Effects of habitat fragmentation on the genetic structure and connectivity of the black-lipped pearl oyster Pinctada margaritifera populations in French Polynesia

Habitat destruction leading to increased fragmentation is detrimental to species by reducing population size and genetic diversity and by restraining population connectivity. However, little is known about the effects of naturally fragmented habitats on wild populations, especially when it comes to marine benthic invertebrates with long pelagic larval duration. In this framework, we investigated the connectivity and genetic diversity variation among nine wild populations of the black-lipped pearl oyster, Pinctada margaritifera, throughout French Polynesia using ten microsatellite DNA markers. Despite the naturally fragmented habitat (South Pacific oceanic islands), we found high values of genetic diversity and population admixture, indicating connectivity at small and large spatial scales within sampled sites of the Tuamotu, and between the Society and Tuamotu Archipelagos. In the meantime, habitat geomorphology increased genetic drift in populations occurring in small, closed lagoons. Significant genetic structure not correlated to geographic distance was detected mainly between closed and open lagoons. The Marquesas Islands hosted the most divergent populations, likely a result of vicariance. Our results also highlight that migration patterns among lagoons are not symmetrical. Altogether, the general pattern of gene flow, nonsymmetrical migration rates among populations, absence of isolation by distance and absence of recent extinction events found in our study strongly suggest that P. margaritifera populations of French Polynesia follow an asymmetrical island model of dispersal.     

Impact of pedological conditions on the distribution of Salicornia species (Southern North Sea coast)

The zonation of different Salicornia species within saltmarshes has been described controversially in prior publications. The aim of this study is to detect substantial relations between pedological conditions and the distribution of different Salicornia species (Salicornia stricta Dumort. 1868, Salicornia europaea L. 1753, and Salicornia procumbens Sm 1813). 37 sites were investigated regarding vegetation pattern, soil morphology and physicochemical and chemical soil properties. A multivariate approach indicate a clear differentiation of the sites dominated by different Salicornia species in respect to sand content, redox potential and water content. However, results of a detailed statistical assessment indicate that redox potential and salinity are the most relevant parameters. Salicornia stricta sites are characterized by a variety of grain sizes, reduced conditions in the rhizosphere, highest water contents (median: 71.5 Vol-%) and lowest Eh values (median: ?19.0 mV), indicating the best adaptation to anaerobic soil conditions. Salicornia procumbens occurs on aerated soils (median Eh: 455.6 mV) with high sand contents independent to position relative to mean high tide level. Exhibiting the lowest (11.5‰) and highest soil salinities (41.7‰), even developing in salt pans (136‰), Salicornia europaea feature a great ecological amplitude regarding temporal variations of salinity. These findings underline the ecotypic and phenotypic plasticity of Salicornia species and offer a promising approach for further experimental settings focussing on phenotypic adaptions and ecological amplitudes of Salicornia taxa and ecotypes.     

Coupling PCSWMM and WASP to Evaluate Green Stormwater Infrastructure Impacts to Storm Sediment Loads in an Urban Watershed

We coupled rainfall–runoff and instream water quality models to evaluate total suspended solids (TSS) in Wissahickon Creek, a mid‐sized urban stream near Philadelphia, Pennsylvania. Using stormwater runoff and instream field data, we calibrated the model at a subdaily scale and focused on storm responses. We demonstrate that treating event mean concentrations as a calibration parameter rather than a fixed input can substantially improve model performance. Urban stormwater TSS concentrations vary widely in time and space and are difficult to represent simply. Suspended and deposited sediment pose independent stressors to stream biota and model results suggest that both currently impair stream health in Wissahickon Creek. Retrofitting existing detention basins to prioritize infiltration reduced instream TSS loads by 20%, suggesting that infiltration mitigates sediment more effectively than detention. Infiltrating stormwater from 30% of the watershed reduced instream TSS loads by 47% and cut the frequency of TSS exceeding 100 mg/L by half. Settled loads and the frequency of high TSS values were reduced by a smaller fraction than suspended loads and duration at high TSS values. A widely distributed network of infiltration‐focused projects is an effective stormwater management strategy to mitigate sediment stress. Coupling rainfall–runoff and water quality models is an important way to integrate watershed‐wide impacts and evaluate how management directly affects urban stream health.     

Topographic, bioclimatic, and vegetation characteristics of three ecoregion classification systems in North America: comparisons along continent-wide transects

Ecoregion classification systems are increasingly used for policy and management decisions, particularly among conservation and natural resource managers. A number of ecoregion classification systems are currently available, with each system defining ecoregions using different classification methods and different types of data. As a result, each classification system describes a unique set of ecoregions. To help potential users choose the most appropriate ecoregion system for their particular application, we used three latitudinal transects across North America to compare the boundaries and environmental characteristics of three ecoregion classification systems [Küchler, World Wildlife Fund (WWF), and Bailey]. A variety of variables were used to evaluate the three systems, including woody plant species richness, normalized difference in vegetation index (NDVI), and bioclimatic variables (e.g., mean temperature of the coldest month) along each transect. Our results are dominated by geographic patterns in temperature, which are generally aligned north-south, and in moisture, which are generally aligned east-west. In the west, the dramatic changes in physiography, climate, and vegetation impose stronger controls on ecoregion boundaries than in the east. The Küchler system has the greatest number of ecoregions on all three transects, but does not necessarily have the highest degree of internal consistency within its ecoregions with regard to the bioclimatic and species richness data. In general, the WWF system appears to track climatic and floristic variables the best of the three systems, but not in all regions on all transects.     

Solubility and calorimetric study of the effects of gas environment on the decomposition of o-nitrobenzoyl chloride

When ortho-nitrated benzoic acids are chlorinated in xylene and acetonitrile, the product gases, HCl and SO₂, dissolve in the solvent mixture. Previously measured solubilities [Lever, S. D., Papadaki, M. (2004a). o-Chlorination of 2-nitrobenzoic acid with thionly chloride in xylene and acetonitrile. Solubility study of hydrogen chloride and sulphur dioxide in xylene and acetonitrile, IChemE transactions part B. Process Safety and Environmental Protection. 48–60.] were compared to other published data and found to be in very good agreement. The heat of solution of SO₂ in xylene was evaluated calorimetrically and compared to the value obtained from our previous experimental work. In our previous work [Lever, S. D., Papadaki, M. (2004b). Study of condition-dependent decomposition reactions—the thermal behaviour and decomposItion of 2-nitrobenzoyl chloride part_I. Journal of Hazardous Materials. 115; pp. 91–100], it was reported that the products of the decomposition are condition dependent. The current study showed that the decomposition is extensively promoted by the presence of HCl. This has important safety implications should the process operating temperature be reduced and HCl solution in the solvent mixture be increased. If a thermal runaway began in the increased availability of HCl, an undesirable escalation of the runaway could occur.     

Innovation in environmental policy: the National Environmental Policy Act of the US and the Resource Management Act of New Zealand

On enactment, both the National Environmental Policy Act (NEPA), 1970 of the US and the Resource Management Act (RMA), 1991 of New Zealand received accolades for innovativeness. However, is such praise justified when these acts are explored through the literature on policy innovation? This paper suggests that it is. More importantly, recognizing how different attributes of innovation contribute to having a policy adopted suggests what the crafters of future environmental policies might do well to consider. It is critical to attend to the political climate in which a policy is being drafted.     

Biodegradation of Dispersed Forties Crude and Alaskan North Slope Oils in Microcosms Under Simulated Marine Conditions

For oil spills in the open sea, operational experience has found that conventional response techniques, such as mechanical recovery, tend to remove only a small fraction of oil during major spills, a recent exception being the Mississippi River spill in Louisiana [Spill Sci. Technol. Bull. 7 (2002) 155]. By contrast, the use of dispersants can enable significant fractions of oil to be removed from the sea surface by dispersing the oil into the water column. It is thought that once dispersed the oil can biodegrade in the water column, although there is little information on the mechanism and rate of biodegradation. Two studies were undertaken on dispersion, microbial colonisation and biodegradation of Forties crude and Alaskan North Slope (ANS) oils under simulated marine conditions. The study using the Forties crude lasted 27 days and was carried out in conditions simulating estuarine and coastal conditions in waters around the UK (15 °C and in the presence of nutrients, 1 mg N-NO₃/l), while the ANS study simulated low temperature conditions typical of Prince William Sound (8 °C) and took place over 35 days. The results of both studies demonstrated microbial colonisation of oil droplets after 4 days, and the formation of neutrally buoyant clusters consisting of oil, bacteria, protozoa and nematodes. By day 16, the size of the clusters increased and they sank to the bottom of the microcosms, presumably because of a decrease in buoyancy due to oil biodegradation, however biodegradation of n-alkanes was confirmed only in the Forties study. No colonisation or biodegradation of oil was noted in the controls in which biological action was inhibited. Oil degrading bacteria proliferated in all biologically active microcosms. Without dispersant, the onset of colonisation was delayed, although microbial growth rates and population size in ANS were greater than observed with the Forties. This difference reflected the greater droplet number seen with ANS at 8 °C than with Forties crude at 15 °C. Although these studies differed by more than one variable, complicating comparison, the findings suggest that dispersion (natural or chemical) changes the impact of the oil on the marine environment, potentially having important implications for management of oil spills in relation to the policy of dispersant use in an oil spill event.     

Green gains? planning by agreement and nature conservation

Current planning policy places increased emphasis on the protection of the natural environment. The negotiation of planning agreements between local authorities and developers has emerged as one route through which the private sector has sought to compensate for the loss of environmental resources arising from development. We argue that the utilization of conservation gain mirrors the valuation procedures for public goods found within cost — benefit techniques, which may be inappropriate for the treatment of natural environmental systems. The paper examines the negotiation of these gains from the perspective of different actors in the land development process. Both quantitative and interview material from four local planning authorities are used. The paper concludes by considering the scope for a broader use of conservation gain.