Strong influence of climatic extremes on diversity of benthic algae and cyanobacteria in a lowland intermittent stream

Freshwater ecosystems are threatened by the global change-induced extreme climatic events worldwide. The unpredictable changes in water supply create strongly disturbed environments and ultimately result in diversity changes. Here, we studied the formation of benthic algal and cyanobacterial assemblages under intermediately disturbed (IDC) and highly disturbed conditions (HDC) in a small lowland intermittent stream. We addressed our hypotheses to the Intermediate Disturbance Theory supposing that intermediate frequencies or intensities of disturbances maximise diversity independently of its level. We expected a larger influence of extremes in water supply on functional than on taxonomic and phylogenetic diversity. Our results only partially proved our first hypothesis highlighting the (i) importance of short-time but intense disturbing effect on biofilm formation and trait composition under IDC period and (ii) the instability within the assemblages caused by large and opposing influences during HDC. Although extreme weather events caused trait extremes (supporting second hypothesis), they did not result in a decrease in functional richness (rejecting the second hypothesis). These findings in accordance with the insurance hypothesis clearly stress that a system with high functional redundancy can keep its functionality even under drastic hydrological conditions and the accompanying loss of species

Functional Dynamics of Phytoplankton Assemblages in Hypertrophic Lakes: Functional- and Species Diversity is Highly Resistant to Cyanobacterial Blooms

Under increasing pressure of climatic change and anthropogenic eutrophication, water blooms, i.e. the formation of high phytoplankton biomass of a single or a few species, have become more and more frequent in lake ecosystems that is caused mostly by Cyanobacteria. The dynamics of phytoplankton under a cyanobacterial pressure may provide important information about what a competitive advantage of Cyanobacteria have over eukaryotic microalgae. The research, therefore focused on the relationship between cyanobacterial blooms and the accompanying species in hypertrophic shallow lakes where nutrients are in excess. The following hypotheses were selected for testing: i) Cyanobacterial blooms negatively affect the species richness and diversity of phytoplankton assemblages in the studied hypertrophic lakes. ii) Cyanobacterial blooms negatively affect the multi-trait functional diversity of phytoplankton assemblages in the studied hypertrophic lakes. iii) The formation of a cyanobacterial bloom causes a shift in the species and trait composition of phytoplankton assemblages. It was found that the species diversity of non-cyanobacterial assemblages was not affected negatively by increasing density of Cyanobacteria. Cyanobacterial biomass negatively affected the functional richness and functional dispersion of the assemblages, but both relationships were only marginally significant. Some temporal shift was detected in the community weighted mean values of width, colonial ability of accompanying microalgae, and also in flagellatedness and mixotrophic ability. We conclude that Cyanobacterial blooms basically alter dominance relations in the phytoplankton and reduce availability of light in waters. However, it does not necessarily coincide with the elimination of other taxa and reduction their species numbers or diversity. The formerly published data on the decrease in species richness can be likely explained by methodological deficiencies, which are responsible for reduced detectability of species. To better understand the seasonal dynamics and resilience of phytoplankton assemblages in hypertrophic water bodies the development of new methodologies by which diversity and succession of subordinate species can be evaluated is required

EGÉSZSÉGES ÉS FERTŐZÖTT MEZŐGAZDASÁGI NÖVÉNYEK, VALAMINT AGARICUS BISPORUS ILLATANYAGPROFILJÁNAK FELTÉRKÉPEZÉSE – ELŐTANULMÁNY

GINOP kutatócsoportunk, E-Orr kutatóműhely „Természetes szagmintázatok elemzése és agrártudományi hasznosítása” címmel 2017-óta működik Martonvásáron. Kutatásaink fő célja egy új típusú mesterséges érzékelő rendszer kifejlesztése, amellyel lehetőség nyílik mezőgazdasági növények komplex illatanyag-összetételének meghatározására. Eddig három növény (búza, árpa, paradicsom), valamint csiperkegomba illatanyagprofil elemzését végeztük el. Méréseink során igazoltuk, hogy különböző fertőzések hatására valóban megváltozik az adott növény illatanyag mintázata, azonban sok esetben csak kis mértékben