R. Nandakumar

Effect of different dosages of zinc on the growth and biomass in five marine microalgae

Marine environment often restrain toxic heavy metals that may enter into the food web via uptake by microalgae and eventually cause severe poisoning problems at higher tropic levels. The effects of Zinc cations upon growth of five native microalgal species, Chlorella marina, Isochrysis galbana, Tetraselmis sp., Nannochloropsis sp., and Dunaliella salina were evaluated. Growth inhibition of the microalgal cells were determined by exposing them to different concentrations of aqueous solutions of zinc metal for 15 days. A major reduction in cell density was observed in all the five cultures in the concentration of 50 ppm. Among the five micro algal species tested, Tetraselmis sp. alone showed growth up to 250 ppm concentration of zinc metal till the final day (15th day) of experiment. Key words: Zinc, microalgae, heavy metal, Chlorella marina, Tetraselmis sp.

Bioremediation of shrimp (Litopenaeus vannamei) cultured effluent using copepod (Oithona rigida) and microalgae (Picochlorum maculatam & Amphora sp.)—An integrated approach

AbstractNitrogenous compounds are major contaminants in aquaculture effluent and thereby needs a potential candidate for removing these nutrients. The present study tested the efficacy of immobilized microalga, diatom Amphora sp. and copepod Oithona rigida to remove excessive nutrients from the shrimp (Litopenaeus vannamei) cultured effluents. Nutrient removal was evaluated with five different combinations: (1) copepod, O. rigida; (2) immobilized Picochlorum maculatum and copepod O. rigida; (3) immobilized P. maculatum; (4) immobilized Amphora sp. and copepod O. rigida; and only (5) immobilized diatom, Amphora sp. Preliminary studies showed maximum reduction of about nitrate 86% and nitrite 88% in treatment 2–4, respectively. The maximum phosphate (69%) and ammonia (91%) removal was recorded in the treatment 3. In disparity, the phosphate concentration recorded was significantly higher (6%) at the end of the experiment in the treatment 1 than other experiments. While in the treatments 1, 2, and 4 the cope...

Preliminary study on the dye removal efficacy of immobilized marine and freshwater microalgal beads from textile wastewater

Discharge of textile wastewater containing toxic dyes can adversely affect aquatic organisms and human health. The objective of the study was to investigate the potential of immobilized marine microalgae ( Chlorella marina, Isochrysis galbana, Tetraselmis sp . Dunaliella salina and Nannochloropsis sp.) and freshwater microalga ( Chlorella sp.) in removing dye from textile wastewater (TW). The present study incorporated the use of 2% sodium alginate matrixes for decoloration. Among the algal species tested, the highest colour removal was noticed in Isochrysis galbana (55%) followed by freshwater Chlorella sp. (43%). The present method is easy to use, cost effective and devoid of technical problems. Keywords: Marine microalga, immobilization, textile wastewater, Chlorella marina, Isochrysis galbana, Dunaliella salina, biosorption, bioremediation. African Journal of Biotechnology , Vol 13(22) 2288-2294

Detection of Cyanotoxins of Cyanobacterial (Microcystis aeruginosa) Strain Using Microtox® Bioluminescence Bioassay

Cyanobacterial bloom sample was collected from Muttukadu backwaters, Chennai, Tamil Nadu, India. The bloom sample was observed under the microscope. The sample was identified as containing primarily of Microcystis aeruginosa. The occurrences of toxic cyanobacterial blooms in aquatic environments, associated with animal deaths, were noticed on 1 June 2012 and have increased the need for rapid, reliable and sensitive methods to detect algal biotoxins. Microtox® bioluminescence assay determines the toxicity of microcystin produced by cyanobacterial bloom. It is suggested that the Microtox® bioluminescence assay may prove useful in the preliminary screening of cyanobacterial blooms for microcystin-based toxicity.

Diversity and Abundance of Marine Copepods in Muthupet Mangrove Waters, Southeast Coast of India

The aim of the study is to evaluate the diversity and relative abundance of copepods in Muthupet waters. Two years (January 2009 to December 2010) of investigation resulted in 75 species of copepods identified in Muthupet waters comprising 51 species of Calanoida, 14 Cyclopoida and 10 Harpacticoida. The copepod population showed a bimodal pattern of distribution, where the first peak was encountered during February and March 2009 and the second peak occurred during February and March 2010. The bulk of copepod population was contributed by species namely, Paracalanus parvus, Nannocalanus minor, Acartia spinicauda, A. danae, Acrocalanus gracilis and Oithona rigida. Generally, calanoid copepods were found to be dominant with 68 % followed by Cyclopoida (18.66 %) and Harpacticoida (13.33 %). Copepods population in Muthupet lagoon has been positively influenced by salinity. Population density, species diversity and species richness were found to be higher in summer due to the stable hydro-graphical conditions. However, high species evenness was observed during the monsoon season indicating that the species were equally distributed. It is concluded that the Muthupet mangrove wetland ecosystem is considered as a rich bio-diversity hot spot for marine copepods.