Magyarország Dinophyta fajainak vizsgálata = The investigation of Hungarian Dinophyta species

A biodiverzitás megőrzése korunk egyik legfontosabb kihívása. Ennek alapfeltétele az, hogy az adott régió/ország élőlény-együtteseit, azon belül a szennyezéseket jól indikáló élőlényeket, jelen esetben a Dinophyta (páncélos-ostoros alga) fajokat a állóvizeinkben és vízfolyásainkban ismerjük. A Dinophyta fajokra vonatkozó elvégzett alapkutatás jellegű ökológiai kutatásaink révén számos faj bioindikációs szerepét, ill. a vízminőségi háttérváltozók kapcsolatát tisztáztuk. Alkalmazott kutatás tekintetében a Dinophyta fajok indikációs sajátságait vizsgáltuk kiemelve szennyezések detektálását és az egyes fajok alkalmazhatóságát a EU Vízgazdálkodási Keretirányelv szerinti gyakorlatban megvalósuló monitorozás során. Az elvégzett munkánk eredményeképpen megfelelő információ áll rendelkezésre „Magyarország Dinophyta fajainak monográfiájának” elkészítéséhez.Nemzetközi vonatkozásban olyan összefoglaló ismereteket adtunk közre a konferenciákon a hazai Dinophyta fajokra állóvizekben való előfordulására vonatkozóan, melyek hasznosíthatók más, a mérsékelt övben található országokban is. Ezt jelzik mindazok az elidult/elinduló nemzetközi kapcsolatok (Horvátország, Németország, Olaszország, Spanyolország, Törökország) melyek révén hazánk is részese lehet az Európában kialakuló Dinophytákra vonatkozó kutatásnak. | The conservation of biodiversity is one of the most important challenges of our age. In order to achieve this goal it is essential to know the living communities in the given region/country – including organisms that indicate contamination well, in this particular case Dinoflagellates in standing waters and rivers. We managed to elucidate the roles of different species in bioindication as well as the relationship between water quality variables by conducting basic ecological researches on Dinophyta species. As an applied research we examined the indication characteristics of Dinophyta species – above all the detection of contaminations and the applicability of different species for monitoring according to the EU Water Framework Directive. Due to our research, the information required to work out „The Monograph of Dinophyta Species in Hungary” is now available. In international aspects, in different conferences we published a comprehensive knowledge on the occurence of Dinophyta species in Hungarian standing waters that is useful in other temperate countries as well. This is indicated by the started/starting international contacts (Croatia, Germany, Italy, Spain, Turkey) that help Hungary to take part in the European researches on Dinoflagellates

Do benthic diatom assemblages reflect abiotic typology: a case study of Croatian streams and rivers

Benthic diatoms are widely used in Europe and worldwide to access ecological status of running waters. One of key goals of Water Framework Directive is to classify rivers and streams using biological quality elements and type specific reference conditions. According to system B which incorporates additional abiotic descriptors, there are 24 water types in Croatia. For biological analyses 92 rivers and streams with 140 sampling points were chosen and sampled for benthic diatoms and water chemistry simultaneously. Self organizing map (SOM) analysis was used to define biotypes from species composition and abundance of benthic diatoms. Grouping of samples in SOM resulted in 10 distinctive groups. Based on their geographical position and site characteristics, groups represent sites with similar properties (as waterbed, catchment size, altitude, size of stream) belonging to different ecoregions in Croatia. Analysis of variance revealed statistically significant differences (p<0.05) among SOM groups concerning ammonia, nitrates and total phosphorus. Indicator species analysis (IndVal) singled out species that were significantly characteristic (p<0.05) for SOM and abiotic types. Compared to abiotic groups, in which 7 out of 24 have no indicator species, all SOM groups have one or several characteristic diatom species, thus indicating diatom assemblages as valuable site descriptors. Canonical analysis of principal coordinates analysis also indicated that SOM grouping of samples is statistically reliable. Grouping of similar sites, although placed into different abiotic types, makes SOM groups with its corresponding representative species an easy tool for water quality assessment and description of reference assemblage

Data Descriptor : A European Multi Lake Survey dataset of environmental variables, phytoplankton pigments and cyanotoxins

Under ongoing climate change and increasing anthropogenic activity, which continuously challenge ecosystem resilience, an in-depth understanding of ecological processes is urgently needed. Lakes, as providers of numerous ecosystem services, face multiple stressors that threaten their functioning. Harmful cyanobacterial blooms are a persistent problem resulting from nutrient pollution and climate-change induced stressors, like poor transparency, increased water temperature and enhanced stratification. Consistency in data collection and analysis methods is necessary to achieve fully comparable datasets and for statistical validity, avoiding issues linked to disparate data sources. The European Multi Lake Survey (EMLS) in summer 2015 was an initiative among scientists from 27 countries to collect and analyse lake physical, chemical and biological variables in a fully standardized manner. This database includes in-situ lake variables along with nutrient, pigment and cyanotoxin data of 369 lakes in Europe, which were centrally analysed in dedicated laboratories. Publishing the EMLS methods and dataset might inspire similar initiatives to study across large geographic areas that will contribute to better understanding lake responses in a changing environment.Peer reviewe

Temperature Effects Explain Continental Scale Distribution of Cyanobacterial Toxins

Insight into how environmental change determines the production and distribution of cyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus on hepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g., anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to their potency. Most studies examine the relationship between individual toxin variants and environmental factors, such as nutrients, temperature and light. In summer 2015, we collected samples across Europe to investigate the effect of nutrient and temperature gradients on the variability of toxin production at a continental scale. Direct and indirect effects of temperature were the main drivers of the spatial distribution in the toxins produced by the cyanobacterial community, the toxin concentrations and toxin quota. Generalized linear models showed that a Toxin Diversity Index (TDI) increased with latitude, while it decreased with water stability. Increases in TDI were explained through a significant increase in toxin variants such as MC-YR, anatoxin and cylindrospermopsin, accompanied by a decreasing presence of MC-LR. While global warming continues, the direct and indirect effects of increased lake temperatures will drive changes in the distribution of cyanobacterial toxins in Europe, potentially promoting selection of a few highly toxic species or strains.Peer reviewe

How length of light exposure shapes the development of riverine algal biomass in temperate rivers?

The impact of cumulative daily solar radiation (CDSR) on the biomass of river phytoplankton (Chl-a) in the growing season was studied using a large dataset of rivers in the Carpathian Basin. The amount of solar radiation was cumulated over the range of 1–60 days. The CDSR–Chl-a relationship could be described by linear regression and appeared to be significant for almost all watercourses with the exception of rivers with short water residence time. To determine the most relevant time period of CDSR impacting phytoplankton biomass, the slopes of regressions were plotted against the accumulating number of days of light exposure (1–60). Two characteristic shapes were obtained: unimodal for rhithral rivers with hard substrate and steady increase for lowland potamal rivers with fine substrate. In both cases, there is an increasing tendency in the slope values with water residence time (WRT). It was demonstrated that CDSR has a pronounced impact on river phytoplankton biomass even in cases when WRT was shorter than the cumulated solar radiation period. These results indicate that development of phytoplankton within the river channel is a complex process in which meroplankton dynamics may have significant impacts. Our results have two implications: First, CDSR cannot be neglected in predictive modelling of riverine phytoplankton biomass. Second, climate models forecast increased drought with subsequently increased CDSR in several regions globally, which may trigger a rise in phytoplankton biomass in light-limited rivers with high nutrient concentrations

Seasonal variation of organic compounds in a eutrophic oxbow lake

In may lakes, high planktonic biomass generates such large quantities that bottom waters become anoxic (Baranovic et al. 1993, Bárdosi et al. 2000, Dévai et al. 2002, Padisák et al. 2003), and massive organic-mineral aggregates occur in the water column, depending on meteorological and biomechanical conditions in the water coloumn (Stachowitsch et al. 1990; Degobbis et al. 1995). Chemical and physical speciation of dissolved organic carbon (DOC) impact the formation of aggregates in marine environment, but few studies have addressed the speciation of DOC in lacustrine ecosystems (V-Balogh et al. 2003). This study reports seasonal variability of DOC, total dissolved carbohydrates (TDCHO), total dissolved free amino acids (TDFAA), and colloidal organic carbon (COC > 1 kDa) in a eutrophic oxbow lake