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Dinoflagellates contain large amounts of omega-3 fatty acids, including the nutritionally important docosahexaenoic acid (DHA). However, their cultivation in suspensions is characterized by low growth rates. Twin-layer porous substrate photobioreactors (TL-PSBRs) have been shown to support growth of different microalgal species, including the robust dinoflagellate Symbiodinium voratum. In the present study, the potential of cultivating marine autotrophic dinoflagellate species in a TL-PSBR for DHA production was explored. Based on initial screening experiments, two Symbiodinium species with high biomass and DHA productivities were selected: the symbiotic Symbiodinium microadriaticum CCAC 2475 B and the free-living Symbiodinium voratum CCAC 3869 B. The effects of three different temperatures (17, 22 and 27 °C) and nitrogen regimes (nitrate, ammonium and nitrogen-free) on biomass growth, total lipid accumulation and fatty acid methyl esters (FAMEs) content, with emphasis on DHA, were evaluated. The two lower temperatures (17 and 22 °C) enhanced growth and total lipid accumulation of S. microadriaticum CCAC 2475 B and S. voratum CCAC 3869 B. Cultivation at 22 °C and nitrogen limitation led to a significant positive effect on DHA productivity. Symbiodinium. microadriaticum CCAC 2475 B reached a DHA productivity of 145.4 mg m−2 day−1 and DHA content in the dry biomass of 2% (w/w) after 4 days of nitrogen depletion. The results of the present study demonstrated that autotrophic dinoflagellates, when cultivated on a TL-PSBR, produce comparable amounts of lipids and fatty acids to other commercially used microalgal species including the valuable DHA.

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.

The concept of community ecology has become a central issue for sustainable biofuel production. However the development of appropriate multi-algae cultures for the industry remains challenging. Natural marine algae blooms collected from coastal areas of Cyprus were induced to form multi-algae cultures, and five (5) of those were developed and tested. Algae growth characteristics, biomass, and lipid productivity were assessed, and the dominant microalga was isolated in all cultures. Growth characteristics, lipid productivity, and FAME composition varied considerably among the different multi-algae cultures as well as their corresponding dominant species. Our results suggest that competitiveness and species complementarity could be crucial factors for biomass and lipid productivity. In material collected from the marina in Larnaca of Cyprus, the induced BL1_LCA bloom was the most promising culture, dominated by Nannochloropsis sp. and accompanied by cyanobacteria assemblages, exhibiting the highest biomass and lipid productivity compared to the other developed blooms. Biomass and lipid productivity of an axenic monoculture of Nannochloropsis sp. were 2.1 and 2.2 times lower compared to those measured in BL1_LCA. The growth parameters of BL1_LCA and its corresponding dominant species were further tested under culture media of different seawater and wastewater ratios. An increase of wastewater ratio in the culture media resulted in a significant reduction of lipid, FAME concentration as well as biomass productivity both in BL1_LCA and its dominant isolate. Overall, our findings suggest that the complex interactions within microalgae community might be crucial for biodiesel production; moreover, the general assumption that wastewater can be applied as an alternative nutrient source should be used cautiously since species-specific responses seem to take place.

To achieve their reproductive potential, barnacles combine tactile exploration of surface structural properties and integration of cellular signals originating from their antennular sensory setae within a developmentally defined, temporally narrow window of settlement opportunity. Behavioural assays with cyprids coupled with biometric analysis of scanning electron microscopy-acquired images in the presence of specific chemical compounds were used to investigate how settlement on a substratum is altered in response to the presence of these compounds. It is shown that impeding tactile exploration, altering cellular signalling and/or inducing malformations of anatomical features of the antennular sensory setae can disrupt the settlement behaviour of the model barnacle species Amphibalanus amphitrite. It is concluded that surface exploration by the cyprids relies on mechanical and nociception-related and calcium-mediated signals while a protein kinase C signalling cascade controls the timely metamorphosis of the cyprids to sessile juveniles.

Phytoplankton is the main indicator group for eutrophication in coastal ecosystems, however its high dispersal potential does not enable the assessment of localized effects of coastal nutrient enrichment. Benthic diatoms are sessile microalgae associated with sandy substrates and have the potential to reflect more localized pollution impacts. Although benthic diatoms are widely used bioindicators in freshwater systems, they have rarely been used for assessing the eutrophication status of oligotrophic environments such as the eastern Mediterranean Sea. In the present study, we assess the efficiency of benthic diatoms as bioindicators of nutrient enrichment in oligotrophic coastal systems, by investigating the effect of different physicochemical conditions and nutrient concentrations on the assemblage composition, diversity and individual species populations. To do this, we sampled along a eutrophication gradient formed by anthropogenic nutrient inputs from a metropolitan area. The main driver of assemblage composition, diversity and biomass of diatoms was nitrogen concentration and its temporal and spatial changes. Nitrogen loadings were positively correlated with increased biomass of Cocconeis spp. and negatively correlated with Mastogloia spp. Our findings suggest that in coastal ecosystems of oligotrophic marine ecoregions, benthic diatom assemblage structure and specific taxonomic groups can be reliable predictors of coastal eutrophication offering higher spatial resolution compared to phytoplankton.

The enactment of the Water Framework Directive (WFD) initiated scientific efforts to develop reliable methods for comparing prevailing lake conditions againstreference(or non-impaired) states, using the state of a set biological elements. Drawing a distinction between impaired and natural conditions can be a challenging exercise, as it stipulates the robust delineation of reference conditions along with the establishment of threshold values for key environmental variables used as proxies for the degree of system impairment. 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 status 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 (e.g. surface area, altitude, salinity). WFD compliance assessments based on 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 and most reservoirs in the Mediterranean Geographical Intercalibration Group (Greece, 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 their 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 especially for the protection and management of Greek/transboundary lakes such as Lake Megali Prespa, one of the oldest lakes in Europe.

Cave Cyanobacteria - thriving in an ‘extreme’ environment with interesting species biodiversity - are supposed to be a potential source of bioactive compounds. Lipid extracts from pure cultures of two recently established Cyanobacteria from Greek caves, Toxopsis calypsus and Phormidium melanochroun, were used for antibacterial screening against human pathogenic bacteria (reference and clinical isolates). Antimicrobial Susceptibility testing for both taxa was carried out using the disc-diffusion (Kirby Bauer) method, while preliminary data applying the standard broth microdilution method for the determination of the Minimal Inhibitory Concentration (MIC) are given only for T. calypsus. Antibacterial activity was demonstrated against the Gram-positive clinical and reference bacteria, mostly pronounced in enterococci; no activity was observed against the Gram-negative bacteria. The above screening is the first record of antibacterial activity from lipid extracts of cave Cyanobacteria enhancing the importance of cave microbiota and the necessity for cave conservation. cave Cyanobacteria; Toxopsis calypsus; Phormidium melanochroun; antimicrobial susceptibility screening

Biotic indices are considered key assessment tools in most national and European policies aimed at improving the quality of coastal waters. At present, several Water Framework Directive (WFD)-compliant biotic indices based on the marine angiosperm Posidonia oceanica have been developed and applied in the Mediterranean Sea. In this study, we investigated the effectiveness of four different P. oceanica indices (POMI, PREI, Valencian CS, and BiPo) in evaluating the ecological status of coastal waters in a case study area of Greece. The evaluation, comparison, and validation of the Ecological Status Class (ESC) assessments obtained by each index were based on a set of eight common sites that encompasses the maximum range of environmental quality in the study area. Four sampling sites separated by tens of km were chosen in each of the two water bodies (WBs) studied. The spatial variations of the features of P. oceanica meadows were examined according to a hierarchical sampling design across four spatial scales, ranging from metres to tens of km, using independent nested analysis of variance. Except for the BiPo index, the reference values for each metric/index were defined by the dataset available for the study area. All biotic indices classified the WBs of the study area in Good ESC category. Only three of the four indices (PREI, Valencian CS, and BiPo) showed high comparability in the assessment of ESC at study site level. It is assumed that the differences found in the remaining index (POMI) are due to the different type of metrics taken into consideration and the different weighting given to them. Our findings suggest that all indices can provide an overall view of the cumulative impact of multiple environmental stressors existing in the study area, and can thus help raise awareness of ecosystem degradation.

The karst cave ‘Vlychada’of Diros, one of the oldest show caves in Peloponnese, sustains extended phototrophic biofilms on various substrata – on rocks inside the cave including speleothems, and especially near the artificial lighting installation (‘Lampenflora’). After a survey of the main abiotic parameters (Photosynthetically Active Radiation -PAR, Temperature -T, Relative Humidity -RH, Carbon Dioxide -CO2) three clusters of sampling sites were revealed according to Principal Component Analysis (PCA): i) the water gallery section predominately influenced by CO2, ii) the dry passages influenced by RH and PAR, and iii) the area by the cave exit at the dry section influenced by temperature. The collected samples from the water gallery section and the dry passages of the cave revealed a total of 43 taxa of Cyanobacteria, with the unicellular/colonial forms being the most abundant. The applied non-metric Multi-dimensional Scaling Ordination (nMDS) of the cumulative species composition showed a clear distinction between the water gallery section and the dry passages of the cave. Further comparison with previous data from other wild caves of Peloponnese (‘Kastria’, ‘Francthi’, and ‘Selinitsa’) was conducted revealing a distinction between the show cave and the wild ones. Apart from the human impact on cave ecosystems – through aesthetic alteration (‘greening’) of cave decorations by the ‘Lampenflora’, and by the cleaning treatments and restoration projects on the speleothems – identification of the organisms constituting the ‘Lampenflora’ might provide taxonomically and ecologically significant taxa.

Caves and hypogean environments host various phototrophic microorganisms, with Cyanobacteria constituting the major group. The spatial and temporal distribution of Cyanobacteria (156 taxa in total) from three Greek caves, located in the limestone arc of Peloponnese and differing in morphology, was studied. The community patterns in different ecological niches were analyzed in relation to environmental parameters (Photosynthetically Active Radiation, Temperature, and Relative Humidity). Cyanobacterial communities were found to thrive in patchy biofilms and showed known protective strategies against desiccation and irradiation. The nMDS analysis of the cumulative seasonal samples per sampling site showed no general pattern of distribution, with a clear differentiation of cyanobacterial communities among the three caves. Only in the typical cave ‘Kastria’, cyanobacterial taxa showed growth habits in accordance with the gradient of light from entrance inwards.

Caves have generally been found to host phototrophic micro-organisms from various taxonomic groups, with cyanobacteria comprising an important group that have adapted to these stable and highly specific environments. A polyphasic study based on aspects of classical morphology and molecular data revealed two new monospecific genera from fresh material of Greek and Spanish caves. Both taxa are characterized by obligatory true branching (T-type, V-type and false branching), the presence of heterocysts, and reproduction by hormocysts and akinetes. They shared some similarities in their morphological characteristics as revealed by light, scanning electron and transmission electron microscopy, but phylogenetic analysis based on 16S rRNA gene sequences showed that the two phylotypes were different (89.8 % similarity); this represents an example of shared morphology in genetically different strains of cave-adapted species. Phenotypic and genetic traits strongly support classification of the phylotypes as independent taxa in the order Stigonematales (the most differentiated and complicated group of cyanobacteria), family Loriellaceae Geitl 1925. Hence, the names Iphinoe spelaeobios Lamprinou and Pantazidou gen. nov., sp. nov. and Loriellopsis cavernicola Hernández-Mariné and Canals gen. nov., sp. nov. are proposed.

The responses of the benthic marine dinoflagellate Prorocentrum lima to nutrient stress induced by unbalanced N:P ratios were the subject of this study. Batch cultures of P. lima cells were grown u ...

Rust-coloured shells of the aquatic gastropod Ventrosia ventrosa, a new record for eastern Greece, indicating presence of iron (EDAX analysis) were studied for detection of iron-encrusted photosynthetic epibionts in a Greek brackish-water thermal spring (38 °C). Microscopic analyses (LM, SEM) revealed the presence of a biofilm consisted of mostly facultative micro-epibionts, i.e. a) 5 periphytic taxa of coccal and filamentous cyanobacteria, including a taxonomically and ecologically interesting morphospecies, Xenococcus cf. pyriformis, dominated exclusively on the shell surface, and b) pennate diatoms with higher species richness (18 periphytic taxa of the genera Amphora, Brachysira, Cymbella, Diatoma, Encyonema, Navicula, Nitzschia, Pleurosigma, Synedra, Ulnaria; 5 taxa as new records for Greece), most of them emerging only after acid treatment of whole gastropod shells. The abundant diatoms thriving directly or nearby the iron-coatings (Cocconeis placentula var. euglypta and Achnanthes brevipes sensu lato) exhibited different modes of attachment ('adnate' and 'pendunculate', respectively). Two euendolithic cyanobacteria (Hyella sp. and Leptolyngbya terebrans; the former with special taxonomic interest) were also found perforating the delicate gastropod shells, with no distinct differentiation in the extent of infestation between live and dead gastropod shells. Moreover, the possible impact of these encrusted photosynthetic assemblages on V. ventrosa was investigated; statistical analysis showed that a) there is no 'drag effect', induced by the epibionts, influencing the gastropod growth (i.e. shell length), b) shell size enlargement provides a favourable space and promotes the intense fouling by both micro-epibionts and macro-epibionts (egg-capsules), and c) the detachment prevention of egg-capsules is attributed to the biofilm development.

The population dynamics of potentially harmful microalgae was investigated in the semi-enclosed shallow Gulf of Kalloni, Greece (Aegean Sea, Eastern Mediterranean), during a 2-year period from August 2004 to March 2006. A total of 21 potentially harmful microalgae (bloom-forming and/or toxic) were identified including 3 diatoms and 18 dinoflagellates. The densities of each species were analyzed in time and space and in relation to environmental parameters. Some species such as Alexandrium insuetum, Heterocapsa circularisquama, Karlodinium veneficum, Scrippsiella trochoidea, and Ceratium spp. developed high cell concentrations, particularly during a Pseudo-nitzschia calliantha winter bloom. Other species such as Dinophysis caudata, Ostreopsis ovata, Prorocentrum minimum, and Protoperidinium crassipes were rare or appeared in small numbers. Densities of the most abundant species were closely associated with freshwater nutrient-rich inputs during winter, being negatively correlated with temperature and salinity and positively correlated with nitrogen. The spatial distribution of the abundant species exhibited a marked increase towards the inner part of the gulf, close to the main freshwater inputs, whereas some species were mainly concentrated in the dilute surface layer (1 m depth). Examination of the abundance–occupancy relationship revealed that the species more prone to bloom are those with wide spatial distribution and frequent presence throughout the year such as the diatom P. calliantha. Although blooms of cyst-forming species are rarer, an increased risk can be foreseen under favorable resource supply and environmental conditions during winter.

The present paper deals with biocommunities of cave Leontari, Attica (Greece) focusing on its lithophytic cyanobacteria, and the associated microfauna. The cave is of archaeological importance, not touristically exploited, naturally lighted through the entrance; it consists of one chamber with poor stalactite and stalagmite limestone decoration. During a survey in three campaigns, samples of cyanobacteria and soil invertebrates were collected from four sites (I-IV) along a light(PAR)-temperature-humidity gradient. Light microscopic observations of natural and cultured material have shown that epilithic and endolithic cyanobacteria were almost the exclusive component of cave photosynthetic microflora. Twenty two taxa were identified including the taxonomically interesting morphotypes Chroococcus spelaeus, Asterocapsa sp. and Chlorogloea sp. Arthropods were found as dominant soil invertebrates represented by nine taxa.

Mediterranean mariculture uses imported strains of marine phytoplankton, raising questions of ecological risk and ability to adapt to local conditions for mass culture outdoors. In this context, we report here on the mass-culture potential and chemical composition of six strains of Prasinophyceae (five strains of Tetraselmis sp. and one Pyramimonas sp.) isolated from a Greek coastal lagoon. Proximate composition had a pattern of 10–20% ash, 35–65% protein, 6–10% lipids, and 25–45% other organics including carbohydrates. The amino acid profiles were typical for the marine representatives of the class. All strains had a high PUFA content with dominant the ω3 fraction in four of them. The fatty acid profiles indicated a Tetraselmis strain with high EPA (14%) and a Pyramimonas strain with high DHA (6%). These strains might be a good alternative for the common commercial strains used in Mediterranean aquaculture.

Potamopyrgus antipodarum (Gastropoda: Hydrobiidae), a New Zealand native species, is recorded for the first time in waterbodies of Greece, being dominant in the gastropod fauna present; waterfowl transportation is suggested as its invasion mode. This species was collected (November 2007) from the aquatic plants Myriophyllum spicatum and Nasturtium officinale in Lake Trichonis (CW Greece) and an adjacent stream. Totally, 332 individuals of various ages were recorded, females being the majority. One diatom (Cocconeis placentula var. euglypta) was found in its digestive tube, also thriving abundantly on the surface of both the invader shell and the aquatic plants, and in association with other cosmopolitan periphytic diatoms (three of them new for the area, with one new record for Greece) or endemic diatoms.

Strains of Cyanobacteria isolated from mats of 9 thermal springs of Greece have been studied for their taxonomic evaluation. A polyphasic taxonomic approach was employed which included: morphological observations by light microscopy and scanning electron microscopy, maximum parsimony, maximum likelihood and Bayesian analysis of 16S rDNA sequences, secondary structural comparisons of 16S-23S rRNA Internal Transcribed Spacer sequences, and finally environmental data. The 17 cyanobacterial isolates formed a diverse group that contained filamentous, coccoid and heterocytous strains. These included representatives of the polyphyletic genera of Synechococcus and Phormidium, and the orders Oscillatoriales, Spirulinales, Chroococcales and Nostocales. After analysis, at least 6 new taxa at the genus level provide new evidence in the taxonomy of Cyanobacteria and highlight the abundant diversity of thermal spring environments with many potential endemic species or ecotypes.

Samples of typical estuarine mollusc shells (Cerastoderma glauca, Abra ovata and Hydrobia acuta), differing in appearance, size and age, were collected from littoral habitats of a saline water lagoon (Ahivadolimni on Milos Island, Greece). Each shell sample was examined for the distribution, frequency and taxonomy of its shell-boring cyanobacteria and chlorophytes, and the associated attached (epizoic) diatoms. The euendolithic microflora was extracted using Pereny's solution and observed by light microscopy (LM). The results of microbial penetration (traces of euendoliths) were examined by scanning electron microscopy (SEM) after a hypochlorite treatment. The three-dimensional patterns of microbial penetration (boring patterns) were investigated under SEM by applying the resin-casting technique for modern euendoliths. Of the five euendolithic cyanobacteria found, one (Cyanosaccus atticus) was established from Greek marine biotopes, three (Hyella caespitosa var. arbuscula, H. inconstans and H. reptans) ar...

Sequences of LSU and SSU ribosomal RNA genes and phylogeny have not been widely investigated for the dinoflagellate Coolia monotis Meunier, and no information is available on the small and large rDNA subunits of Mediterranean strains. A strain isolated from the Thermaikos Gulf in northern Greece was identified as C. monotis —a new record for the Greek algal flora—using thecal morphology by light, epifluorescence and scanning electron microscopy. The small subunit and partial (D1/D2) large subunit sequences were analyzed and compared to other strains of C. monotis and dinoflagellates from various regions. Thecal architecture showed that the Greek strain of C. monotis was phenotypically similar, but not identical, to other strains reported in literature. The partial LSU sequence (700 bp) was found to vary by 113 bp positions (16%) from the C. monotis strain from New Zealand, whereas the SSU (1757 bp) had 15 bp differences (0.85%) from the strain from Norway. Phylogenetic tree construction showed that the Greek strain fell within the Coolia clade and had a close relationship with the families Ostreopsidaceae and Goniodomaceae of the order Gonyaulacales. Preliminary findings suggest the existence of different genotype strains of C. monotis with large intraspecific genetic variability and minimal morphological differentiation (similar phenotypes). Certain ecological and evolutionary implications of these findings are discussed.

There is continuous interest in many countries in maintaining and manipulating the rich ecological value of hypersaline ecosystems for aquaculture. The Megalon Embolon solar saltworks (northern Greece) were studied in sites of increasing salinity of 60–144 ppt to evaluate Dunaliella salina abundance and microalgal composition, in relation to physical and chemical parameters. Cluster and ordination analyses were performed based on the biotic and abiotic data matrices. Using fresh aliquots from 60 and 140 ppt salinity waters, phytoplankton performance was appraised with flask cultures in the laboratory by varying the inorganic PO4-P concentration at 23 °C and 30 °C. At the saltworks, among the most abundant microalgae identified were species of the genera Dunaliella, Chlamydomonas, Amphora, Navicula, and Nitzschia. Dunaliella salina populations were predominant comprising 5–22% of the total microalgal assemblages during spring, but only 0.3–1.0% during the summer, when grazing by Artemia parthenogenetica and Fabrea salina was intense. D. salina cell density in April–July was in the range of 0.4–12.5 × 106 L−1 with typical densities of 1.5–4.5 × 106 L−1. Overall, microalgal densities were high in salinities of ≥100 ppt when inorganic-P concentrations were ≥0.20 mg L−1 within saltworks waters. Multivariate analysis of species abundance showed that algal growth responses were primarily related to variation in salinity and inorganic-P concentrations, but also to NO3-N concentration. In the laboratory, experiments indicated effective fertilization and denser microalgal growth under high inorganic PO4-P applications (4.0 and 8.0 mg L−1) at 60 ppt salinity and 23 °C. The lower PO4-P applications (0.6–2.0 mg L−1) were more effective at 60 ppt salinity and 30 °C. At 140 ppt salinity, microalgal growth response was less obvious at any of the corresponding phosphorus concentrations or temperatures. In both salinity experiments, Dunaliella salina bloomed easily and was predominant among the microalgae. Our observations indicate that Dunaliella salina populations and the overall rich microalgal profile of the saltworks, along with their performance in laboratory mono–and mixed cultures hold promise for mass cultivation within the M. Embolon saltworks basins.

An updated checklist of the green seaweeds (Ulvophyceae) of the Greek coasts is provided, based on both literature records and new collections. The total number of species and infraspecific taxa currently accepted is 95. The occurrence of each taxon in the North Aegean, South Aegean and Ionian Seas is given. In addition, 12 taxa pending confirmation of their presence, 9 excludenda and 14 inquirenda are briefly discussed.

During four seasonal in situ experiments (1995-1996) phytoplankton productivity and species composition were studied at one central station in the Polyphytos Reservoir, northwestern Greece. A total of 69 algal taxa were identified. Suspended algal assemblages were dominated by diatoms and green algae. Phytoplankton cell abundance ranged from 0.03 to 2.677. 10 6 cells per 1, chlorophyll a concentrations from 1.07 to 4.76 mg m -3 and primary productivity from 7.1 to 137.9 mg m -3 h -1 C. Since the 1980s, the reservoir evolved from a mesotrophic to a eutrophic state.

Phytoplankton communities from the lower reaches of the Aliakmon River, Greece, have been studied over a period of one year. Seasonal phytoplankton dynamics was described on the basis of its species composition and abundance, biomass and chlorophyll-a concentrations. Phytoplankton assemblages comprised diatoms (mainly Cyclotella meneghiniana, Nitzschia palea and Fragilaria ulna), cyanobacteria (mainly Pseudanabaena limnetica, Aphanizomenon sp. and Limnothrix cf. redekei) and green algae (various species of Scenedesmus and Chlamydomonas, Coelastrum microporum and Monoraphidium contortum). Many benthic diatoms were also present. An important growth of euglenophytes was observed during summer, mainly Lepocinclis steinii, L. ovum, Euglena intermedia, E. viridis and Phacus caudatus. The spring maximum of centric diatoms extended into the summer. The qualitative and quantitative composition of the phytoplankton is compared to communities of other European rivers. With regard to phytoplankton assemblages, Aliakmon resembles more the relatively fast-flowing, individual-poor European rivers. Its widely varying discharge volume, turbidity and shallowness, seem to be the main factors controlling phytoplankton communities in its lower reaches.

Epiphytic macroalgal assemblages growing on Cystoseira species were examined at typical oligotrophic and eutrophic sites of the east coast of Attica (Aegean Sea, Greece) from November 1995 to September 1996. The epiphytic patterns of C. spinosa Sauvageau thriving in the oligotrophic area of Dikastika and of C. compressa (Esper) Gerloff & Nizzamudin growing in the eutrophic environment of Avlida, were compared through a cross-transplantation experiment. Seasonality effects on epiphytic assemblages were observed. The species composition was exclusive for each locality, reflecting differences in the trophic status of the two sites. No specific pattern of epiphytes' distribution was found on the hosts. The prolific epiphytic growth in the oligotrophic site resulted in a reduction of the photosynthetic tissue of both hosts (C. spinosa and the transplanted C. compressa) and the survivorship of host plants was not negatively affected by the physical drag caused by the high epiphyte densities. Cystoseira spinosa survived in oligotrophic conditions despite its heavy epiphytic load. C. compressa was also able to cope with the adverse epiphytic influence in the eutrophic conditions of Avlida; although being perennial, it sheds parts of its stipe and branches before the resting period and sprouts prior to other algae at the beginning of spring.

Samples from two flood plain lakes (Umuorodog-wum I and II) and one permanent natural lake (Oguta) of the lower Niger Delta system (Imo State, Nigeria), representing the outcome of a single sampling campaign in January 1993, are analysed taxonomically. Emphasis is given on the diatom flora but also on some other accompanying algae; a list of 172 algal taxa is currently presented for the area. The relative species abundance patterns and autecology data confirm the frequent occurrence of taxa capable of tolerating the wide environmental fluctuations determined by local conditions of climate and water chemistry. Comparisons are made between the studied lakes including one disturbed site. The results on the water chemistry and biology corroborate findings from similar ecosystems in West Africa.

Phytoplankton assemblages of the warm monomictic lakeTrichoniswere studied during the period April 1985 to February 1986.Speciescomposition and biomass data are presented along withinformationon the seasonal periodicity of dominant taxa of microalgae.Multivariate methods were used to analyze community structureandannual succession. Population succession patterns correspondtochanges in environmental variables. According to thegeneralizedphytoplankton sequences Trichonis is classified as anoligotrophiclake.

Limnological characteristics of lake Amvrakia, a deep warm monomictic and sulphate lake in western Greece, are presented. A set of physical and chemical variables were monitored for one year cycle (October 1988–September 1989). Phytoplankton community structure and biomass are given for the entire depth of the water column. The trophic status of the lake is compared to that of other temperate and tropical lakes.

Based on aspects of the classical LM morphology, and a combination of ultrastructural and molecular data, a new true-branched cyanobacterium, i.e. Spelaeonaias floccida Lamprinou, Christodoulou, Hernández-Mariné et Economou-Amilli, gen. nov. sp. nov., is described from the Greek cave Vlychada (part of the ‘Diros’ cave complex, Peloponnese, Greece). The new monospecific genus bears a Y-like type of branching, intercalary heterocytes and terminal heterocytes at the ensheathed hormogonia, thus morphologically resembling Symphyonemopsis. The subaerophytic growth of the ensheathed hormogonia is considered as the autapomorphic feature for Spelaeonaias. The 16S rRNA sequencing revealed that S. floccida forms a well congruent monophyletic cluster along with two stigonematalean strains SA1301 and SP302 from Maltese catacombs (GenBank: HQ917695 and HQ917696 respectively).

Strains of Tetraselmis , a genus with systematic and biotechnological interest and one of the most prominent genera in marine phytoplankton, were studied. Five strains of T. verrucosa f. rubens, a taxon first documented in coastal lagoons of Greece, are examined herein under a multivariate approach i.e. in relation to their morphological variability under light and transmission electron microscopy (LM and TEM, respectively), and taking into account certain molecular and biochemical attributes as taxonomic markers, including the plastid-encoded rbcL and nuclear-encoded 18S rRNA gene sequences, and the fatty acid profile. The molecular markers were used to verify the phylogenetic position of the strains within the genus Tetraselmis and the class Chlorodendrophyceae. For that purpose, the original Tetraselmis verrucosa f. rubens isolate (CCAP strain 66/6) was included in the analysis. The molecular data are in agreement with the classification based on morphology. The five strains grouped firmly together and formed a monophyletic group with the original T. verrucosa f. rubens isolate. Lipid analysis of the strains was performed using the FAME (Fatty Acid Methyl-Ester) method and the resulting profile might be used as an additional taxonomic marker.

Representatives of a new cyanobacterial genus, Toxopsis Lamprinou & Pantazidou gen. nov., were found in fresh material from Cave ‘Francthi’ (Peloponnese, Greece) and isolated in cultures. Ecological data relating to the environmental parameters of the sampling sites are provided, such as the photosynthetically active radiation (PAR), temperature and relative humidity. Morphological characteristics and the life cycle of the type species Toxopsis calypsus Lamprinou & Pantazidou sp. nov. were studied using light microscopy and scanning and transmission microscopy. Molecular analysis based on the 16S rRNA gene sequence was also conducted. Toxopsis calypsus sp. nov. is a false-branched nostocalean cyanobacterium with both isopolar and heteropolar filaments bearing mono-pored and bi-pored heterocysts, and also hormogonia and akinetes. Isopolar filaments adhere by the centre to the substrate and are found mainly in fresh material and in young cultures; heteropolar filaments bearing a basic mono-pore heterocyst are dominant in aged (more than one-year-old) cultures. According to the revised taxonomic classification system of Komárek & Anagnostidis (1989) [Komárek, J. & Anagnostidis, K. (1989). Algol Stud, 56, 247–345] based mainly on morphological data, the new genus described here shares morphological characters with both nostocalean families Scytonemataceae and Microchaetaceae, showing similarities in particular to Scytonematopsis contorta [Vaccarino, M. A. & Johansen, J. R. (2011). Fottea 11, 149–161], Microchaetaceae. Molecular data from the 16S rRNA sequence determined in this paper showed that Toxopsis calypsus sp. nov. is more related to the family Microchaetaceae, and the five phylotypes analysed by PCR showed that the closest nostocalean relatives are Tolypothrix distorta SAG 93.79 (GenBank accession no. GQ287651) and Coleodesmium sp. ANT.L52B.5 (AY493596) with 95–96 % and 96 % similarity, respectively. In contrast, the five phylotypes showed a distant similarity to Scytonematopsis contorta (Toxopsis calypsus Lamprinou & Pantazidou gen. nov., sp. nov. is proposed.

The diatom family Rhaphoneidaceae is characterized by high generic diversity and low species diversity with most genera known to have long stratigraphic ranges. The genera within this family are neritic marine, and mostly epipsammic. A new modern and epipsammic genus, Meloneis gen. nov., is described herein and is compared to all genera within Rhaphoneidaceae and especially to Rhaphoneis Ehrenberg s.l. Within Meloneis three new species and one variety are distinguished and described herein: M. mimallis sp. nov., M. mimallis var. zephyria var. nov., M. akytos sp. nov., and M. gorgis sp. nov.

A new fossil species of Cyclotella, C. elymaea, has been studied by LM and SEM. It was dominant in Neogene deposits of the Kozani-Aeani-Servia basin, northern Greece, accompanied by numerous hemispherical valves which are assumed to be or derive from initial cells. Analysis of morphometric parameters revealed significant variation in valve structure, mostly related to the degree of silicification of the frustules and the decrease in valve diameter resulting from cell division. This comprised variation in the pattern of ornamentation in the central zone, in the density of the marginal fultoportulae and in the structure of the striae. However, since the general characteristics of the valve are constant throughout C. elymaea and transitional forms can be recognized between the variants, it is suggested that the morphotypes are all part of the same life cycle. In the informal subdivision of Cyclotella that has been proposed, C. elymaea would fall within the “andancensis” group. © 1991 Taylor and Francis Group, LLC.

Cyclotella distinguenda Hust. was studied in material from Lake Kournas in the Island of Crete, Greece. It is characterised by a highly variable central area without any processes, a striate zone of varying width with simple alveoli, a single marginal rimoportula. and several marginal fultoportulae. Analyses of the populations reveal two clusters of morphotypes, distinguished by size range and the relative size of the central area, which appears to represent life cycle variation. The affinity of C. distinguenda with other species of Cyclotella is discussed.

In the present study the potential of a biofilter containing a mixture of dried micro-algal/bacterial biomass for removing heavy metals (Cu2+, Cd2+) from dilute electroplating waste was tested. The biomass was produced in an artificial stream using the effluent of a municipal waste water treatment plant as a nutrient source, with the additional benefit of reducing phosphorus and nitrogen loadings. Baseline batch experiments determined that optimum adsorption for both metals (80–100%) were achieved with the deionized-H2O conditioned biomass at initial pH 4.0. Other biosorption variables (contact time, initial metal concentration) were also tested. Biosorption data were fitted successfully by the Langmuir model and results showed a high affinity of the used biomass for both metals (qmax 18–31 mg metal/g.d.w). Flow-through column experiments containing Ca-alginate/biomass beads showed that metal adsorption depends also on flow-rate and volume of treated waste. Desorption of both metals with weak acids was very successful (95–100%) but the regeneration of the columns was not achieved due to the destabilization of beads.