  проходящие стажировку на кафедрах прикладной экологии и ихтиологии и гидробиологии. Ниже, Вы можете ознакомиться с темами и аннотациями докладов.

Transport and reactivity of dissolved organic matter in a Mediterranean river.

Elisabet Ejarque Gonzalez

Rivers play a key role in the global biogeochemical functioning, as they link the biogeochemical cycles of the terrestrial and oceanic systems. In the framework of the carbon cycle, rivers receive dissolved organic matter (DOM) from the land and it is subsequently transported downstream and delivered to the oceans. However, there is increasing evidence that this step involves not only a relocation of DOM from the land to the seas, but also an important in-stream processing which modifies its quality and properties and, to some extent, outgas it to the atmosphere as CO2. However, up to now it has not been assessed how these modifications occur along a longitudinal continuum and, most importantly, the role that hydrology plays in such downstream patterns of DOM processing. During this research I explored the transport and reactivity of DOM along a Mediterranean river under a variety of hydrological conditions ranging from flash floods to summer droughts.

First, the composition of DOM was determined using 2D fluorescence spectroscopy (emission-excitation matrices) and a novel chemometric approach based on a self-organising maps analysis coupled with a correlation analysis. Next, the relevance of in-stream transformations over transport were explicitly quantified by calculating a mass balance at thirteen consecutive downstream segments.

The findings of this research demonstrate that the riverine passage is a decisive step that defines the quantity and quality of the DOM that is finally delivered to the oceans. Moreover, the hydrological seasonality typical of Mediterranean rivers shapes a temporally-changing DOM character which may have complex repercussions for its fate once in the coastal systems.

Climate-induced changes in resource-consumer trophic interactions in headwater streams

Esther Mas Martí

Changes in temperature and precipitation due to climate change are expected to increase stream water temperature and reduce their discharge. Consequently, more streams might face temporality, experiencing flow intermittency or complete streambed drying. The aim of our study was to determine how climate-induced changes in stream hydrology (drought) and water temperature (warming) influence resource-consumer trophic interactions. Our results show that both drought and warming affect the quality of benthic resources, though in opposite directions and that change in stream flow influences their relative abundance. These effects, in addition to direct effects of temperature on invertebrate metabolism, affected consumer feeding behaviour, nutrient assimilation efficiencies, growth and pupation. Finally, the simultaneous effects of increased metabolism due to warmer stream temperatures and lower resource quality due to stream flow fragmentation resulted in synergistic effects on stream detritivores physiology and fitness. Consequently, these results suggest potential effects on stream food webs and ecosystem functioning through changes in leaf litter decomposition, detritivore-mediated nutrient cycling and secondary production.

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