A Simulation-Based Assessment of Alternative Explanations for Apparent Confounding in “PM Decomposition” Studies

Environmental Modeling & Assessment - Determining whether there is a causal link between chronic exposure to PM2.5 (atmospheric particulate matter with a diameter of 2.5 µm or...     

Effects of relaxed predation pressure on visual predator recognition in the guppy

Many prey species have a genetic predisposition to recognise and respond to predators and can fine-tune their anti-predator behaviour following appropriate experience. Although the Trinidadian guppy ( Poecilia reticulata) has become a model species for the investigation of adaptive behaviour, the extent to which experience mediates predator recognition remains unclear. In this study, we examined the effects of relaxed predation pressure on patterns of anti-predator behaviour in populations differing in evolutionary history. The anti-predator behaviour of wild- and laboratory-born guppies from high- and low-predation localities in Trinidad were compared using three models resembling Crenicichla alta, a dangerous guppy predator, Aequidens pulcher, a less dangerous piscivore, and a snake. Snakes are not known to prey on guppies in Trinidad. Specifically, the following predictions were tested: (1) wild caught fish from the high-predation localities (where guppies co-occur with C. alta and A. pulcher) would respond to the three models according to their perceived level of threat, whereas guppies from the low-predation site would show a reduced response to all of the predator models; (2) high-predation laboratory-reared fish would display a reduced but qualitatively similar response to their wild counterparts; and (3) there would be no behavioural differences between wild- and laboratory-reared low-predation fish. In accordance with these predictions, the results revealed that wild fish originating from high-predation sites responded more strongly to the models than fish from low-predation sites. When reared in the laboratory, guppies from the high-predation population showed a reduced response compared to their wild-caught counterparts, but there was no difference in the behaviour of wild- and laboratory-reared low-predation fish. Model type affected predator inspection behaviour but not schooling tendency, and both wild- and laboratory-reared guppies were more wary of the fish models than the snake. These results suggest that early experience differentially mediates the anti-predator responses of fish from high-risk localities.     

Feeding ecology of herring (Clupea harengus) larvae in the turbid Blackwater Estuary

Most studies on feeding by herring larvae (Clupea harengus) have taken place in clear, open waters, but several herring stocks around the world spawn in inshore and estuarine regions. An example is the spring-spawning Blackwater Estuary (Essex, England) stock. Samples were collected in this estuary to examine prey selectivity and feeding levels in relation to biological and environmental conditions. Herring larvae negatively selected copepod nauplii, but positively selected the copepodite and adult stages of Acartia spp. Gastropod larvae were also positively selected. Particles >150 μm width were preferred, whilst particles smaller than this value were preferentially rejected. Concentrations of potential prey items in the water were in the range of 6.0 to 49.7 organisms l⁻¹ with a median concentration of 15.0 organisms l⁻¹ (n = 26). These values are towards the low end of prey concentrations quoted in the literature as being required to sustain herring larval growth and survival. However, theoretical considerations suggest that, in this environment, levels of tidally-induced turbulence enhance encounter rates between larval herring and their prey. On the other hand, turbidity is also related to tidal current speed and might reduce feeding success by decreasing underwater light levels. Measurements at two sites in the estuary confirmed that tidally-induced turbidity reduced the effective water depth in which herring larvae could visually feed by up to 50% at times of peak current speed. However, with the gut-content data available in the present study, it was not possible to discern any clear relationships between feeding success and the state of the tide. Feeding success appeared to be more strongly influenced by surface light-levels. Received: 24 June 1998 / Accepted: 17 February 1999     

Female tactics to reduce sexual harassment in the Sumatran orangutan (Pongo pygmaeus abelii)

Orangutan males demonstrate intrasexual dimorphism with corresponding alternative mating strategies. Sexual harassment is the predominant feature of the mating strategy that subadult males pursue. This study investigated the countertactics that females employ to reduce sexual harassment by subadult males. I observed 207 copulations during more than 9,000 h of focal follows of wild Sumatran orangutans at the Suaq Balimbing Research Station over a 23-month period. Rates of copulations initiated by subadult males increased during months of high fruit abundance, and most mating attempts were directed toward females with weaned infants. Simultaneous harassment by multiple subadult males increased significantly during months of high fruit abundance, and nearly all adult female-adult male consortships occurred during periods of high fruit abundance. Females who maintained spatial association with adult males, either via consortship or by nonmating temporary parties, received lower rates of harassment, as measured by the success rate of subadult male mating attempts. Adult female-adult male parties did not always result in mating between the associating dyad. Female initiation of protective services by adult males is one social tactic that female orangutans employ to reduce sexual harassment. Females therefore receive direct services from adult males, which may be one factor that influences female mate choice in Sumatran orangutans.     

Role of iron chemistry in controlling the release of pollutants from resuspended sediments

Aquatic sediments often contain a large number of chemical contaminants that are potential pollutants. It is often presumed that such contaminants are released to the water column during sediment resuspension and, in there, adversely impact aquatic life and other beneficial uses of the water. However, extensive laboratory and field studies of about 100 contaminated sediments from across the United States that specifically addressed this type of release showed that of about 30 common heavy metals, organic compounds, and other potential pollutants, only manganese II and ammonia were released to then remain in the water column after sediment resuspension. These results indicated that the chemistry of aqueous iron controls the availability of many contaminants in resuspended sediment. The formation of ferric hydroxide during sediment suspension into the water column, as a result of the reaction between ferrous iron in the sediments and dissolved oxygen in the water column, leads to rapid scavenging of many contaminants in the Fe(OH)₃ precipitate. The scavenged contaminants are redeposited in the sediments. This article reviews the role of the aqueous chemistry of iron as it relates to controlling the release of potential pollutants from resuspended sediments. © 2005 Wiley Periodicals, Inc.     

Too small to count? Making Land Use Transformations in Chiquitano communities of San Ignacio de Velasco,East Bolivia,visible

ABSTRACT

The Santa Cruz lowlands, east Bolivia, are one of South America’s most dynamic agricultural frontiers. In the Chiquitania, bordering Brazil, San Ignacio de Velasco was in 2017 ranked first nationally in terms of deforestation. There, two deforestation fronts meet with mechanized agriculture expanding from the West and South and cattle ranching from the East. Chiquitano communities are demographically dominant locally but often face land scarcity. Because of their comparatively low impact on forest vegetation, they are not well represented in broad-scale quantitative Land Use/Land Cover (LULC) studies. Based on an empirical, human geographical approach, this paper investigates the transformation of the local indigenous productive matrix, the associated land-use patterns and potential socio-ecological implications. The overall aim is to bear witness to the rapid and profound reconfiguration of traditional livelihoods with their integration in the market economy and to highlight the significance of micro-scale LULC-processes at global scale.     

Spatial and Geographical Variations of Urban, Suburban and Rural Atmospheric Concentrations of Phenols and Nitrophenols (7 pp)

Goal, Scope and Background Atmospheric sampling (gas and particles) of 5 phenols (phenol, m-cresol, p-cresol, o-cresol, pentachlorophenol) and 15 nitrophenols (3-methyl-2-nitrophenol, 3-nitrophenol, 4-methyl-2-nitrophenol, 5-methyl-2-nitrophenol, 2-methyl-3nitrophenol, 3-methyl-4-nitrophenol, 2,6-dinitrophenol, bromoxynil, 2,5-dinitrophenol, 2,6-dinitro-p-cresol, 2,4-dinitrophenol, ioxynil, DNOC, 3,4-dinitrophenol, dinoseb) on XAD-2 resin (20 gr) and glass fibre filters, respectively, were performed in 2002 by using 'Digitel DA80' high volume samplers. These measurements were undertaken in order to show spatial and geographical variations of concentrations and the role of traffic in the emissions of these compounds to the atmosphere. Methods Sampling were performed in Strasbourg (eastern France), in its vicinity (Schiltigheim) and in Erstein. Sites were chosen to be representative of urban (Strasbourg), suburban (Schiltigheim) and rural (Erstein) conditions. Field campaigns were undertaken simultaneously in urban and suburban sites during all the seasons during 4 hours at a flow rate of 60 m3.h-1, which gives a total of 240 m3 of air per sample. Period of sampling varied between 06h00 to 10h00, 11h00 to 15h00 and 18h00 to 22h00 in order to evaluate a variation of concentration during automobile traffic between urban, suburban and rural areas. Gas and particle samples were separately Soxhlet extracted for 12 h with a mixture of CH2Cl2 / n-hexane (50:50 v/v), concentrated to about 1 mL with a rotary evaporated and finally dried under nitrogen. Dry extracts were dissolved in 1 mL of CH3CN. Before analysis, extracts were sylilated by using MTBSTFA. Analysis was performed by GC/MSD in the SIM mode. Results and Discussion Partitioning of phenolic compounds between gas and particle phases seems to be mainly correlated with vapour pressure. Among phenolic compounds analysed, phenol, p-cresol, pentachlorophenol and 2.4-dinitrophenol were detected in all samples and emissions from traffic seems to be the major source for the presence of these compounds to the atmosphere. No increase of concentrations in autumn tend to confirm this hypothesis since, with the use of domestic heating in colder months, increases of PAHs concentrations were observed and these compounds are known to be emitted by all combustion processes. Pentachlorophenol is a special case since this molecule is only used as wood preservative. Its presence in all atmospheric samples, whatever the locations and the period of time is the consequence of its persistence. Conclusions and Perspectives These measurements demonstrate that phenols and nitrophenols are emitted to the atmosphere and further measurements, in order to confirm their sources, their behaviour and their potential impact to the air quality and to human health should be undertaken especially since the literature collected is relatively old. Concentrations of pentachlorophenol measured are very low and, due to its toxicity, further investigations should be undertaken. - * The basis of this peer-reviewed paper is a presentation at the 9th FECS Conference on 'Chemistry and Environment', 29 August to 1 September 2004, Bordeaux, France.     

Soil microbial response to waste potassium silicate drilling fluid

Potassium silicate drilling fluids(PSDF) are a waste product of the oil and gas industry with potential for use in land reclamation. Few studies have examined the influence of PSDF on abundance and composition of soil bacteria and fungi. Soils from three representative locations for PSDF application in Alberta, Canada, with clay loam, loam and sand textures were studied with applications of unused, used once and used twice PSDF. For all three soils, applying ≥ 40 m3/ha of used PSDF significantly affected the existing soil microbial flora. No microbiota was detected in unused PSDF without soil. Adding used PSDF to soil significantly increased total fungal and aerobic bacterial colony forming units in dilution plate counts, and anaerobic denitrifying bacteria numbers in serial growth experiments.Used PSDF altered bacterial and fungal colony forming unit ratios of all three soils.     

Spatial and Temporal Trends in Organochlorine Contamination and Bill Deformities in Double-Crested Cormorants (Phalacrocorax Auritus) from the Canadian Great Lakes

The levels of organochlorine contaminants (OCs) in the eggs of double-crested cormorants (Phalacrocorax auritus) from the Canadian Great Lakes, Lake Nipigon and Lake-of-the-Woods were monitored between 1970 and 1995. PCBs and p,p-DDE were present at the highest concentrations. Significant declines in OC concentrations on the Great Lakes were observed over this period for Lake Ontario, Lake Superior, Georgian Bay and North Channel but not Lake Erie where levels remained relatively stable. In the early 1970s, the greatest OC levels were generally observed in cormorant eggs from nesting sites in Georgian Bay and North Channel of Lake Huron. Between 1984 and 1995 mirex and PCB levels were consistently highest in samples from Lakes Ontario and Erie, respectively. Similar levels of PCDDs and PCDFs were observed from all regions of the Canadian Great Lakes in 1989. In general, OC levels in cormorant eggs between 1984-95 were ranked as follows: Lake Erie>Lake Ontario Lake Superior>Lake Huron. In 1995, eggshell thickness in Canadian Great Lakes cormorants, ranged from 0.423 to 0.440 mm and was on average only 2.3% thinner than pre-DDT era values. Between 1988 and 1996, 31 cormorant chicks with bill defects were observed at 16 different colonies (21% of all colonies surveyed) in Lakes Ontario and Superior, Georgian Bay and North Channel, and the main body of Lake Huron. No bill deformities were observed at reference sites in northwestern Ontario (Lake Nipigon and Lake-of-the-Woods). For the period 1988-96, the prevalence of bill defects in cormorant chicks (0.0 to 2.8/10,000 chicks) did not differ significantly (P > 0.05) among most regions in the Canadian Great Lakes. Georgian Bay was the only region to show a significant decrease in the prevalence of bill defects between the periods 1979-87 and 1988-95.     

Monitoring the Elimination of Persistent Toxic Substances from the Great Lakes; Chemical and Physiological Evidence from Adult Herring Gulls

To assess progress towards virtual elimination of PCBs, DDE, dieldrin and Mirex and their associated physiological effects, we compared their concentrations in pooled livers of adult herring gulls (Larus argentatus) repeatedly sampled at 8 Great Lakes colonies and a reference colony on the Atlantic coast between 1974 and 1993. We measured the relative thyroid mass and concentrations of highly carboxylated porphyrins and retinyl palmitate in the liver of each individual. PCBs, dieldrin and mirex declined in 7 of 8 colonies while DDE decreased in six. The greatest decreases occurred pre-1985. PCBs and DDE did not decrease in gulls from Middle Island in western L. Erie. Middle Island and Saginaw Bay had the highest concentrations of PCBs of 11 Great Lakes colonies in the 1990s. Thyroids of gulls from Great Lakes colonies were slightly enlarged but the degree of enlargement has decreased over time. In 1991, gulls from Great Lakes colonies had slight to moderately elevated concentrations of highly carboxylated porphyrins. In the early 1990s, hepatic stores of retinyl palmitate were very seriously depleted in gulls from the Detroit River, western basin of Lake Erie, and Lake Ontario, reflecting decreased availability and altered storage. We conclude that PCBs and/or other persistent toxic substances in the food of herring gulls have not been virtually eliminated.