Ecosystem structure and trophic dynamics of an exploited ecosystem of Bay of Bengal,Sundarban Estuary,India

A trophic structure model for commercial fisheries of Sundarban Estuary in the northern Bay of Bengal (BoB) is developed using the mass balance modeling software Ecopath (Version 6.4.10992.0). In this model, we simulated 15 functional groups spread across an area of 17,049 km². The mean trophic level of the present study area is 2.716. The ecotrophic efficiency of the present studied ecosystem is in the range of 0.424 of medium demersals and 0.961 of medium pelagics. Penaeid prawn, small pelagics, and medium pelagics are the most exploited groups of this ecosystem. The coastal northern BoB food web is mainly detritivorous and planktivorous; phytoplankton and detritus positively affected almost all the functional groups, and top predators are essentially absent in the system. The zooplankton and benthos have negative impacts on themselves because of cannibalistic behavior. The average catch per net primary production, i.e. the gross efficiency of the system is around 0.001. The system is low trophic and efficient. Proper ecosystem-based management practice can improve the efficiency of this overexploited ecosystem.     

Effect of dietary protein level on excretion of ammonia in Indian major carp, Labeo rohita, fingerlings

The study was conducted to investigate the effect of dietary protein on nitrogenous excretion in the form of ammonia in Indian major carp, Labeo rohita (Ham.), fingerlings (3.0 ± 0.25 g). Fish were fed to satiation in a metabolism chamber. Approximately isoenergetic diets containing 230, 280, 330 and 380 g kg⁻¹ protein were used at 28°C. Ammonia-N excretory energy ( U ) as a percentage of ingested food energy ( C ) increased with an increase in dietary protein level: from 4.3% in fish fed 230 g kg⁻¹ to 6.0% in fish fed 380 g kg⁻¹ dietary protein. The relationship between excretory energy and dietary protein level is modelled.     

Simultaneous assessment of key properties of arid soil by combined PXRF and Vis–NIR data

Arid soil is common worldwide and has unique properties that often limit agronomic productivity, specifically, salinity expressed as soluble salts and large amounts of calcium carbonate and gypsum. Currently, the most common methods for evaluating these properties in soil are laboratory‐based techniques such as titration, gasometry and electrical conductivity. In this research, we used two proximal sensors (portable X‐ray fluorescence (PXRF) and visible near‐infrared diffuse reflectance spectroscopy (Vis–NIR DRS)) to scan a diverse set (n = 116) of samples from arid soil in Spain. Then, samples were processed by standard laboratory procedures and the two datasets were compared with advanced statistical techniques. The latter included penalized spline regression (PSR), support vector regression (SVR) and random forest (RF) analysis, which were applied to Vis–NIR DRS data, PXRF data and PXRF and Vis–NIR DRS data, respectively. Independent validation (30% of the data) of the calibration equations showed that PSR + RF predicted gypsum with a ratio of performance to interquartile distance (RPIQ) of 5.90 and residual prediction deviation (RPD) of 4.60, electrical conductivity (1:5 soil : water) with RPIQ of 3.14 and RPD of 2.10, Ca content with RPIQ of 2.92 and RPD of 2.07 and calcium carbonate equivalent with RPIQ of 2.13 and RPD of 1.74. The combined PXRF and Vis–NIR DRS approach was superior to those that use data from a single proximal sensor, enabling the prediction of several properties from two simple, rapid, non‐destructive scans.     

Study of trace metals in Indian major carp species from wastewater‐fed fishponds of East Calcutta Wetlands

Fish grown in the East Calcutta Wetland (ECW) areas in West Bengal, India amass waste elements within their body through nutritional uptake and accumulation. The present investigation had been carried out to study the extent of accumulation of different waste elements in tissues of Indian major carps (IMCs) commonly cultured in composite industrial wastewater‐fed fishponds in ECW, India. Energy‐dispersive X‐ray fluorescence spectrometric studies were used to estimate metals like chromium (Cr), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn) and lead (Pb) in water and sediment of fishponds, and in fish tissues (gill, liver and muscle) of three economically important IMCs, rohu (Labeo rohita), katla (Catla catla) and mrigel (Cirrhinus mrigala), collected from contaminated and control sites. It is evident from the study that mainly liver is the site of maximum accumulation of the elements, while gill, in most cases, is the site of least metal accumulation in the three IMC species studied. Principal component analysis reveals that Fe and Cr were in the first component and thereby must be having a major influence in trace metals uptake and bioaccumulation. Tissue‐specific and species‐specific patterns of metal concentration and partitioning were apparent from our present study.     

Mycelial compatibility reactions of Australian Fusarium graminearum and F. pseudograminearum isolates compared with AFLP groupings

Using the mycelial reactions of 435 combinations of 14 Fusarium pseudograminearum and 15 F. graminearum isolates, it was demonstrated for the first time that mycelial reactions/barrage formation cannot be clearly used to distinguish F. graminearum and F. pseudograminearum. Mutually compatible isolates produced very different patterns of compatibility with other isolates. However, about 60% of pairings between F. graminearum and F. pseudograminearum isolates were compatible, indicating common ancestry. The Mantel tests used to determine any possible associations between mycelial compatibility reactions and AFLP genotypic diversity data revealed no association between the two systems in either species. In addition, no association was found between mycelial compatibility reactions and sexual reproduction in the two species. Implications of the higher frequency of mycelial compatibility reactions observed in F. pseudograminearum than in F. graminearum are discussed.     

Microbial biomass and its activities in salt-affected coastal soils

Seasonal fluctuations in salinity are typical in coastal soils due to the intrusion of seawater in the groundwater. We studied the effect of salinity on the microbial and biochemical parameters of the salt-affected soils of the coastal region of Bay of Bengal, Sundarbans, India. The average pH values and average organic C (OC) contents of soils from nine different sites cultivated with rice (Oryza sativa) ranged from 4.8 to 7.8 and from 5.2 to 14.1 g kg⁻¹, respectively. The average electrical conductivity of the saturation extract (EC_e) during the summer season was about five times higher than that during the monsoon season. Within the nine sites, three soils (S₃, S₄, and S₅) were the most saline. The average microbial biomass C (MBC), average basal soil respiration (BSR), and average fluorescein diacetate hydrolyzing activity (FDHA) were lowest during the summer season, indicating a negative influence of soil salinity. About 59%, 50%, and 20% variation in MBC/OC, FDHA/OC, and BSR/MBC (metabolic quotient, qCO₂), respectively, which are indicators of environmental stress, could be explained by the variation in EC_e. The decrease in MBC and microbial activities with a rise in salinity is probably one of the reasons for the poor crop growth in salt-affected coastal soils.     

Rapid induction of small heat shock proteins improves physiological adaptation to high temperature stress in peanut

With the changing climatic scenario and increasing global mean temperature, heat stress became a major limiting factor for today's agriculture. To identify the underlying mechanism associated with heat tolerance in peanut, two experiments (field and growth chamber) were conducted with four genotypes (ICGS 44, GG 7, AK 159 and DRG 1) having differential high temperature stress sensitivity. Field grown plants under three different temperature (D₁, D₂ and D₃) regimes simulated three temperature treatment effects with a variability of 3–4/4–5°C in mean day/night temperature, respectively. In growth chamber, imposition of heat shock (10°C above ambient inside growth chamber) revealed not only rapid induction (within 0.5 hr) of HSPs, especially small HSPs (HSP 17, HSP 40) in tolerant genotypes, but also its sustenance for longer duration (2 hr), which might help them to have better physiological adaptation strategies under high temperature stress. This was evident from significant advancement in phenophases observed with increase in temperature by 15–18 days at physiological maturity, while pollen viability and membrane stability reduced below 50% and 41%, respectively in DRG 1 with increase in mean day/night temperature. Maintenance of higher photosynthesis and transpiration rate and stomatal conductance helped the tolerant genotype ICGS 44 to keep relatively cooler canopy and higher photosynthates, ensuring better physiological condition in this genotype under heat stress. Significant increase (~2.5‐fold) in inositol and hexoses (glucose and fructose) content and reduction (>50%) in sucrose content in leaf tissues indicated degradation of storage carbohydrates for improved osmotic adjustment especially in tolerant genotypes under elevated temperature.     

Evaluation of gross protein and lipid requirements in formulated feed for honey gourami,Trichogaster chuna (Hamilton 1822)

Gross protein and fat requirements in formulated feeds designed for the honey gourami, Trichogaster chuna (initial weight 1.34–1.38 g), were investigated. Feeds containing 30%, 40%, and 50% protein and 6% and 9% lipid at each protein level were tested. Protein and energy sources used were from fishmeal, shrimp meal, clam meal, soy flour, and wheat flour. An equal mixture of crude sardine oil and groundnut oil was used as the source of lipids. Comparison of the whole gourami amino acid profiles before and after the dietary treatments indicated a relative decline in all amino acids except methionine and lysine. Fatty acid profiles of whole individuals after dietary treatment showed a substantial increase in monounsaturated fatty acids relative to the initial fatty acid profiles. No significant differences were observed in fish growth between dietary treatments (p > .05). Feeds containing 30% protein and 6% lipid were found to be adequate for normal growth, while feeds with 40% protein and 6% lipid were seen to help accelerate growth and reproduction. In this study, protein and lipid levels required for regular maintenance, sexual maturation, and spawning of aquarium‐reared gourami were established.     

Fenvalerate induced stress mitigation by dietary supplementation of multispecies probiotic mixture in a tropical freshwater fish, Labeo rohita (Hamilton)

Five experimental diets with various combinations of probiotics, namely T1 & T6 (basal feed (BF) without probiotics), T2 & T7 (BF + Bacillus subtilis + Lactococcus lactis), T3 & T8 (BF + L. lactis + Saccharomyces cerevisiae), T4 & T9 (BF + B. subtilis + S. cerevisiae) and T5 & T10 (BF + B. subtilis + L. lactis + S. cerevisiae) were fed to Labeo rohita fingerlings for 30 days. Treatment groups T1, T2, T3, T4 and T5 were exposed to Fenvalerate, at a concentration of 1.79 μg L⁻¹. The SOD and CAT activity was significantly affected (P < 0.01) in fenvalerate treated groups. However, the supplementation of the three-probiotic mixture at equal concentration showed markedly reduced activity. Similarly, RBC, Hb, NBT, total protein and albumin values were reduced significantly (P < 0.01) in the fenvalerate exposed fish as compared to the probiotic supplemented fish. Fenvalerate exposure also showed increased serum ALP, ACP and Bilirubin values (P < 0.01) in comparison to the non-exposed fish. Histological observations of the gills, kidney and liver showed tissue degeneration after fenvalerate exposure, which however showed marked recovery on the three-probiotic mixture supplementation. Therefore, these results indicate that a mixture of multi-species probiotic supplementation in equal concentration acts beneficially in mitigating the stressful effects of fenvalerate.     

N-acylanilines, herbicide-CHA chimera, and amino acid analogues as novel chemical hybridizing agents for wheat (Triticum aestivum L.)

In the absence of viable alternative technology of hybrid wheat development, chemical induction of male sterility mediated technology based on chemical hybridizing agents (CHAs) holds a great potential. N-Acylaniline derivatives, namely, ethyl 4'-fluoro oxanilate (1) and ethyl 4'-trifluoromethyl oxanilate (2) containing halogen atoms in the para position of the aryl ring and substituted amide linkage (-CO-NH-) in the acyl side chain induced >98% spikelet sterility on three genotypes of wheat, namely, PBW 343, HD 2046 and HD 2733, at 1500 ppm. The active moieties were incorporated in the form of herbicide-CHA chimera and amino acid analogues using glycine and alanine as templates. The target activity was made more selective by synthesizing chimeric structure of herbicide (2,4-dichlorophenoxyacetic acid and dalapon) and the most active CHA templates, namely, 4- fluoroanilinyl and beta-ethoxycarbonyl moieties. Among herbicide-CHA chimera ethyl 2',4'-dichlorophenyl oxalate (14) induced 79.11% male sterility, whereas benzyl methyl 2-oxo-3-azaadipate (20) was the best, inducing 73.87% male sterility in HD 2733, among amino acid analogues. The CHAs were found to modify the reproductive biology to ensure cross-pollination in the cleistogamous wheat flowers, increasing the probability for the development of hybrids.