Whole-lake dissolved inorganic 13C additions reveal seasonal shifts in zooplankton diet

Sustained whole-lake additions of 13C-enriched dissolved inorganic carbon (DIC), intended to increase experimentally the delta13C of DIC in the epilimnion of a small lake with high dissolved organic carbon (DOC), were made during three seasonal periods (spring, summer, and autumn). Coupled with carbon and nitrogen stable isotope analysis of zooplankton and several of their putative food sources, these additions were used to investigate seasonal changes in the relative contributions of different food sources to zooplankton diet in the lake. Four main potential food sources were considered: phytoplankton, heterotrophic bacteria (HB), methanotrophic bacteria (MOB), and green sulfur bacteria (GSB). Because the number of potential food sources exceeded the number of isotopes analyzed, a computer program (IsoSource) was used to estimate the range of possible contributions of the various food sources. During all three periods the added inorganic 13C quickly increased the epilimnetic DIC delta13C by between 18 per thousand and 21 per thousand above the initial value of approximately -21 per thousand. This 13C enrichment of DIC was rapidly transmitted to the particulate organic matter (POM), which included photosynthetic phytoplankton. In spring and summer, delta13C of both adult and juvenile Daphnia increased by approximately 10 per thousand, indicating that Daphnia utilized autochthonous carbon. However, this 13C labeling of Daphnia was not so obvious during the autumn period, when their delta13C generally decreased. According to the IsoSource model outputs based on both delta13C and delta15N values, Daphnia utilized all four potential food source types during spring, summer, and autumn, but in different proportions. The possible contribution of phytoplankton to Daphnia diet was substantial (25-71%) in all seasons. The possible contributions of the bacterial food sources were more variable. The possible contribution of GSB was minor (0-20%) at all times and negligible in autumn. The possible contribution of HB was higher but very variable. Methanotrophic bacteria always made a significant contribution to Daphnia diet and were likely the single most important food source in autumn. Since both HB and MOB in this high-DOC lake probably depend largely on allochthonous organic carbon, our results highlight the seasonal variability in the potential importance of ecosystem subsidies in lake food webs.     

Trait-mediated effects on flowers: artificial spiders deceive pollinators and decrease plant fitness

Although predators can affect foraging behaviors of floral visitors, rarely is it known if these top-down effects of predators may cascade to plant fitness through trait-mediated interactions. In this study we manipulated artificial crab spiders on flowers of Rubus rosifolius to test the effects of predation risk on flower-visiting insects and strength of trait-mediated indirect effects to plant fitness. In addition, we tested which predator traits (e.g., forelimbs, abdomen) are recognized and avoided by pollinators. Total visitation rate was higher for control flowers than for flowers with an artificial crab spider. In addition, flowers with a sphere (simulating a spider abdomen) were more frequently visited than those with forelimbs or the entire spider model. Furthermore, the presence of artificial spiders decreased individual seed set by 42% and fruit biomass by 50%. Our findings indicate that pollinators, mostly bees, recognize and avoid flowers with predation risk; forelimbs seem to be the predator trait recognized and avoided by hymenopterans. Additionally, predator avoidance by pollinators resulted in pollen limitation, thereby affecting some components of plant fitness (fruit biomass and seed number). Because most pollinator species that recognized predation risk visited many other plant species, trait-mediated indirect effects of spiders cascading down to plant fitness may be a common phenomenon in the Atlantic rainforest ecosystem.     

Interaction between sorption and biodegradation processes in the contaminant transport

The main goal of this work is to examine in detail the equilibrium and non-equilibrium sorption in a multiple species contaminant transport system undergoing multiplicative Monod biodegradation kinetics, which characterizes a scenario of subsurface contamination by organic contaminants. Mathematically, the problem is given by a nonlinear advection-diffusion-reaction partial differential system coupled by the reaction terms, associated with the biodegradation process. A new operator splitting approach is proposed for treating in a sequential fashion the convective-diffusive and reactive terms. A predictor-multicorrector algorithm with Newton–Raphson and stabilized finite element (streamline-upwind Petrov-Galerkin, SUPG) methods is used in the time and spatial discretizations, respectively. Numerical results illustrate the good applicability of the present approach, corroborating the well-known observation nonlinear physical and biological processes should be inserted in the model that to better predict the contamination scenarios.     

A finite element method to solve a population dynamics stage-structured model of intertidal barnacles

Many marine organisms are fixed or highly sedentary as adults but the adult population may be strongly dependent on the oceanic transport of planktonic larvae. In order to assess interactions between oceanographic and biological processes that determine the population dynamics of marine organisms with a sessile adult phase restricted to the coastline and a planktonic larval phase, we present a stage-structured finite element model for the barnacle Balanus glandula that inhabits the rocky intertidal zone of central California, USA.     

Nanogreen is the new future: the conversion of lignin and lignocellulosic wastes into nanomaterials

Environmental Science and Pollution Research - The lignocellulose biorefinery industry has assumed an important role within the current scenario. Lignin is an abundant and available biopolymer and...     

Antecedents and consequences of collective psychological ownership: The validation of a conceptual model

We investigate team member feelings of collective psychological ownership (CPO) over teamwork products, the psychological paths that lead to it, and its impact on team workers' evaluations of team effectiveness, turnover intentions, and intentions to champion teamwork products. We focus on the teamwork product as an important target of ownership feelings, building on theories of self-extension, psychological ownership, and team emergent states. In Study 1, we validate measures for three ownership activating experiences (OAE) that have been proposed as paths to CPO (control over, intimate knowledge regarding, and investment in the teamwork product) using two samples of individual team workers (n = 210 and n = 140). In Study 2 (n = 183) and Study 3 (n = 200), we use surveys and a multiwave design to show that team workers' feelings of CPO mediate the relationship between investment in and intimate knowledge regarding the product and team effectiveness evaluations, team turnover intentions, and intentions to champion the work product. In Study 4 (n = 48 teams), CPO was predicted by the ownership activating experiences, at the team level. This research additionally highlights the benefits to organizations of creating conditions for the emergence of employee feelings of shared ownership over teamwork products.     

Remediation potential of caffeine,oxybenzone, and triclosan by the salt marsh plants <Emphasis Type="Italic">Spartina maritima</Emphasis> and <Emphasis Type="Italic">Halimione portulacoides</Emphasis>

Pharmaceuticals and personal care products (PPCPs) have attracted increasing concern during the last decade because of their widespread uses and continuous release to the aquatic environment. This work aimed to study the distribution of caffeine (CAF), oxybenzone (MBPh), and triclosan (TCS) when they arrive in salt marsh areas and to assess their remediation potential by two different species of salt marsh plants: Spartina maritima and Halimione portulacoides. Experiments were carried out in the laboratory either in hydroponics (sediment elutriate) or in sediment soaked in elutriate, for 10 days. Controls without plants were also carried out. CAF, MBPh, and TCS were added to the media. In unvegetated sediment soaked in elutriate, CAF was mainly in the liquid phase (83%), whereas MBPh and TCS were in the solid phase (90% and 56%, respectively); the highest remediation was achieved for TCS (40%) and mainly attributed to bioremediation. The presence of plants in sediment soaked in elutriate-enhanced PPCPs remediation, decreasing CAF and TCS levels between approximately 20-30% and MBPh by 40%.. Plant uptake, adsorption to plant roots/sediments, and bio/rhizoremediation are strong hypothesis to explain the decrease of contaminants either in water or sediment fractions, according to PPCPs characteristics.     

Synthesis of Polymeric Matrices for Adsorption and Purification of Endoglucanase

Chitosan (CHS), chitosan–Eudragit® EPO (CHS–EPO) and chitosan beads partially cross-linked with glutaraldehyde (CHS–GLUT) were obtained in order to improve the adsorption selectivity of endoglucanase from a fungal culture obtained under SSF by Aspergillus niger using soybean harvest residues as support. The matrices synthetized were characterized in terms of physical and chemical changes. Fourier-transformed infrared spectroscopy with attenuated total reflectance device (FTIR-ATR) was employed to verify the chemical changes on the CHS matrix after the synthesis of CHS–GLUT and CHS–EPO. Scanning electron microscopy (SEM) was performed to compare the surface morphology of the polymeric beads. Two variables, purification factor and yield percentage of the adsorption process, were analyzed using a bifactorial ANOVA considering the matrix–time first order interaction. SEM results exhibited greater surface roughness in the CHS–GLUT and CHS–EPO matrices which may enhance endoglucanase adsorption. FTIR-ATR results confirmed an effective chemical modification of the CHS matrix after crosslinking with GLUT and corroborated the efficiency of the synthesis of the CHS–EPO matrix by the presence of chemical groups of the EPO polymer. An endoglucanase purification factor close to 9 was achieved with the CHS–GLUT matrix and a yield percentage of 60% was obtained with the CHS–EPO matrix. Bifactorial ANOVA results showed the matrix–time interaction to be significant for both variables. The CHS–GLUT matrix with low crosslinking times and the novel CHS–EPO matrix could be included in the bioseparation stage of endoglucanase using a simple and a low-cost method such as batch adsorption.     

Climate change impact on the potential yield of Arabica coffee in southeast Brazil

Regional Environmental Change - The Intergovernmental Panel on Climate Change (IPCC) projections of global mean temperature rises are worrisome for coffee crop due to the intolerance of the Arabica...     

Removal of a red dye using noncommercial peroxidase extracted from rice bran

The present study investigates the application of a noncommercial peroxidase enzyme, which was extracted from rice bran, to decolorize wastewater that was simulating effluent from a textile manufacturer using a red dye in its coloration process.