Investigating efficiency of <Emphasis Type="Italic">Lampito mauritii</Emphasis> (Kinberg) and <Emphasis Type="Italic">Perionyx ceylanensis</Emphasis> Michaelsen for vermicomposting of different types of organic substrates

The vermicomposting ability of Lampito mauritii (Kinberg) and Perionyx ceylanensis Michaelsen was evaluated by using three different types of organic substrates such as leaf litter of Polyalthia longifolia, Pennisetum typhoides cobs (pearl millet) and a weed, Rottboellia exaltata (whole plant except the roots) in combination with cowdung (1:1). Vermicomposting studies (120 days) conducted to optimize the number of worms required for efficient conversion based on the reduction of C/N ratio, percentage decomposition of organic substrates, total number and biomass of earthworms recovered from the vermibed substrates clearly showed that vermibeds with 4 kg of organic materials can hold about 60–80 L. mauritii and about 90–120 P. ceylanensis for efficient decomposition. The percentage decomposition of each organic substrate treated with different numbers of L. mauritii (20, 40, 60, 80 and 100 earthworms) and P. ceylanensis (30, 60, 90, 120 and 150) showed significant difference (P < 0.001) between numbers of worms introduced per vermibed but the difference between substrates was not significant within the treatments. Vermicomposting resulted in significant increase in electrical conductivity (28.54–49.82%), total nitrogen (43.96–90.83%), total phosphorus (27.42–68.10%) and total potassium (27.42–113.18%), whereas decrease in organic carbon (35.05–49.74%), C/N ratio (55.48–73.18%) and C/P ratio (50.46–66.90%) in different vermibeds introduced with L. mauritii and P. ceylanensis. Both the earthworm species can be used for vermicomposting different organic substrates; however, duration of vermicomposting with P. ceylanensis is not as much of L. mauritii. The use of L. mauritii for vermicomposting of other substrates has been well established by other workers also but standardization of P. ceylanensis, a locally available species, for vermicomposting of different organic substrates is a new finding and the species could be useful for vermiconversion of organic substrates under local conditions.     

Growth and fecundity of earthworms: <Emphasis Type="Italic">Perionyx excavatus</Emphasis> and <Emphasis Type="Italic">Perionyx sansibaricus</Emphasis> in cattle waste solids

Epigeic earthworms (Oligochaeta) have been appeared as key organisms to convert organic waste resources into value-added products, i.e., vermicompost and worm biomass. The assessment of reproduction potential of composting earthworm may be beneficial for large-scale earthworm production. Although, the waste minimizing potential of Perionyx excavatus and Perionyx sansibaricus is well proved, but little information is available about their fecundity rate. In this study, the efforts have been made to explore the growth and reproduction biology of P. excavatus and P. sansibaricus, using cattle waste solid as culture substrate, under laboratory conditions. Earthworms were weighed weekly and number of cocoons produced per week assessed. Biomass productions, fecundity, maturation, natality all were significantly different between P. excavatus and P. sansibaricus. The highest mean individual biomass was 767.7 ± 18.4 mg and 612.6 ± 20.6 mg, respectively in P. sansibaricus and P. excavatus. However, the highest cocoon numbers occurred in P. excavatus (492.3 ± 13.6), significantly higher than P. sansibaricus (269.6 ± 17.1). Fecundity was slightly different in both species: 1.38 ± 0.77 cocoons adult worm⁻¹ week⁻¹ (P. excavatus) and 1.58 ± 0.74 cocoons adult worm⁻¹ week⁻¹ (P. sansibaricus). The hatchling success rate (%) was highest in P. excavatus. Overall natality (juveniles adult⁻¹ week⁻¹) was highest in P. sansibaricus (1.52) than P. excavatus (1.26), which suggests that P. sansibaricus may be a better candidate for rapid propagation of earthworms in cattle waste solid.     

Production of vermifertilizer from guar gum industrial wastes by using composting earthworm <Emphasis Type="Italic">Perionyx sansibaricus</Emphasis> (Perrier)

Efforts have been made to convert the guar gum industrial waste into a value-added product, by employing a new earthworm species for vermicomposting e.g. Perionyx sansibaricus (Perrier) (Megascolecidae), under laboratory conditions. Industrial lignocellulosic waste was amended with other organic supplements (saw dust and cow dung); and three types of vermibeds were prepared: guar gum industrial waste + cow dung + saw dust in 40: 30: 30 ratio (T₁), guar gum industrial waste + cow dung + saw dust in 60: 20: 20 ratio (T_2,), and guar gum industrial waste + cow dung + saw dust in 75: 15: 10 ratio (T₃). As compared to initial concentrations, vermicomposts exhibited a decrease in organic C content (5.0–11.3%) and C:N ratio (11.1–24.4%) and an increase in total N (18.4–22.8%), available P (39.7–92.4%), and exchangeable K (9.4–19.7%) contents, after 150 days of vermicomposting. A vermicomposting coefficient (VC) was used to compare of vermicomposting with the experimental control (composting). P. sansibaricus exhibited maximum value of mean individual live weight (742.8 ± 21.1 mg), biomass gain (442.94 ± 21.8 mg), growth rate (2.95 ± 0.15 mg day⁻¹), cocoon numbers (96.0 ± 5.1) and reproduction rate (cocoons worm⁻¹ day⁻¹) (0.034 ± 0.001) in T₂ treatment. In T₃ maximum mortality (30.0 ± 4.01 %) in earthworm population was observed. Overall, T₂ vermibed appeared as an ideal substrate to manage guar gum industrial waste effectively. Vermicomposting can be proposed as a low-input basis technology to convert industrial waste into value-added biofertilizer.     

Influence of Mowing <Emphasis Type="Italic">Artemisia tridentata</Emphasis> ssp. <Emphasis Type="Italic">wyomingensis</Emphasis> on Winter Habitat for Wildlife

Mowing is commonly implemented to Artemisia tridentata ssp. wyomingensis (Beetle & A. Young) S.L. Welsh (Wyoming big sagebrush) plant communities to improve wildlife habitat, increase forage production for livestock, and create fuel breaks for fire suppression. However, information detailing the influence of mowing on winter habitat for wildlife is lacking. This information is crucial because many wildlife species depended on A. tridentata spp. wyomingensis plant communities for winter habitat and consume significant quantities of Artemisia during this time. Furthermore, information is generally limited describing the recovery of A. tridentata spp. wyomingensis to mowing and the impacts of mowing on stand structure. Stand characteristics and Artemisia leaf tissue crude protein (CP), acid detergent fiber (ADF), and neutral detergent fiber (NDF) concentrations were measured in midwinter on 0-, 2-, 4-, and 6-year-old fall-applied mechanical (mowed at 20 cm height) treatments and compared to adjacent untreated (control) areas. Mowing compared to the control decreased Artemisia cover, density, canopy volume, canopy elliptical area, and height (P < 0.05), but all characteristics were recovering (P < 0.05). Mowing A. tridentata spp. wyomingensis plant communities slightly increases the nutritional quality of Artemisia leaves (P < 0.05), but it simultaneously results in up to 20 years of decrease in Artemisia structural characteristics. Because of the large reduction in A. tridentata spp. wyomingensis for potentially 20 years following mowing, mowing should not be applied in Artemisia facultative and obligate wildlife winter habitat. Considering the decline in A. tridentata spp. wyomingensis-dominated landscapes, we caution against mowing these communities.     

Metal contamination of surface water,sediment and <Emphasis Type="Italic">Tympanotonus fuscatus</Emphasis> var. <Emphasis Type="Italic">radula</Emphasis> of Iko River and environmental impact due to Utapete gas flare station,Nigeria

Inter-seasonal studies on the trace metal load of surface water, sediment and Tympanotonus fuscatus var. radula of Iko River were conducted between 2003 and 2004. The impact of anthropogenic activities especially industrial effluent, petroleum related wastes, gas flare and episodic oil spills on the ecosystem are remarkable. Trace metals analyzed included cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), lead (Pb), manganese (Mn), nickel (Ni), vanadium (V) and zinc (Zn). Sediment particle size analysis revealed that they were characteristically psammitic and were predominantly of medium to fine grained sand (>73%), less of silt (<15%) and clay (<10%). These results correlated with low levels of trace elements such as Pb (0.03 ± 0.02 mg kg⁻¹), Cr (0.22 ± 0.12 mg kg⁻¹), Cd (0.05 ± 0.03 mg kg⁻¹), Cu (0.04 ± 0.02 mg kg⁻¹) and Mn (0.23 ± 0.22 mg kg⁻¹) in the sediment samples. This observation is consistent with the scarcity of clayey materials known to be good scavengers for metallic and organic contaminants. Sediments indicated enhanced concentration of Fe, Ni and V, while other metal levels were relatively low. The concentrations of all the metals except Pb in surface water were within the permissible levels, suggesting that the petroleum contaminants had minimal effect on the state of pollution by trace metals in Iko River. Notably, the pollutant concentrations in the sediments were markedly higher than the corresponding concentrations in surface water and T. fuscatus tissues, and decreased with distance from point sources of pollution.     

Influence of different nitrogen rich supplements during cultivation of <Emphasis Type="Italic">Pleurotus </Emphasis><Emphasis Type="Italic">florida</Emphasis> on corn cob substrate

The cultivation of white rot edible fungus Pleurotus florida was performed in polybags. The corn cob was employed as basal substrate while eight different additives such as urea, ammonium sulphate, gram flour, soybean meal, ground nut cake and molasses were used with corn cob. Three different levels of variable combinations with corn cob were evaluated in response to different parameters of mushroom viz., mycelial growth, spawn running, primordial initiation, fruit body yield and its biological efficiency. Each additive at different combinations showed variable impact on the different stages of mushroom life cycle. The primordial initiation was observed for the first time during 20.2–35.1 days. The biological efficiencies in every supplemented set were increased over un-supplemented control set. Increasing the level of additives, the biological efficiency was negatively affected at higher levels. The cotton seed cake was found the best supplement producing 93.75% biological efficiency while soybean meal was the second best additive producing 93.00% yield. The highest growth rate, rapid mycelia run, early primordial initiation, highest yield and biological efficiency were recorded in the combination of corn cob and cotton seed cake at 2% (98 + 2) level.     

Heavy metal distribution in crab (<Emphasis Type="Italic">Callinectes amnicola</Emphasis>) living on the shores of Ojo Rivers,Lagos, Nigeria

Crab samples, both male and female specie, were purchased from fishermen at the Ojo Rivers, Lagos, Nigeria. The samples separated into abdomen, muscle tissue, and thorax were oven dried at 80°C for 3 days. The dried samples were then pulverized in a clean acid-washed mortar and pestle. Approximately 1.00 g each of the pulverized samples was weighed and Zn, Cr, Pb, and Cd were determined in the solution of the aqua regia digested samples by means of AAS (Buck Scientific 210 GVP model). The results obtained showed Zn metal to be consistently higher in all the female parts compared to the male with values of 12.92 ± 3.65 μg/g to 16.03 ± 1.08 μg/g and 9.33 ± 1.77 μg/g to 15.75 ± 1.02 μg/g, respectively. Mean values of 0.39 ± 0.09 μg/g and 0.22 ± 0.02 μg/g cadmium were found in the abdomen and tissue of the male crab as against 0.35 ± 0.07 μg/g and 0.17 ± 0.07 μg/g in the female crab. The tissues of both species have comparable value of chromium. Lead was below the detection limit of 0.05 μg/g in the tissues of male crab but the female tissue contained 0.83 ± 0.13 μg/g and in other parts identified, lead was consistently higher than the 2.00 μg/g permissible level of WHO in foods. A simple pair t-test did not demonstrate any significant difference in the distribution of metals between the male and female crabs. The coefficient of variation (CV) calculated for each metal with respect to the studied parts showed Pb to be widely distributed (56.23–89.54%) while Cr did not vary widely (4.17–8.20%).     

Petroleum hydrocarbons and limiting nutrients in <Emphasis Type="Italic">Macura reptantia</Emphasis>, <Emphasis Type="Italic">Procambarus clarkii</Emphasis> and benthic sediment from Qua Iboe Estuary,Nigeria

The levels of total petroleum hydrocarbons in two commonly consumed benthopelagic shellfishes, Macura reptantia and Procambarus clarkii, harvested from benthic sediment of Qua Iboe Estuary were determined using a gas chromatography with flame-ionization detector. Seventy-two (72) samples each of benthic sediment and the shellfishes were collected monthly between June 2003 and February 2004 covering the peak periods of the wet and dry seasons. Concentrations of hydrocarbons were highly variable and ranged between 5.00 and 232.00 μg/g dry weight of benthic sediment, 3.05 and 11.30 μg/g dry weight of M. reptantia, 1.62 and 9.00 μg/g dry weight of P. clarkii. Pearson’s correlation analysis of total hydrocarbon concentrations in subtidal sediments with levels in the fauna species yielded positive significant (P < 0.05) correlations in M. reptantia (r = 0.737) and P. clarkii (r = 0.924). This is indicative of a long term and chronic accumulation of hydrocarbons in the estuarine ecosystem, reflecting the potential for exposure of the resident biota and the risk to human health.     

Abundance of Jackfruit (<Emphasis Type="Italic">Artocarpus heterophyllus</Emphasis>) Affects Group Characteristics and Use of Space by Golden-Headed Lion Tamarins (<Emphasis Type="Italic">Leontopithecus chrysomelas</Emphasis>) in <Emphasis Type="Italic">Cabruca</Emphasis> Agroforest

Cabruca is an agroforest of cacao trees shaded by native forest trees. It is the predominant vegetation type throughout eastern part of the range of the golden-headed lion tamarins, Leontopithecus chrysomelas, an endangered primate endemic to Atlantic Forest. Understanding how lion tamarins use this agroforest is a conservation priority. To address this question, we documented the diet, home range size, group sizes and composition, density, number of litters and body condition of lion tamarins living in cabruca, and other habitats. Jackfruit, Artocarpus heterophyllus, was the most used species used by lion tamarins in cabruca and was widely available and used throughout the year. In cabruca, home range size was the smallest (22–28 ha) and density of lion tamarins was the highest (1.7 ind/ha) reported for the species. Group size averaged 7.4 individuals and was not significantly different among the vegetation types. In cabruca, groups produced one or two litters a year, and all litters were twins. Adult males in cabruca were significantly heavier than males in primary forest. Our study is the first to demonstrate that breeding groups of golden-headed lion tamarins can survive and reproduce entirely within cabruca agroforest. Jackfruit proved to be a keystone resource for lion tamarins in cabruca, and bromeliads were important as an animal prey foraging microhabitat. In cases where cabruca contains concentrated resources, such as jackfruit and bromeliads, lion tamarins may not only survive and reproduce but may fare better than in other forest types, at least for body condition and reproduction.     

Phytoremediation of heavy metals by <Emphasis Type="Italic">Eichhornia crassipes</Emphasis>

Eichhornia crassipes was tested for its ability to bioconcentrate 8 toxic metals (Ag, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) commonly found in wastewater from industries. Young plants of equal size were grown hydroponically and amended with 0, 0.1, 0.3, 0.5, 1.0, 3.0, and 5.0 mM of each heavy metal individually for 21 days. The test plant had the lowest and the highest tolerance indices for Hg and Zn, respectively. A significant (P ≤ .05) reduction in biomass production was observed in metal treated plants compared with the control. All strace elements accumulated to higher concentrations in roots than in shoots. Trace element concentrations in tissues and the bioconcentration factors (BCF) were proportional to the initial concentration of individual metal in the growth medium and the duration of exposure. From a phytoremediation perspective, E. crassipes is a promising plant species for remediation of natural water bodies and/or wastewater polluted with low levels of Zn, Cr, Cu, Cd, Pb, Ag and Ni.     

Development of a sprayable slow-release formulation for the sex pheromone of the Mediterranean Corn Borer, <Emphasis Type="Italic">Sesamia nonagroides</Emphasis>

In the FAIR project “Pheromaize”, CT96-1302, the main objective is to provide European growers with a reliable, cost effective and environmentally friendly technology based on pest mating disruption. The project is mainly focused on Mediterranean Corn Borer (MCB), Sesamia nonagroides, the key pest of maize grown under Mediterranean conditions. TNO has developed a sprayable formulation consisting of a biodegradable matrix in which␣the pheromone is dissolved, together with a UV––stabilizer, an antioxidant, a surfactant and a sticker material. During outdoor exposure experiments release of pheromone was found to be high enough for more than 30 days. This formulation has been tested in large scale field experiments by helicopter spraying on 5 ha maize by field partners in Spain, Greece and France.     

Arsenic uptake and phytotoxicity of T-aman rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.) grown in the As-amended soil of Bangladesh

A pot-culture experiment was conducted in open-field conditions with highly cultivated locally transplanted (T) aman rice (Oryza sativa L.) named BR-22 in arsenic (As)-amended soil (0, 1.0, 5.0, 10.0, 20.0, 30.0, 40.0 and 50.0 mg kg⁻¹ As) of Bangladesh to see the effect of As on the growth, yield and metal uptake of rice. Arsenic was applied to soil in the form of sodium arsenate (Na₂HAsO₄). Arsenic affected the plant height, tiller and panicle numbers, grain and straw yield of T-aman rice significantly (P ≤ 0.05). The grain As uptake of T-aman rice was found to increase with increase of As in soil and a high grain As uptake was observed in the treatments of 30–50 mg kg⁻¹ As-containing soil. These levels exceed the food hygiene concentration limit of 1.0 mg kg⁻¹ As. However, the straw As uptake varied significantly (P ≤ 0.05) from a low concentration of As in soil (5 mg kg⁻¹) and the highest uptake was noticed in 20 mg kg⁻¹ As treatment.     

Effect of spent engine oil on the growth parameters and chlorophyll content of <Emphasis Type="Italic">Corchorus olitorius</Emphasis> Linn

The effect of spent engine oil on the height, leaf number, leaf area, stem girth, chlorophyll, and moisture contents of Corchorus olitorius grown on 0, 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 2.0%, and 3.0% (v/w oil/soil) oil-contaminated soil was investigated. The engine oil at all concentrations delayed the germination of C. olitorius by 2 days (compared to control) and there was a general significant reduction in all the growth parameters in plants grown on contaminated soil compared to control plants. The highest leaf area of 26.8 cm² was found in the control plant and least was found in the 0.6% soil (0.11 cm²) after 3 weeks while no values were recorded on the 0.8–3.0% engine-oil-contaminated soil after 5 weeks of experiment. The highest chlorophyll content was also found in the control plant (11.5 mg/l). This showed that spent engine oil has an adverse effect on the growth of C. olitorius plant.     

Changing effluent chemistry affect survival,growth and physiological function of <Emphasis Type="Italic">Acacia nilotica</Emphasis> seedlings in northwestern region of India

Recycling and conservation efforts for water are the need of the day because of the lack of new water sources and the ever-increasing demand for drinking water. Seedlings of Acacia nilotica L. were irrigated with: canal water (T₁, control); municipal effluent (T₂); textile effluent (T₃); steel effluent (T₄); textile + municipal effluent in 1:1 ratio (T₅); steel + municipal effluent in 1:2 ratio (T₆); steel + textile in 1:2 ratio (T₈) and steel + municipal + textile in 1:2:2 ratio (T₇) with views to observe effluents effect on the seedlings and its adaptability and to recommend safe disposal of these effluents. Seedlings in T₆, T₇ and T₈ showed 50% lesser height and collar diameter than those in control. Seedlings in T₂ attained greatest height, collar diameter, numbers of branches and produced 140 g dry biomass seedling⁻¹. Highest concentration of manganese (Mn), iron (Fe), copper (Cu) and zinc (Zn) and lowest concentration of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg) in the seedlings of T₄, T₆, T₇ and T₈ resulted in nutritional imbalance, mineral toxicity and reduction in photosynthetic (Pn) and transpiration (E) rates and caused seedling mortality. Seedlings of T₃ had highest sodium concentration and low concentration of Ca, Mg and micronutrients resulting in nutritional imbalance, augmented chlorosis and reduced gas exchange and biomass by half as compared to control. Increased growth, Pn and E and biomass in seedlings of T₅ over T₃ and survival period in T₆, T₇ and T₈ seedlings suggested a beneficial effect of effluents mixing. Unscientific disposal should be avoided and toxic concentration of metal ions␣may be reduced for long-term application and harmless disposal of effluents in afforestation and urban development.     

Dynamics of Plains Cottonwood (<Emphasis Type="Italic">Populus deltoides</Emphasis>) Forests and Historical Landscape Change along Unchannelized Segments of the Missouri River,USA

Construction of six large dams and reservoirs on the Missouri River over the last 50–75 years has resulted in major landscape changes and alterations in flow patterns, with implications for riparian forests dominated by plains cottonwood (Populus deltoides). We quantified changes in land cover from 1892–1950s and the 1950s–2006 and the current extent and age structure of cottonwood forests on seven segments (two reservoir and five remnant floodplain) comprising 1127 km (53 %) of the unchannelized upper two-thirds of the Missouri River. Riparian forest area declined by 49 %; grassland 61 %; shrubland 52 %; and sandbar habitat 96 %; while agricultural cropland increased six-fold and river/reservoir surface area doubled from 1892 to 2006. Net rates of erosion and accretion declined between the 1892–1950s and 1950s–2006 periods. Accretion exceeded erosion on remnant floodplain segments, resulting in declines in active channel width, particularly in 1950s–2006. Across all study segments in 2006, most cottonwood stands (67 %) were >50 years old, 22 % were 25–50 years old, and only 10 % were <25 years old. Among stands <50 years old, the higher proportion of 25–50 year old stands represents recruitment that accompanied initial post-dam channel narrowing; while declines in sandbar and shrubland area and the low proportion of stands <25 years old suggest declines in geomorphic dynamism and limited recruitment under recent river management. Future conservation and restoration efforts should focus both on limiting further loss of remnant cottonwood stands and developing approaches to restore river dynamics and cottonwood recruitment processes.     

Morphological and anatomical effects of crude oil on <Emphasis Type="Italic">Pistia stratiotes</Emphasis>

Fresh whole plants of Pistia stratiotes were exposed to varying doses of crude oil (0–100 ppm) for 28 days at normal temperature of 30 ± 2°C. Samples were taken weekly during this period for determination of changes in leaf area, root length, number of leaves, and number of sprouts. The cross-section of one terminal end of the major roots and cellular distribution of the meristematic region were also examined. The results show that crude oil was toxic to the plant at all concentrations in all investigated parameters for as low as 10 ppm. Association was also observed between crude oil toxicity and certain metals inherent in the crude oil such as manganese and lead. Cell shape disruptions, changes in mitotic indices, and the distortion of cellular anatomy and structure at the apical region also characterized the presence of crude oil in the environment of P. stratiotes. P. stratiotes may not be a good bio-accumulator of crude oil but may be used for the detection of pollution.     

Physiological and Morphological Response Patterns of <Emphasis Type="Italic">Populus deltoides</Emphasis> to Alluvial Groundwater Pumping

We examined the physiological and morphological response patterns of plains cottonwood [Populus deltoides subsp. monilifera (Aiton) Eck.] to acute water stress imposed by groundwater pumping. Between 3 and 27 July 1996, four large pumps were used to withdraw alluvial groundwater from a cottonwood forest along the South Platte River, near Denver, Colorado, USA. The study was designed as a stand-level, split-plot experiment with factorial treatments including two soil types (a gravel soil and a loam topsoil over gravel), two water table drawdown depths (∼0.5 m and >1.0 m), and one water table control (no drawdown) per soil type. Measurements of water table depth, soil water potential (Ψ_s), predawn and midday shoot water potential (Ψ_pd and Ψ_md), and D/H (deuterium/hydrogen) ratios of different water sources were made in each of six 600-m² plots prior to, during, and immediately following pumping. Two additional plots were established and measured to examine the extent to which surface irrigation could be used to mitigate the effects of deep drawdown on P. deltoides for each soil type. Recovery of tree water status following pumping was evaluated by measuring stomatal conductance (g _s ) and xylem water potential (Ψ_xp) on approximately hourly time steps from before dawn to mid-afternoon on 11 August 1996 in watered and unwatered, deep-drawdown plots on gravel soils. P. deltoides responded to abrupt alluvial water table decline with decreased shoot water potential followed by leaf mortality. Ψ_pd and percent leaf loss were significantly related to the magnitude of water table declines. The onset and course of these responses were influenced by short-term variability in surface and ground water levels, acting in concert with physiological and morphological adjustments. Decreases in Ψ_pd corresponded with increases in Ψ_md, suggesting shoot water status improved in response to stomatal closure and crown dieback. Crown dieback caused by xylem cavitation likely occurred when Ψ_pd reached −0.4 to −0.8 MPa. The application of surface irrigation allowed trees to maintain favorable water status with little or no apparent cavitation, even in deep-drawdown plots. Two weeks after the partial canopy dieback and cessation of pumping, g _s and Ψ_xp measurements indicated that water stress persisted in unwatered P. deltoides in deep-drawdown plots.     

Alteration in Rhizosphere Soil Properties of Afforested <Emphasis Type="Italic">Rhamnus lycioides</Emphasis> Seedlings in Short-Term Response to Mycorrhizal Inoculation with <Emphasis Type="Italic">Glomus intraradices</Emphasis> and Organic Amendment

The reestablisment of autochthonous plant species is an essential strategy for recovering degraded areas under semiarid conditions. A field experiment was carried out to assess the short-term effect of two reafforestation methods involving mycorrhizal inoculation and compost addition on soil quality parameters and Rhamnus lycioides seedling growth. The nutrient content (NPK) and enzymatic activities (dehydrogenase, urease, protease-BAA, acid phosphatase and β-glucosidase) increased and bulk density decreased in the rhizosphere soil with the organic amendment. Biomass C of rhizosphere soil increased by at least 240% with respect to the control soil after mycorrhizal inoculation and the combination of compost addition + mycorrhizal inoculation. Both mycorrhizal inoculation and composted organic residue addition increased R. lycioides seedling growth in the same proportion. In the short term, we conclude that the application of both reafforestation methods not only enhances the establishment of R. lycioides seedlings, but also improves soil quality.     

Effect of stocking density and food quality on the growth and fecundity of an epigeic earthworm (<Emphasis Type="Italic">Eisenia fetida</Emphasis>) during vermicomposting

Physico-chemical characteristics of the feed and optimum worm density are important parameters for the efficient working of a vermicomposting system. Overcrowding of worms can affect the efficiency of a vermicomposting system even if all other parameters have been optimized. This article reports the effect of stocking density and feed quality on the growth and fecundity of Eisenia fetida under laboratory conditions. The feed mixtures contained cow dung and textile mill wastewater sludge in different ratios. Three feed mixtures and five stocking rates (1, 2, 4, 8, and 12) were tested for 12 weeks. The results showed that E. fetida growth rate was faster at higher stocking densities; however, biomass gain per worm was faster at lower stocking densities. Sexual maturity was attained earlier at higher stocking densities. Growth rate was highest in 100% cow dung at all the stocking densities when compared to textile mill wastewater sludge containing feed mixtures. A worm population of 27–53 worms per kg of feed was found to be the most favorable stocking density.     

Accretion of heavy metals in the catfish <Emphasis Type="Italic">Bagrus bayad</Emphasis> from Taylor Creek,southern Nigeria

Heavy metals in the aquatic environment have, to date, come essentially from naturally occurring geochemical resources. However, this has been enhanced by anthropogenic activities such as crude oil exploration and exploitation activities, resulting in pollution in the Taylor Creek aquatic ecosystem. The catfish species Bagrus bayad and other environmental segments were collected from five selected sites along Taylor Creek, southern Nigeria, and total metal concentration determined. The concentration levels of the metals in B. bayad were higher than the values reported in the literature for fresh fish and may lead to a higher risk of harmful effects. The bivariate regression models relating metals in B. bayad and metals in the surface waters were significant (R ² ≥ 0.9002). The log (bio-concentration factor; BCF) values of Cr and Zn in B. bayad were the highest, whereas the lowest was found for Ni. The ecological distribution of the log (BCF) values was, for all the heavy metals, moderately stable over the creek. All log-transformed bio-magnification factors (BMF) in the creek were positive, which indicates that the metal concentration was greater in B. bayad than in suspended particulate matter (SPM). The absolute log (BMF) values of heavy metals can, therefore, be ranked in order of decreasing magnitude: Cr (3.26) > Zn (2.99) > Cd (2.93) > Fe (2.76) > Pb (2.66) > Mn (2.36) > Ni (2.24). This sequence indicates that toxic metals such as Cd, Cr and Pb are undergoing significant bio-reduction from SPM to B. bayad. The degree of correlation between the metals was different in B. bayad, which suggests that the sources of the metals polluting Taylor Creek were diverse.