The environmental cost of pesticide usage in the United Kingdom

Organic pesticides have been used for more than 50 years, and have made a major contribution to the profound alteration of agricultural practice which has occurred during this period. Among the many effects arising from these developments in agriculture, various environmental changes have been identified, which have been the subject of considerable public debate and disagreement. Attention has focussed particularly on the popularly assumed adverse influence of pesticides on the natural flora and fauna. This review examines the position in the United Kingdom where interest in wildlife has always been extensive and where many amateur observations and professional scientific studies have been brought to bear on the problem. It differentiates between ‘direct’ effects which may be attributed to particular uses of certain compounds and ‘indirect’ effects normally arising from changes in habitat or food supply brought about by pesticides. The approach adopted has been to assess the effects of pesticide use on populations rather than attempting to place a financial estimate on any adverse environmental effect attributed to pesticides. Systems of surveillance are described and their ability to detect adverse effects is assessed. The difficulty of correlating such effects with pesticide use is examined. In general, it is concluded that other than for insects the levels of surveillance have been adequate to detect adverse effects on fauna and flora arising from pesticide use. Where direct effects have been discerned in the past, action has, where possible, been taken to rectify the position and it is suggested that this will continue. Overall there is little evidence that the survival of individual species is threatened by the direct effects of pesticides. Indirect effects are neither simple to delineate nor readily corrected and it is recommended that more research be carried out to develop the ability to assess their influence.     

The Genetic Diversity of Native, Stocked, and Hybrid Populations of Brook Trout in the Southern Appalachians

Using mitochondrial DNA (mtDNA) restriction analysis and starch-gel electrophoresis of the CK-A2 locus product, we examined genetic variation in 311 brook trout (Salvelinus fontinalis) from 11 native, 5 hatchery-derived, and 8 hybrid populations in the southern Appalachian Mountains. Native southern Appalachian fish were genetically distinct from hatchery-derived fish. Southern and hatchery-derived fish were reliably distinguished based on three mtDNA restriction sites. Native southern haplotypes differed from hatchery-derived haplotypes by an average of 0.84%. Northern hatchery-derived haplotypes varied little in mtDNA compared to native southern haplotypes. Introgression of mtDNA haplotypes and the CK-A2 locus varied among populations, and introgression of allozyme and mtDNA markers was positively correlated. Continued introductions of nonnative strains of brook trout in the southern Appalachians could simplify the genetic structure of native brook trout populations and eliminate unique genotypes.     

Inorganic nitrogen metabolism in marine bacteria: Nitrate uptake and reduction in a marine pseudomonad

Growth experiments in batch cultures indicated that the uptake of nitrate by the marine pseudomonad PL1 was inhibited in the presence of ammonia provided that the ammonia concentration was higher than 1 mM. At ammonia concentrations of less than about 1 mM, however, both nitrate and ammonia were utilised simultaneously. The saturation constants for nitrate and ammonia uptake were both 2.6x10^-4 M, and similar to the Michaelis constants of nitrate reductase for nitrate (2.9x10^-4 M) and glutamine synthetase for ammonia (2x10^-4 M). Nitrate reductase activity linked to NADH was detected in chemostat-grown cultures with nitrate as nitrogen source, and in cultures containing limiting concentrations of nitrate and ammonia, ammonia or glutamate. Enzyme synthesis appeared to be repressed in cultures containing an excess of ammonia or glutamate. Chemostat cultures utilised ammonia or glutamate in preference to nitrate, while there was no marked preference between ammonia and glutamate.     

Incidental detection of premature centromere separation in amniocytes associated with a mild form of Roberts syndrome

Premature centromere separation (PCS) was detected in amniocytes after an amniocentesis was done because of markedly elevated maternal serum alpha-fetoprotein values in a healthy primiparous young woman. PCS has been associated with the Roberts-SC phocomelia syndrome (RS). By 23 weeks' gestation, ultrasonic evaluations did not reveal abnormal fetal development. The pregnancy continued and a male infant was born with mild manifestations of RS. PCS was confirmed in cord blood lymphocytes. This case illustrates that PCS, when detected in amniotic fluid cell cultures, requires a thorough evaluation.     

Severe bilateral renal disease: Correlation of antenatal and autopsy findings

We report 20 infants with severe bilateral renal disease examined by prenatal ultrasound and by autopsy. In 17, the prenatal and pathologic diagnoses correlated well. Although the prenatal and autopsy findings differed in the three remaining cases, the autopsy confirmed the presence of severe bilateral renal abnormalities. All 20 pregnancies were complicated by oligohydramnios, which was severe in 60 per cent. Most of these fetuses had malformation of other organ systems. This series supports the utility of prenatal ultrasound examinations, but emphasizes the need for postnatal evaluation of congenital renal disease including pathologic examination of tissue when possible for correct classification and genetic counselling.     

Effects of pharmaceuticals on Daphnia survival, growth, and reproduction

Pharmaceuticals have been globally detected in surface waters, and the ecological impacts of these biologically-active, ubiquitous chemicals are largely unknown. To evaluate the aquatic toxicity of individual pharmaceuticals and mixtures, we performed single species laboratory toxicity tests with Daphnia magna, a common freshwater zooplankton. We conducted acute (6-day) and chronic (30-day) exposure pharmaceutical bioassays and evaluated survivorship and morphology of adults and neonates, adult length, resting egg production, brood size (fecundity), and the proportion of male broods produced (sex ratio). In general, exposure to a single pharmaceutical in the 1-100 microg/l range yielded no apparent effects on the normal life processes of Daphnia. However, chronic fluoxetine exposure (36 microg/l) significantly increased Daphnia fecundity, and acute clofibric acid exposure (10 microg/l) significantly increased sex ratio. A mixture of fluoxetine (36 microg/l) and clofibric acid (100 microg/l) caused significant mortality; the same fluoxetine concentration mixed with 10 microg/l clofibric acid resulted in significant deformities, including malformed carapaces and swimming setae. Mixtures of three to five antibiotics (total antibiotic concentration 30-500 microg/l) elicited changes in Daphnia sex ratio. We conclude: (1) individual and mixtures of pharmaceuticals affect normal development and reproduction of Daphnia magna, (2) aquatic toxicity of pharmaceutical mixtures can be unpredictable and complex compared to individual pharmaceutical effects, and (3) timing and duration of pharmaceutical exposure influence aquatic toxicity.     

Assessment of the phototoxicity of weathered Alaska North Slope crude oil to juvenile pink salmon

Petroleum products are known to have greater toxicity to the translucent embryos and larvae of aquatic organisms in the presence of ultraviolet radiation (UV) compared to toxicity determined in tests performed under standard laboratory lighting with minimal UV. This study assessed the acute phototoxicity of the water accommodated fractions of weathered Alaska North Slope crude oil (ANS) to juvenile pink salmon, which are a heavily pigmented life stage. Fish in the highest ANS treatments exhibited melanosis, less mobility, reduced startle response, erratic swimming, and loss of equilibrium. Gills from fish exposed to ANS had elevated levels of hydroperoxides in oil-only, UV-only, and oil+UV treatments compared to control fish, which was indicative of increased lipid peroxidation in gill tissue. Under the test conditions of moderate salinity, low UV and high short-term oil exposure there were no indications of photoenhanced toxicity as assessed by elevation of mortality, behavioral impairment, or gill lipid peroxidation in oil+UV treatments. The results of this study suggest that pink salmon may be at less risk from photoenhanced toxicity compared to the translucent early-life stages of several other Alaska species.     

ChemChar process for carbon re-activation

The ChemChar reverse-burn gasification process was evaluated to determine its feasibility for use in the regeneration of spent activated carbon. This non-incinerative, thermochemical gasification process pyrolyzes the sorbed wastes and restores the sorptive capacity of the carbon in one energy-efficient step. The effects of moisture and supplemental fuel addition on regeneration were determined with a laboratory-scale reactor and a flow-through assay method was developed for determining regeneration effectiveness. The process produces good quality regenerated carbon simply and inexpensively with a minimum of carbon loss. Carbons can be regenerated several times and the method is non-polluting.     

Waterborne and sediment toxicity of fluoxetine to select organisms

Ecological risk assessments of pharmaceuticals are currently difficult because little-to-no aquatic hazard and exposure information exists in the peer-reviewed literature for most therapeutics. Recently several studies have identified fluoxetine, a widely prescribed antidepressant, in municipal effluents. To evaluate the potential aquatic toxicity of fluoxetine, single species laboratory toxicity tests were performed to assess hazard to aquatic biota. Average LC(50) values for Ceriodaphnia dubia, Daphnia magna, and Pimephales promelas were 0.756 (234 microg/l), 2.65 (820 microg/l), and 2.28 microM (705 microg/l), respectively. Pseudokirchneriella subcapitata growth and C. dubia fecundity were decreased by 0.044 (14 microg/l) and 0.72 microM (223 microg/l) fluoxetine treatments, respectively. Oryias latipes survival was not affected by fluoxteine exposure up to a concentration of 28.9 microM (8.9 mg/l). An LC(50) of 15.2 mg/kg was estimated for Chironomus tentans. Hyalella azteca survival was not affected up to 43 mg/kg fluoxetine sediment exposure. Growth lowest observed effect concentrations for C. tentans and H. azteca were 1.3 and 5.6 mg/kg, respectively. Our findings indicate that lowest measured fluoxetine effect levels are an order of magnitude higher than highest reported municipal effluent concentrations.     

Group size and growth rate in hatchling green iguanas (Iguana iguana)

Summary The post-hatching growth and sleeping group sizes of green iguanas (Iguana iguana) were followed on Barro Colorado Island, Panama, for 3 successive years. The laboratory clearing was subdivided and surveyed routinely for iguanas, most intensively the six weeks following onset of hatching. A similar pattern of influx of iguanas into the clearing took place each May. Over the early weeks the size of groups generally increased. Animals sleeping in larger groups had significantly faster growth rates. Animals that disappeared from the clearing prior to July had larger group sizes prior to disappearance than those that remained. Growth rates measured in animals that remained declined markedly after June. Possible reasons for the social grouping of young iguanas are discussed.