Non-detection errors in a survey of persistent, highly-detectable vegetation species

Rare, small or annual vegetation species are widely known to be imperfectly detected with single site surveys by most conventional vegetation survey methods. However, the detectability of common, persistent vegetation species is assumed to be high, but without supporting research. In this study, we evaluate the extent of false-negative errors of perennial vegetation species in a systematic vegetation survey in arid South Australia. Analysis was limited to the seven most easily detected persistent vegetation species and controlled for observer skill. By comparison of methodologies, we then predict the magnitude of non-detection error rates in a second survey. The analysis revealed that all but one highly detectable perennial vegetation species was imperfectly detected (detection probabilities ranged from 0.22 to 0.83). While focussed in the Australian rangelands, the implications of this study are far reaching. Inferences drawn from systematic vegetation surveys that fail to identify and account for non-detection errors should be considered potentially flawed. The identification of this problem in vegetation surveying is long overdue. By comparison, non-detection has been a widely acknowledged, and dealt with, problem in fauna surveying for decades. We recommend that, where necessary, vegetation survey methodology adopt the methods developed in fauna surveying to cope with non-detection errors.     

Developing a New Operations Plan for the Bow River Basin Using Collaborative Modeling for Decision Support

The Bow River Basin is a cornerstone of Alberta's development. In 2010, stakeholders representing interests from agriculture, municipalities, environment, and more formed the Bow River Project Research Consortium to help determine the potential for improving the operations in the basin. At present, upstream reservoirs are operated primarily for hydropower, whereas downstream reservoirs are operated for irrigation. Through Collaborative Modeling for Decision Support the stakeholders were able to develop a new method for operating the system that would dramatically improve environmental performance. The main components of the new operating strategy called for: purchase or setting aside of a small amount of storage volume in the power reservoirs; a set of rules for releases from that storage; an agreement by the major irrigation districts with the largest water licenses to utilize their ability to shift deliveries to and from their large offstream storage reservoirs to allow for increased instream flows, and to allow junior water license holders (mainly municipal and industrial supplies) an uninterrupted water supply; limitations of reservoir fluctuations to improve inreservoir habitat for fisheries; and increased minimum flows throughout the system leading to improved environmental outcomes. Costs of this strategy were minimal, impacts on power revenue were estimated at <US$2 million/yr on average. Compensatory arrangements should be possible.     

Modelling and optimisation for design of hydrogen networks for multi-period operation

Hydrogen management is a problem of increasing importance: hydrogen consumption of refineries is rising sharply with additional capacities of hydrocracking and hydrotreating units in order to comply with cleaner fuel specifications. Product Specifications for transportation fuels are becoming increasingly stringent to ensure production of environmentally more benign fuels. Hydrogen management techniques currently do not account for varying operating conditions of hydrogen consuming processes and assume constant operating conditions. A novel approach is developed for the design of flexible hydrogen networks that can remain optimally operable under multiple periods of operation. The proposed methodology for multi-period design of hydrogen networks can take into account pressure differences, maximum capacity of existing equipment, and optimal placement of new equipment such as compressors.     

Effects of chytrid fungus and a glyphosate-based herbicide on survival and growth of wood frogs (Lithobates sylvaticus)

Anthropogenic-derived stressors in the environment, such as contaminants, are increasingly considered important cofactors that may decrease the immune response of amphibians to pathogens. Few studies, however, have integrated amphibian disease and contaminants to test this multiple-stressor hypothesis for amphibian declines. We examined whether exposure to sublethal concentrations of a glyphosate-based herbicide and two strains of the pathogenic chytrid fungus, Batrachochrytrium dendrobatidis (Bd) could: (1) sublethally affect wood frogs (Lithobates sylvaticus) by altering the time to and size at metamorphosis, and (2) directly affect survivability of wood frogs after metamorphosis. Neither Bd strain nor herbicide exposure alone significantly altered growth or time to metamorphosis. The two Bd strains did not differ in their pathogenicity, and both caused mortality in post-metamorphic wood frogs. There was no evidence of an interaction between treatments, indicating a lack of herbicide-induced susceptibility to Bd. However, the trends in our data suggest that exposure of wood frogs to a high concentration of glyphosate-based herbicide may reduce Bd-caused mortality compared to animals exposed to Bd alone. These results exemplify the complexities inherent when populations are coping with multiple stressors. In this case, the perceived stressor, glyphosate-based herbicide, appeared to affect the pathogen more than the host's immune system, relieving the host from disease-caused effects. This suggests caution when invoking multiple stressors as a cause for increased disease susceptibility and indicates that the effects of multiple stressors on disease outcome depend on the interrelationships of stressors to both the pathogen and the host.     

Stabilising cooperation through pragmatic tolerance: the case of the Parties to the Nauru Agreement (PNA) tuna fishery

Purse seine fishing of skipjack tuna in the Western and Central Pacific Ocean (WCPO) raises concern over increasing impacts on yellowfin and bigeye tuna by-catch. To address sustainability concerns, the Parties to the Nauru Agreement (PNA) adopted the vessel day scheme (VDS) for the management of purse seine fishing in the WCPO. The VDS has the potential to improve economic benefits for PNA members and to contribute to sustainability of the tuna stocks, and since 2012, has become an important mechanism to regulate fishing access rights in PNA waters. Despite this, monitoring and enforcement remains weak leading to violations of the agreement. Using a game theoretic framework, this paper examines the effectiveness of the VDS and its implications for fisheries regionalism. We examine the payoffs of member countries of the Nauru Agreement under full compliance and payoffs under the currently observed partial compliance. Our findings indicate that member states’ partial compliance with VDS rules plays a role in stabilising the agreement. Requiring full compliance, on the other hand, may encompass strong incentives for PNA members to deviate from the VDS since third parties offer attractive benefits in return for privileged access to fishing grounds. However, pragmatic tolerance of deviations from full VDS compliance seems to play a facilitative role in promoting cooperation and fisheries regionalism.

     

Midwest U.S. landscape change to 2020 driven by biofuel mandates

Meeting future biofuel targets set by the 2007 Energy Independence and Security Act (EISA) will require a substantial increase in production of corn. The Midwest, which has the highest overall crop production capacity, is likely to bear the brunt of the biofuel-driven changes. In this paper, we set forth a method for developing a possible future landscape and evaluate changes in practices and production between base year (BY) 2001 and biofuel target (BT) 2020. In our BT 2020 Midwest landscape, a total of 25 million acres (1 acre = 0.40 ha) of farmland was converted from rotational cropping to continuous corn. Several states across the Midwest had watersheds where continuous corn planting increased by more than 50%. The output from the Center for Agriculture and Rural Development (CARD) econometric model predicted that corn grain production would double. In our study we were able to get within 2% of this expected corn production. The greatest increases in corn production were in the Corn Belt as a result of conversion to continuous corn planting. In addition to changes to cropping practices as a result of biofuel initiatives we also found that urban growth would result in a loss of over 7 million acres of productive farmland by 2020. We demonstrate a method which successfully combines economic model output with gridded land cover data to create a spatially explicit detailed classification of the landscape across the Midwest. Understanding where changes are likely to take place on the landscape will enable the evaluation of trade-offs between economic benefits and ecosystem services allowing proactive conservation and sustainable production for human well-being into the future.     

Simulated interior floods and the flood experience in urban communities

The Hydrologic Engineering Center (HEC-1) model was used to construct synthetic hydrographs for isolated interior urban floods. Flood peak and lag time were very well preserved in simulated flows. Total volume was not adequately expressed. Lag time varied inversely with both urban development and storm intensity. Peak discharge varied with storm intensity, but this variability was well defined only at very high urbanization levels. An 175% increase in storm intensity produced a change of about 15% in peak discharge. Claims for flood damage correlated well with estimates of peak flow and lag time combined. Other measures of flood experience also correlated with the two features. Within the range of storms utilized, urban development factors consistently outranked storm intensity as a determining factor in flood damage.     

How does burrowing by the isopod <Emphasis Type="Italic">Limnoria agrostisa</Emphasis> (Crustacea: Limnoriidae) affect the leaf canopy of the southern Australian seagrass <Emphasis Type="Italic">Amphibolis griffithii</Emphasis>?

In south-western Australia, the isopod Limnoria agrostisa commonly burrows into leaf clusters and immature shoots of Amphibolis griffithii. The isopod also burrows into the sheath and rhizomes of Posidonia species. In A. griffithii, the isopod consumes new tissue within the sheath, damaging or destroying the meristem. This results in malformation of new leaves or destruction of whole leaf clusters with the potential to reduce the photosynthetic area of a shoot. The isopod has been found in all but one meadow of A. griffithii examined over 1,000 km of the Western Australian coastline. It was present throughout the year and showed little variation in abundance. Young were produced year round, but were more abundant in the summer months. Females, 3.5 mm in length or larger, produced 2–5 young that were brooded within the leaf cluster or base of an immature shoot. Within a meadow, 40–70% of shoots and 10–20% of leaf clusters were damaged by isopods. Seasonal trends were not consistent, but damage appeared to be higher in summer when isopod abundance was higher. Approximately 40% of clusters were destroyed by isopod damage. Isopods attack shoots of all ages, but damage was often located on apical clusters. There was no evidence that isopod damage initiated branching or leaf cluster formation. Estimations of clusters damaged or destroyed may be conservative, as only those clusters remaining on a shoot could be counted, and cluster loss could not be quantified. Examination of defoliated stems on upright shoots and horizontal rhizomes indicated that many were destroyed by isopods. The effect of L. agrostisa although substantial appears to be a feature of healthy seagrasses throughout southern Australia.     

Social–ecological system responses to Hurricane Sandy in the Hudson-Raritan Estuary

The impact of Hurricane Sandy on the Hudson-Raritan estuary (HRE) provided a valuable case study for exploring interactions between long-term environmental degradation, new climatic disturbance stressors, and human behavioral responses. We extend previous research on the ecological effects of major storms to compare water quality and biological parameters three years before and three years after Hurricane Sandy and consider how ecosystem shifts relate to anglers’ perceptions. Results indicate that water clarity and nutrients returned to pre-storm conditions in about one year, while shifts in the biological community, including a significant increase in harmful algal species and declines in zooplankton and Atlantic menhaden, persisted for multiple years, and anglers continued to fish amidst ecosystem decline. Biotic recovery time in the HRE was longer than reports for other shallow estuaries frequently disturbed by hurricanes. Ecological and social responses suggest that the post-storm regime shifts and continued fishing pressure could further environmental degradation.