Asterionella

Conway, H.L. 1978. Sorption of arsenic and cadmium and their effects on growth, micronutrient utilization, and photosynthetic pigment composition of Asterionella formosa. Jour. Fish. Res. Board Canada 35 286-294. 

Figure 2. Periodicity of Asterionella formosa Hass., Fragilaria Crotonensis and fluctuations in the concentration of dissolved silica, in 0—5-meter water...

Phytoplanktonic microalgae, which are important sources of food in both oceans and fresh water habitats, use an activated form of chemical defense to reduce grazing by predators. Damaged microalgal cells convert unsaturated fatty acids into unsaturated aldehydes which affect reproductive outcomes in herbivorous cope-pods and other planktonic grazers.30 Representative products of these biotransformations include the C10 aldehydes 1 and 2 in the diatom Thalassiosira rotula, and Cg diene hydrocarbons and the trienoic acid aldehyde 3 in Asterionella formosa.31... 

However, if the net is equipped with a suitable flow meter or if the volume of water filtered tlirough the net is carefully noted, accuracy can be improved. Fig. 5 shows a typical result of aparticle size analysis of a netplankton sample of reservoir water during a bloom of dominant Dmtoma and Asterionella. Within a particle size range 7.0—30.0 jUm, different maxima in the particle size distribution were observed caused by the presence of both individual cells and of 2—5 celled colonies. A correlation coefficient of = 0.67 was found between the netplankton count by microscopy and the netplankton count by particle counter (cf. Fig. 6). 

Entomoneidaceae Entomoneis punctulata (Grunow) Osada Kobayasi Fragilariaceae Asterionella formosa Hassall... 

Asterionella, Chaetoceros Leptocylindrus, Skeletonema Thalassiosira, Pseudo-nitzschia Cafeteria... 

Asterionella formosa F Bacillariophyta, Fragilariophyceae 3.3 Tett and Droop (1988) note (3)... 

Fig. 4.9. Characteristic genera of aquatic algae 1 — Chlorella, 2 — Protococcu3, 3 — Scendesmus, 4 — Naviculla, 5 — Euglena, 6 — Chlamydomonas, 7 — Tabellaria, 8 — Aficractintum, 9 — Asterionella, 10 — Peridinium, 11 — Nitschia, 12 — Ulothrix, 13 — Dinobryon, 14 — Phacus, 15 — Synedra, 16 — Cladophora and...

This inhibiting activity on the part of the algae and the role it plays in the natural environment were established by the observations of Sieburth and Pratt (1962) on the inhibition of coliforms and Vibrio in Neur ansett Bay, following the blooms of the diatom Skeletonema costatum. Similarly, studies carried out by Aubert and co-workers (1967—1975) showed that biosecretions of some diatoms Asterionella japonica, Asterionella notata. 

In a different connection, Aubert et al. (1967) have observed that, at some periods of the year and especially during spring, diatoms cease to synthesise antibacterial substances, a phenomenon which corresponds with the peak density of dinoflagellate populations. In vitro it has been shown that the proximity of Prorocentrum micans inhibits production of one of the antibacterial substances in Asterionella japonica (Aubert et al., 1970b). The substance released by the dinoflagellate which accounted for that effect was found to be proteinaceous with a very low threshold of activity 10 M (Aubert and Pesando, 1971 Aubert et al., 1972a). 

Fig. 5. Interactions between three marine microorganisms a dinoflagellate Prorocentrum micans), a diatom Asterionella japonica) and a bacterium (marine or terrestrial), involving four chemical telemediators TMC) TMCI and TMC2 are secondary mediators, the antibiotics of A. japonica being primary mediators.

Gauthier, M.J., 1969a. Activite antibacterienne d une Diatomee marine Asterionella notata (Grun.). Rev. Int. Oceanogr. Med., 15—16 103—171. 

Winter 1982 Skeletonema costatum Chaetoceros spp., and Asterionella japonica... 

Hombeck, M. and Boland, W. (1998) Biosynthesis of the algal pheromone fucoser-ratene by the freshwater diatom Asterionella formosa (Bacillariophyceae). Tetrahedron. 54, 11033-11042... 

Diatoms—major group of algae, and one of the most common types of phytoplankton. Most diatoms are unicellular, although they can exist as colonies in the shape of filaments or ribbons (e.g., Fragil-laria), fans (e.g., Meridion), zigzags (e.g., Tabellaria), or stellate colonies (e.g.,Asterionella). 

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