College and university environmental programs as a policy problem (part 2): strategies for improvement

Environmental studies and environmental sciences programs in American and Canadian colleges and universities seek to ameliorate environmental problems through empirical enquiry and analytic judgment. In a companion article (Part 1) we describe the environmental program movement (EPM) and discuss factors that have hindered its performance. Here, we complete our analysis by proposing strategies for improvement. We recommend that environmental programs re-organize around three principles. First, adopt as an overriding goal the concept of human dignity??defined as freedom and social justice in healthy, sustainable environments. This clear higher-order goal captures the human and environmental aspirations of the EPM and would provide a more coherent direction for the efforts of diverse participants. Second, employ an explicit, genuinely interdisciplinary analytical framework that facilitates the use of multiple methods to investigate and address environmental and social problems in context. Third, develop educational programs and applied experiences that provide students with the technical knowledge, powers of observation, critical thinking skills and management acumen required for them to become effective professionals and leaders. Organizing around these three principles would build unity in the EPM while at the same time capitalizing on the strengths of the many disciplines and diverse local conditions involved.     

Scaling range sizes to threats for robust predictions of risks to biodiversity

Assessments of risk to biodiversity often rely on spatial distributions of species and ecosystems. Range‐size metrics used extensively in these assessments, such as area of occupancy (AOO), are sensitive to measurement scale, prompting proposals to measure them at finer scales or at different scales based on the shape of the distribution or ecological characteristics of the biota. Despite its dominant role in red‐list assessments for decades, appropriate spatial scales of AOO for predicting risks of species’ extinction or ecosystem collapse remain untested and contentious. There are no quantitative evaluations of the scale‐sensitivity of AOO as a predictor of risks, the relationship between optimal AOO scale and threat scale, or the effect of grid uncertainty. We used stochastic simulation models to explore risks to ecosystems and species with clustered, dispersed, and linear distribution patterns subject to regimes of threat events with different frequency and spatial extent. Area of occupancy was an accurate predictor of risk (0.81<|r|<0.98) and performed optimally when measured with grid cells 0.1–1.0 times the largest plausible area threatened by an event. Contrary to previous assertions, estimates of AOO at these relatively coarse scales were better predictors of risk than finer‐scale estimates of AOO (e.g., when measurement cells are <1% of the area of the largest threat). The optimal scale depended on the spatial scales of threats more than the shape or size of biotic distributions. Although we found appreciable potential for grid‐measurement errors, current IUCN guidelines for estimating AOO neutralize geometric uncertainty and incorporate effective scaling procedures for assessing risks posed by landscape‐scale threats to species and ecosystems.     

Estimated lead (Pb) exposures for a population of urban community gardeners

Urban community gardens provide affordable, locally grown, healthy foods and many other benefits. However, urban garden soils can contain lead (Pb) that may pose risks to human health. To help evaluate these risks, we measured Pb concentrations in soil, vegetables, and chicken eggs from New York City community gardens, and we asked gardeners about vegetable consumption and time spent in the garden. We then estimated Pb intakes deterministically and probabilistically for adult gardeners, children who spend time in the garden, and adult (non-gardener) household members. Most central tendency Pb intakes were below provisional total tolerable intake (PTTI) levels. High contact intakes generally exceeded PTTIs. Probabilistic estimates showed approximately 40 % of children and 10 % of gardeners exceeding PTTIs. Children’s exposure came primarily from dust ingestion and exposure to higher Pb soil between beds. Gardeners’ Pb intakes were comparable to children’s (in µg/day) but were dominated by vegetable consumption. Adult household members ate less garden-grown produce than gardeners and had the lowest Pb intakes. Our results suggest that healthy gardening practices to reduce Pb exposure in urban community gardens should focus on encouraging cultivation of lower Pb vegetables (i.e., fruits) for adult gardeners and on covering higher Pb non-bed soils accessible to young children. However, the common practice of replacement of root-zone bed soil with clean soil (e.g., in raised beds) has many benefits and should also continue to be encouraged.     

Bateman gradients in a promiscuous mating system

The Bateman gradient is increasingly used to measure sexual selection and characterize mating systems. In a landmark paper, Arnold and Duvall (Am Nat 143:317–348, 1994) formulated predictions about the relationships between sex-specific Bateman gradients and the major types of mating system. In promiscuous species, gradients are expected to be strong and similar in both sexes. Current support for this prediction however remains equivocal as reported male gradients are almost constantly steeper than female gradients. Here, we estimated Bateman gradients in a wild population of Eastern chipmunks (Tamias striatus) over two reproductive seasons characterized by extreme levels of promiscuity and unbiased operational sex ratios. We found significant and positive Bateman gradients for both sexes. The gradients were not different among sexes suggesting that the strength of sexual selection was similar for males and females. The opportunity for selection was also particularly strong for a promiscuous species and not different among sexes. Our results thus support the predicted Bateman gradients for a promiscuous mating system.     

Global protected-area coverage and human pressure on tidal flats

Tidal flats are a globally distributed coastal ecosystem important for supporting biodiversity and ecosystem services. Local to continental-scale studies have documented rapid loss of tidal habitat driven by human impacts, but assessments of progress in their conservation are lacking. With an internally consistent estimate of distribution and change, based on Landsat satellite imagery, now available for the world's tidal flats, we examined tidal flat representation in protected areas (PAs) and human pressure on tidal flats. We determined tidal flat representation and its net change in PAs by spatially overlaying tidal flat maps with the World Database of Protected Areas. Similarly, we overlaid the most recent distribution map of tidal flats (2014–2016) with the human modification map (HM_c) (range from 0, no human pressure, to 1, very high human pressure) to estimate the human pressure exerted on this ecosystem. Sixty-eight percent of the current extent of tidal flats is subject to moderate to very high human pressure (HM_c > 0.1), but 31% of tidal flat extent occurred in PAs, far exceeding PA coverage of the marine (6%) and terrestrial (13%) realms. Net change of tidal flat extent inside PAs was similar to tidal flat net change outside PAs from 1999 to 2016. Substantial shortfalls in protection of tidal flats occurred across Asia, where large intertidal extents coincided with high to very high human pressure (HM_c > 0.4–1.0) and net tidal flat losses up to 86.4 km² (95% CI 83.9–89.0) occurred inside individual PAs in the study period. Taken together, our results show substantial progress in PA designation for tidal flats globally, but that PA status alone does not prevent all habitat loss. Safeguarding the world's tidal flats will thus require deeper understanding of the factors that govern their dynamics and effective policy that promotes holistic coastal and catchment management strategies.     

The primary productivity of marine macrophytes from a rocky intertidal community

This study represents the first report of primary production rates for Southern California intertidal producers. The production rates of 18 marine macrophytes near Wilson Cove, San Clemente Island, are close to those for other marine algal communities. No apparent relationship was revealed between the productivity of an alga and the division to which it belongs; however, productivity was associated with growth form. Encrusting prostrate forms were the lowest producers in terms of g C/m²/h and g C/g dry weight/h; sheet-like and finely-branched forms showed a greater productivity than coarsely-branched forms. Gelidium pusillum and Ulva californica had considerably greater production rates than the other algae measured.     

A test of sequential extractions for determining metal speciation in sewage sludge-amended soils

Sequential extraction procedures are widely used to estimate the quantity of trace metals bound to different solid fractions in contaminated soils. However, reliability of speciation of trace metals by these procedures remains largely unexamined. In the present study, the selectivity of each extraction step was tested by observing the effect of reversing the extraction order in the procedure. Two different sequential extraction methods and their reversed modes were used for metal fractionation in sewage sludge-amended soils. Significantly increased amounts of extractable metals (Cd, Cu, Pb and Zn) were evident in the sludge-amended soils compared to control soil by all extraction schemes; however, the amounts of metals extracted by each step were strongly dependent on the order of extraction, the type of reagents and the nature of the individual metals. Caution is advised in deducing the forms of soil metals from sequential extraction results from metal-contaminated soils.     

Application of the method of temporal moments to interpret solute transport with sorption and degradation

In this note, we applied the temporal moment solutions of [Das and Kluitenberg, 1996. Soil Sci. Am. J. 60, 1724] for one-dimensional advective-dispersive solute transport with linear equilibrium sorption and first-order degradation for time pulse sources to analyse soil column experimental data. Unlike most other moment solutions, these solutions consider the interplay of degradation and sorption. This permits estimation of a first-order degradation rate constant using the zeroth moment of column breakthrough data, as well as estimation of the retardation factor or sorption distribution coefficient of a degrading solute using the first moment. The method of temporal moment (MOM) formulae was applied to analyse breakthrough data from a laboratory column study of atrazine, hexazinone and rhodamine WT transport in volcanic pumice sand, as well as experimental data from the literature. Transport and degradation parameters obtained using the MOM were compared to parameters obtained by fitting breakthrough data from an advective-dispersive transport model with equilibrium sorption and first-order degradation, using the nonlinear least-square curve-fitting program CXTFIT. The results derived from using the literature data were also compared with estimates reported in the literature using different equilibrium models. The good agreement suggests that the MOM could provide an additional useful means of parameter estimation for transport involving equilibrium sorption and first-order degradation. We found that the MOM fitted breakthrough curves with tailing better than curve fitting. However, the MOM analysis requires complete breakthrough curves and relatively frequent data collection to ensure the accuracy of the moments obtained from the breakthrough data.     

Recognize fish as food in policy discourse and development funding

The international development community is off-track from meeting targets for alleviating global malnutrition. Meanwhile, there is growing consensus across scientific disciplines that fish plays a crucial role in food and nutrition security. However, this ‘fish as food’ perspective has yet to translate into policy and development funding priorities. We argue that the traditional framing of fish as a natural resource emphasizes economic development and biodiversity conservation objectives, whereas situating fish within a food systems perspective can lead to innovative policies and investments that promote nutrition-sensitive and socially equitable capture fisheries and aquaculture. This paper highlights four pillars of research needs and policy directions toward this end. Ultimately, recognizing and working to enhance the role of fish in alleviating hunger and malnutrition can provide an additional long-term development incentive, beyond revenue generation and biodiversity conservation, for governments, international development organizations, and society more broadly to invest in the sustainability of capture fisheries and aquaculture.Electronic supplementary materialThe online version of this article (10.1007/s13280-020-01451-4) contains supplementary material, which is available to authorized users.     

Trace metal speciation and bioavailability in urban soils

Urban soils often contain concentrations of trace metals that exceed regulatory levels. However, the threat posed by trace metals to human health and the environment is thought to be dependent on their speciation in the soil solution rather than the total concentration. Three inactive railway yards in Montréal, Québec, were sampled to investigate the speciation and bioavailability of Cd, Cu, Ni, Pb and Zn. Soil solutions were obtained by centrifuging saturated soil pastes. In the soil solutions, up to 59% of the dissolved Cd was in its free ionic form. For Cu, Pb and Zn, organic complexes were the predominant species. Over 40% of Ni was present as inorganic complexes if the solution pH exceeded 8.1. Multiple regression analyses showed that pH and total metals in soil were significantly correlated with the activities of free metal ions, except for Cd(2+), which only had a weak correlation with soil pH. Free, dissolved and total soil metals were tested for their ability to predict metal uptake by plants in the field. However, none of these metal pools were satisfactory predictors. The results indicated that in these urban soils, trace metals were mainly in stable forms and bioavailability was extremely low.