Distribution survey of Cyanobacteria in three Greek caves of Peloponnese

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

The systematics of Seminavis (Bacillariophyta): The lost identities of Amphora angusta, A. ventricosa and A. macilenta

Amphora angusta Gregory, Amphora ventricosa Gregory and Amphora macilenta Gregory have been misunderstood for the last 140 years. Gregory described these species from sublittoral sediments off the west coast of Scotland. Although the illustrations were excellent for their time (1857), it is impossible to be confident of identification using Gregory's paper, and subsequent authors have created such confusion that records of these taxa must be regarded as untrustworthy unless backed by photographic evidence. In this paper, the first to describe in detail the recently established genus Seminavis, we show that A. angusta is in fact a species of Amphora Ehrenberg, whereas A. Ventricosa sensu Gregory represents two independent species of the genus Seminavis D. G. Mann, namely Seminavis Ventricosa (Gregory) Garcia-Baptista (non S. ventricosa sensu Garcia-Baptista 1993) and Seminavis arranensis Danielidis & D. G. Mann, sp. nov. The form usually known as A. ventricosa is neither of these and requires a new name, Seminavis robusta Danielidis & D. G. Mann sp. nov. The long forgotten and misclassified species A. macilenta Gregory is shown to be yet another Seminavis species, requiring a new combination as S. macilenta (Gregory) Danielidis & D. G. Mann, comb. nov.; contrary to previous claims, it is separate from A. ergadensis Gregory, which is a true Amphora. Valve and girdle ultrastructure, plastid arrangement and auxosporulation are described for Seminavis and resemble those in the Naviculaceae sensu stricto

New species and new combinations in the genus seminavis (bacillariophyta)

A previous study, leading to the redefinition of Seminavis ventricosa (Gregory) Garcia-Baptista and some related taxa, made it clear that a considerable number of species exist within Seminavis D.G. Mann. Many species are still classified under Amphora Ehrenberg, although they clearly share common morphological features with Seminavis. Some of these species are described as new or transferred here, whereas others are only mentioned because of insufficient evidence, lack of original material, or poor documentation, so that taxonomic changes would be unwise at present. The species S. basilica Danielidis sp. Nov., S. heidenii D.G. Mann sp. Nov., S. strigosa (Hustedt) Danielidis & Economou-Amilli comb, nov., S. latior (A. Schmidt) Danielidis & D.G. Mann comb, et stat. Nov., and S. obtusiuscula (Grunow) Danielidis & D.G. Mann comb. Nov. all share the characteristic valve shape, areola structure and raphe constraction of typical Seminavis. Furthermore, in those species where fresh material was available, two plate-like, girdle-appressed chloroplasts were evident, as in other Seminavis and in almost all members of the Naviculaceae Kützing emend. D.G. Mann. The identity of S. cymbelloides (Grunow) D.G. Mann is discussed, although original material has not been available to us and may not exist. Lectotypes for A. angusta var. angustissima Van Heurck, A. diducta A. Schmidt, S. latior (A. Schmidt) Danielidis & D. G. Mann, and S. obtusiuscula (Grunow) Danielidis & D.G. Mann are also designated. © 2003 Taylor & Francis Group, LLC

Transfer of amphora eulensteinii grunow to the genus seminavis d. g. mann

The taxonomie status of the species Amphora eulensteinii Grunow is at present insufficiently known. The study of morphology and fine structure of this species, discovered in core samples from Rhode Island, revealed that it is characterized by the presence of lineolate, slitlike areolae, a dorsally widened axial area and a ventrally displaced raphe that runs internally on a dorsally bended silica rib. All of these structures together with the shape of the valve clearly place this species in the genus Seminavis as it was established by Mann (in Round et al. 1990). The lack of verified original material has led to the designation of a neotype for Seminavis eulensteinii (Grunow) Danielidis, Ford & Kennett comb. nov. © 2006 Taylor & Francis Group, LLC

Recurrent Pseudo-nitzschia calliantha (Bacillariophyceae) and Alexandrium insuetum (Dinophyceae) winter blooms induced by agricultural runoff

A winter bloom dominated by Pseudo-nitzschia calliantha Lundholm, Moestrup et Hasle (Bacillariophyceae), a potential domoic acid producer, is reported for the first time in the Aegean Sea, Greece, in a semi-enclosed embayment (Kalloni Gulf) surrounded by agricultural land and drained by intermittent rivers. Abundances of this species in the inner part of the Gulf during February were extremely high (max 1.1 × 107 cells l−1). The species Alexandrium insuetum Balech (Dinophyceae) was also found in considerable cell numbers (max 1.4 × 105 cells l−1) during the bloom and reached up to 40% of the total biovolume. This study demonstrates an evident cause and effect relationship between nutrient inflows originating from agricultural activities in the watershed and the development of a potential HAB. The massive bloom formation was observed soon after an episodic rainfall event during the fertilizer application period (December to February). A bloom was also observed the following year, but it was less pronounced due to the fact that rainfalls were more evenly spaced in time and were of moderate intensity

Recurrent Pseudo-nitzschia calliantha (Bacillariophyceae) and Alexandrium insuetum (Dinophyceae) winter blooms induced by agricultural runoff

A winter bloom dominated by Pseudo-nitzschia calliantha Lundholm, Moestrup et Hasle (Bacillariophyceae), a potential domoic acid producer, is reported for the first time in the Aegean Sea, Greece, in a semi-enclosed embayment (Kalloni Gulf) surrounded by agricultural land and drained by intermittent rivers. Abundances of this species in the inner part of the Gulf during February were extremely high (max 1.1 × 107 cells l-1). The species Alexandrium insuetum Balech (Dinophyceae) was also found in considerable cell numbers (max 1.4 × 105 cells l-1) during the bloom and reached up to 40% of the total biovolume. This study demonstrates an evident cause and effect relationship between nutrient inflows originating from agricultural activities in the watershed and the development of a potential HAB. The massive bloom formation was observed soon after an episodic rainfall event during the fertilizer application period (December to February). A bloom was also observed the following year, but it was less pronounced due to the fact that rainfalls were more evenly spaced in time and were of moderate intensity. © 2007 Elsevier B.V. All rights reserved

Meloneis gen. nov., a new epipsammic genus of rhaphoneidaceae (bacillariophyceae)

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. © 2012 Louvrou et al

Spatial and temporal variability of small-sized copepod assemblages in a shallow semi-enclosed embayment (Kalloni Gulf, NE Mediterranean Sea)

The small-sized copepod community structure (<1 mm) and its response to environmental variability was examined during an annual cycle in Kalloni Gulf, a semi-enclosed coastal system in the NE Aegean Sea. ' 90 m net was used in order to adequately sample the smaller copepod fractions. In the copepod ecology the spatial patterns dominated over the seasonal. Total copepod abundance increased towards the inner gulf area while diversity indices followed the opposite trend. The inner gulf copepod assemblage area was affected by the increasing magnitude of eutrophication, characterized by high abundance values, low species richness and dominance of a single species (e.g. Oithona nana). A clear seasonal succession of species was observed, ordered by temperature, salinity, chlorophyll a, heterotrophic bacterial biomass, organic and inorganic nutrients. Freshwater inputs and the subsequent nutrient inflow was a dominant phenomenon enhancing copepod production and negatively affecting the biodiversity of the assemblage. The great contribution of copepod larval stages in the total community and their year-round presence indicate the continuous production of copepods during the annual cycle, highlight the importance of the smaller size fraction and encourage the use of finer mesh-size nets when assessing the structure and dynamics of copepod communities. © 2014 Marine Biological Association of the United Kingdom