Agronomic Water Mass Balance vs. Well Measurement for Assessing Ogallala Aquifer Depletion in the Texas Panhandle

The Ogallala Aquifer is depleting faster than it is being replenished. Interpretation of well data suggests that the water table in some counties is not declining, or not as much as might be expected in view of the amount of land being irrigated. As the Ogallala Aquifer in the Texas Panhandle receives almost no recharge, a possible explanation is that the current method of using well data for estimating the quantity of water remaining in the aquifer is underestimating water in storage. This study used an agronomic water mass balance approach to estimate how much water has been used for irrigation compared to amounts estimated by well data. The major finding was in counties where irrigation well capacities have declined significantly but irrigation is continuing, there is likely more water in storage than presently estimated, but the amounts of water being used for irrigation in those counties are greater than estimated changes of water in storage. The proposed hypothesis for this difference is there are mounds of water between wells that are not being accounted for and data are presented and discussed to support this conjecture.     

A review of ecological mitigation measures in UK environmental statements with respect to sustainable development

SUMMARY

The European and UK legislation on environmental assessment (EA), as well as requiring assessment of significant ecological effects, also requires development proponents to recommend mitigation measures for adverse impacts.

Drawing on a review of proposed ecological mitigation measures in 194 environmental statements (ES) for UK development proposals, this paper highlights problems with the current legislation in ensuring that ecological impacts are mitigated effectively, with a view to sustainable development.

The review reveals confusion about the extent to which ecological mitigation is required. First, there is no objective basis for deciding which potentially adverse impacts should be mitigated. Proposed mitigation measures do not always relate directly to the ecological impacts identified in ES and there is a high risk of residual adverse effects. Second, there is no generally accepted method for evaluating the effectiveness of proposed mitigation measures, despite a clear recommendation from the UK's Department of the Environment (DOE, 1989) that an ‘assessment of the likely effectiveness’ of mitigation measures should be included in ES. Methods which can be used to evaluate the likely feasibility, costs and redistributional effects of ecological mitigation measures in EA are needed. Some of the factors which should be taken into account are considered in this paper.     

Microbial community phylogenetic and trait diversity declines with depth in a marine oxygen minimum zone

Oxygen minimum zones (OMZs) are natural physical features of the world's oceans. They create steep physiochemical gradients in the water column, which most notably include a dramatic draw down in oxygen concentrations over small vertical distances (<100 m). Microbial communities within OMZs play central roles in ocean and global biogeochemical cycles, yet we still lack a fundamental understanding of how microbial biodiversity is distributed across OMZs. Here, we used metagenomic sequencing to investigate microbial diversity across a vertical gradient in the water column during three seasons in the Eastern Tropical South Pacific (ETSP) OMZ. Based on analysis of small subunit ribosomal RNA (SSU rRNA) gene fragments, we found that both taxonomic and phylogenetic diversity declined steeply along the transition from oxygen-rich surface water to the permanent OMZ. We observed similar declines in the diversity of protein-coding gene categories, suggesting a decrease in functional (trait) diversity with depth. Metrics of functional and trait dispersion indicated that microbial communities are phylogenetically and functionally more overdispersed in oxic waters, but clustered within the OMZ. These dispersion patterns suggest that community assembly drivers (e.g., competition, environmental filtering) vary strikingly across the oxygen gradient. To understand the generality of our findings, we compared OMZ results to two marine depth gradients in subtropical oligotrophic sites and found that the oligotrophic sites did not display similar patterns, likely reflecting unique features found in the OMZ. Finally, we discuss how our results may relate to niche theory, diversity-energy relationships and stress gradients.     

The Influence of Age on Cadmium Concentrations in Seabirds

The effects of age on cadmium concentrations was investigated in Cory's shearwater, Calonectris diomedea, Lesser black-backed gull, Larus fuscus, and great skuas, Catharacta skua. There was no evidence for the continued accumulation of cadmium with increasing adult age. Adult shearwaters did have higher concentrations of cadmium compared to young fledglings, but there was no significant difference between cadmium concentrations in adult and sub-adult gulls. In addition, the sample of great skuas were of known age (3–22 yrs old) and showed no evidence of increasing cadmium concentrations with adult age in liver or kidney. However, it is possible that age accumulation of cadmium in great skuas was masked by individual dietary preferences overriding the effects of increasing age. It is often assumed that cadmium concentrations continue to accumulate with increasing adult age, but seabirds may have evolved some as yet unknown mechanism for excretion or more rapid turnover of cadmium than previously thought. The implications of this for the use of seabirds as biomonitors is discussed.     

Elevated atmospheric ozone increases concentration of insecticidal Bacillus thuringiensis (Bt) Cry1Ac protein in Bt Brassica napus and reduces feeding of a Bt target herbivore on the non-transgenic parent

Sustained cultivation of Bacillus thuringiensis (Bt) transgenic crops requires stable transgene expression under variable abiotic conditions. We studied the interactions of Bt toxin production and chronic ozone exposure in Bt cry1Ac-transgenic oilseed rape and found that the insect resistance trait is robust under ozone elevations. Bt Cry1Ac concentrations were higher in the leaves of Bt oilseed rape grown under elevated ozone compared to control treatment, measured either per leaf fresh weight or per total soluble protein of leaves. The mean relative growth rate of a Bt target herbivore, Plutella xylostella L. larvae was negative on Bt plants in all ozone treatments. On the non-transgenic plants, larval feeding damage was reduced under elevated ozone. Our results indicate the need for monitoring fluctuations in Bt toxin concentrations to reveal the potential of ozone exposure for altering dosing of Bt proteins to target and non-target herbivores in field environments experiencing increasing ozone pollution.     

Housing growth,forests, and public lands in Northern Wisconsin from 1940 to 2000

Rural, forested areas throughout the United States are experiencing strong housing growth with potentially detrimental impacts on the environment. In this paper, we quantify housing growth in Northern Wisconsin over the last sixty years to determine if growth rates were higher near public lands, which may represent an important recreational amenity. We used data from the U.S. Census to produce decadal housing density estimates, “backcasts,” from 1940 to 2000 for northern Wisconsin to examine “rural sprawl” in northern Wisconsin and its relationship to forested areas and public lands. We integrated housing density estimates with the 1992/1993 National Land Cover Dataset to examine the relationship between rural sprawl and land cover, especially forests. Between 1940 and 2000, private land with <2 housing units/km² decreased from 47% to 21% of the total landscape. Most importantly, housing growth was concentrated along the boundaries of public lands. In 14 of the 19 counties that we studied, housing growth rates within 1 km of a public land boundary exceeded growth rates in the remainder of the county, and three of the five counties that did not exhibit this pattern, were the ones with the least amount of public land. Future growth can be expected in areas with abundant natural amenities, highlighting the critical need for additional research and effective natural resource management and regional planning to address these challenges.     

The effect of summer drought on the predictability of local extinctions in a butterfly metapopulation

The ecological impacts of extreme climatic events on population dynamics and community composition are profound and predominantly negative. Using extensive data of an ecological model system, we tested whether predictions from ecological models remain robust when environmental conditions are outside the bounds of observation. We observed a 10-fold demographic decline of the Glanville fritillary butterfly (Melitaea cinxia) metapopulation on the Åland islands, Finland in the summer of 2018 and used climatic and satellite data to demonstrate that this year was an anomaly with low climatic water balance values and low vegetation productivity indices across Åland. Population growth rates were strongly associated with spatiotemporal variation in climatic water balance. Covariates shown previously to affect the extinction probability of local populations in this metapopulation were less informative when populations were exposed to severe drought during the summer months. Our results highlight the unpredictable responses of natural populations to extreme climatic events.     

Sustainable Use of Biotechnology for Bioenergy Feedstocks

Done correctly, cellulosic bioenergy should be both environmentally and economically beneficial. Carbon sequestration and decreased fossil fuel use are both worthy goals in developing next-generation biofuels. We believe that biotechnology will be needed to significantly improve yield and digestibility of dedicated perennial herbaceous biomass feedstocks, such as switchgrass and Miscanthus, which are native to the US and China, respectively. This Forum discusses the sustainability of herbaceous feedstocks relative to the regulation of biotechnology with regards to likely genetically engineered traits. The Forum focuses on two prominent countries wishing to develop their bioeconomies: the US and China. These two countries also share a political desire and regulatory frameworks to enable the commercialization and wide release of transgenic feedstocks with appropriate and safe new genetics. In recent years, regulators in both countries perform regular inspections of transgenic field releases and seriously consider compliance issues, even though the US framework is considered to be more mature and stringent. Transgene flow continues to be a pertinent environmental and regulatory issue with regards to transgenic plants. This concern is largely driven by consumer issues and ecological uncertainties. Regulators are concerned about large-scale releases of transgenic crops that have sexually compatible crops or wild relatives that can stably harbor transgenes via hybridization and introgression. Therefore, prior to the commercialization or extensive field testing of transgenic bioenergy feedstocks, we recommend that mechanisms that ensure biocontainment of transgenes be instituted, especially for perennial grasses. A cautionary case study will be presented in which a plant’s biology and ecology conspired against regulatory constraints in a non-biomass crop perennial grass (creeping bentgrass, Agrostis stolonifera), in which biocontainment was not attained. Appropriate technologies that could be applied to perennial grass feedstocks for biocontainment are discussed.     

What have we learnt from the European Union's Emissions Trading System?

The EU Emissions Trading System (ETS) demonstrated the ability to design and launch a large-scale trading system in a short period of time. The path from initial reticence about emissions trading to implementation of the world's largest program is an important history. Three issues play a large role in the evaluation of the program to date and its on-going development: allocation plans, cost uncertainty, and leakage of emissions to abroad. Decisions in Phase I and II (2005-2012) were responsive to questions of political feasibility and implementation, but some of these decisions including allocation in particular will be substantially revised in Phase III (2013-2020).