Redefinition of cell size classification of phytoplankton – a potential tool for improving the quality and assurance of data interpretation

To date, phytoplankton cell size classification is based on linear metrics (nano: 2-20 μm; micro: 20-200 μm; macro: >200 μm) although three-dimensional metrics are used for cell or body size descriptions of all terrestrial and aquatic organisms. This study proposes a redefinition of phytoplankton size classification expressed in terms of cell volume (μm3) metrics by analyzing statistically a data set of 397 species from three major groups of eukaryotic taxa (diatoms, dinoflagellates, coccolithophores). The three size classes based on cell volume metrics are nanoplankton (10-103 μm3), microplankton (103-106μm3) and macroplankton (106-109μm3). Size spectra of cell volume frequencies, species richness-cell size and cell abundance-cell size relationships were evaluated with the use of cell volume (μm3) metrics while fitting of the relevant equations significantly accounted for the data. The analysis of size classes versus taxonomic composition based on cell volume metrics revealed taxonomic group (diatoms, dinoflagellates, coccolithophores) differentiations in nano-micro-macro size classes, thus providing an accurate size classification within and among taxa. This classification offers more precise information on the taxon-size relationships, which are valuable for phytoplankton community structure studies and useful for further development of the remote sensing models designed for differentiating phytoplankton taxa by satellite

Pollution effects on the phytoplankton-zooplankton relationships in an inshore environment

The quantitative and qualitative relationships between the phytoplankton and zooplankton populations were examined for one year in an inshore environment (Elefsis Bay) of the Aegean Sea. It was found that quantitative relationships among these populations were influenced by the trophic level of the environment and their stocks were significantly correlated only in non-polluted conditions. The quantitative relationship between the principal grazers in the zooplankton population (Acartia clausi, Oithona nana) and the phytoplankton dominant species Exuviaella baltica, upon which these copepods were believed to graze preferentially, was tested and the results were discussed. © 1980 Dr. W. Junk b.v. Publishers

Pollution effects on the phytoplankton-zooplankton relationships in an inshore environment

The quantitative and qualitative relationships between the phytoplankton and zooplankton populations were examined for one year in an inshore environment (Elefsis Bay) of the Aegean Sea. It was found that quantitative relationships among these populations were influenced by the trophic level of the environment and their stocks were significantly correlated only in non-polluted conditions. The quantitative relationship between the principal grazers in the zooplankton population (Acartia clausi, Oithona nana) and the phytoplankton dominant species Exuviaella baltica, upon which these copepods were believed to graze preferentially, was tested and the results were discussed. © 1980 Dr. W. Junk b.v. Publishers

Monosaccharide and aminoacid composition of mucilage material produced from a mixture of four phytoplanktonic taxa

A series of multi-taxa cultures containing five blue-green algae, three diatoms, one prymnesiophyte and one dinoflagellate was set up by using as inoculum sea water collected during a mucus-forming phytoplankton bloom in Euboikos Gulf, Aegean Sea. The cultured algae produced mucilage material that undergone quantitative and qualitative pigment, monosaccharide and aminoacid analyses with the use of HPLC methodology. Eight pigments (chlorophyll a, chlorophyll c, fucoxanthin, zeaxanthin, 19'-butanoylofucoxanthin, 19'-hexanoylofucoxanthin, peridinin and phaeophytin a) were identified and confirmed the species viability and their state of senescence. The qualitative composition of the recorded 8 monosaccharides (glucose, galactose, xylose, fucose, mannose, rhamnose, arabinose and glucosamine) and 15 aminoacids (arginine, glutamine, aspartate, serine, lysine, glysine, threonine, alanine, tyrosine, methionine, valine, phenylalanine, isoleucine, leucine and histidine) was similar in all cultures, but their quantitative composition differed among them and this might be due to their differences in species composition. The results also showed that the relative abundance of aminoacids and monosaccharides depended on the physiological state of the cells, the former being more abundant during the exponential phase and the latter mainly during the stationary phase of the cultures

A Survey of Estuarine Benthic, Zoo‐planktonic and Phytoplanktonic Communities of Amvrakikos Gulf, Ionian Sea

Abstract. The estuarine ecosystem of the Amvrakikos Gulf, a semi‐enclosed embayment of the Ionian Sea, was surveyed at 9 stations in June, 1980. Quantitative and qualitative relationships among the phytoplanktonic, zooplanktonic and benthic populations were examined and related to environmental parameters. It was found that quantitative maxima of each of the three components occurred at different stations. When stations were grouped according to a similarity index of each community, it could be shown that the stations were very similar with regard to phytoplankton and slightly less similar with regard to zooplankton. The stations differed considerably as far as the benthos is concerned. The phytoplankton also exhibited a lower species diversity (0.08‐0.82 bits‐indiv.‐1) than the zooplankton (1.08‐2.10 bits indiv.‐1) and the benthos (0.85‐5.06 bits indiv.‐1). Differences in salinity among stations showed no significant correlation with the abundance or species diversity of phytoplankton, zooplankton or benthos. Copyright © 1983, Wiley Blackwell. All rights reserve

A Survey of Estuarine Benthic, Zoo‐planktonic and Phytoplanktonic Communities of Amvrakikos Gulf, Ionian Sea

Abstract. The estuarine ecosystem of the Amvrakikos Gulf, a semi‐enclosed embayment of the Ionian Sea, was surveyed at 9 stations in June, 1980. Quantitative and qualitative relationships among the phytoplanktonic, zooplanktonic and benthic populations were examined and related to environmental parameters. It was found that quantitative maxima of each of the three components occurred at different stations. When stations were grouped according to a similarity index of each community, it could be shown that the stations were very similar with regard to phytoplankton and slightly less similar with regard to zooplankton. The stations differed considerably as far as the benthos is concerned. The phytoplankton also exhibited a lower species diversity (0.08‐0.82 bits‐indiv.‐1) than the zooplankton (1.08‐2.10 bits indiv.‐1) and the benthos (0.85‐5.06 bits indiv.‐1). Differences in salinity among stations showed no significant correlation with the abundance or species diversity of phytoplankton, zooplankton or benthos. Copyright © 1983, Wiley Blackwell. All rights reserve

Seasonal horizontal and vertical variability in primary production and standing stocks of phytoplankton and zooplankton in the Cretan Sea and the Straits of the Cretan Arc (March 1994-January 1995)

Phytoplankton communities, production rates and chlorophyll levels, together with zooplankton communities and biomass, were studied in relation to the hydrological properties in the euphotic zone (upper 100 m) in the Cretan Sea and the Straits of the Cretan Arc. The data were collected during four seasonal cruises undertaken from March 1994 to January 1995. The area studied is characterised by low nutrient concentrations, low 14C fixation rates, and impoverished phytoplankton and zooplankton standing stocks. Seasonal fluctuations in phytoplankton densities, chlorophyll standing stock and phytoplankton production are significant; maxima occur in spring and winter and minima in summer and autumn. Zooplankton also shows a clear seasonal pattern, with highest abundances occurring in autumn-winter, and smallest populations in spring-summer. During summer and early autumn, the phytoplankton distribution is determined by the vertical structure of the water column. Concentrations of all nutrients are very low in the surface waters, but increase at the deep chlorophyll maximum (DCM) layer, which ranges in depth from about 75-100 m. Chlorophyll-a concentrations in the DCM vary from 0.22-0.49 mg m-3, whilst the surface values range from 0.03-0.06 mg m-3. Maxima of phytoplankton, in terms of cell populations, are also encountered at average depths of 50-75 m, and do not always coincide with chlorophyll maxima. Primary production peaks usually occur within the upper layers of the euphotic zone. There is a seasonal succession of phytoplankton and zooplankton species. Diatoms and 'others' (comprising mainly cryptophytes and rhodophytes) dominate in winter and spring and are replaced by dinoflagellates in summer and coccolithophores in autumn. Copepods always dominate the mesozooplankton assemblages, contributing approximately 70% of total mesozooplankton abundance, and chaetognaths are the second most abundant group. (C) 2000 Elsevier Science Ltd

Seasonal horizontal and vertical variability in primary production and standing stocks of phytoplankton and zooplankton in the Cretan Sea and the Straits of the Cretan Arc (March 1994-January 1995)

Phytoplankton communities, production rates and chlorophyll levels, together with zooplankton communities and biomass, were studied in relation to the hydrological properties in the euphotic zone (upper 100 m) in the Cretan Sea and the Straits of the Cretan Arc. The data were collected during four seasonal cruises undertaken from March 1994 to January 1995. The area studied is characterised by low nutrient concentrations, low 14C fixation rates, and impoverished phytoplankton and zooplankton standing stocks. Seasonal fluctuations in phytoplankton densities, chlorophyll standing stock and phytoplankton production are significant; maxima occur in spring and winter and minima in summer and autumn. Zooplankton also shows a clear seasonal pattern, with highest abundances occurring in autumn-winter, and smallest populations in spring-summer. During summer and early autumn, the phytoplankton distribution is determined by the vertical structure of the water column. Concentrations of all nutrients are very low in the surface waters, but increase at the deep chlorophyll maximum (DCM) layer, which ranges in depth from about 75-100 m. Chlorophyll-a concentrations in the DCM vary from 0.22-0.49 mg m-3, whilst the surface values range from 0.03-0.06 mg m-3. Maxima of phytoplankton, in terms of cell populations, are also encountered at average depths of 50-75 m, and do not always coincide with chlorophyll maxima. Primary production peaks usually occur within the upper layers of the euphotic zone. There is a seasonal succession of phytoplankton and zooplankton species. Diatoms and 'others' (comprising mainly cryptophytes and rhodophytes) dominate in winter and spring and are replaced by dinoflagellates in summer and coccolithophores in autumn. Copepods always dominate the mesozooplankton assemblages, contributing approximately 70% of total mesozooplankton abundance, and chaetognaths are the second most abundant group. (C) 2000 Elsevier Science Ltd