Undesirable Ecological Consequences Research Articles

Remediation of imidacloprid and carbamazepine in polluted soil using TiO2 with LED lamps

Imidacloprid and carbamazepine are recognised as emerging contaminants (ECs) due to their ubiquitous presence in environmental compartments and their potential to cause undesirable ecological effects. Wastewater treatment plants are relevant routes for these compounds to enter environment since they are continuously released through treated wastewater. The progressively more extended custom of reusing treated wastewater for agricultural irrigation has also enlarged the risks for ECs accumulation in soil and their translocation to crops, posing a constant threat to both humans and wildlife. This work is aimed to study the behaviour of imidacloprid and carbamazepine and its main transformation products generated in soil during photocatalytic treatments using commercial TiO2 (Degussa P25) and ultraviolet light emitting diode (UV-LED) lamps as light source. Prior to remediation trial, the influence of catalyst load and soil moisture content in ECs degradation was studied. Experiments were performed using a photochemical reactor equipped with LED lamps running at 365 nm, exposing polluted soils to different treatments in presence and absence of photocatalyst. A significant degradation (93.4 and 96.2% for imidacloprid and carbamazepine, respectively) was observed after 4 days of photocatalytic treatment. The main transformation products were identified during the different treatments. Our results suggest that TiO2-photocatalytic treatment combined with UV-LED could be considered a promising technology to remove ECs from soils.

Insights of smallholder farmers on the trade-offs of eucalyptus plantation

Eucalyptus is a popular evergreen perennial tree that grows quickly. Due to its diverse economic value and wide range of adaptations, the eucalyptus is commonly grown in tropical and subtropical regions. Eucalyptus is an economically important tree. However, the economic importance of eucalyptus ensued at the expense of undesirable ecological consequences. This qualitative study reports the advantages and disadvantages of eucalyptus woodlot establishment on the productivity of arable and grazing lands. In this study, nine knowledgeable farmers were involved in an in-depth individual interview and four focus group discussions were conducted. Farmers have frequently reported the negative impact of eucalyptus plantations on the productivity of the agricultural system. Eucalyptus serves as a refuge for crop pests and pathogens such as aphids and rust. Besides, the shade suppresses the development of the understory and adjacent crops, pastures, fodder, and other species of native trees and shrubs if they are planted together. Eucalyptus has increasingly replaced eco-friendly native trees and shrubs traditionally used as hedges, windbreaks, fodder, shelters for domestic and wild animals, and enhancers of soil fertility. Besides deteriorating soil fertility, structure, and moisture, it drains wetlands, springs, and streams and reduces the flow of rivers. Nevertheless, farmers acknowledged the importance of eucalyptus as a construction material, a source of fuelwood and charcoal, and income. To make the best use of eucalyptus woodlots without imposing adverse effects on agroecology, farmers have suggested that plantation sites should be marginally suitable for crop and livestock production. The expanded plantation needs to be contracted by removing a significant proportion of the established eucalyptus woodlots. Plantations of eucalyptus around watering points should be discouraged. Fast-growing, resilient, and eco-friendly tree species, such as those from Grevillea and Populus species, and sibling (leguminous) trees and shrubs delivering comparable products and services should be sought after to replace the significant proportion of the established eucalyptus woodlot.

Ecotoxicological Evaluation of Methiocarb Electrochemical Oxidation

The ecotoxicity of methiocarb aqueous solutions treated by electrochemical oxidation was evaluated utilizing the model organism Daphnia magna. The electrodegradation experiments were performed using a boron-doped diamond anode and the influence of the applied current density and the supporting electrolyte (NaCl or Na2SO4) on methiocarb degradation and toxicity reduction were assessed. Electrooxidation treatment presented a remarkable efficiency in methiocarb complete degradation and a high potential for reducing the undesirable ecological effects of this priority substance. The reaction rate followed first-order kinetics in both electrolytes, being more favorable in a chloride medium. In fact, the presence of chloride increased the methiocarb removal rate and toxicity reduction and favored nitrogen removal. A 200× reduction in the acute toxicity towards D. magna, from 370.9 to 1.6 toxic units, was observed for the solutions prepared with NaCl after 5 h treatment at 100 A m−2. An increase in the applied current density led to an increase in toxicity towards D. magna of the treated solutions. At optimized experimental conditions, electrooxidation offers a suitable solution for the treatment and elimination of undesirable ecological effects of methiocarb contaminated industrial or agricultural wastewaters, ensuring that this highly hazardous pesticide is not transferred to the aquatic environment.

Sedimentary ancient DNA metabarcoding delineates the contrastingly temporal change of lake cyanobacterial communities

Harmful cyanobacterial blooms consisting of toxic taxa can produce a wide variety of toxins to threaten water quality, ecosystem functions and services. Of greater concern was the changing patterns of cyanobacterial assemblage were not well understood due to the lack of long-term monitoring data over the temporal scale. Biodiversity change in cyanobacterial community and paleoenvironmental variables over the past 170 years in Lake Chenghai were investigated based on sedimentary ancient DNA metabarcoding and traditional paleolimnological analysis. The results showed species richness and homogenization of cyanobacterial assemblage increased in the most recent decades, which were synchronized with the growth of artificial fertilization and decline in precipitation. Cyanobacterial co-occurrence network analysis revealed more complex interactions and weak community stability after the change point of ∼1987, while the rare cyanobacterial genera such as Anabaena, Planktothrix, Oscillatoria and Microcystis were identified to be keystone taxa affecting cyanobacterial assemblage. Furthermore, an increase of toxin-producing cyanobacterial taxa was significantly and positively associated with TN and TP, as well as TN/IP and TN/TP, which was verified by quantitative real-time PCR of mcyA and rpoC1 genes. Threshold in total nitrogen (TN) concentration should be targeted no more than 0.60 mg/L to alleviate nuisance cyanobacterial blooms in Lake Chenghai. These findings reinforce the comprehensive understanding for the long-term dynamics of cyanobacterial assemblage responding to environmental change, which could contribute to proactively regulate environmental conditions for avoiding undesirable ecological consequences.

Assessment of the Performance of Osmotically Driven Polymeric Membrane Processes

The universal water scarceness and the extensive ordeals with energy cost in conjunction with the undesirable ecological effects have advanced the improvement of novel osmotically driven membrane processes. Membrane processes which are osmotically driven are developing type of membrane separation procedures that apply concentrated brines to separate liquid streams. They are adaptable in various applications; hence, allow them to be an attractive substitute for drug release, wastewater treatment and the production and recovery of energy. Although, internal concentration polarization (ICP) occurs in membrane practises which are osmotically driven as a consequence of hindered diffusion of solute in a porous stratum, their interest has even increased. Here we review two natural membrane processes that are osmotically driven; Forward osmosis (FO) and Pressure retarded osmosis (PRO). Thus, the major points are as follows: 1) it was highlighted in this review, that the major developments in FO process, important for the process efficiency is to choose a suitable membrane and draw solution. 2) The recent evaluation, understanding and optimizing the activities of fouling throughout the osmotic dilution of seawater employing FO was discussed. 3) Recent advancements of FO in the application of food processing was reviewed. 4) It was highlighted that the main concept of PRO for power generation is the energy of mixing that offers great assessment of the non-expansion work which could be generated from mixing; nonetheless, the development of effective membranes with appropriate arrangement and performance is needed for the advancement of PRO process for power generation. 5) One major challenge of osmotically driven membrane processes, most recent developments and model development to predict their performances were discussed.

Neonicotinoids in excretion product of phloem-feeding insects kill beneficial insects.

Pest control in agriculture is mainly based on the application of insecticides, which may impact nontarget beneficial organisms leading to undesirable ecological effects. Neonicotinoids are among the most widely used insecticides. However, they have important negative side effects, especially for pollinators and other beneficial insects feeding on nectar. Here, we identify a more accessible exposure route: Neonicotinoids reach and kill beneficial insects that feed on the most abundant carbohydrate source for insects in agroecosystems, honeydew. Honeydew is the excretion product of phloem-feeding hemipteran insects such as aphids, mealybugs, whiteflies, and psyllids. We allowed parasitic wasps and pollinating hoverflies to feed on honeydew from hemipterans feeding on trees treated with thiamethoxam or imidacloprid, the most commonly used neonicotinoids. LC-MS/MS analyses demonstrated that both neonicotinoids were present in honeydew. Honeydew with thiamethoxam was highly toxic to both species of beneficial insects, and honeydew with imidacloprid was moderately toxic to hoverflies. Collectively, our data provide strong evidence for honeydew as a route of insecticide exposure that may cause acute or chronic deleterious effects on nontarget organisms. This route should be considered in future environmental risk assessments of neonicotinoid applications.

Optimisation of <i>Bacillus thuringiensis</i> var. <i>israelensis</i> (Vectobac<sup>®</sup>) applications for the blackfly control programme on the Orange River, South Africa

The Orange River, South Africa's largest river, is a critical water resource for the country. In spite of the clear economic benefits of regulating river flows through a series of impoundments, one of the significant undesirable ecological consequences of this regulation has been the regular outbreaks of the pest blackfly species Simulium chutteri and S. damnosum s.l. (Diptera: Simuliidae). The current control programme, carried out by the South African National Department of Agriculture, uses regular applications, by helicopter, of the target-specific bacterial larvicide Bacillus thuringiensis var. israelensis. While cost-benefit analyses show significant benefits to the control programme, benefits could potentially be further increased through applying smaller volumes of larvicide in an optimised manner, which incorporates upstream residual amounts of pesticide through downstream carry. Using an optimisation technique applied in the West African Onchocerciasis Control Programme, to a 136 km stretch of the Orange River which includes 31 blackfly breeding sites, we demonstrate that 28.5% less larvicide could be used to potentially achieve the same control of blackfly. This translates into potential annual savings of between R540 000 and R1 800 000. A comparison of larvicide volumes estimated using traditional vs. optimised approaches at different discharges, illustrates that the savings on optimisation decline linearly with increasing flow volumes. Larvicide applications at the lowest discharge considered (40 m3·s-1) showed the greatest benefits from optimisations, with benefits remaining but decreasing to a theoretical 30% up to median flows of 100 m3·s-1. Given that almost 70% of flows in July are less than 100 m3·s-1, we suggest that an optimised approach is appropriate for the Orange River Blackfly Control Programme, particularly for flow volumes of less than 100 m3·s-1. We recommend that trials be undertaken over two reaches of the Orange River, one using the traditional approach, and another using the optimised approach, to test the efficacy of using optimised volumes of B.t.i.

On the Problem of Gypsum Deposition in the Dead Sea in the Case of Two Seas Canal Construction

The Dead Sea is a terminal lake, being the lowest and one of the most saline lakes on earth. For more than last fifty years the water level of the Dead Sea drastically decreased resulting in a drop of more than 30 m since beginning of sixties of the last century. The present level and size of the Dead Sea and its development are determined by a negative water balance between precipitation, runoff and evaporation. One of the possible ways to stop reducing the surface level of the Dead See and even to reverse this process, it is to supply seawater by connecting the Dead Sea with a world ocean system. The first and the most suitable choice discussed from the seventies of the last century was a canal connecting the Dead Sea with the Mediterranean Sea. However, due to geopolitical situation in this region the project of Dead Sea - Mediterranean Sea canal was abandoned, and another two seas canal variant has been studying for the last several decades, namely a canal between the Dead Sea and the Rea Sea via the Gulf of Eilat/Aqaba. The problems attracting the wide public attention for this canal construction are the ecological effects of mixing the waters of the Dead Sea and seawater from the Red Sea if the canal between these two seas will be built. There are some fears that under certain conditions, a layer of gypsum crystals floating on the Dead Sea surface will be formed causing some undesirable ecological effects in local environment. In the present article the rates of the deposition of gypsum crystals in the mixtures of the Dead Sea water with seawater were estimated by using the experimental viscosity and density values of these waters mixtures. The results of these calculations allowed us to assume that there is no danger that gypsum crystals, which can be formed under certain conditions during mixing of Dead Sea and seawater, will float on the Dead Sea water surface forever and after a relatively short period of time, depending on the dimensions of the crystals, gypsum crystals will sink to the bottom.

Studies on the metabolism and degradation of vancomycin in simulated in vitro and aquatic environment by UHPLC-Triple-TOF-MS/MS

Vancomycin is one of the most commonly used glycopeptide antiobiotics, and as such is an important emerging environmental contaminant. Pharmaceuticals and personal care products (PPCPs), such as antibiotics, are problematic since wastewater treatment processes are not completely effective at removing these chemical compounds. Since wastewater treatment processes are not completely effective, vancomycin occurs in surface water. Vancomycin and its metabolites in vivo and degradation products in aquatic environment may lead to undesirable ecological effects that threaten the environment or cause undesirable reactions that affect human health. We aimed to study vancomycin metabolism in vitro and its natural degradation in aquatic environment, as well as explore for related metabolites and degradation products. Accordingly, we established four systems, using a constant temperature oscillator at 37 °C for 10 days for vancomycin in activated rat liver microsomes (experimental system), inactivated rat liver microsomes (control system), phosphate buffer saline (PBS system) and pure water (pure water system), as well as an additional system of activated rat liver microsomes without vancomycin (blank system). The metabolism and degradation of vancomycin were studied using a high resolution and high sensitivity ultra-high performance liquid chromatography (UHPLC)-Triple-time of flight (TOF)-mass spectrometry (MS) method in positive ion mode. The compared result of activated rat liver microsomes system and inactivated rat liver microsomes system confirms that vancomycin is not metabolized in the liver. Vancomycin was degraded in the four non-blank incubation systems. The MetabolitePilot 2.0 software was used for screening the probable degradation products, as well as for establishing its associated degradation pathways. Eventually, four degradation products were identified and their chemical structures were deduced. The results of this study provide a foundation for evaluation of the effects of vancomycin and its degradation products on environmental safety and human health in the future.

Antibiotics in Crab Ponds of Lake Guchenghu Basin, China: Occurrence, Temporal Variations, and Ecological Risks

Antibiotics are widely used in aquaculture, however, this often results in undesirable ecological effects. To evaluate the occurrence, temporal variations, and ecological risk of antibiotics in five crab ponds of Lake Guchenghu Basin, China, 44 antibiotics from nine classes were analyzed by rapid resolution liquid chromatography-tandem mass spectrometry (RRLC-MS/MS). Twelve antibiotics belonging to six classes were detected in the aqueous phase of five crab ponds, among which sulfonamides and macrolides were the predominant classes, and six compounds (sulfamonomethoxine, sulfadiazine, trimethoprim, erythromycin-H2O, monensin, and florfenicol) were frequently detected at high concentrations. In general, the antibiotic levels varied between different crab ponds, with the average concentrations ranging from 122 to 1440 ng/L. The antibiotic concentrations in crab ponds exhibited obvious seasonal variations, with the highest concentration and detection frequency detected in summer. Multivariate analysis showed that antibiotic concentrations were significantly correlated with environmental variables, such as total organic carbon, phosphate, ammonia nitrogen, and pH. Sulfadiazine, clarithromycin, erythromycin-H2O, and ciprofloxacin posed a high risk to algae, while the mixture of antibiotics could pose a high risk to aquatic organisms in the crab ponds. Overall, the usage of antibiotics in farming ponds should be comprehensively investigated and controlled to preserve a healthy aquaculture ecosystem.

Assessment of Hydrologic Alterations in Elbe and Rhine Rivers, Germany

In light of recent anthropogenic-induced climate change, a burning question at present is how these changes influence the water regime of rivers, which are of vital importance for humans as well as for biota. In this study, we investigate the changes in the hydrologic regime of two major German rivers, Elbe and Rhine, after the middle of the 20th century. Here, we use the widely adopted Range of Variability Approach (RVA) method on daily streamflow data from five (Elbe) and seven (Rhine) hydrological stations to determine the variability and spatial pattern of hydrologic alterations. We discuss the potential effect of climate change on the water regime of these two rivers, as well as other potential causes. For both rivers, we find that some hydrologic parameters are highly altered, especially the number of reversals, indicating higher variability. The highest impact is found at Ems hydrological station on Rhine River. The order of affected hydrological stations follows mostly the downstream course of both rivers. Our study indicates that the hydrological behavior of Elbe and Rhine Rivers has altered since the middle of the 20th century, a probable consequence of climate change. These hydrologic alterations can lead to undesirable ecological effects on local biota.

Functional nonredundancy of elephants in a disturbed tropical forest

Conservation efforts are often motivated by the threat of global extinction. Yet if conservationists had more information suggesting that extirpation of individual species could lead to undesirable ecological effects, they might more frequently attempt to protect or restore such species across their ranges even if they were not globally endangered. Scientists have seldom measured or quantitatively predicted the functional consequences of species loss, even for large, extinction-prone species that theory suggests should be functionally unique. We measured the contribution of Asian elephants (Elephas maximus) to the dispersal of 3 large-fruited species in a disturbed tropical moist forest and predicted the extent to which alternative dispersers could compensate for elephants in their absence. We created an empirical probability model with data on frugivory and seed dispersal from Buxa Tiger Reserve, India. These data were used to estimate the proportion of seeds consumed by elephants and other frugivores that survive handling and density-dependent processes (Janzen-Connell effects and conspecific intradung competition) and germinate. Without compensation, the number of seeds dispersed and surviving density-dependent effects decreased 26% (Artocarpus chaplasha), 42% (Careya arborea), and 72% (Dillenia indica) when elephants were absent from the ecosystem. Compensatory fruit removal by other animals substantially ameliorated these losses. For instance, reductions in successful dispersal of D. indica were as low as 23% when gaur (Bos gaurus) persisted, but median dispersal distance still declined from 30% (C. arborea) to 90% (A. chaplasha) without elephants. Our results support the theory that the largest animal species in an ecosystem have nonredundant ecological functionality and that their extirpation is likely to lead to the deterioration of ecosystem processes such as seed dispersal. This effect is likely accentuated by the overall defaunation of many tropical systems.

Effects of TiO2 nanoparticles and sunscreens on coastal marine microalgae: Ultraviolet radiation is key variable for toxicity assessment

Given the large numbers of sunbathers on beaches, sunscreen compounds are being released into the coastal aquatic environment in significant amounts. Until now the effect of these potential pollutants on microbiota has been not well-known. Phytoplankton is a key component of the microbiota community. It forms the basis of the aquatic trophic networks, and any change in the natural population of phytoplankton can affect the structure of aquatic biota. This paper describes an experiment performed outdoors (in natural sunlight conditions including ultraviolet radiation (UVR) and with UVR blocked) on mixed microalgae populations (four species from different key marine taxonomic groups, Nannochloropsis gaditana, Chaetoceros gracilis, Pleurochrysis roscoffensis and Amphidinium carterae), for three days, exposed to a range of concentrations of three commercial sunscreens (with variable TiO2 concentrations: highest concentration for sunscreen C, followed by sunscreen A; and sunscreen B did not contain TiO2 in its composition).With regard to UVR effect, in the absence of sunscreens, the most sensitive species is the centric diatom, Chaetoceros gracilis, and the least is Nannochloropsis gaditana; this last species presented the same behavior in the absence of UVR and with high sunscreen concentrations. The toxicity gradient obtained for sunscreens and nanoparticles under UVR is: TiO2 NPs>Sunscreen C>Sunscreen A>Sunscreen B. The differential sensitivity of microalgae to sunscreens and TiO2 NPs can produce a change in the dynamics of phytoplankton populations and provoke undesirable ecological effects (such as giving dinoflagellates more prominence). The effects of UVR, commonly neglected in bioassays, could alter the results in important ways and should be considered when performing environmentally-relevant bioassays. The toxicity mediated by hydrogen peroxide production associated with the concentration of TiO2 NPs cannot be considered the only factor responsible for the toxicity: the organic compounds in the sunscreens must also be taken into account.

Occurrence of antibiotics and their impacts to primary productivity in fishponds around Tai Lake, China

Antibiotics are widely used to improve the health and yields of farmed animals, including fish, but their use is accompanied by undesirable ecological effects. Relatively little is known about the water-body burden of antibiotics and their influence on primary productivity in aquaculture ecosystem. In this study, antibiotics usage within 24 fishponds, covering 4 areas, sampled 5 times, and having 5 fish species, was investigated surrounding Tai Lake in China. The study analyzed 15 antibiotics (including 5 sulfonamides, 2 quinolones, 3 β-lactams, 3 tetracyclines, 1 amphenicol, and 1 macrolide), and all of them were detected in water samples, with a detection frequency of 2–60%. Sulfonamides were the most prevalent, and concentrations of sulfamethoxazole, sulfamonomethoxine, and florfenicol being over 2000 ng L−1 in some samples, while the other antibiotics levels ranged from ND (no detection) to 551.18 ng L−1. Significant differences were observed in antibiotic burden among different regions for total antibiotics, sulfonamides, quinolones, and amphenicols; among time points for quinolones, β-lactams, and tetracyclines; and among species for quinolones and macrolides. Furthermore, basing on the risk quotient (RQ) method, the assessment revealed that florfenicol was of highest risk to algae with RQ values exceeding 0.1, while macrolide erythromycin posed the second highest risk. The partial correlation coefficient between total antibiotics and chlorophyll (a) was −0.035 that clearly indicated total antibiotics were detrimental to green algae growth, while the nutrient input and other physical – chemical factors were much more beneficial. Overall, holistic far-reaching measures of antibiotics control are recommended to preserve aquaculture ecosystem health.

Irrigation Capability Evaluation of Illushi Floodplain, Edo State, Nigeria

Many irrigation projects, especially in the developing tropical regions, are embarked upon without any land capability assessment, resulting in avoidable and undesirable ecological consequences. The aim of this study is to assess the irrigation capability potentials of the soils of a rice growing Illushi/Ega community in Edo State of Nigeria. Soils of Illushi/Ega (200ha) were studied to establish their irrigation capabilities. Water samples were collected from the rivers within and near the sites at the proposed points of intake structures and analyzed for salinity (ECw), permeability (SAR) and ion toxicity [Chlorine (Cl) and Boron (B)]. Gravity irrigation suitability assessment was carried out following the guidelines of the United States Bureau for Land Reclamation (USBR, 1953) and FAO (1979). Results showed that about 5.5 % of the land was non-irrigable, 11.5 % was marginally irrigable, 30.5% was moderately irrigable and 52.5 % highly irrigable.Thus about 83 % of the total land area was found to be irrigable. The results of analyses of irrigation water [ECw, SAR and Cl and B (ion toxicity) problems in water sources were 0.1 – 0.7 dS m-1, 1.2 – 1.7, 0.6 – 1.8 cmol kg-1 and 0.5 – 0.7mgkg-1] also show that there is no indication of salinity or ion toxicity problem.

Assessment of Hydrologic Alterations Caused by the Three Gorges Dam in the Middle and Lower Reaches of Yangtze River, China

Hydrologic regime plays a major role in structuring biotic diversity within river ecosystems by controlling key habitat conditions within the river channel and floodplain. Daily flow records from seven hydrological stations and the range of variability approach were utilized to investigate the variability and spatial pattern of the hydrologic alterations induced by the construction of the Three Gorges Dam (TGD) in the middle and lower reaches of the Yangtze River, China. Results show that the impoundment of the TGD disturbed the hydrologic regime downstream and directly affected the streamflow variations. The rate of changes and the annual extreme conditions were more affected by the TGD, particularly the low-flow relevant parameters. The alterations in the hydrologic regime were mainly caused by the TGD storing water during early autumn and releasing water during winter and spring. The effects on spatial patterns decreased as the distance from the dam increased, which was mainly attributed to the inflows from large tributaries along the Yangtze River as well as the interaction with the two largest natural lakes (i.e., Dongting Lake and Poyang Lake). These hydrologic alterations not only break the natural balance of eco-flow regimes but also result in undesirable ecological effects, particularly in terms of habitat availability for the fish community.

Molecular Strategies for Addressing Gene Flow Problems and Their Potential Applications in Abiotic Stress Tolerant Transgenic Plants

Transgenic plant technology provides a powerful tool to improve abiotic stress tolerance of crop plants. However, introgression of stress tolerance genes into weedy relatives may increase the potential for persistence and invasiveness, resulting in undesirable ecological consequences. A variety of gene confinement strategies have been developed to reduce unwanted transgene movement. In this review, we discuss some of these strategies, such as male and female sterility, GeneSafe™, parthenocarpy, chloroplast transformation and gene deletor technologies. In the case of the gene deletor technology, all transgenes from pollen, seeds, fruits or other organs may be eliminated once the transgene functions are no longer needed at the stage when the presence of the transgene becomes a cause for ecological or public concern. The gene deletor and other technologies can be useful to reduce unintended dispersal of stress tolerance genes and thus may facilitate commercialization of transgenic crops with enhanced tolerance to abiotic stresses.

Land, Food, and Biodiversity

Land, Food, and Biodiversity

Bacterial community structure and denitrifier (nir-gene) abundance in soil water and groundwater beneath agricultural land in tropical North Queensland, Australia

We explored the microbial ecology of water draining through the soil (lysimeter samples) and in the shallow aquifers (bore samples) underlying sugarcane and banana fields near the Great Barrier Reef (GBR), Australia. Lysimeter and bore water samples were collected and analysed chemically and with DNA fingerprinting methods (PCR-DGGE and clone library sequencing) to characterise the structure of the bacterial community. Bacterial communities in soil water and bore water were distinct (P < 0.05), and a primary factor linked with bacterial community structure was water pH (P < 0.05), particularly in water sampled from lysimeters. Irrespective of treatment, >80% of all rRNA gene sequences originated from proteobacteria. However, groundwater communities differed from those in soil water by greater occurrence of Neisseriales and Comamonadaceae (P < 0.01). qPCR was used to measure copy numbers of the nirK and nirS genes encoding NO-forming nitrite reductases. Copy numbers of both genes were greater in soil water samples than groundwater (P = 0.05), with the difference in nirK being greater under sugarcane than banana. These differences in nirK-gene abundance show that there is greater potential for denitrification in soil water under sugarcane, leading to low concentrations of nitrate in the underlying groundwater. This knowledge can be used towards development of soil and land-use management practices promoting bacterial denitrification in groundwater to lessen the undesirable ecological consequences where groundwater discharges lower in the GBR catchment zones.

Genetically modified organisms in agriculture: can regulations work?

Genetically modified (GM) crops have been recognised to be economically beneficial to subsistence farmers and have been projected as essential tools for addressing challenges in hunger, environmental sustainability and international development. Yet the uncertainty of their effects on human health and the undesirable ecological consequences of these organisms have raised concerns on the rapid pace of their production. Regulating the release of these organisms is a critical environmental issue. The Cartagena protocol on bio-safety, the principle legal arrangement for the regulation of these organisms, has ratifications from only 157 countries and has proven to be a weak regulator. Countries like India and Brazil have seen the proliferation of unapproved stealth GM varieties which make regulation even more difficult. In this paper, we explore the debate surrounding the introduction of GM organisms and analyse the effectiveness of existing legal regimes to regulate their use.