ECONOMIC COSTS AND BENEFITS OF INSTREAM FLOW PROTECTION FOR ENDANGERED SPECIES IN AN INTERNATIONAL BASIN1

ABSTRACT: The U.S. Endangered Species Act (ESA) restricts federal agencies from carrying out actions that jeopardize the continued existence of any endangered species. The U.S. Supreme Court has emphasized that the language of the ESA and its amendments permits few exceptions to the requirement to give endangered species the highest priority. This paper estimates economic costs associated with one measure for increasing instream flows to meet critical habitat requirements of the endangered Rio Grande silvery minnow. Impacts are derived from an integrated regional model of the hydrology, economics, and institutions of the upper Rio Grande Basin in Colorado, New Mexico, Texas, and Mexico. One proposal for providing minimum streamflows to protect the silvery minnow from extinction would provide guaranteed year round streamflows of at least 50 cubic feet per second in the San Acacia reach of the upper Rio Grande. These added flows can be accomplished through reduced surface diversions by New Mexico water users in dry years when flows would otherwise be reduced below the critical level required by the minnow. Based on a 44‐year simulation of future inflows to the basin, we find that some agricultural users suffer damages, but New Mexico water users as a whole do not incur damages from a policy that reduces stream depletions sufficiently to provide habitat for the minnow. The same policy actually benefits downstream users, producing average annual benefits of over $200,000 per year for west Texas agriculture, and over $1 million for El Paso municipal and industrial water users, respectively. Economic impacts of instream flow deliveries for the minnow are highest in drought years.     

Dam Design can Impede Adaptive Management of Environmental Flows: A Case Study from the Opuha Dam, New Zealand

The Opuha Dam was designed for water storage, hydropower, and to augment summer low flows. Following its commissioning in 1999, algal blooms (dominated first by Phormidium and later Didymosphenia geminata) downstream of the dam were attributed to the reduced frequency and magnitude of high-flow events. In this study, we used a 20-year monitoring dataset to quantify changes associated with the dam. We also studied the effectiveness of flushing flows to remove periphyton from the river bed. Following the completion of the dam, daily maximum flows downstream have exceeded 100 m³ s^?1 only three times; two of these floods exceeded the pre-dam mean annual flood of 203 m³ s^?1 (compared to 19 times >100 m³ s^?1 and 6 times >203 m³ s^?1 in the 8 years of record before the dam). Other changes downstream included increases in water temperature, bed armoring, frequency of algal blooms, and changes to the aquatic invertebrate community. Seven experimental flushing flows resulted in limited periphyton reductions. Flood wave attenuation, bed armoring, and a shortage of surface sand and gravel, likely limited the effectiveness of these moderate floods. Floods similar to pre-dam levels may be effective for control of periphyton downstream; however, flushing flows of that magnitude are not possible with the existing dam infrastructure. These results highlight the need for dams to be planned and built with the capacity to provide the natural range of flows for adaptive management, particularly high flows.     

Ambient ozone effects on gas exchange and total non-structural carbohydrate levels in cutleaf coneflower (Rudbeckia laciniata L.) growing in Great Smoky Mountains National Park

Ozone-sensitive and -tolerant individuals of cutleaf coneflower (Rudbeckia laciniata L.) were compared for their gas exchange characteristics and total non-structural carbohydrates at Purchase Knob, a high elevation site in Great Smoky Mountains National Park, USA. Photosynthesis and stomatal conductance decreased with increased foliar stipple. Sensitive plants had lower photosynthetic rates for all leaves, except the very youngest and oldest when compared to tolerant plants. Stomatal conductance decreased with increasing leaf age, but no ozone-sensitivity differences were found. Lower leaves had less starch than upper ones, while leaves on sensitive plants had less than those on tolerant plants. These results show that ambient levels of ozone in Great Smoky Mountains National Park can adversely affect gas exchange, water use efficiency and leaf starch content in sensitive coneflower plants. Persistence of sensitive genotypes in the Park may be due to physiological recovery in low ozone years.     

A Method to Assess and Define Environmental Flow Rules for Large Jurisdictional Regions1

Snelder, Ton, Doug Booker, and Nicolas Lamouroux, 2011. A Method to Assess and Define Environmental Flow Rules for Large Jurisdictional Regions. Journal of the American Water Resources Association (JAWRA) 47(4):828‐840. DOI: 10.1111/j.1752‐1688.2011.00556.x Abstract: Hydrological rules of thumb are used across jurisdictional regions to set minimum flows and allocation limits that apply by default (i.e., when more detailed site‐scale studies have not been carried out). Uniform rules do not account for spatial variation in environmental characteristics, resulting in inconsistent consequences for the protection of ecosystems, and the reliability of water resources. We developed a method for assessing hydrological rules of thumb that describes their consequences for protection of the ecosystem (in terms of retention of physical habitat) and the reliability of the water resource. The method links regionalized flow duration curves, at‐station hydraulic geometry, and generalized physical habitat models to make assessments at many locations across a region. The method estimates, for a given set of rules, the retained physical habitat for specified taxa/life stages and the proportion of the time abstractions are restricted. We applied the method to assess a set of rules that are proposed as default minimum flows and allocation limits for New Zealand rivers. The assessment showed that the minimum flow rules had variable consequences. The method could be used to quantify the tradeoff between environmental protection and water resources availability and reliability.     

State and potential management to improve water quality in an agricultural catchment relative to a natural baseline

Land use change and the expansion of dairying are perceived as the cause of poor water quality in the 1881 km² Pomahaka catchment in Otago, New Zealand. A study was conducted to determine the long-term trend at four sites, and current state in 13 sub-catchments, of water quality. Drains in 2 dairy-farmed sub-catchments were also sampled to determine their potential as a point source of stream contamination. Data highlighted an overall increase in the concentration of phosphorus (P) fractions at long-term sites. Loads of contaminants (nitrogen (N) and P fractions, sediment and Escherichia coli) were greatest in those sub-catchments with the most dairying. Baseline (without human influence) contaminant concentrations suggested that there was considerable scope for decreasing losses. At most sites, baseline concentrations were <20% of current median concentrations. Contaminant losses via drainage were recorded despite there being no rainfall that day and attributed to applying too much effluent onto wet soil. Modelling of P concentrations in one dairy-farmed sub-catchment suggested that up to 58% of P losses came from point sources, like bad effluent practice and stock access to streams. A statistical test to detect “contaminated” drainage was developed from historical data. If this test had been applied to remove contaminated drainage from samples of the two dairy-farmed sub-catchments, median contaminant concentrations and loads would have decreased by up to 58% (greater decreases were found for E. coli, ammoniacal-N and total P than other contaminants). This suggests that better uptake of strategies to mitigate contamination, such as deferred effluent irrigation (and low rate application), could decrease drainage losses from dairy-farmed land and thereby improve water quality in the Pomahaka catchment.     

Predicting Periphyton Cover Frequency Distributions across New Zealand's Rivers

Regression models of mean and mean annual maximum (MAM) cover were derived for two categories of periphyton cover (filaments and mats) using 22 years of monthly monitoring data from 78 river sites across New Zealand. Explanatory variables were derived from observations of water quality variables, hydrology, shade, bed sediment grain size, temperature, and solar radiation. The root mean square errors of these models were large (75‐95% of the mean of the estimated values). The at‐site frequency distributions of periphyton cover were approximated by the exponential distribution, which has the mean cover as its single parameter. Independent predictions of cover distributions at all sites were calculated using the mean predicted by the regression model and the theoretical exponential distribution. The probability that cover exceeds specified thresholds and estimates of MAM cover, based on the predicted distributions, had large uncertainties (~80‐100%) at the site scale. However, predictions aggregated by classes of an environmental classification accurately predicted the proportion of sites for which cover exceeded nominated criteria in the classes. The models are useful for assessing broad‐scale patterns in periphyton cover and for estimating changes in cover with changes in nutrients, hydrological regime, and light.     

Ecological issues related to ozone: agricultural issues

Research on the effects of ozone on agricultural crops and agro-ecosystems is needed for the development of regional emission reduction strategies, to underpin practical recommendations aiming to increase the sustainability of agricultural land management in a changing environment, and to secure food supply in regions with rapidly growing populations. Major limitations in current knowledge exist in several areas: (1) Modelling of ozone transfer and specifically stomatal ozone uptake under variable environmental conditions, using robust and well-validated dynamic models that can be linked to large-scale photochemical models lack coverage. (2) Processes involved in the initial reactions of ozone with extracellular and cellular components after entry through the stomata, and identification of key chemical species and their role in detoxification require additional study. (3) Scaling the effects from the level of individual cells to the whole-plant requires, for instance, a better understanding of the effects of ozone on carbon transport within the plant. (4) Implications of long-term ozone effects on community and whole-ecosystem level processes, with an emphasis on crop quality, element cycling and carbon sequestration, and biodiversity of pastures and rangelands require renewed efforts.The UNECE Convention on Long Range Trans-boundary Air Pollution shows, for example, that policy decisions may require the use of integrated assessment models. These models depend on quantitative exposure-response information to link quantitative effects at each level of organization to an effective ozone dose (i.e., the balance between the rate of ozone uptake by the foliage and the rate of ozone detoxification). In order to be effective in a policy, or technological context, results from future research must be funnelled into an appropriate knowledge transfer scheme. This requires data synthesis, up-scaling, and spatial aggregation. At the research level, interactions must be considered between the effects of ozone and factors that are either directly manipulated by man through crop management, or indirectly changed. The latter include elevated atmospheric CO(2), particulate matter, other pollutants such as nitrogen oxides, UV-B radiation, climate and associated soil moisture conditions.     

Reframing the concept of alternative livelihoods

Alternative livelihood project (ALP) is a widely used term for interventions that aim to reduce the prevalence of activities deemed to be environmentally damaging by substituting them with lower impact livelihood activities that provide at least equivalent benefits. ALPs are widely implemented in conservation, but in 2012, an International Union for Conservation of Nature resolution called for a critical review of such projects based on concern that their effectiveness was unproven. We focused on the conceptual design of ALPs by considering their underlying assumptions. We placed ALPs within a broad category of livelihood‐focused interventions to better understand their role in conservation and their intended impacts. We dissected 3 flawed assumptions about ALPs based on the notions of substitution, the homogenous community, and impact scalability. Interventions based on flawed assumptions about people's needs, aspirations, and the factors that influence livelihood choice are unlikely to achieve conservation objectives. We therefore recommend use of a sustainable livelihoods approach to understand the role and function of environmentally damaging behaviors within livelihood strategies; differentiate between households in a community that have the greatest environmental impact and those most vulnerable to resource access restrictions to improve intervention targeting; and learn more about the social–ecological system within which household livelihood strategies are embedded. Rather than using livelihood‐focused interventions as a direct behavior‐change tool, it may be more appropriate to focus on either enhancing the existing livelihood strategies of those most vulnerable to conservation‐imposed resource access restrictions or on use of livelihood‐focused interventions that establish a clear link to conservation as a means of building good community relations. However, we recommend that the term ALP be replaced by the broader term livelihood‐focused intervention. This avoids the implicit assumption that alternatives can fully substitute for natural resource‐based livelihood activities.     

Leaf extracellular ascorbate in relation to O(3) tolerance of two soybean cultivars

Soybean [Glycine max (L.) Merr.] cultivars Essex and Forrest that exhibit differences in ozone (O(3)) sensitivity were used in greenhouse experiments to investigate the role of leaf extracellular antioxidants in O(3) injury responses. Charcoal-filtered air and elevated O(3) conditions were used to assess genetic, leaf age, and O(3) effects. In both cultivars, the extracellular ascorbate pool consisted of 80-98% dehydroascorbic acid, the oxidized form of ascorbic acid (AA) that is not an antioxidant. For all combinations of genotype and O(3) treatments, extracellular AA levels were low (1-30nmolg(-1) FW) and represented 3-30% of the total antioxidant capacity. Total extracellular antioxidant capacity was twofold greater in Essex compared with Forrest, consistent with greater O(3) tolerance of Essex. The results suggest that extracellular antioxidant metabolites in addition to ascorbate contribute to detoxification of O(3) in soybean leaves and possibly affect plant sensitivity to O(3) injury.     

The challenge of making ozone risk assessment for forest trees more mechanistic

Upcoming decades will experience increasing atmospheric CO₂ and likely enhanced O₃ exposure which represents a risk for the carbon sink strength of forests, so that the need for cause-effect related O₃ risk assessment increases. Although assessment will gain in reliability on an O₃ uptake basis, risk is co-determined by the effective dose, i.e. the plant's sensitivity per O₃ uptake. Recent progress in research on the molecular and metabolic control of the effective O₃ dose is reported along with advances in empirically assessing O₃ uptake at the whole-tree and stand level. Knowledge on both O₃ uptake and effective dose (measures of stress avoidance and tolerance, respectively) needs to be understood mechanistically and linked as a pre-requisite before practical use of process-based O₃ risk assessment can be implemented. To this end, perspectives are derived for validating and promoting new O₃ flux-based modelling tools.