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  • 1
    Publication Date: 2019-02-01
    Description: In a literature search, the presence of Haematococcus in phytoplankton communities and its biogeography were investigated. Haematococcus, although showing a wide biogeographical distribution, has been rarely found in phytoplankton communities. Simultaneously, the colonization potential of air-dispersed Haematococcus in ephemeral waters and its interactions with coexisting phytoplankton taxa were examined by microscopy and molecular methods. Haematococcus was a successful colonist, appearing among the first taxa in the experimental containers. According to principal component analysis, Haematococcus growth rate was negatively correlated with the abundance and species richness of the other autotrophs. Furthermore, a negative correlation between Haematococcus and Chlamydomonas and a positive one between Haematococcus and Chlorella were found. Overall, Haematococcus appears to be an effective air-dispersed alga that can successfully colonize and establish populations in small ephemeral water bodies. However, its absence from phytoplankton in larger permanent water bodies could be related to its high light requirements, its competitive disadvantages against other algae, and the grazing pressures from predators. The results of our study suggest a life strategy based on adaptation to higher light intensities in very shallow waters compared with optical dense lakes. Therefore, ephemeral waters are the regular habitat for Haematococcus instead of being “stepping stones” for the colonization of lake phytoplankton.
    Type: Article , PeerReviewed
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  • 2
    Publication Date: 2019-02-01
    Description: Highlights: • We propose a new Phytoplankton Index for monitoring the ecological status of lakes. • We develop a community index integrating the response to anthropogenic pressure. • We link high frequency Secchi depth with low frequency phytoplankton monitoring. • We demonstrate the correlation of the index with land use on the watershed scale. • The index offers a cost-effective tool, practical for medium-qualified personnel. Abstract: We propose and test a new Phytoplankton Community Index (PhyCoI) for monitoring the ecological status of lakes and reservoirs. The design of our PhyCoI is based on the fact that phytoplankton biomass and community structure respond to changes in water quality (mainly eutrophication) and by themselves also influence water quality. In order to accommodate this double role of phytoplankton as indicator and impact, PhyCoI is based on phytoplankton community properties at different hierarchical levels combining both specific metrics (total biomass, taxonomic group biomass, cyanobacteria contribution, taxonomic group species richness) and new or modified sub-indices. It is calculated from the scores of the different metrics/sub-indices resulting in a final index value in the range from 0 to 5, to assess water quality on the basis of five ecological classes according to the Water Framework Directive (WFD). The test of PhyCoI was based on Carlson's Trophic State Index (TSISD) based on water transparency (Secchi depth) in 26 Greek lakes and reservoirs covering the entire spectrum from oligotrophic to hypertrophic. A highly significant relationship at p 〈 0.001 between the two variables was found, with the values of the PhyCoI declining with increasing TSISD. Furthermore, a significant relationship between the PhyCoI and land use types at the watershed of the studied freshwaters was found identifying permanent crops, pastures and shrubs and herbaceous vegetation associations as significant predictors of PhyCoI values. Because of the amount of labor involved in obtaining the PhyCoI we suggest to combine low frequency PhyCoI determinations with a high frequency Secchi depth measurements for practical monitoring purposes.
    Type: Article , PeerReviewed
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  • 3
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    In:  [Other] In: 17. Workshop of the International Association of Phytoplankton Taxonomy and Ecology (IAP), 14.-21.09.2014, Kastoria, Greece .
    Publication Date: 2014-12-19
    Type: Conference or Workshop Item , NonPeerReviewed
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  • 4
    Publication Date: 2020-02-06
    Description: Highlights: • Airborne bacterial abundance, biomass and composition were studied in Thessaloniki. • The highest values of bacterial abundance were recorded during summer. • No significant seasonal differences were found between summer and winter. • Air temperature was found to significantly affect the airborne bacterial community. • The majority of OTUs were affiliated to taxa derived from soil and wastewater. Abstract: The abundance, biomass and the taxonomic composition of the total airborne bacterial communities in a coastal urban area of Northeastern Mediterranean Sea were examined. In total, 27 air samples were collected across three seasons from a sampling point of approximately 30 m altitude in the center of the city. The abundance and biomass were determined with the use of epifluorescent microscopy, while the taxonomic composition was characterized by next-generation sequencing methods. Overall, the highest values of bacterial abundance were recorded during summer, with values exceeding abundances recorded in other urban sites across Europe, reaching 41 × 104 cells m−3. Out of 6 core meteorological parameters, only air temperature was found to significantly affect the abundance and biomass of airborne bacteria. Concerning the taxonomic composition of the airborne bacterial community, the group of Proteobacteria was the most diverse, with 47% of the total number of OTUs belonging to them, followed by Firmicutes, Actinobacteria and Bacteroidetes. The most dominant OTU belonged to γ-Proteobacteria, and was closely affiliated to Pseudomonas sp., a taxon commonly found to actively participate in the formation of ice-nuclei in the atmosphere. Finally, 19 OTUs were shared between all seasons and were found to be among the most dominant overall. The majority of these OTUs were affiliated to genera from soil and wastewater origin, while several were affiliated to genera that include known or opportunistic pathogens. Yet, only rare OTUs were affiliated to taxa with possible marine origin (e.g. Synechococcus sp.). The results showed that the atmosphere of the study area harbors a diverse and abundant bacterial community.
    Type: Article , PeerReviewed
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  • 5
    Publication Date: 2022-01-31
    Description: The enactment of the Water Framework Directive (WFD) initiated scientific efforts to develop reliable methods for comparing prevailing lake conditions against reference (or nonimpaired) states, using the state of a set biological elements. Drawing a distinction between impaired and natural conditions can be a challenging exercise. Another important aspect is to ensure that water quality assessment is comparable among the different Member States. In this context, the present paper offers a constructive critique of the practices followed during the WFD implementation in Greece by pinpointing methodological weaknesses and knowledge gaps that undermine our ability to classify the ecological quality of Greek lakes. One of the pillars of WDF is a valid lake typology that sets ecological standards transcending geographic regions and national boundaries. The national typology of Greek lakes has failed to take into account essential components. WFD compliance assessments based on the descriptions of phytoplankton communities are oversimplified and as such should be revisited. Exclusion of most chroococcal species from the analysis of cyanobacteria biovolume in Greek lakes/reservoirs and most reservoirs in Spain, Portugal, and Cyprus is not consistent with the distribution of those taxa in lakes. Similarly, the total biovolume reference values and the indices used in classification schemes reflect misunderstandings of WFD core principles. This hampers the comparability of ecological status across Europe and leads to quality standards that are too relaxed to provide an efficient target for the protection of Greek/transboundary lakes such as the ancient Lake Megali Prespa.
    Type: Article , PeerReviewed
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