Growth and ultrastructure of the marine unicellular alga <Emphasis Type="Italic">Dunaliella salina</Emphasis> (Chlorophyta) after chronic selenium intoxication

The effects of selenium (0.01, 0.5, 1, 5 and 10 mg/liter) on the growth and ultrastructure of the microalga Dunaliella salina were investigated following its transfer into clean water. Selenium concentrations of 5 and 10 mg/liter were toxic to D. salina, and reinoculation of microalga into clean water did not prevent it from total mortality. When reinoculated from medium with 0.01 mg Se/liter, the cell population density of D. salina was restored in 14 days. The number of ultrastructural alterations in cells was the same as in the control, while the excretory activity of microalga between days 4 and 10 of this experiment was higher. Cell population growth of D. salina transferred from 0.5 and 1 mg Se/liter was lower than in the control. No ultrastructural defects were observed in microalga reinoculated from medium with a selenium concentration of 0.5 mg/liter and the excretion level corresponded to that at 0.01 mg/liter. Various types of ultrastructural damage were found in microalga from medium with 1 mg Se/liter, which was previously reported to be threshold for D. salina; however, the number of cell injuries decreased with increasing time in clean medium. Excretory activity was decreased at the beginning of experiment; but after 7 days, it was restored to the control level. Though there were no ultrastructural alterations in microalgal cells from medium with 0.5 mg Se/liter, we assume that they had molecular defects that could inhibit the cell population growth. The study of microalgae following their reinoculation from medium containing toxicants into clean medium can be a useful method for evaluating algal survival after toxic exposure.     

Influence of changes in sea water salinity on the growth,photosynthetic pigment content,and cell size of the benthic alga <Emphasis Type="Italic">Attheya ussurensis</Emphasis> Stonik,Orlova et Crawford, 2006 (Bacillariophyta)

The study deals with the effect of changes in salinity from 32 to 4‰ (at an interval of 4‰) on the growth, chlorophyll a and carotenoid contents, and cell size of the benthic alga Attheya ussurensis (Bacillariophyta). A. ussurensis showed high tolerance to reduced salinity and ability to adapt to salinity changes from 16 to 12‰. In this salinity range, the cells restored their shapes, sizes, and physiological functions. The number of cells and photosynthetic pigment content were highest at a salinity reduction to 24‰. At 8‰, algal cells remained alive, but the process of cell division was inhibited; as a result, the number of cells was significantly lower than in the control, the cells did not restore their sizes and shapes and remained deformed until the end of the experiment. A drop in salinity to 4‰ caused a complete loss of cell viability of A. ussurensis within a day of exposure to this factor.     

Diatoms of the genus Attheya west, 1860 from the Sea of Japan

This paper documents the species diversity of the diatom genus Attheya from the Sea of Japan. Two species (A. arenicola and A. longicornis) were studied in field samples and in culture. Their morphology is described using light and electron microscopy; the ecology and the distribution data are provided. A. arenicola is a new record for the seas of Russia.     

Reproduction and larval development of the gastropodAlaba vladivostokensis in Vostok Bay, the Sea of Japan

The reproduction and development of the prosobranch gastropodAlaba vladivostokensis Bartsch were studied. In Vostok Bay,A. vladivostokensis reproduces in the warmest season at water temperatures of 19–23°C. The females lay egg masses in the shape of flat, coiled bands on eelgrass leaves and on sargosso thalluses. The total period of development from egg laying to larval settling takes 25–27 days. The reproduction and development patterns and larval morphology ofA. vladivostokensis are similar to that ofAustralaba picta (A. Adams), which inhabits the coast of Japan. It is suggested that the population ofA. vladivostokensis in Peter the Great Bay should considered as part of the wide geographical range ofA. picta.     

Changes in the Fatty Acid Composition of Hepatopancreas of the Mollusk Mytilus trossulus Fed on Microalgae

The influence of diet on the fatty acid composition of the hepatopancreas of Mytilus trossulus was studied. Three groups of mollusks were fed monocultures of the microalgae Phaeodactylum tricornutum, Chaetoceros muelleri (Bacillariophyceae), and Nannochloropsis sp. (Eustigmatophyceae) for 10 days. After 10 days, the proportion of polyunsaturated fatty acids, mainly eicosapentaenoic and docosahexaenoic, increased in the total lipids of the hepatopancreas in all mollusk groups. The content of saturated fatty acids in the mussel tissues decreased and was not dependent on the amount in the algal diet. Toward the end of the experiment, the fatty acid composition of the hepatopancreas of mussels was similar irrespective of the fatty acid composition of their food. The fatty acid analysis of M. trossulus feces suggests a selective assimilation by mussels of predominantly the n-3 polyunsaturated fatty acids. The role of fatty acid metabolism in M. trossulus is discussed.     

Influence of extrametabolites of marine microalgae on the reproduction of the bacterium <Emphasis Type="Italic">Listeria monocytogenes</Emphasis>

The biological potency of extrametabolites produced by marine microalgae against reproductive forms of Listeria monocytogenes is examined. Extrametabolites of marine microalgae in exponential growth phase had no effect on L. monocytogenes. In the middle steady-state growth phase, extrametabolites of algal cultures boosted the reproduction of Listeria. An exception was Skeletonema costatum: extrametabolites of this alga in the middle steady-state growth phase showed an antibacterial effect against L. monocytogenes.     

Collection of marine microalgae at the A. V. Zhirmunsky institute of marine biology

This article presents information about a special collection of marine microalgae at the Institute of Marine Biology (Far East Branch of the Russian Academy of Sciences). A list of microalgae currently maintained in the collection is given, and the main directions of the work with them are identified.     

The species composition,morphology, and seasonal distribution of diatoms of the genus <Emphasis Type="Italic">Attheya</Emphasis> West, 1860 from the Sea of Japan

Six species that belong to the diatom genus Attheya were found in the Russian waters of the Sea of Japan. A. cf. flexuosa is a new record for the seas of Russia. A. decora is recorded for the first time for the Sea of Japan. The peculiarities of the morphology of A. decora and A. cf. flexuosa are described and illustrated. The study of the seasonal distribution, abundance, and ecology of Attheya species in the northwestern Sea of Japan showed that A. longicornis and A. ussurensis were the most numerous and widespread species, reaching maximum densities (up to 1.5 × 10⁶ and 1.8 × 10⁴ cells/liter, respectively) in the spring, summer, and fall. A. cf. flexuosa and A. septentrionalis were rare and were found in low numbers in the winter and early spring. Based on the ultrastructure of the girdle bands, the form and number of chloroplasts, the presence/absence of rimoportula on the valve, and habitat features, we distinguished two groups of species of the genus Attheya from the Sea of Japan. The first group includes psammophytes A. decora, A. arenicola, and A. ussurensis; the second one comprises A. longicornis and A. cf. flexuosa epiphytic on other diatoms, as well as A. septentrionalis, which is found in the under-ice plankton and is able to attach to the underside of ice.