A study of the relative efficiency of mustard oil cake and urea and the effect of salinity in plankton production in indian fishponds

Augmentation of plankton production in Indian fishponds by application of manure and inorganic fertilisers was studied in laboratory experiments. The effects of the salinity of the medium were also examined.Laboratory trials were made with mustard oil cake and urea on equivalent nutrient bases in media with varying degrees of salinity (0–30 ppt at 2 ppt. intervals). It was observed that Closterium, Fragilaria, Pinnularia and Gyrosigma grew well in the higher salinity range between 24 to 30 ppt. whereas lower salinities ranging from a trace to 8 ppt. are suitable for improved production of Anabaena, Synedra, Navicula, Amphipleura, Amphora and Nitzschia. Comparatively better production of plankton was recorded with urea than with mustard oil cake.     

Hydromechanical stimulation of bioluminescent plankton

The response of the bioluminescent dinoflagellate Pyrocystis fusiformis was investigated for different hydraulic conditions (‘hydromechanical stimulation’). Pipe flow and oscillating shear produced luminescence, whereas changes in hydrostatic pressure were not stimulating. More intense fluid motion led to higher intensity, mainly due to a higher probability of cell response. The organism was also able to emit light in a glucose–salt mixture. The experiments suggest that the cells are effectively stimulated if the flow conditions change in time. Copyright © 2002 John Wiley & Sons, Ltd.     

The analysis of planktonic rotifer populations: A plea for long-term investigations

Short-term species succession, and long-term community development, of planktonic rotifer populations of the temperate zone and factors influencing species' abundance (ie., physical and chemical limitations, food and exploitative competition, mechanical interference competition, predation, parasitism) are described and discussed. The long-term development of plankton communities in three European lakes is described and the major events are discussed in relation to ecological interactions. Frequently, the shortcomings of our knowledge about population ecology and ecophysiology of rotifers prevent explanations of short-term and, especially, of long-term developments of these plankton organisms. The need for qualitative and quantitative observations in the field and in the laboratory over long periods becomes obvious.     

Sediment toxicity testing in two areas of concern of the Laurentian Great Lakes: Toronto (Ontario) and Toledo (Ohio) Harbours

The impact of elutriated sediment-associated contaminants from Toronto and Toledo Harbours on ultraplankton (5–20 µm) and microplankton/netplankton (> 20 µm) carbon assimilation rates was determined using Algal Fractionation Bioassays (AFBs). All of the Toronto elutriate caused significant inhibition of ultraplankton carbon assimilation. The Toronto Site 2 elutriate caused the greatest significant inhibition (38 percent, p < 0.001) with a 20 percent dose of standard elutriate. Similarly, all Toledo elutriates caused significant inhibition of ultraplankton productivity. Toledo Site 2 elutriate was the most toxic with the 20 percent elutriate dose (35 percent, p < 0.001).The treatment of elutriates with Chelex-100 resin was used to remove dissolved free metal ions which, in some samples, resulted in the recovery of ¹⁴C assimilation. This was attributed to the elimination of the toxic effects of dissolved metals removed by the Chelex treatment. Residual toxicity after the Chelex treatment was ascribed to the high PCB levels observed in the sediment samples taken from both harbours and possibly to other organic contaminants. Due to the extreme sensitivity of the technique, an EC25 is proposed as an early warning indicator for applied use by regulatory agencies. Our procedure has been included amongst a battery of tests recommended by the International Joint Commission for monitoring areas of concern in the Laurentian Great Lakes.     

Pigment and lipid compositions of algal and bacterial communities in Ace Lake,Vestfold Hills,Antarctica

The compositions of carotenoids, chlorophylls and lipids at four depths in Ace Lake have been determined as a means of studying the vertical zonation of species in the lake and for comparison with the lipids found in the bottom sediments. The four major species of phytoplankton found in the lake were identified by electron microscopy. The most abundant phytoplankter was Pyramimonas gelidicola McFadden (Chlorophyta, Prasinophyceae) which occurred in greatest numbers at 10 m, the base of the oxylimnion. The pigments and lipids at this depth were mainly derived from this alga. At 11 m (the top of the anoxylimnion) only traces of lipids and pigments attributable to P. gelidicola were found, indicating only limited settling of algal cells through to the anoxylimnion, at least in summer. The pigments at 11 m were dominated by bacteriochlorophylls c derived from green photosynthetic bacteria Chlorobium spp. These pigments were also abundant at 23 m suggesting the presence of intact bacterial cells which had settled out from higher in the water column. Major non-polar lipid classes in the sediments included sterols, alcohols, hydrocarbons and an unusual suite of very long-chain unsaturated ketones and esters which have not previously been reported from antarctic environments. Several novel compounds, not found previously in either sediments or organisms, are reported. These include tri- and tetra-unsaturated straight-chain C₃₉ methyl ketones and C₄₀ ethyl ketones and the methyl ester of a tetra-unsaturated straight-chain C₃₆ fatty acid. The distributions of lipids in the sediment were markedly different from those in the water column indicating extensive bacterial degradation and recycling of labile lipids.     

Horizontal distribution of crustaceans in Lake Glubokoe

A study has been made on the distribution of crustaceans along a profile of 6–9 stations from depths of less than 2 m to 20 m, in summer, autumn and early spring. The species composition, abundance, size-frequency distribution, biomass and diurnal dynamics were estimated. Many species abundant in the pelagic zone were found to be absent or scarce out to depths of 5 m. In the daytime, at depths out to 3 m, crustaceans greater than 1.0 mm were seldom found, while those 0.15–0.40 mm long were most abundant. At depths out to 5 m, not only was the total average size of crustaceans found to be smaller, but also that of individual species, including small ones: Ceriodaphnia and Chydorus. The biomass of crustaceans in shallow water and in the open lake differs in summer by more than 100 times, and in late autumn and early spring by more than 10 times. At the depth of 1 m, in none of the seasons did it exceed 0.026 mg l^-1. All the crustaceans except for nauplii and Chydorus considerably increased in numbers in the shallow water at night. The impoverishment of the littoral plankton in Lake Glubokoe is regarded as a specific case of the well-known phenomenon of ‘avoidance of the littoral’ by euplankton (Hutchinson, 1967; Kiselyov, 1980). It is pointed out that there is a possible relationship between diurnal horizontal migrations of plantivorous fish and the impoverishment of plankton near the shore. An attempt has been made to substantiate the assumption that the ‘avoidance of the littoral’ by pelagic crustaceans is due to high numbers of fish in shallow water.     

Limnology and plankton periodicity of Jos Plateau water reservoir,Nigeria, West Africa

Limnological data (Dec. 1980–Jan. 1982) on the plankton and water chemistry of Lamingo Dam, located within the Jos biotite granite area of the Plateau State (Nigeria) are presented. The water-body falls in Beadle's (1981) category I of African lakes (conductivity < 40 µS cm^–1). Alkalinity (% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0Jf9crFfpeea0xh9v8qiW7rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGabmiEayaara% aaaa!3914!\[\bar x\] = 0.3 meq l^–1), principally composed of bicarbonates, dominated the anions % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0Jf9crFfpeea0xh9v8qiW7rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaK4waiaajI% eacaqIdbGaaK4tamaaxababaGaeyOeI0caleaacaaIZaaabeaakiaa% b6dacaqIdbGaaKiBaiaaj2cacaqG+aGaaK4uaiaaj+eadaqhaaWcba% GaaKinaaqaaiaajkdacaqITaaaaOGaaKyxaaaa!4657!\[\user1{[HCO}\mathop -\limits_3 {\text{ > }}\user1{Cl - }{\text{ > }}\user1{SO}_\user1{4}^{\user1{2 - }} \user1{]}\]The plankton were characterized by a moderate standing crop of phytoplankton, and zooplankton were, generally, very limited in species and abundance. The order of dominance for the categories of phyto and zooplankton was: [Bacillariophyceae > Chlorophyceae > Dinophyceae] and [Rotifera > Crustacea] respectively. A diel cycle was characterized by nocturnal upward migration of the zooplankton, and the reverse behaviour in the phytoplankton.Interrelations between the biotic assemblages of plankters and various physical and chemical variables are discussed.     

Phytoplankton pigments and adenosine triphosphate (ATP) in Lake Peipsi-Pihkva

The material for pigment analysis was collected 1–3 times a year from Lake Peipsi-Pihkva in 1983, 1987, 1988, 1991 and 1992–1995. Concentrations of chlorophyll a, b and c (Chla, Chlb, Chlc), pheopigment (Pheo) and adenosine triphosphate (ATP) were measured biweekly in 1985–1986. The mean of all Chla values was 20.2 mg m^–1 (median 13.3 mg m^–1) indicating the eutrophic state of the lake. Average Chlb, Chlc, Pheo and carotenoid (Car) contents were 3.7 mg m^–3, 4.1 mg m^–3, 3.0 mg m^–3 and 4.8 mg m^–3, respectively. The average Chlb/Chla ratio was 22.9%, Chlc/Chla 23.4%, Pheo/Chla 38%, Car/Chla 37% and ATP/Chla 3%, the medians being 14.3, 13.6, 17.5, 39.4 and 1.9%, respectively. The proportion of Chla in phytoplankton biomass was 0.41%, median 0.32%. There were no significant differences in temperature, oxygen concentration, Chla, and ATP between the surface and bottom water; the lake was polymictic during the vegetation period. The Chla concentration had its first peak in May followed by a decrease in June and July. In late summer Chla increased again achieving its seasonal maximum in late autumn. The ATP concentration was the highest during spring and early summer, decreasing drastically in autumn together with the decline of primary production. ATP/Chla was the highest during the clear water period in June and early July, which coincided also with the high proportion of Chla in phytoplankton biomass. The highest Chla occurred in November (average 37.2 mg m^–3) when Secchi transparency was the lowest (1.05 m). Concentrations of Chlb, Chlc and carotenoids were the highest in August, that of Pheo in June. Concentrations of Chla and other pigments were the lowest in the northern part of Lake Peipsi (mean 14.7 mg m^–3, median 12.5 mg m^–3) and the highest in the southern part of Lake Pihkva (mean 47.9 mg m^–3, median 16.3 mg m^–3). An increase of Chla and decrease of Secchi depth could be noticed in 1983–1988, while in 1988–1994 the tendency was opposite.     

Comparative limnology,species diversity and biomass relationship of zooplankton and phytoplankton in five freshwater lakes in Kenya

Comparative studies on the limnology, species diversity and standing stock biomass of phytoplankton and zooplankton in five freshwater lakes, Naivasha and Oloidien, Ruiru, Masinga and Nairobi reservoirs, were undertaken. Phytoplankton chlorophyll a, dissolved oxygen and temperature were also measured. Thermocyclops oblongatus (Copepoda) was dominant in all the lakes. Ceriodaphnia cornuta and Diaphanosoma excisum (Cladocera) dominated in lakes Naivasha and Oloiden, whereas in Ruiru, Masinga and Nairobi reservoirs, Brachionus angularis and Hexarthra mira (Rotifera) were the dominant zooplankters. Phytoplankton biomass as chlorophyll a was lowest in Ruiru dam 5.64 ± 4.0 µg l^-1 and highest in the eutrophic Nairobi dam 71.5 ± 12.02 µg l^-1. The endorheic lakes Naivasha and Oloidien showed medium values of 24.5 ± 4.0 µg l^-1.     

Nitrogen fixation by periphyton and plankton on the Amazon floodplain at Lake Calado

Nitrogen fixation by periphyton and plankton was measured on the Amazon flood-plain using the acetylene reduction method calibrated with¹⁵N-N₂. The average ratio (± SD) of moles C₂H₄ reduced per mole N₂-N fixed was 3.4 ± 0.7, similar to other studies. Periphyton and plankton had high rates of light-dependent nitrogen fixation, with dark nitrogen fixation averaging 26% of the average rates in the light. The average daily (24 h) rates for periphyton nitrogen fixation in 1989 and 1990 were 1.79 and 0.51 mmol N₂-N·m^–2·d^–1 respectively, which are comparable to summer rates in many temperate cyanobacterial assemblages. Nitrogen fixation was depressed at N0₃ ^– concentrations as low as 0.5 M, and was below detection limits at concentrations of 4 M, which occurred during periods of river flooding. Planktonic nitrogen fixation rates were high (0.5–0.8 mmol N₂-N·m^–2·d^–1) during the high-water and drainage phases of the annual hydrograph when the floodplain waters were draining towards the river (low NO₃ ^–), but rates were undetectable (< 0.05 mmol N₂-N·m^–2·d^–1) when there was river flooding (high NO₃ ^–). Nitrogen fixation by periphyton and plankton in 1989–1990 accounted for approximately 8% of previously reported total annual nitrogen inputs to the floodplain at Lake Calado.