Microalgal Diversity Research Articles

Biofouling on Steel Slag Hydrated Matrix in Enclosed Coastal Area

Biofouling on a steel slag hydrated matrix using steel-making slag as the aggregate and ground granulated blast-furnace slag as the main binder was investigated in enclosed coastal areas, and was compared with that on concrete and a natural rocky shore. The steel slag hydrated matrix tended to display larger microalgal density and diversity than concrete from the initial period at the start of the test, confirming that microalgae readily grow on the steel slag-based material. At a seawall where large-scale works were executed, the biofouling on the steel slag hydrated matrix was equal or superior to that on the natural rocky shore. Based on these results, the steel slag hydrated matrix was judged to be excellent in biofouling performance.

BIODIVERSITY OF HYDROCARBON-PRODUCING MICROALGAE FROM OIL CONTAMINATED IN COASTAL ZONE OF BATAM ISLAND

Addressing to the environmental and energy crises in Indonesia, the new alternative of green-economic-energy sources is required. In this study marine microalgae were isolated from oil-polluted coastal zone in Batam Island for alternative energy sources. The research was carried out by collecting the sea water samples from several peninsulas of Batam Island. The abundance of microalgal diversity was observed. The isolation was done by capillary micropipette technique. The method of specific screening for hydrocarbon-producing microalgae was done using selected media, CO2 rate and light intensity period treatments. The results showed that the Cyanobacteria and diatom occupied the Batam's coastal waters. From the isolated samples, 11 strains positively deposit the hydrocarbon in their cells. Further study for determining the isolates and their properties is still in progress.

Alimentación de la ascidia Ecteinascidia turbinata (Ascidiacea: Perophoridae) en dos áreas de manglar de Cuba

Diet of the ascidian Ecteinascidia turbinata (Ascidiacea: Perophoridae) in two mangrove areas of Cuba. Stomach contents of 88 zooids ofEcteinascidia turbinata Herdman 1880 and the qualitative and quantitative composition of phytoplankton in the water column were studied in Santa Fe (North Coast of Havana) and Punta del Este (SW of Cuba). We identified 59 microalgal species and four tintinnids in the stomachs. Cell size was 75-165 microm in length and 2-105 microm in width. There were not significant differences in microalgal diversity in the water column in the two locations. In both locations, the diatoms had the largest number of species and individuals in stomachs and water. In Santa Fe, dinoflagellate biomass was larger in water and stomach contents, while in Punta del Este the contribution of each group to the stomach content was similar to that of the water column. This species filters in a constant and irregular way during the day, independently of food availability.

Diversity of benthic microalgae in response to colonization time and eutrophication

The factors regulating species diversity have received increasing attention in the face of the global biodiversity loss, but are not well understood for unicellular organisms. We conducted in situ experiments in Kiel Fjord in order to analyze the response of microalgal diversity to colonization time and to artificial eutrophication. Diversity decreased throughout colonization time (maximum: 12 weeks), whereas species richness initially increased to about 25 species before it leveled off. The proposed unimodal time course of diversity during succession could not be detected for diversity or species richness. The rapid decrease of evenness indicated a greater importance of algal growth on the substrata compared to the arrival of new species. Artificial eutrophication led to an decrease of diversity, which could be correlated to the supply concentrations of the limiting nutrient: P in spring, N in summer and Si in the presence of high concentrations of N and P. The decrease was due to an increased dominance of few species (i.e. reduced evenness), whereas species richness was not or positively correlated to nutrient supply. Species richness was negatively correlated to evenness and diversity measures. Thus, species diversity indices are useful response variable to measure environmental effects on local periphyton communities.

Benthic microalgal diversity enhanced by spatial heterogeneity of grazing.

This study presents model experiments on the effect of the spatial pattern of herbivory on primary producer diversity. Microalgal biofilms (periphyton) were exposed to different mixtures of two benthic herbivores, the isopod Idothea chelipes and the gastropod Littorina littorea. The herbivores are similar in their feeding selectivity but differ strongly in the spatial pattern of grazing. Idothea did not increase the spatial heterogeneity of algal cell densities beyond the level of ungrazed controls (<1 order of magnitude between local minima and maxima at the 1 mm2 scale). Littorina grazing, in contrast, created a pronounced spatial heterogeneity with maximum:minmum ratios of almost 3 orders of magnitude. When algae were exposed to mixtures of both gazers, the spatial heterogeneity of microalgal cell densities increased with an increasing proportion of Littorina in the herbivore mixture. Algal species richness, diversity and evenness also increased with increasing proportions of Littorina, and was highly significantly correlated with the spatial heterogeneity of cell densities.

Marine microbenthic community structure regulated by nitrogen loading and grazing pressure

Generalisations on the combined effects of consumers and resources on autotrophs in aquatic food webs largely rely on freshwater studies. In this study, we tested these general concepts with marine benthic microalgae, which are important components of coastal food webs. We manipu- lated nitrogen availability and herbivore presence in a factorial field experiment in the Western Baltic Sea. Moreover, we investigated how herbivore control varied among 3 sites and 2 seasons and tested for trophic cascades by enhancing demersal fish density at 2 sites. Nitrogen availability and herbivore presence had strong and antagonistic effects on microalgal biomass, species composition and diver- sity. Herbivores significantly reduced algal biomass, whereas nutrient enrichment led to an increase in biomass. Herbivore effects on microalgal biomass increased with increasing nitrogen availability, indicating a functional response of herbivores to nutrient enrichment. The response of microalgae at the species level suggested a trade-off between nutrient use and grazing resistance which appeared to be linked to algal growth form. Compared to other growth forms, large erect species were most responsive to both nitrogen loading and herbivory. Grazing reduced microalgal diversity at low nutri- ent supply, but enhanced it at high nutrient supply. Herbivore effects varied considerably among dif- ferent sites and were stronger in spring than in summer. Manipulations of fish density during sum- mer did not have any effects on microalgal community structure. In conclusion, our results demonstrate that herbivores and nutrients have strong and balancing effects on marine microbenthic community structure.

The impact of herbivore type and grazing pressure on benthic microalgal diversity

Benthic microalgae and the herbivores Idothea chelipes (Isopoda) and Littorina littorea (Gastropoda) were used as an experimental model system to study the effect of herbivore type on primary producer diversity. Both herbivores enhanced diversity at intermediate grazing pressures, the enhancing effect being stronger with Littorina. This difference is explained by differences in the spatial heterogeneity of the grazed microalgal biofilm caused by behavioural differences in spatial grazing patterns. Idothea spreads its grazing pressure rather evenly in space (“lawn‐mower” type), whereas Littorina creates pronounced spatial heterogeneity by moving slowly over the biofilm and decimating it within the grazing tracks (“bulldozer” type). Idothea grazing did not enhance biomass patchiness beyond the level of ungrazed controls (maximum/minimum from 1.7 to 5.5), whereas Littorina strongly increased patchiness (maximum/minimum from 45 to 850).

Primary Colonization by Microalgae in Relation to Spatial Variation in Edaphic Factors on Antarctic Fellfield Soils

1. The causes of variations in the composition of microalgal communities on frost-sorted soil polygons on Signy Island, maritime Antarctica, were investigated, based on analyses of physical and chemical conditions and microalgal communities from 65 polygons. 2. Interpolygon variations in all environmental factors measured were small and not much greater than the intrapolygon variations. Microalgal diversity was low. Only seven taxa occurred in sufficient numbers to be included in statistical analyses, two of which, Nostoc spp., were found on only one polygon. The filamentous cyanobacterium Phormidium autumnale occurred on all polygons and usually provided the largest component of the total biovolume. 3. Microalgal communities were qualitatively constant within polygons, but varied markedly between polygons. Principal components analysis indicated that each taxon varied independently of the others, and hence it was not possible to correlate community structure with any specific environmental factor. 4. Correlations between numbers of individual taxa and edaphic factors were low and accounted for a maximum of 18% of the observed interpolygon variation or 12% of the total variation. It is suggested that the observed differences in the microalgal communities were due to the vagaries of the colonization process and reflect the probability of successful colonization of these ecosystems by microalgae.

Variety of Cell Size of Cosmarium spp. and Euastrum spp. (Desmidiaceae, Charophyte) from the Aquatic Environment around Palangka Raya, Central Kalimantan, Indonesia

Desmids (Desmidiaceae) is the family of green algae that characterized by cells that are shaped of two symmetrical semicells and it is estimated that there up to 12,000 species of Desmids. Cosmarium and Euastrum are two genera of Desmids that considered as the most representative taxa of this family. They are vary widely in size and shape of the cells. Based on the results of preliminary observations, in the aquatic enviroment around University of Palangka Raya is rich in microalgal diversity including Desmids. Cell size and shape are the most important points to be known to study the microalgae. This research is aimed to study the variety of cell size of Cosmarium spp. and Euastrum spp. from the aquatic environment around Palangka Raya. The results of this study show that the Cosmarium cells have the dimension of 17-80 μm long and 14-57 μm wide; Euastrum cells have the dimension of 24-89 μm long and 17-80 μm wide.