An integrated approach for predicting fates of reintroductions with demographic data from multiple populations

We devised a novel approach to model reintroduced populations whereby demographic data collected from multiple sites are integrated into a Bayesian hierarchical model. Integrating data from multiple reintroductions allows more precise population-growth projections to be made, especially for populations for which data are sparse, and allows projections that account for random site-to-site variation to be made before new reintroductions are attempted. We used data from reintroductions of the North Island Robin (Petroica longipes), an endemic New Zealand passerine, to 10 sites where non-native mammalian predators are controlled. A comparison of candidate models that we based on deviance information criterion showed that rat-tracking rate (an index of rat density) was a useful predictor of robin fecundity and adult female survival, that landscape connectivity and a binary measure of whether sites were on a peninsula were useful predictors of apparent juvenile survival (probably due to differential dispersal away from reintroduction sites), and that there was unexplained random variation among sites in all demographic rates. We used the two best supported models to estimate the finite rate of increase (λ) for populations at each of the 10 sites, and for a proposed reintroduction site, under different levels of rat control. Only three of the reintroduction sites had λ distributions completely >1 for either model. At two sites, λ was expected to be >1 if rat-tracking rates were <5%. At the other five reintroduction sites, λ was predicted to be close to 1, and it was unclear whether growth was expected. Predictions of λ for the proposed reintroduction site were less precise than for other sites because distributions incorporated the full range of site-to-site random variation in vital rates. Our methods can be applied to any species for which postrelease data on demographic rates are available and potentially can be extended to model multiple species simultaneously.     

DIFFERENCES IN WARM-SEASON,RAINSTORM-GENERATED STORMFLOWS FOR NORTHEASTERN ILLINOIS URBANIZED BASINS1

ABSTRACT: Precipitation, streamflow, and population data were analyzed over the 1941–1990 period to determine whether changes in stormflows and net (post. minus pre-rainstorm) stormflows, associated with warm-season large rainstorms, were similar for two urbanized northeastern Illinois basins. Warm season large rainstorms were defined as April through October rainfall events in which ? 5.1 cm occurred in a 48-hour period over the basin. To minimize differences associated with varying large rainstorm amounts over time, the net sthrmflow for each event was divided by the large rainstorm amount. This ratio, Ui, indicated that the two urbanized basins experienced significant, yet different, increases (102 percent and 49 percent) in flow amount per centimeter of rainfall from 1941–1965 to 1966–1990. Results of a regression analysis between Ui and population showed that the increase in U_i per 100,000 increase in population ranged from 0.59 to 0.67 m³s^-1 per cm of rainfall for the two basins. These results demonstrate the varying degree of change that urban planners can expect in stormflows associated with large warm season rainstorms for areas undergoing urbanization.     

Effects of field storage method on <Emphasis Type="Italic">E. coli</Emphasis> concentrations measured in storm water runoff

Storm water runoff is increasingly assessed for fecal indicator organisms (e.g., Escherichia coli, E. coli) and its impact on contact recreation. Concurrently, use of autosamplers along with logistic, economic, technical, and personnel barriers is challenging conventional protocols for sample holding times and storage conditions in the field. A common holding time limit for E. coli is 8 h with a 10 °C storage temperature, but several research studies support longer hold time thresholds. The use of autosamplers to collect E. coli water samples has received little field research attention; thus, this study was implemented to compare refrigerated and unrefrigerated autosamplers and evaluate potential E. coli concentration differences due to field storage temperature (storms with holding times ≤24 h) and due to field storage time and temperature (storms >24 h). Data from 85 runoff events on four diverse watersheds showed that field storage times and temperatures had minor effects on mean and median E. coli concentrations. Graphs and error values did, however, indicate a weak tendency for higher concentrations in the refrigerated samplers, but it is unknown to what extent differing die-off and/or regrowth rates, heterogeneity in concentrations within samples, and laboratory analysis uncertainty contributed to the results. The minimal differences in measured E. coli concentrations cast doubt on the need for utilizing the rigid conventional protocols for field holding time and storage temperature. This is not to say that proper quality assurance and quality control is not important but to emphasize the need to consider the balance between data quality and practical constraints related to logistics, funding, travel time, and autosampler use in storm water studies.     

A new approach to characterize emission contributions from area sources during optical remote sensing technique testing

In the method termed “Other Test Method-10,” the U.S. Environmental Protection Agency has proposed a method to quantify emissions from nonpoint sources by the use of vertical radial plume mapping (VRPM) technique. The surface area of the emitting source and the degree to which the different zones of the emitting source are contributing to the VRPM computed emissions are often unknown. The objective of this study was to investigate and present an approach to quantify the unknown emitting surface area that is contributing to VRPM measured emissions. Currently a preexisting model known as the “multiple linear regression model,” which is described in Thoma et al. (2009 Thoma, E.R., Green, R., Hater, G., Goldsmith, C., Swan, N., Chase, M. and Hashmonay, R. 2010. Development of EPA OTM-10 for landfill applications. J. Environ. Eng., 136: 769–776. [Crossref], [Web of Science ®] , [Google Scholar]), is used for quantifying the unknown surface area.

The method investigated and presented in this paper utilized tracer tests to collect data and develop a model much like that described in Thoma et al. (2009 Thoma, E.R., Green, R., Hater, G., Goldsmith, C., Swan, N., Chase, M. and Hashmonay, R. 2010. Development of EPA OTM-10 for landfill applications. J. Environ. Eng., 136: 769–776. [Crossref], [Web of Science ®] , [Google Scholar]). However, unlike the study used for development of the multiple linear regression model, this study is considered a very limited study due to the low number of pollutant releases performed (seven total releases). It was found through this limited study that the location of an emitting source impacts VRPM computed emissions exponentially, rather than linearly (i.e., the impact that an emitting source has on VRPM measurements decreases exponentially with increasing distances between the emitting source and the VRPM plane). The data from the field tracer tests were used to suggest a multiple exponential regression model. The findings of this study, however, are based on a very small number of tracer tests. More tracer tests performed during all types of climatic conditions, terrain conditions, and different emissions geometries are still needed to better understand the variation of capture efficiency with emitting source location. This study provides a step toward such an objective.

Implications The findings of this study will aid in the advancement of the VRPM technique. In particular, the contribution of this study is to propose a slight improvement in how the area contributing to flux is determined during VRPM campaigns. This will reduce some of the technique's inherent uncertainties when it is employed to estimate emissions from an area source under nonideal conditions.     

Matrix diffusion coefficients in volcanic rocks at the Nevada test site: influence of matrix porosity, matrix permeability, and fracture coating minerals

Diffusion cell experiments were conducted to measure nonsorbing solute matrix diffusion coefficients in forty-seven different volcanic rock matrix samples from eight different locations (with multiple depth intervals represented at several locations) at the Nevada Test Site. The solutes used in the experiments included bromide, iodide, pentafluorobenzoate (PFBA), and tritiated water ((3)HHO). The porosity and saturated permeability of most of the diffusion cell samples were measured to evaluate the correlation of these two variables with tracer matrix diffusion coefficients divided by the free-water diffusion coefficient (D(m)/D*). To investigate the influence of fracture coating minerals on matrix diffusion, ten of the diffusion cells represented paired samples from the same depth interval in which one sample contained a fracture surface with mineral coatings and the other sample consisted of only pure matrix. The log of (D(m)/D*) was found to be positively correlated with both the matrix porosity and the log of matrix permeability. A multiple linear regression analysis indicated that both parameters contributed significantly to the regression at the 95% confidence level. However, the log of the matrix diffusion coefficient was more highly-correlated with the log of matrix permeability than with matrix porosity, which suggests that matrix diffusion coefficients, like matrix permeabilities, have a greater dependence on the interconnectedness of matrix porosity than on the matrix porosity itself. The regression equation for the volcanic rocks was found to provide satisfactory predictions of log(D(m)/D*) for other types of rocks with similar ranges of matrix porosity and permeability as the volcanic rocks, but it did a poorer job predicting log(D(m)/D*) for rocks with lower porosities and/or permeabilities. The presence of mineral coatings on fracture walls did not appear to have a significant effect on matrix diffusion in the ten paired diffusion cell experiments.     

Reducing Nitrogen Export from the Corn Belt to the Gulf of Mexico: Agricultural Strategies for Remediating Hypoxia

SPAtially Referenced Regression on Watershed models developed for the Upper Midwest were used to help evaluate the nitrogen‐load reductions likely to be achieved by a variety of agricultural conservation practices in the Upper Mississippi‐Ohio River Basin (UMORB) and to compare these reductions to the 45% nitrogen‐load reduction proposed to remediate hypoxia in the Gulf of Mexico (GoM). Our results indicate that nitrogen‐management practices (improved fertilizer management and cover crops) fall short of achieving this goal, even if adopted on all cropland in the region. The goal of a 45% decrease in loads to the GoM can only be achieved through the coupling of nitrogen‐management practices with innovative nitrogen‐removal practices such as tile‐drainage treatment wetlands, drainage–ditch enhancements, stream‐channel restoration, and floodplain reconnection. Combining nitrogen‐management practices with nitrogen‐removal practices can dramatically reduce nutrient export from agricultural landscapes while minimizing impacts to agricultural production. With this approach, it may be possible to meet the 45% nutrient reduction goal while converting less than 1% of cropland in the UMORB to nitrogen‐removal practices. Conservationists, policy makers, and agricultural producers seeking a workable strategy to reduce nitrogen export from the Corn Belt will need to consider a combination of nitrogen‐management practices at the field scale and diverse nitrogen‐removal practices at the landscape scale.     

A major increase in snake pipefish (<Emphasis Type="Italic">Entelurus aequoreus</Emphasis>) in northern European seas since 2003: potential implications for seabird breeding success

Since the early 2000s routine fish surveys have recorded increasing numbers of snake pipefish, Entelurus aequoreus, in the northeast Atlantic. Fishermen and divers have also commented on this increase and pipefish have started to appear in the diet of seabirds and other marine predators. This paper collates information from these diverse sources and assesses the current status of snake pipefish. We found compelling evidence of a dramatic increase in the abundance of snake pipefish starting around 2003 and continuing up to the present (2006) and a range expansion northwards to Spitzbergen and the Barents Sea. Since 2004 snake pipefish have been increasingly recorded in the diet of many species of seabird breeding in colonies around the coast of the UK, and in Norway, Iceland and the Faeroe Islands. Information on the nutrient value of snake pipefish is currently lacking but their rigid, bony structure makes them difficult for young seabirds to swallow and there are numerous records of chicks choking to death. Thus, in the case of avian predators during the breeding season, it appears unlikely that increased abundance of snake pipefish will provide a useful alternative prey. The reason for the rapid and dramatic increase in numbers of snake pipefish is currently unclear but such events are characteristic of marine ecosystems and will almost certainly have an effect on food web dynamics.     

An unintended experiment in fisheries science: a marine area protected by war results in Mexican waves in fish numbers-at-age

Marine protected areas (MPAs) are attaining increasing importance in the management of marine ecosystems. They are effective for conservation in tropical and subtropical areas (mainly coral and rocky reefs), but it is debated whether they are useful in the management of migratory fish stocks in open temperate regions. World War II created a large marine area within which commercial fishing was prevented for 6 years. Here we analyse scientific trawl data for three important North Sea gadoids, collected between 1928 and 1958. Using statistical models to summarise the data, we demonstrate the potential of MPAs for expediting the recovery of over-exploited fisheries in open temperate regions. Our age-structured data and population models suggest that wild fish stocks will respond rapidly and positively to reductions in harvesting rates and that the numbers of older fish in a population will react before, and in much greater proportion, than their younger counterparts in a kind of Mexican wave. Our analyses demonstrate both the overall increase in survival due to the lack of harvesting in the War and the form of the age-dependent wave in numbers. We conclude that large closed areas can be very useful in the conservation of migratory species from temperate areas and that older fish benefit fastest and in greater proportion. Importantly, any rise in spawning stock biomass may also not immediately result in better recruitment, which can respond more slowly and hence take longer to contribute to higher future harvestable biomass levels.