Influence of clay minerals on selenium toxicity to algae

In this study, selenite was found to be acutely toxic to the fresh water algae Anabaena constricta and Chlorella ellipsoidea. However, the latter was more tolerant. Severe reduction in chlorophyll a content was significant reaching 65.2%, 61.4% for Anabaena and Chlorella respectively at 30mg L[-1] Se after 24 hrs incubation. The EC50 values were: 138 mg SeL-1, 141 mg Se L[-1] at one day; 120 mg Se L[-1], 126 mg Se L[-1] at 3 days; 91 mg Se L[-1], 100 mg Se L[-1] at 5 days and 67 mg Se L[-1], 70 mg Se L[-1] at 7 days for Anabaena and Chlorella, respectively. Addition of the clay minerals kaolinite and bentonite decreased selenite toxicity considerably, bentonite was more effective. The EC50 values for combined effect of selenium and either kaolinite or bentonite in reducing growth after 7 days incubation were 76,83 mg Se L[-1] for Anabaena and 73, 81 mg Se L[-1] for Chlorella. Phosphorus uptake by Chlorella was enhanced and went parallel with a concomitant elevation in pH values of the medium with increasing selenite concentrations, and observation which was controversely to that exhibited in Anabaena cultures. Acid and alkalize phosphatase activity decreased in both organisms with increasing Se concentrations

Nutrient enrichment and its effects on growth and metabolism of chlorella vulgaris and phormidium laminosum

In this study, the dry weight and chlorophyll a content of Chlorella vulgaris and Phormidium laminosum progressively increased with elevation of phosphate and nitrate doses supplemented to the culture media. The accumulation of total carbohydrates in both organisms were suppressed at all phosphate levels, but in Phormidium, it was stimulated under nitrate treatments. Both salts singly caused a drop in nitrate uptake which was associated by decrease in protein and total nitrogen contents. All phosphate levels stimulated the phosphorus absorption from the media and the phosphorus contents of both organisms while, the nitrate effect showed no constant trend. Irrespective of some fluctuations there was a clear trend for the mixture effects which are expressed by increase in dry weight, chlorophyll a, total carbohydrate accumulation, nitrate uptake, phosphorus uptake and contents in both algae. Total nitrogen and protein accumulation were adversely affected in most mixture treatments. Lowering the concentration of either phosphate or nitrate in both algal cultures below control levels suppressed the growth and inactivate the physiological processes. The N/P uptake ratios were generally decreased following limitation and/or enrichment with nitrate and phosphate

Interactive effects of salinity with some hormonal and non hormonal growth substances on chlorella fusca I- biomass and photosynthetic pigments

The response of Chlorella fusca to different salinization treatment was followed. Dry weight and pigment concentrations were stimulated with salinization up to the levels of 80 mM NaCl, beyond which they were retarded. Also, growth and pigment contents were stimulated at 10-6, 10-5 M concentrations of IAA, kinetin, GA3 and thiourea relevant to control. These chemicals counterated the adverse effect of salinity on Chlorella cells. IAA was the most effective substance followed by kinetin, GA3 and thiourea

Interactive effects of salinity with some hormonal and non-hormonal growth substances on chlorella fusca II- nitrate reductase activity, proline and protein contents

Sodium chloride at 320 mM increased proline content but suppressed protein accumulation and nitrate reductase activity of Chlorella fusca. 10-5 M, 10-6 M of GA3, IAA, kinetin and thiourea increased protein, proline and NRA of the algal cells relevant to control. The four used growth substances reacted in antagonism with NaCl in the same parameters. In counteracting, the adverse effect of salinity, IAA was more effective, while thiourea was the least effective one

Dynamics of phytoplankton succession in the river Nile at Minia [upper Egypt]; as influenced by agricultural runoff

The influence of agricultural wastewater effluents dumped to the Nile water at Minia [Upper Egypt] on phytoplankton distribution, diversity, succession and standing crop was monthly evaluated in a comprehensive study for one year. Autumn harboured the highest standing crop at all sites. Bacillariophyta contributed the highest percentage composition. Chlorophyta and Cyanophyta rated second and third in the order of dominance, Euglenophyta was poorly represented however, some members of the three groups tended to form blooms at certain times. The agricultural runoff induced gross changes in physico chemical characteristics of the Nile water and community structure of phytoplankton populations. Species of high occurrence being densely encountered at all sites were excelled by: Tabellaria fenestrata. Cyclotella bandanica, Cocconeis caespidata and Microcystis aeruginosa

Physiological responses of the cyanobacterium calothrix parietina and green alga scenedesmus dimorphus to iron, manganese, sulphate and sulphite

The uptake of manganese and iron ions by Scenedesmus dimorphus and Calothrix parietina was significantly increased by increasing the doses supplemented to the culture media of both algae up to 10[-5]molar concentration. The ability of Scenedesmus to accumulate the two metals was greater than that of Calothrix. Higher concentrations of sulphate, sulphite and manganese ions inhibited the accumulation of total carbohydrates in the two phytoplankter cells. All iron levels stimulated synthesis of total carbohydrates in Calothrix, but inhibited it in Scenedesmus. Under all concentrations of the four pollutant salts, nitrogen secretion by the two organisms, total nitrogen and almost all nitrogen fractions were increased particularly at moderate rates. However, 10[-4] M and 300 micro g S ml[-1] of iron and sulphite attenuated the synthesis of protein N in Calothrix, Sulphate, sulphite and iron suppressed phosphorus uptake by Calothrix but stimulated it in Scenedesmus. Manganese ions at all concentrations, encouraged phosphorus uptake from nutrient media by Calothrix. Sulphite, at al concentrations lowered total phosphorus content, total soluble and total insoluble phosphorus in the two organisms, a phenomenon that was associated with marked disturbances in phosphorus metabolism. Sulphite, at all concentrations inhibited the biosynthesis of nucleic acids [RNA, DNA] in Calothrix, while its low and moderate concentrations stimulated their biosynthesis in Scenedesmus. Sulphate and manganese on the other hand, stimulated their biosynthesis in the two phytoplankters. Iron, at 10[-8] M level encouraged the biosynthesis of nucleic acids in Calothrix, whereas 10[-6] M and 10[-4]M concentrations suppressed their formation in Scenedesmus. At all levels of manganese and sulphate, the cell length and width of both organisms and the diameters of heterocyst in Calothrix were increased. At all concentrations of iron and sulphite, the cell length and width of both organisms and also diameters of heterocysts in Calothrix were decreased

Interactive effects of some pollutant salts on Nile water phytoplankton populations in batch cultures

The addition of some pollutant ions [SO2-4; SO2-3; Fe 3+ Mn2+] either singly or in combinations to Nile water cultures resulted generally in a remarkable alterations in species composition, percentage distribution of the main phytoplankton groups and total cell count of all populations. The magnitude of change in such parameters was considerably controlled by both the order of combination and concentrations of different ions, inducing either synergistic or antagonistic effects

Interactive effects of molybdenum and vanadium on the nitrogenase and nitrate reductase activities of aulosira fertilissima

The effects of molybdenum and vanadium interactions on the nitrogenase and nitrate reductase enzymatic systems in the cyano-bacterium Aulosira fertilissima were investigated at different time intervals. Addition.of Va to + Mo cultures up to 0.015 ppm increased both dry weight gain and pigment biosynthesis. Beyond this concentration significant inactivation of such enzymes was observed at all growth periods. Nitrogenase and nitrate reductase activities were significantly increased by addition of Va at different levels to the cultures augmented with Mo, a phenomenon that was reversed by increasing Va concentrations. Maximum nitrogenase activity was recorded after 48 hr of incubation, whereas the highest enzymatic potential was maintained after 96 hr incubation period. Nitrogenase and nitrate reductase activities in + Mo cultures were significantly higher than in -Mo cultures. Addition of Va to + Mo Aulosira cultures resulted in a marked elevation in heterocyst frequency particularly after 48 hr incubation

Amino acid content and transaminases activities in anabaena oryzae and nostoc muscorum as affected by some pesticides

Dimethoate and Karathane induced statistically highly -significant decreases in GOT activities of Nostoc and Anabaena. Dursban was less effective, whereas trifluralin encouraged the enzyme activity in Anabaena, but hardly affected it in Nostoc. GPT, behaved differently in both organisms, as a result of pesticides application. Since it was stimulated in dimethoate treated cultures of either cyanobacterium. Dursban, Karathane, and trifluralin, although favored the enzyme activity in Anabaena, yet they inhibited or even totally arrested its potentiality in Nostoc. The moderate doses of dimethoate, Karathane and trifluralin attenuated synthesis of all individual amino acids in both organisms, though valine was hardly affected. Dursban on the other hand, encouraged the biosynthesis of all individual amino acids in Nostoc and Anabaena; an effect that led subsequently to significant elevation in total amino acid content of the two cyanobacterial biomasses. The applied pesticides, at all levels, accelerated heterocyst development in Anabaena, but were of no detectable effects on its differentiation in Nostoc