Easing conservation? Conservation easements, public accountability and neoliberalism

This paper examines the use of conservation easements, with a focus on California. Conservation easements are now the dominant tool used for private land conservation in the United States. Easements are in many ways a paradigmatic neoliberal environmental policy tool. They privatize and re-scale a great deal of land conservation decision-making authority; they are market-based; they provide financial incentives for participation rather than punishment for non-compliance; and they commodify new property rights. However, these neoliberalisms are incorporated in uneven, and sometimes contradictory, ways that emphasize the gulf between neoliberal ideologies and “actually existing neoliberalisms.” Most critically, as a result of extensive public funding and management, conservation easements are not nearly as private (and thus not as neatly neoliberal) as they sometimes seem. Conservation easements are often heralded as a “win–win” land conservation strategy. I argue that the extent to which conservation easements may be construed as win–win solutions depends a great deal on who is included in the calculation of winners and losers. I contend that using and governing easements as if they are private elides complex questions about larger public costs and benefits. This obscures the large number of people and institutions (both state and private) that will likely need to be involved in governing conservation easements in the long term.     

Ecological Signatures of Anthropogenically Altered Tidal Exchange in Estuarine Ecosystems

One of the most conspicuous anthropogenic disturbances to estuaries worldwide has been the alteration of freshwater and tidal influence through the construction of water control structures (dikes, tide gates, culverts). Few studies have rigorously compared the responses of differing groups of organisms that serve as contrasting conservation targets to such anthropogenic disturbances in estuarine ecosystems. Elkhorn Slough in central California includes a spectrum of tidally restricted habitats behind water control structures and habitats experiencing full tidal exchange. To assess community composition for several different taxa in habitats with varying tidal exchange, we employed a variety of field approaches and synthesized results from several different studies. Overall, we found that communities at sites with moderately restricted tidal exchange were fairly similar to those with full tidal exchange, but those with extremely restricted tidal exchange were markedly different from other categories. These differences in community composition are likely the result of several factors, including restricted movement due to physical barriers, differences in water quality characteristics, and differences in habitat structure. Indeed, in this study, we found that water quality characteristics strongly vary with tidal restriction and may strongly influence patterns of species presence or absence. We also found that different conservation targets showed contrasting responses to variation in tidal exchange. Full exchange appears to favor native oysters, commercially valuable flatfish, migratory shorebirds, and site-level biodiversity. Minimal tidal exchange due to water control structures supports a suite of estuarine endemics (including the tidewater goby and California brackish snail) not represented elsewhere and minimizes invasions by non-native marine species. Altogether, our results suggest that total estuary-wide biodiversity may be enhanced with a mosaic of tidal exchange regimes.     

High-accuracy measurements of total dissolved inorganic carbon in the ocean: comparison of alternate detection methods

High-accuracy measurements of total dissolved inorganic carbon in the ocean are currently performed using an automated coulometric system based on that described by Johnson et al. (1987). These measurements require highly-trained technicians and the manipulation of expensive and hazardous chemicals. We tested an alternate detection method based on non-dispersive infra-red analysis. All of the dissolved carbonate species from a seawater sample were extracted as CO₂ gas by acidification and nitrogen stripping. The CO₂ gas was then quantitatively detected with either a coulometric system or an infra-red analyzer. The reproducibility of the two detection methods is similar. Although the infra-red system requires further testing, it holds promise as an alternative to coulometry. The detection of the CO₂ gas by infra-red analysis presents several advantages over coulometric detection: it simplifies and reduces the cost of the measurements, shortens the analysis time, reduces the sample size requirement by at least a factor of five, and allows us to consider complete automation of the system for underway surface seawater measurements.     

Current state of water quality indicators in urban streams in New Zealand

ABSTRACT

National assessments have highlighted that urban streams have some of the poorest water quality in New Zealand, yet there has been no analysis focussing on these streams. In this study we defined urban streams as >15% catchment urban land cover and used monitoring data to assess several indicators of water quality including dissolved metals, nutrients, bacteria and the macroinvertebrate community index. We investigated associations between the indicators and urban land cover, imperviousness and geographic location. Water quality was highly variable, within and between monitored sites; and invariably poor when compared to water quality criteria. Dissolved zinc was positively related to the proportion of urban land cover and imperviousness in the upstream catchment. There were significant differences in ammoniacal-N, nitrate-N, turbidity, MCI, dissolved zinc and E. coli between geographic locations. The analysis indicates that if urban development continues in its current form, increases in urban land cover around New Zealand can be expected to result in further declines in water quality and a reduced likelihood that water quality objectives will be achieved at impacted locations.     

Tidal-Fluvial and Estuarine Processes in the Lower Columbia River: II. Water Level Models,Floodplain Wetland Inundation,and System Zones

Spatially varying water-level regimes are a factor controlling estuarine and tidal-fluvial wetland vegetation patterns. As described in Part I, water levels in the Lower Columbia River and estuary (LCRE) are influenced by tides, river flow, hydropower operations, and coastal processes. In Part II, regression models based on tidal theory are used to quantify the role of these processes in determining water levels in the mainstem river and floodplain wetlands, and to provide 21-year inundation hindcasts. Analyses are conducted at 19 LCRE mainstem channel stations and 23 tidally exposed floodplain wetland stations. Sum exceedance values (SEVs) are used to compare wetland hydrologic regimes at different locations on the river floodplain. A new predictive tool is introduced and validated, the potential SEV (pSEV), which can reduce the need for extensive new data collection in wetland restoration planning. Models of water levels and inundation frequency distinguish four zones encompassing eight reaches. The system zones are the wave- and current-dominated Entrance to river kilometer (rkm) 5; the Estuary (rkm-5 to 87), comprised of a lower reach with salinity, the energy minimum (where the turbidity maximum normally occurs), and an upper estuary reach without salinity; the Tidal River (rkm-87 to 229), with lower, middle, and upper reaches in which river flow becomes increasingly dominant over tides in determining water levels; and the steep and weakly tidal Cascade (rkm-229 to 234) immediately downstream from Bonneville Dam. The same zonation is seen in the water levels of floodplain stations, with considerable modification of tidal properties. The system zones and reaches defined here reflect geological features and their boundaries are congruent with five wetland vegetation zones.     

Plant and insect remains from the Wisconsinan interstadial/stadial transition at Wedron, north-central Illinois

Organic material exposed within a small swale fill in Pit 6 of the Wedron Silica Sand Co. near Wedron in LaSalle County, Illinois, includes well-preserved pollen, plant macrofossils, and insect remains. This material occurs in slackwater sediment in the lower part of the Peddicord Formation, which was deposited as existing valleys were dammed by fluvial aggradation during the initial late Wisconsinan advance of Laurentide ice into the Wedron area. Wood from the organic horizon has a radiocarbon age of 21,460 ± 470 yr B.P. (ISGS-1486). The pollen spectrum is dominated by Picea, Pinus, and Cyperaceae. Plant macrofossils comprise a mix of boreal-forest taxa, including Picea, Larix laricina, and the moss Campylium stellatum; subarctic species including Betula glandulosa, Empetrum nigrum, and Selaginella selaginoides; along with the predominantly arctic Vaccinium uliginosum var. alpinum, Dryas integrifolia, and Rhododendron lapponicum. The insect fauna contains the western montane ground beetle Opisthius richardsoni; several arctic-subarctic ground beetles including Diacheila polita, Helophorus sibiricus, and Pterostichus (Cryobius) caribou; and a diverse assemblage of insects that today inhabit the boreal forest. We interpret the biotic record to record a phase in the transition from closed boreal forest to open tundra as climatic conditions deteriorated in advance of continental glaciation.     

Cations in olivine,Part 2: Diffusion in olivine xenocrysts,with applications to petrology and mineral physics

Diffusivities for calcium, iron, magnesium, manganese and aluminum have been measured for St. John's olivine undergoing cation exchange with synthetic basaltic melts. The variety of temperature, pressure and fO₂ conditions under which the diffusivities were measured complement the equilibrium-partitioning study of calcium in olivine-bearing basalts by Jurewicz and Watson, 1988. Olivine was found to be anisotropic with respect to the diffusion of calcium, iron, magnesium and manganese. This anisotropy is a weak function of temperature, but strongly dependent upon oxygen fugacity.Because diffusion is independent of olivine composition over the small range of compositions used in this study, it could be shown that the absolute values of the diffusion coefficients were also functions of temperature and fO₂. At near-atmospheric total pressure and an oxygen fugacity of 10^–8atm, D _Fe>D _Mn>D _Ca and D _MgD _Mn for a range of geologically reasonable temperatures. These relative diffusivities were shown to change with oxygen fugacity. The power-law dependence of diffusion on oxygen partial-pressure was determined for each cation and the results are consistent with the range of values given by Stocker (1978) and by other workers.For Ca and Fe, the effect of hydrostatic pressure on diffusion appears to be weak, at least for transport parallel to the c crystallographic direction. Unfortunately, no true activation volumes (or other pressure-related parameters) could be computed because the oxygen fugacity was not held constant over changes in pressure, and because accurate post-experiment reconstruction of sample orientation was not possible. Al was found to enter high-pressure olivines at concentrations of up to 0.14 weight percent, thus allowing aluminum diffusion to be characterized. The diffusivity of aluminum is, within error, the same as iron at 20 kb at 1430° C at the ambient fO₂ of our piston-cylinder cells. This correspondence suggests that diffusion of Al may depend on transport of either Fe or of Fe ⁺³ defects. While the results of these experiments are generally consistent with results published elsewhere, there are important inconsistencies. Tracer diffusion and interdiffusion in pure, ordered, olivine endmembers (e.g., tephroite and forsterite) showed significantly higher activation energies. This discrepancy could reflect the role of Fe⁺³ defects in diffusion; however, it may also suggest that order-disorder phenomena may be significant factors influencing diffusion in analog systems.The results of this study are applied to four petrologic problems: (1) calculation of rates of equilibration for olivine xenocrysts; (2) calculation of closure temperatures for the CaO/MgO olivine/basalt geothermometer (Jurewicz and Watson 1988); (3) delineation of an intrinsic-/O₂ geobarometer; and (4) investigation of the dependence of olivine dissolution upon crystallographic orientation. In addition, it is demonstrated that diffusion-exchange experiments are useful for studying the dominant point-defect mechanisms for cation diffusion.Currently, a visiting scientist with Air Force Wright Aeronautical Laboratories Materials Laboratory (MLLM), Wright-Patterson AFB, OH 45433     

Combined stomach content and δ13C/δ15N analyses of oilfish,escolar, snake mackerel and lancetfish in the western North Atlantic

Large, mesopelagic teleost fishes have a potentially keystone position in the ecology of the pelagic water column, yet remain relatively unstudied when compared with large, commercially important, epipelagic fishes. Here, the ecological roles of four, large, vertically migrating teleosts were examined. Stomach content analyses were performed on 48 oilfish (Ruvettus pretiosis), 35 escolar (Lepidocybium flavobrunneum), 32 snake mackerel (Gempylus serpens) and seven lancetfish (Alepisaurus spp.) collected from pelagic longline gear in the Western North Atlantic Ocean from 2007 to 2010. Of these specimens, stable carbon and nitrogen isotope analyses were also performed on white dorsal muscle tissue from 33 oilfish, 16 escolar, 27 snake mackerel and seven lancetfish. Based on literature length‐at‐maturity values, all escolar, snake mackerel and lancetfish specimens were mature, while 13 of the 33 oilfish were juveniles. Crustaceans, annelids, salps, cephalopods and teleosts were present in the stomachs and were presumed to be prey items. A Kruskal–Wallis test showed the four species to be isotopically segregated in both δ¹³C and δ¹⁵N. Escolar were the most depleted in δ¹³C, followed by adult oilfish, juvenile oilfish and lancetfish, with snake mackerel the most enriched. The depletion in δ¹³C of adult oilfish and escolar may have been attributable to high C/N values, which were strongly correlated with length in oilfish, weakly correlated with length in escolar and moderately correlated with length in snake mackerel and lancetfish. The high C/N was likely due to the high lipid concentration of these fishes. Other factors that may have contributed to the depletion in δ¹³C may include spawning or a change in carbon source within the ecosystem. Large escolar occupied the highest trophic level (δ¹⁵N = 10.20), followed by snake mackerel (δ¹⁵N = 9.66), adult oilfish (δ¹⁵N = 9.32), lancetfish (δ¹⁵N = 9.05) and juvenile oilfish (δ¹⁵N = 7.83). A marked change in oilfish δ¹³C and C/N at 30–35 cm fork length coincided with a presumed length‐at‐maturity.     

A multi-tiered earthquake hazard model for Australia

Earthquakes result from tectonic processes, and their distribution is strongly influenced by large-scale geology and the tectonic stress field. However, earthquake hazard estimates, particularly ground motion recurrence, have traditionally been computed using source models based primarily on instrumental and historical seismicity. In areas of low to moderate seismicity such as Australia, large earthquakes commonly occur in areas which have experienced little or no recent activity, making it difficult to develop source models based solely on seismicity.

The seismotectonic model developed for Australia that is presented here (AUS5) is based on geology, geophysics, tectonics and seismicity. The model was developed using a number of tiers of information, so that new information can easily be incorporated. The information used includes, but is not limited to, tectonic provinces, basins and ranges, gravity, magnetic, topography, and seismicity, all on a regional scale. On a local scale, for a site-specific earthquake hazard study, active faulting can be incorporated to provide fault source zones.

An earthquake hazard map showing peak ground acceleration with a 10% chance of exceedance in 50 years for southeastern Australia using the geologically defined seismotectonic model AUS5 is presented as an indication of how the model performs.