Dinoflagellate community structure from the stratified environment of the Bay of Bengal, with special emphasis on harmful algal bloom species

Harmful algal blooms (HABs) have been documented along the coasts of India and the ill effects felt by society at large. Most of these reports are from the Arabian Sea, west coast of India, whereas its counterpart, the Bay of Bengal (BOB), has remained unexplored in this context. The unique characteristic features of the BOB, such as large amount of riverine fresh water discharges, monsoonal clouds, rainfall, and weak surface winds make the area strongly stratified. In this study, 19 potentially harmful species which accounted for approximately 14% of the total identified species (134) of dinoflagellates were encountered in surface waters of the BOB during November 2003 to September 2006. The variations in species abundance could be attributed to the seasonal variations in the stratification observed in the BOB. The presence of frequently occurring HAB species in low abundance (≤ 40 cell L(?-1)) in stratified waters of the BOB may not be a growth issue. However, they may play a significant role in the development of pelagic seed banks, which can serve as inocula for blooms if coupled with local physical processes like eddies and cyclones. The predominance of Ceratium furca and Noctiluca scintillans, frequently occurring HAB species during cyclone-prone seasons, point out their candidature for HABs.     

Variations in phytoplankton community in a monsoon-influenced tropical estuary

In a monsoon-affected tropical estuary, oscillations in freshwater discharge during monsoon shifted the phytoplankton blooms from those adapted to low salinities to high salinities and vice versa. Salinity stratification during monsoon (onset and restart after an intermittent break) favored diatom (Skeletonema) bloom in low-saline surface waters. In high-saline, nutrient-rich bottom waters, Fragilariopsis (diatom) bloom was observed during onset of monsoon and persisted till the end of monsoon. The break period in monsoon altered the phytoplankton community leading to mixed species bloom of large-sized diatoms and harmful dinoflagellates (Gymnodinium catenatum and Cochlodinium polykrikoides) under high-saline, nutrient-poor, non-stratified, and transparent water column. Such variations in community should be considered for better understanding the biogeochemistry of monsoon-influenced tropical estuaries. The dominance of Skeletonema is determined positively by the extent of low-saline stratified condition whereas most of the observed taxa were favored by high-saline, nutrient-poor, and transparent waters.     

Epibiotic community of the horseshoe crab Tachypleus gigas

Horseshoe crabs act as moving substrata for simple to complex communities of small marine organisms. Amplexed adult pairs migrate for breeding once every 2 weeks from deep waters towards nearshore waters during highest high tide. Female horseshoe crabs bury themselves to the level of the lateral eyes to deposit eggs while the male crabs fertilize them. Subsequently eggs are buried by the female. Tachypleus gigas (Müller) is the most abundant horseshoe crab species above available along the Orissa coast (India). Adults reach terminal anecdysis once sexually mature and live with their carapace for 4 to 9 years. In spite of this, epibiosis is limited. In the current investigation, differences in the epibiotic community (diatoms and macro-epibionts) present on horseshoe crabs, according to gender, were evaluated, and the macro-epibiont population from different regions of the carapace was mapped. In general, female horseshoe crabs harbored fewer epibionts than the males. Among the diatoms, Navicula spp., Nitzschia spp. and Skeletonema sp. were dominant in both sexes. However, the abundance and diversity of diatoms was greater on the carapaces of male crabs. Among the macro-epibionts, the acorn barnacle (Balanus amphitrite Darwin) and encrusting bryozoan (Membranipora sp.) were the most dominant forms. Barnacles and bryozoans were greater in abundance in the “rough” zone (cardiopthalmic region and anterior region of the opisthosoma). Mapping of the macro-epibionts from different regions of the carapace revealed differential distribution in males and females. Such differentiated distribution of the macro-epibionts can be related to factors such as changing habitat by the horseshoe crabs during breeding, mechanical abrasion and surface availability during mating and nesting periods, requirements of epizootic larvae and surface properties of the carapace (wettability and roughness). In the case of females, mechanical abrasion and surface availability played an important role in the epibiotic community structure and distribution patterns. The surface wettability measurements indicated male carapace to be slightly more hydrophobic than the female carapace. Scanning electron microscopy revealed that the male carapace was comparatively rough compared to the smooth carapace of females. A comparison of surface properties of the carapace indicated that the male carapace is more conducive for epibiosis. Received: 23 August 1999 / Accepted: 25 January 2000     

Removal of Cr(VI) from aqueous solution using waste weed, Salvinia cucullata

Biosorption studies of Cr(VI) were carried out using waste weed, Salvinia cucullata. Various adsorption parameters were studied, such as agitation speed, contact time, pH, particle size, and concentrations of adsorbent and adsorbate. The equilibrium was achieved in 12 h. A lower pH favoured adsorption of Cr(VI). The kinetics followed pseudo-second-order rate equations. The adsorption isotherm obeyed both the Langmuir and Freundlich models. The calculated activation energy (1.1 kJ mol^-1) suggested that the adsorption followed a diffusion-controlled mechanism. Various thermodynamic parameters such as Δ G^°, Δ H^°, and Δ S^° were also calculated. The positive values of enthalpy indicated the endothermic nature of the reaction, and Δ S^° showed the increasing randomness at the solid liquid interface of Cr(VI) on the adsorbent, which revealed the ease of adsorption reaction. These thermo-dynamic parameters showed the spontaneity of the reaction. The maximum adsorption of uptake (232 mg g^-1) compared well with reported values of similar adsorbents. The rate-determining step was observed to follow an intra-particle diffusion model.     

Effectiveness of Treatment Technologies for Wastewater Pollution Generated by Indian Pulp Mills

India has a large number of paper manufacturing units, with mills varying in size of operations and type of product, scattered all over the length and breadth of the country. Present study deals with the survey of four different pulp and paper mills (Mill A, Mill B, Mill C and Mill D) in India, differing in their scale of operation as well as raw material usage. Physico-chemical characterization of wastewaters produced by different processing units like digestor house liquors, bleaching section, paper machine backwaters, combined inlet to the ETP and outlet to ETP, for all the four mills, was conducted. Different parameters like pH, Color, COD, BOD, percent Na, SAR, TDS and Total hardness were analyzed and compared. Highly significant differences were thus found between all the processing units of all four mills with p values < 0.01. This evaluation showed that though these mills have effluent treatment facilities installed in their premises, improvements are still needed to increase their efficiencies for treating the discharged wastewaters.     

Nutrient concentrations affect the antimicrobial resistance profiles of cattle manures

Environmental Science and Pollution Research - Antimicrobial resistance (AMR) in cattle is widespread because of the increased use of antibiotics to combat microbial diseases and enhance milk...     

Biodegradation of Pro-oxidant Filled Polypropylene Films and Evaluation of the Ecotoxicological Impact

The biodegradability of calcium stearate (CaSt) and cobalt stearate (CoSt) filled polypropylene (PP) films were investigated in this work. The PP films were prepared using melt blending technique followed by hot press moulding. On the basis of their tensile properties, the optimum amount of pro-oxidants was taken as 0.2 phr. Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used for the characterization of optimized films. Presence of pro-oxidant in the PP was confirmed by the FTIR studies. Addition of pro-oxidants in the films decreased the thermal stability as revealed by TGA analysis. Crystallinity of the pro-oxidant filled PP decreased with addition of pro-oxidants as showen by DSC. The maximum biodegradation of CaSt and CoSt containing PP films was showen 7.65 and 8.34%, respectively with 0.2 phr. Both the microbial test and plant growth test (on corn and tomato) indicated that biodegradation intermediates were non toxic.     

Challenges of small protected areas in urban cities: a case study of Okhla Bird Sanctuary,India

Protected areas have been earmarked throughout the world for the purpose of conserving the biodiversity. The protected areas are facing serious threats due to rapid urban growth, especially in the developing countries like India. The current threats and impacts of urbanization on the Okhla Bird Sanctuary (Delhi, India) have been presented in this paper as a case in point. Uncontrolled urbanization and the lack of policy implementation have been identified as one of the major contributors to incessant biodiversity loss in India and other countries. In addition, a possible management framework for a smaller protected area in an urban setting is presented in brief.     

Effects of technical and allocative inefficiencies on energy and nonenergy elasticities: an analysis of energy-intensive industries in China

Elasticity of substitution is traditionally estimated while ignoring technical and allocative inefficiencies, which could bias the estimates. We estimate elasticity of substitution for Chinese energy-intensive sectors by incorporating these inefficiencies. The results show most of the sectors are low substitutes between input factors and stress important differences among energy-intensive sectors. Concerning the cross-price elasticity for energy, with respect to capital (labor), the sectors are mainly characterized by weak substitutability or complementary. These imply the production structure is quite rigid and capital cannot be so readily used as a substitute for energy.     

Persistence and risk assessment of spiromesifen on tomato in India: a multilocational study

Supervised field trials were conducted at four different agro-climatic locations of India to evaluate the dissipation pattern and risk assessment of spiromesifen on tomato. Spiromesifen 240 SC was sprayed on tomato at 150 and 300 g a.i.?ha^?1. Samples of tomato fruits were drawn at 0, 1, 3, 5, 7, 10 and 15 days after treatment and soil at 15 days after treatment. Quantification of residues was done on gas chromatograph–mass spectrophotometer in selective ion monitoring mode in the mass range of 271–274 (m/z). The limit of quantification of the method was found to be 0.05 mg kg^?1, while the limit of determination was 0.015 mg kg^?1. Residues were found below the LOQ of 0.05 mg kg^?1 in 10 days at both the doses of application at all the locations. Spiromesifen dissipated with a half-life of 0.93–1.38 days at the recommended rate of application and 1.04–1.34 days at the double the rate of application. Residues of spiromesifen in soil were detectable level (<0.05 mg kg^?1) after 15 days of treatment. A preharvest interval (PHI) of 1 day has been recommended on tomato on the basis of data generated under All India Network Project on Pesticide Residues. Spiromesifen 240 SC has been registered for its use on tomato by Central Insecticide Board and Registration Committee, Ministry of Agriculture, Government of India. The maximum residue limit (MRL) of spiromesifen on tomato has been fixed by Food Safety Standard Authority of India, Ministry of Health and Family Welfare, Government of India as 0.3 μg/g after its risk assessment.