Showing papers in "Applied Ecology and Environmental Research in 2005"
TL;DR: The mobility, bioavaliability and plant response to presence of soil heavy metals, classifies the plants according to phytoextraction mechanism and discusses the pathway of metal in plants.
Abstract: This review presents the status of phytoremediation technologies with particular emphasis on phytoextraction of soil heavy metal contamination. Unlike organic compounds, metals cannot be degraded, and cleanup usually requires their removal. Most of the conventional remedial technologies are expensive and inhibit the soil fertility; this subsequently causes negative impacts on the ecosystem. Phytoremediation is a cost effective, environmental friendly, aesthetically pleasing approach most suitable for developing countries. Despite this potential, phytoremediation is yet to become a commercially available technology in India. This paper reports about the mobility, bioavaliability and plant response to presence of soil heavy metals. It classifies the plants according to phytoextraction mechanism and discusses the pathway of metal in plants. Various techniques to enhance phytoextraction and utilization of by-products have been elaborated. Since lot of biomass is produced during this process, it needs proper disposal and management. It also gives an insight into the work done by authors, which focuses on high biomass extractor plants. High biomas weeds were selected to restrict the passage of contaminants into the food chain by selecting non-edible, disease resistant and tolerant plants, which can provide renewable energy. Thus making phytoextraction more viable for present utilization. Keywords. heavy metals, phytoextraction, hyperaccumulator, indicator, excluder species
1,096 citations
TL;DR: The effect of various animal wastes on growth and reproduction of an epigeic earthworm Eisenia foetida was studied and the earthworms grew rapidly in cow, sheep, and goat wastes.
Abstract: The effect of various animal wastes on growth and reproduction of an epigeic earthworm Eisenia foetida was studied under identical laboratory conditions. For each waste, viz., cow, buffalo, horse, donkey, sheep, goat and camel, five hatchlings per 100 g of waste were inoculated and monitored for biomass gain, mortality, sexual maturity, cocoons production periodically for 15 weeks. No mortality was observed in any waste. The earthworms grew rapidly in cow, sheep, and goat wastes. Maximum weight gain and highest growth rate were attained in sheep waste. Net biomass gain/earthworm in different animal wastes was in the order of: sheep > donkey > buffalo > goat ≈ cow ≈ horse > camel. The number of cocoons produced per earthworm per day in different wastes was in the order: sheep > cow ≈ horse ≈ goat > camel > donkey > buffalo. Increase in the number of earthworms was 39.5-fold in horse waste and 26-fold in cow waste. Keywords. Eisenia foetida, animal waste, physicochemical characteristics, biomass, cocoon
124 citations
TL;DR: It has now become possible to isolate, detect and characterize the methanogens and methanotrophs by using molecular biological tools like PCR, FISH, etc.
Abstract: Methane has profound impact on the physico-chemical properties in atmosphere leading to global climate change. Out of the various sources of CH4, rice fields are the most significant contributors. The processes involved in the emission of CH4 from rice fields to the atmosphere include CH4 production (methanogenesis) in the soil by methanogens, methane oxidation (methanotrophy) by methanotrophs and vertical transfer of CH4 via plant transport and diffusion or ebullition. In the overall methane dynamics rice plants act as : a) source of methanogenic substrate, b) conduit for CH4 through well developed system of inter cellular air space (aerenchyma), and c) potential methane oxidizing micro-habitat in the rhizosphere by diffusing oxygen which favour the growth and multiplication of methanotrophs. Apart from mechanistic uncertainties, there are several other uncertainties in the estimation of CH4 flux. Methane dynamics in the paddy field is controlled by a complex set of parameters linking the biological and physical characteristics of soil environment like temperature, carbon source, Eh, pH, soil microbes and properties of rice plants, etc. It has now become possible to isolate, detect and characterize the methanogens and methanotrophs by using molecular biological tools like PCR, FISH, etc. techniques. The apparent half saturation constant (Km) and maximum oxidation rate (Vmax) are distinctive parameters which determine the ability of bacteria to survive on atmospheric methane. Keywords. methane; methanotrophs; methanotrophy; methanogens; molecular tools
113 citations
TL;DR: In this paper, the impacts of crude oil pollution on a sandy loam soil and the influence of incorporation of poultry manure alone and in combination with alternate carbon substrates (glucose or starch) and surfactants (Goldcrew or Corexit) were investigated.
Abstract: The impacts of crude oil pollution on a sandy loam soil and the influence of incorporation of poultry manure alone and in combination with alternate carbon substrates (glucose or starch) and surfactants (Goldcrew or Corexit) were investigated. Oil pollution increased soil organic carbon and reduced soil nitrates and phosphorus, thus imposing a condition that impaired oil degradation in the soil. Treatment of the soil with poultry manure alone, enhanced oil degradation but the extent of this was influenced by the incorporation of alternate carbon substrates or surfactants. Addition of glucose or Corexit encouraged crude oil degradation, while addition of starch or Goldcrew reduced the extent of degradation obtained. The soil amendments interacted in affecting crude oil degradation. This was optimal with a combination of poultry manure (2.0%w/w) + glucose (2.0%w/w) which yielded a crude oil degradation of 7.42±1.02% after sixteen weeks incubation. Keywords. alternate carbon substrates, crude oil degradation, poultry manure, surfactants
98 citations
TL;DR: The results indicated that P. karka showed much greater tolerance to metals than other plants, though the uptake was low, and all the tested weeds were better for chromium extraction than the accumulator Brassica species.
Abstract: Plant species have been recently used for heavy metal accumulation and most of the studies have been done on hyperaccumulator tolerant species. Metal hyperaccumulator plants though useful to phytoextract metal contaminant from soil, have many shortcomings such as low biomass, edible nature and difficult to harvest. This study is part of a series of studies that attempt to evaluate the phytoextraction potential of commonly found high biomass weed species that are harmless, non-edible in nature. We have investigated and compared five weed species (Ipomoea carnea, Dhatura innoxia, Phragmytes karka Cassia tora and Lantana camara), with two accumulator plants (Brassica juncea and Brassica campestris), in a pot study to assess Cr uptake in the range of 5 to 200 mg kg -1 soil. The results indicated that P. karka showed much greater tolerance to metals than other plants, though the uptake was low. It was more effective at translocating Cr from soil to plant shoot. The order of Cr extraction was I. carnea > D. innoxia > C. tora > P. karka > B. juncea > L. camara > B. campestris. Among the studied plants I.carnea showed maximum chromium extraction and biomass growth, but the difference of shoot by root chromium concentration was least. Other than Lantana camara, all the tested weeds were better for chromium extraction than the accumulator Brassica species. To save the Brassica species infested by army moth, pesticide application was required, whereas weeds required no care.
97 citations
TL;DR: The physicochemical qualities of a refinery effluent and water and sediment of an effluent receiving water body were investigated in this article, where high concentrations of phenol (5.13-16.17 mg/l) were observed in water or sediment samples respectively, at the point of effluent impact, though it was undetectable in the effluent itself or water sample.
Abstract: The physicochemical qualities of a refinery effluent and water and sediment of an effluent receiving water body were investigated. The treated refinery effluent contained very high concentrations of phenol (11.06 mg/l), oil and grease (7.52 mg/l), ammonia (8.52 mg/l), COD (91.76 mg/l), TDS (390.6 mg/l) and phosphate (6.2 mg/l), but low in sulphide, nickel, lead, copper and chromium, which were undetectable. High concentrations of phenol (5.13-16.38 mg/l), oil and grease (10.56-15.23 mg/l), and ammonia (4.31-13.17 mg/l) were observed in water and sediment samples respectively, at the point of effluent impact. A high concentration of sulphide (3.74 mg/l) was accumulated in the sediment at the point of impact of the refinery effluent, though it was undetectable in the effluent itself or water sample. The concentrations of these parameters as well as of phosphate, nitrate, zinc and COD declined progressively with distance from the point of impact but were still significantly higher than in control water and sediment in samples 1.5 km downstream from the point of impact. Higher concentrations of the pollutants were recorded in the dry season than rainy season except for phosphate and nitrate, which showed the reverse trend. Nickel, lead, copper, chromium and cyanide were neither detected in the effluent nor impacted water body. Keywords. contaminant concentrations, sediment accumulation, seasonal changes
92 citations
TL;DR: In this paper, outdoor airborne microflora (bacteria) at different locations, viz; institutional, health care, commercial, traffic, industrial and agricultural areas of Tirupati a semi-arid urban region, southern peninsular India was investigated during winter season, 2004.
Abstract: In the present study, outdoor airborne microflora (bacteria) at different locations, viz; institutional, health care, commercial, traffic, industrial and agricultural areas of Tirupati a semi-arid urban region, southern peninsular India was investigated during winter season, 2004. Concentrations of airborne viable bacteria averaged between 19 ± 5 CFU/m 3 (IE) and 3 ± 5 CFU/m 3 (SVU) and observed the following trend among the locations: IE > TG > CBS > TUDA > RUYA > SVU. Airborne Gram- positive bacteria were most abundant, with more than 60 to 90% of the measured population at each location. Developed regression models have been explained about 50% (or greater) variation in bacteria concentration at each location (except RUYA), due to the effect of meteorological factors - temperature, RH, and wind speed. Among these factors, wind speed had the most pronounced influence on bacterial concentration, with the regression coefficient (β) varied between 0.225 and 2.092, followed by the temperature. The overall air quality index (ABQI) with respect to bacterial composition of aerosol is found to be 22.33 which signifies that the quality of air is good. The results reveal that the airborne bacteria are contributed from terrestrial (soil) sources greatly followed by the little contribution from point sources. Keywords. Bioaerosol, airborne bacteria, meteorological factors, multiple linear regression, quality index, India.
87 citations
TL;DR: Results in general indicated that the groundwaters in the shallow aquifers were found to be deteriorated and some of the dug wells were characterised by high amount of sodium and chloride indicating the influence of saline water incursion.
Abstract: The coastal aquifers of Kerala, India experience severe degradation of water quality due to various anthropogenic activities. An attempt is made here to study the groundwater chemistry of aquifers, which lie along the coastal zone of central Kerala. Results in general indicated that the groundwaters in the shallow aquifers were found to be deteriorated. Based on Hill-Piper trilinear diagram it is confirmed that some of the dug wells were characterised by high amount of sodium and chloride (>200 mg/l) indicating the influence of saline water incursion. The presence of E. coli in all dug wells indicated potentially dangerous fecal contaminations, which require immediate attention. The study further raises points for the need of action for a sustainable utilization of precious resources. Keywords. coastal aquifer, groundwater, trilinear diagram, saline water incursion
73 citations
TL;DR: It is concluded that small sized light and numerous seeds produced by Tithonia diversifolia accounts for its wide dispersal and rapid spread in colonized areas and its perennial habit and ability to reproduce sexually and vegetatively accounts for the species colonizing and stabilizing fast in new habitats.
Abstract: Seed germination and reproductive strategies of Tithonia diversifolia and Tithonia rotundifolia, two invasive species introduced into Africa from North and Central America, were studied. The aim was to determine the characteristics that make them invasive species in the continent. Tithonia diversifolia is a perennial and polycarpic plant reproducing both sexually and asexually while Tithonia rotundifolia is an annual monocarpic plant reproducing only sexually. The seeds of these species exhibit a period of dormancy before germinating. Tithonia diversifolia produces small sized light and numerous seeds while Tithonia rotundifolia produces larger sized, heavier and fewer seeds. Tithornia rotundifolia allocates a high proportion of of dry matter (41.6 %) and Tithonia diversifolia low proportion (10.5 %) to reproduction. It is concluded that small sized light and numerous seeds produced by Tithonia diversifolia accounts for its wide dispersal and rapid spread in colonized areas. Also its perennial habit and ability to reproduce sexually and vegetatively accounts for the species colonizing and stabilizing fast in new habitats. While the larger heavier seeds and high reproductive effort of Tithonia rotundifolia ensures its early vigorous start in seedling growth, quick establishment, survival for longer and to grow to more aggressive size in an environment that is starved of resources. Seed dormancy exhibited by the two species ensures they survive adverse conditions in their environment as seeds and germinate only when the environmental conditions favour the survival of their seedlings. Keywords. Tithonia species, reproductive strategies, seed dormancy.
49 citations
TL;DR: Eight populations of Epipactis helleborine (L.) Crantz originating from the area of Lower Silesia in Poland (Central Europe) were examined in respect to composition of their nectar and its influence on the insect attraction in field conditions.
Abstract: Eight populations of Epipactis helleborine (L.) Crantz originating from the area of Lower Silesia in Poland (Central Europe) were examined in respect to composition of their nectar and its influence on the insect attraction in field conditions. The chemical composition of Epipactis helleborine (L.) Crantz nectar was studied by means of GC/MS SIM. A number of compounds with potential narcotic properties were identified in the nectar, namely 3-{2-{3-{3-(benzyloxy)propyl}-3-indol, 7,8-didehydro- 4,5-epoxy-3,6-d-morphinan and oxycodone. Pollinator and visitor insects were identified. The key role of ethanol in the process of alluring and stunning of the insects was discussed. A scheme of the influence of the identified compounds on the pollinators was proposed. Keywords. Epipactis helleborine, toxic nectar, morphinan derivatives, indol derivatives, ethanol
40 citations
TL;DR: There is a need to build a conservation ethic among wetland users by educating them to sustainably utilize wetland resources and training them to practise sustainable agriculture.
Abstract: Effect of farming practices on wetlands in Kisii District was determined through assessment of farmers’ environmental awareness. Effective conservation of wetlands in the district cannot depend on prohibitions but should be based on users’ knowledge and attitudes of wetlands. The present study examined farmers’ knowledge of the environmental effect of agricultural expansion to wetlands; absence of knowledge of characteristics of farming activities and the attitudes of farmers with respect to planning mechanisms that might be used to support wetland protection in the area. The majority of farmers ignored the effect of agriculture on wetlands. Those who occupied wetland areas practiced intensive agriculture and were ignorant of the effect of this on water quality, soil and landscape. The government should implement training programmes for all wetland users in Kisii District to make them more environmentally aware of the impacts of farming practices on wetlands. This is meant to make them become more environmentally aware of the effects of farming practices on these ecosystems and eventually change their behavior. There is a need to build a conservation ethic among wetland users by educating them to sustainably utilize wetland resources and training them to practise sustainable agriculture.
TL;DR: Comparative studies revealed low diversity indices correspondingly to the increase in trace metal level in benthic species collected from four sites except Doha wherein high abundance of certain benthics species and high trace metal levels due to manmade perturbations were observed altering the diversity indices.
Abstract: Benthic organisms diversity were observed in the sequence of Annelida > Mollusca > Crustacea > "Diversa" group. Levels of trace metals in benthic organisms were in the range 0.12-96.86 µg/g during winter and 0.98-54.13 µg/g in summer. Species diversity index (H'), evenness index (J) and index of dominance (λ) were in the range 0.951-1.368 bits/unit, 0.475-0.684, and 0.19-0.33 respectively, for benthic organisms sampled in Kuwait Bay sites. Evenness index (-) was found to increase with increasing H'. Seasonally, an inverse correlation was observed between species richness (R1 and R2). Comparative studies revealed low diversity indices correspondingly to the increase in trace metal level in benthic species collected from four sites except Doha wherein high abundance of certain benthic species and high trace metal levels due to manmade perturbations were observed altering the diversity indices. Furthermore, these indices will validate benthic organisms as an indicator to trace metal pollution in Kuwait marine ecosystem. Keywords. benthic organisms; trace metals; species diversity
TL;DR: An ecological model-system is developed which is suitable for generating realistic patterns highly resembling to the observed temporal patterns, and by the help of which predictions can be given to alternative situations of climatic circumstances not experienced before, and furthermore; which can simulate experimental circumstances.
Abstract: Our aim was to approach an important and well-investigable phenomenon - connected to a relat- ively simple but real field situation - in such a way, that the results of field observations could be directly comparable with the predictions of a simulation model-system which uses a simple mathematical apparatus and to simultaneously gain such a hypothesis-system, which creates the theoretical opportunity for a later experimental series of studies. As a phenomenon of the study, we chose the seasonal coenological changes of aquatic and semiaquatic Heteroptera community. Based on the observed data, we developed such an ecological model-system, which is suitable for generating realistic patterns highly resembling to the observed temporal patterns, and by the help of which predictions can be given to alternative situations of climatic circumstances not experienced before (e.g. climate changes), and furthermore; which can simulate experimental circumstances. The stable coenological state-plane, which was constructed based on the principle of indirect ordination is suitable for unified handling of data series of monitoring and simulation, and also fits for their comparison. On the state-plane, such deviations of empirical and model-generated data can be observed and analysed, which could otherwise remain hidden.
TL;DR: It was concluded that different genus of moulds which were found, are in dependence of geographical locations and seasons.
Abstract: Moulds can be found in milk as contaminants from the environment. The specific qualities of climate, vegetation and land are the important factors affecting the quality of moulds and determinators of genus and species in connection with a certain geographical location. The study was carried out in 297 milk samples taken from different geographical location: A. lowlands, B. hilly-mountainous, C. alluvial plains by the river, D. submountainous and part of basin by the river in course of four seasons. The following media were used for growing moulds in laboratory conditions as: Sabouroud dextrosa agar, Czapek agar, Potato dextrosa agar. Moulds determination was carried out according to their micromorphological properties using moulds determination keys. According to the result of study it was conclude that moulds count in raw milk samples were as follows: A. region: Fusarium genus (44.1%) in spring, Aspergillus genus (30.8%) in summer, Penicillium genus (30.2%) in autumn and the same (32.1%) in winter; B. region: Fusarium genus (55%) in spring, Penicillium genus (34.8%) in summer, Penicillium genus (23.1%) in autumn and Cladosporium + Penicillium genera (28.6%) in winter; C. region: Penicillium genus (69.3%) in spring and the same (31.8%) in summer, Geotrichum genus (24.6%) in autumn and Aspergillus genus (20.9%) in winter; D. region: Penicillium genus (42.9%) in spring and the same (50.73%) in summer, Cladosporium genus (43.2%) in autumn and Penicillium genus (45.21%) in winter. Finally we concluded that different genus of moulds which were found, are in dependence of geographical locations and seasons.
TL;DR: The results showed that the pollution situation in Jinyun Mountain was more favourable than that in the other acid rain regions of southern China and Chongqing urban areas and the high concentration of NH4 and Ca neutralized greatly the acidity of acid ions, which resulted in relatively high pH and lower frequency of acid rain, but the acidifying rain may exert potential injury to forest ecosystem.
Abstract: The pH and chemical composition of 126 precipitation samples, which were collected from April 1998 to November 1999 in Jinyun Mountain, Chongqing, China, were analyzed. The results showed: the average pH was 5.23 and the average electrical conductivity was 33.90 μs/cm, which showed that the pollution situation in Jinyun Mountain was more favourable than that in the other acid rain regions of southern China and Chongqing urban areas. The concentration of SO4 accounted for 84.61% of total anions, and the concentration of NH4 and Ca accounted for 77.36% of total cations of rainfall in Jinyun Mountain. The high concentration of NH4 and Ca neutralized greatly the acidity of acid ions, which resulted in relatively high pH and lower frequency of acid rain, but the acidifying rain may exert potential injury to forest ecosystem. The seasonal variations in the rainfall pH and chemical composition were evident, which may be related to the seasonal variations in precipitation amount in Jinyun Mountain. The effects of acid rain on forest ecosystem have time lag, so it is necessary to study the dynamic characteristics of acid deposition more carefully and comprehensively.
TL;DR: Experiments were carried out that demonstrated that the steady state growth could be attained and be controlled by the nutrient concentration, flow rate, and recharge intervals, and that the cultures could be kept at steady state over 21 days of the Lemna test period.
Abstract: To overcome the problems associated with high concentrations of nutrient and test chemicals in laboratory Lemna gibba bioassays, a semi-continuous culture system was adopted, and specific equipment was designed and constructed to simulate steady-state conditions of the most natural aquatic systems. The equipment for Lemna semicontinuous culture consists of a growth chamber and a circulation control unit. Lemna gibba is kept in the growth chamber in a growth pot (with 1 mm diameter perforation at about 10 cm above the bottom), which retains the plant but allows an efficient exchange of the growth medium. Flow rate and composition of the medium is therefore varied independently of the L. gibba population density. The media are kept in circulation, and recharges or discharge of the media are controlled. The system took into consideration chemical processes such as O2 and CO2 exchange and maintained a degree of turbulence through continuous shaking of the growth chambers. It is also possible to investigate growth under different supply of O2 and CO2, and pH control with dissolved CO2 or reducing conditions with N2 gases. Theoretical analysis of growth in the steady state shows that integrated activation time of the dilution pump is proportional to the growth rate of L. gibba. Theoretical analysis was also used to determine the minimum flow-rate and nutrient concentration of the medium to cover the requirements of L. gibba. Experiments were carried out that demonstrated that the steady state growth could be attained and be controlled by the nutrient concentration, flow rate, and recharge intervals. The cultures could be kept at steady state over 21 days of the Lemna test period. Keywords. Lemna gibba, steady state, semicontinuous culture, batch culture, nutrient media
TL;DR: In this paper, the authors analyzed the biological aspects of three sturgeon species: beluga (Huso huso Linnaeus, 1758), Russian Sturgeon (Acipenser gueldenstaedti Brand, 1833) and stellate sturgeons (Acipient stellatus, Brandt, 18 33) and compared them with formerly registered data and scientific information.
Abstract: Marine migratory sturgeons form one of the most valuable fish population of the Lower Danube River ecosystem and are also extremely important for the economy of Romania and some other riverside countries and freshwater fisheries. Decreasing sturgeon presence in the last several decades has been a true concern either for commercial fishermen and biologists. This paper is trying to analyze some biological aspects of three sturgeon species: beluga (Huso huso Linnaeus, 1758), Russian sturgeon (Acipenser gueldenstaedti Brand, 1833) and stellate sturgeon (Acipenser stellatus, Brandt, 1833) and to compare them with formerly registered data and scientific information. This paper also tries to reveal some ecological particularities concerning their migration and natural reproduction process that could help scientists and other people to find the most probable causes of the tendency why stocks are decreasing and suggesting some pertinent actions to be done on the necessary mitigation and protection activities concerning actual and further presence of these very interesting sturgeon species in Danube River.
TL;DR: The reeds sampling site proved to be the richest, while the cattail microhabitat is close behind, open water (with submerged macrophytes) is the least diverse microhabITat.
Abstract: In the years 2002, 2003 and 2004 we collected samples of macroinvertebrates on a total of 36
occasions in Badacsony bay, in areas of open water (in the years 2003 and 2004 reed-grassy) as well as
populated by reed (Phragmites australis) and cattail (Typha angustifolia). Samples were taken using a stiff
hand net. The sampling site includes three microhabitats differentiated only by the aquatic plants inhabiting
these areas. Our data was gathered from processing 208 individual samples. The quantity of
macroinvertebrates is represented by biovolume value based on volume estimates. We can identify taxa in
abundant numbers found in all water types and ooze; as well as groups associated with individual microhabitats
with various aquatic plants. We can observe a notable difference between the years in the volume of
invertebrate macrofauna caused by the drop of water level, and the multiplication of submerged macrophytes.
There are smaller differences between the samples taken in reeds and cattail stands. In the second
half of 2003 – which was a year of drought – the Najas marina appeared in open waters and allowed to
support larger quantities of macroinvertebrates. In 2004 with higher water levels, the Potamogeton perfoliatus
occurring in the same area has had an even more significant effect. This type of reed-grass may support
the most macroinvertebrates during the summer. From the aspect of diversity relations we may suspect
different characteristics. The reeds sampling site proved to be the richest, while the cattail microhabitat is
close behind, open water (with submerged macrophytes) is the least diverse microhabitat.
TL;DR: It is found that the average percentage of the drought intolerant and middle type of PFTs both increased significantly from 1986 to 1994, which indicates that the drought intolerance P FTs is vulnerable to the current environmental change.
Abstract: Studying the spatial variability of plant functional types at large scale is important to understand the effects of environmental change on ecosystems. Here we classified the tree species in the forest area of Northeast China Transect (a middle-latitude transect and its environmental gradient was mainly driven by moisture) into three plant functional types (PFTs): drought tolerant, drought intolerant and middle type PFTs. We found that the average percentage of the drought intolerant and middle type of PFTs both increased significantly from 1986 to 1994. The drought tolerant and middle type of PFTs increased their covered areas at the western part of transect, but the covered area of the drought intolerant PFTs decreased about 48% at the western part. The dominance of the drought intolerant PFTs decreased while the dominance of the other PFTs increased. The net increments of these three PFTs were higher at 0-220 km than at 220-400 km. The negative net increments concentrated mainly at 150-350 km. The spatial autocorrelation of the drought intolerant and middle type of PFTs changed slightly from 1986 to 1994. The information entropy of the drought intolerant PFT increased across all scales and it indicated that impact from local disturbances was limited. All these indicate that the drought intolerant PFTs is vulnerable to the current environmental change. The spatial variations of different PFTs at large scales were mainly caused by the fluctuations of gradient of annual precipitation along this transect. Keywords. Northeast China Transect, plant functional type, precipitation gradient, spatial variation, tree species
TL;DR: Equal enzyme activity in both light and dark for the two Rivularia strains (non hair-forming) implies that phosphatase activity may not be affected by changes in light regimes in rice fields which do occur due to the plant growth.
Abstract: Phosphatase activity of Rivularia strains II and I isolated from a deepwater rice field was studied. When grown under conditions of P-limitation the strains did not form hair and showed great variations in induction time and pattern of enzyme activity in relation to growth. Phosphomonoesterase activity (PMEase) was induced earlier in the Rivularia strain I which was maintained in high phosphate concentration in the medium before the study. Rivularia strain II on the other hand showed induction of PMEase activity after 3-4 days and this strain was maintained in low phosphorus concentrations in the medium before the study. The comparison of Km and Vmax values early in the growth phase showed that affinity of both PMEase (phosphomonester) and PDEase (phosphodiester) for the substrate was higher in early growth phase rather than in later stages suggesting that there is presence of more than one phosphatase enzymes in these organisms. The observations from the above study have important implications in rice fields where constant fluctuations in nutrients can be observed - especially by phosphorus in its most available form phosphate. Equal enzyme activity in both light and dark for the two strains (non hair-forming) implies that phosphatase activity may not be affected by changes in light regimes in rice fields which do occur due to the plant growth. This can in turn contribute significantly to maintain the growth of cyanobacteria for prolonged periods even under unfavorable conditions of phosphorus depletions. These strains of Rivularia can therefore biotechnologically exploited as bio- fertilizers (phosphatic fertilizer) when there is phosphorus deficiency. During the unfavorable conditions of phosphorus deficiency, phosphatase activity may play a significant role in providing phosphate for its own growth and for the rice plants.
TL;DR: The main aspects of sturgeons fished in Romanian sector of Danube River are shown to discuss some relevant aspects that could help people to understand the real issues on this topic better and eventually find the best way to stop the decreasing tendency of wild population of three very interesting species ofSturgeons.
Abstract: Study of fish captures could bring out valuable information on tendencies in stocks dynamics as well as on the level of “fishing pressure” on natural fish population. Decreasing amount of annual captures of marine migratory sturgeons that migrate in Danube River for spawning indicates a decline of natural stocks of these species. Present paper tries to show the main aspects of sturgeons fished in Romanian sector of Danube River, to discuss some relevant aspects that could help people to understand the real issues on this topic better and eventually find the best way to stop the decreasing tendency of wild population of three very interesting species of sturgeons: beluga (Huso huso Linnaeus, 1758), Russian sturgeon (Acipenser gueldenstaedti Brand, 1833) and stellate sturgeon (Acipenser stellatus, Brandt, 1833).