Perfluorooctane sulfonic acid and organohalogen pollutants in liver of three freshwater fish species in Flanders (Belgium): relationships with biochemical and organismal effects

A perfluorooctane sulfonic acid (PFOS) assessment was conducted on gibel carp (Carassius auratus gibelio), carp (Cyprinus carpio), and eel (Anguilla anguilla) in Flanders (Belgium). The liver PFOS concentrations in fish from the Ieperlee canal (Boezinge, 250-9031 ng/g wet weight, respectively) and the Blokkersdijk pond (Antwerp, 633-1822 ng/g wet weight) were higher than at the Zuun basin (Sint-Pieters-Leeuw, 11.2-162 ng/g wet weight) and among the highest in feral fish worldwide. Eel from the Oude Maas pond (Dilsen-Stokkem) and Watersportbaan basin (Ghent) had PFOS concentrations ranging between 212 and 857 ng/g wet weight. The hepatic PFOS concentration was significantly and positively related with the serum alanine aminotransferase activity, and negatively with the serum protein content in eel and carp. The hepatic PFOS concentration in carp correlated significantly and negatively with the serum electrolyte concentrations whereas a significant positive relation was found with the hematocrit in eel. Although 13 organochlorine pesticides, 22 polychlorinated biphenyl (PCB) congeners and 7 polybrominated diphenyl ethers (PBDEs) were also measured in the liver tissue, only PCB 28, PCB 74, gamma-hexachlorocyclohexane (gamma-HCH) and hexachlorobenzene (HCB) were suggested to contribute to the observed serological alterations in eel.     

Defense against parasites by hitchhikers in leaf-cutting ants: a quantitative assessment

Summary A curious behavior in leaf-cutting ants in the genus Atta is the hitchhiking of small minim workers on leaf fragments carried by larger workers. Two functions of these hitchhikers have been proposed: (1) defense of leaf carriers against parasitic flies in the family Phoridae (ant protection hypothesis; Eibl-Eibesfeldt and Eibl-Eibesfeldt 1967) and (2) reduction of transport costs of small minims that collect plant fluids (energy conservation hypothesis; Stradling 1978).We studied hitchhiking behavior in colonies of Atta colombica on Barro Colorado Island, Panama, and found strong evidence in favor of the ant protection hypothesis. Females of Apocephalus attophilus (Diptera: Phoridae) attack leaf carriers of A. colombica and deposit eggs in the head capsules of these ants. Our observations indicate that parasites require leaf fragments to stand on during oviposition, and, as a result, only leaf carriers are susceptible to parasitic attack. The presence of hitchhikers reduces significantly both the time parasites spend on leaf fragments and the probability that they will land in the first place. Results of experimental introductions of parasites and a year of biweekly censuses at ten colonies indicate that leaf-cutting ants adjust the level of hitchhiking to accommodate both daily and seasonal changes in the abundance of parasites.We found little evidence in support of the energy conservation hypothesis. If it is assumed that all minim workers hitchhike back to the nest, our calculations indicate that total transport costs along a foraging trail are reduced by 10% or less. However, our observations indicate that only 50% of returning minim workers hitchhike, and therefore energy savings are actually considerably less than 10%. Leaf-cutting ants in the genera Atta and Acromyrmex are attacked by over 20 species of parasitic phorids. In the discussion we review what is known about these associations and suggest that these parasites have influenced the ecology and evolution of polyethism in leaf-cutting ants. Offprint requests to: D.H. Feener (at his present address)     

Initial tree establishment on blocky quarry waste ameliorated with hydrogel or slate processing fines

Pocket planting reclamation techniques developed in the 1970s for revegetating blocky quarrying waste have met with very limited success, often because the low water-holding capacity of the waste and limited root development within a small volume of planting pocket material result in severe drought mortality. We tested pocket planting approaches for waste tip reclamation at Europe's largest slate quarry, and compared materials for enhancing the continuity of water- and nutrient-holding down into the interior of the waste tip. When small compost-filled pocket planting bags were placed above slate processing fines (SPF) or water absorbent cross-linked polyacrylamide gel ("hydrogel"), tree growth rates increased in comparison with pocket planting bags alone. The SPF significantly improved tree survival especially during severe drought, but survival was not enhanced by the use of hydrogel. The sorption characteristics of hydrogel indicated that its presence may help to reduce nutrient leaching, but that it may have a negative effect on nitrogen availability. A more likely explanation for the poor performance of pure hydrogel is that it did not maintain sufficient available water, because of discontinuities caused by shrinkage and movement of the hydrogel, and/or degradation of water-holding capacity with environmental exposure. However, the root growth observed in the hydrogel treatments suggests that this technique, if adapted to reduce the effects of hydrogel shrinkage by using finer-grade hydrogel, mixing it with other soil-forming material, and reducing its exposure to extremes of temperature or sunlight, might have the potential to improve the growth and survival of trees planted on sites where delivery of heavy materials such as SPF is impractical. Fine mineral processing waste is freely available at active quarries and should be seen as a key resource for reclamation schemes.     

Microbial methylation of mercury in the water-level fluctuation zone of the Three Gorges Reservoir, China

正Methylmercury(MeHg)is an organic form of the global pollutant mercury(Hg)which readily accumulates in fish tissue.A majority of Hg methylation is a result of microbial activity and the abundance of inorganic Hg within the water reservoirs(Eckley et al.,2017).Compared to natural lakes and rivers,reservoirs have elevated Hg levels from the decomposition of recently flooded organic material which promote Hg     

Using envirodaemon to search the internet for environmental information and building custom search engines

The Internet holds vast stores of information pertaining to pollution prevention and environmental issues, and with each day more is added. Yet, as this storehouse grows, the difficulty of finding specific information increases. This article details how EnviroDaemon was built to ease the task of finding this information and knowledge base. It automatically builds and updates a catalog of objects at pre-selected Internet sites that are related to pollution prevention. Users search for information by submitting keywords. Searches can be restricted to small subsets of the indexed sites by choosing one of five search criteria, or the entire catalog can be searched. The results are returned rapidly and are embedded in several lines of text to provide context. If the text looks promising, the user can click on a hyperlink to access the full article. Since its release in March, EnviroDaemon has seen increasing use, especially following its demonstration at the National Pollution Prevention Roundtable Conference. The authors also discuss the process of building this search engine to show interested readers how to create other environmental custom search engines.     

Knowledge and Perceptions in Costa Rica Regarding Environment, Population, and Biodiversity Issues

Public understanding of general environment- and population-related issues is critical for successful conservation efforts. We interviewed 300 residents of Costa Rica, distributed among three socioeconomic groups, to survey knowledge and perceptions about the environment. We focused on Costa Rica because it is an international model for sustainable development and because of its direct economic interest in biodiversity preservation for ecotourism. Our results indicate that Costa Ricans generally have a limited awareness of environment- and population-related problems. In all socioeconomic groups environmental problems were considered less important than various other problems, but 91% of respondents indicated a willingness to pay more for water or electricity if the extra money were used to protect biodiversity. Residents of San Jose's lower-class neighborhoods more strongly perceived the effects of population growth and environmental degradation than did residents of urban, upper-class, or rural neighborhoods. Of those interviewed, 69% thought the rate of population growth should decrease. Only 52% of those surveyed, however, perceived any link between population size or growth rate and environmental quality; of those, 33% could not describe the link. Our findings and others suggest a number of ways to enhance the effectiveness of environmental education programs worldwide: (1) include information on the relationship between population and environmental quality; (2) explain the socioeconomic implications of environmental degradation; (3) in addition to formal education, utilize the mass media more; (4) tailor messages to local circumstances.     

Facultative sex ratio manipulation in American kestrels

Summary For animals that are sexually dimorphic in size, the larger sex is expected to be more costly to raise to independence. Manipulating offspring sex ratios may thus be one means by which parents can fine-tune their reproductive effort to resource availability. Parents in poor physical condition or during poor food years should produce more of the cheaper (smaller) sex. We examined the sex ratios of 259 broods of American kestrels (Falco sparverius) between 1988 and 1990 in relation to food abundance (small mammals) and various attributes to the parents. The proportion of males at hatching increased as the food supply declined, and both male and female parents in poor physical condition were more likely to have male-biased broods than those in good condition. The mortality of eggs and young did not appear to be responsible for the biased sex ratios. The sex ratio was independent of the laying date; however, it was correlated with female body size. Small females produced more sons, perhaps because small size is more detrimental for females than males. Offprint requests to: G.R. Bortolotti     

Mangrove recruitment after forest disturbance is facilitated by herbaceous species in the Caribbean.

Plant communities along tropical coastlines are often affected by natural and human disturbances, but little is known about factors influencing recovery. We focused on mangrove forests, which are among the most threatened ecosystems globally, to examine how facilitation by herbaceous vegetation might improve forest restoration after disturbance. We specifically investigated whether recovery of mangrove forests in harsh environments is accelerated by nurse plants and whether the beneficial effects are species-specific. Quantification of standardized effects allowed comparisons across performance parameters and over time for: (1) net effect of each herbaceous species on mangrove survival and growth, (2) effects of pre- and post-establishment factors associated with each herbaceous species, and (3) need for artificial planting to enhance growth or survival of mangrove seedlings. Mangrove recruitment in a clear-cut forest in Belize was accelerated by the presence of Sesuvium portulacastrum (succulent forb) and Distichlis spicata (grass), two coastal species common throughout the Caribbean region. The net effect of herbaceous vegetation was positive, but the magnitude of effects on mangrove survival and growth differed by species. Because of differences in their vegetative structure and other features, species effects on mangroves also varied by mechanism: (1) trapping of dispersing propagules (both species), (2) structural support of the seedling (Distichlis), and/or (3) promotion of survival (Sesuviumn) or growth (Distichlis) through amelioration of soil conditions (temperature, aeration). Artificial planting had a stronger positive effect on mangrove survival than did edaphic conditions, but planting enhanced mangrove growth more in Sesuvium than in Distichlis patches. Our study indicates that beneficial species might be selected based on features that provide multiple positive effects and that species comparisons may be improved using standardized effects. Our findings are not only relevant to the coastal environments found in the Caribbean region, but our assessment methods may be useful for developing site-specific information to restore disturbed mangrove forests worldwide, especially given the large pool of mangrove associates (>45 genera) available for screening.     

Effects of salinity and ozone,individually and in combination,on the growth and ion contents of two chickpea (Cicer arietinum L.) varieties

The aim of this study was to determine the effects of ozone and salinity, singly and in combination, on the growth and ion contents of two chickpea (Cicer arietinum L.) varieties. Chickpea plants were grown in non-saline and saline conditions, with and without a repeated exposure to ozone. Salinity at a concentration of 30 mM NaCl caused a substantial reduction in plant height, number of leaves and the dry weights of the leaves, stems and roots. Biomass allocation to the leaves increased, predominantly at the expense of the roots. Ozone at a concentration of 85 nmol mol(-1) for 6 h per day for 25 days reduced plant height and dry weights but had no effect on leaf number. The results show substantial effects of salinity and ozone on chickpea growth and ion concentrations. When ozonated plants are grown in the presence of salinity, further reductions in growth occur.     

Surface metal adsorption on zooplankton carapaces: implications for exposure and effects in consumer organisms

The current study aimed to determine the potential of two important aquatic invertebrate crustacean species, Daphnia magna and Ceriodaphnia dubia, to adsorb cadmium on to their carapaces from aqueous solution. Using the Langmuir equation to model data outputs, it was shown that cadmium readily became associated with the carapace surfaces of both species, with uptake being dependent on exposure time and concentration. Maximum carapace-adsorption potential was found to be directly related to surface area, so that at predicted carapace saturation, D. magna neonates bound approximately five times more cadmium than the smaller C. dubia neonates. However, adsorption per unit surface area was found to be similar under the same exposure conditions. Results of surface metal adsorption studies in C. dubia suggested that short term exposures to high concentrations of aqueous cadmium would lead to similar levels of adsorption as obtained with long-term exposures to low concentrations. The study illustrates that contaminants adsorbed to prey surfaces may be an important mechanism of exposure to predators, and highlights some potential problems of feeding organisms during long-term toxicity tests.