A strategy for species introduction into evolving model ecosystems

Using a recently developed technique, a realistic method of introducing species into an evolving ecosystem simulation model is presented. A single unit, preemption strength, provides an index which combines strictly preemptive and strictly head-of-the-line colonization strategies. An optimization of priority strategies is presented. The relevance of the realistically evolving model to the stability-complexity problem is emphasized.     

Winter bird use of seed-rich habitats in agri-environment schemes

To assess the effectiveness of over-winter seed provision by agri-environment schemes, bird use of patches of seed-bearing crops was compared with that of other seed-rich habitats on 53 farms in eastern Scotland over three winters. Seed-bearing crops were the most frequently selected habitat, and held 28% of birds of the 10 species recorded. Outside schemes, cereal stubble was the most selected habitat and held 44% of birds. For nine species, seed-bearing crops were used by more birds than expected from the area of crop available in at least one winter, and five species were more likely to occur in first-winter patches, reflecting a greater abundance of cereal grain than in second-winter patches. For cereal grain specialists such as buntings, sowing cereal-based crops annually would ensure that grain is available in each winter, whilst either a 1-year or a 2-year crop would be appropriate for finches that favour oilseeds, and species with a more generalist diet.     

A global assessment of chromium pollution using sperm whales (Physeter macrocephalus) as an indicator species

Chromium (Cr) is a well-known human carcinogen and a potential reproductive toxicant, but its contribution to ocean pollution is poorly understood. The aim of this study was to provide a global baseline for Cr as a marine pollutant using the sperm whale (Physeter macrocephalus) as an indicator species. Biopsies were collected from free-ranging whales around the globe during the voyage of the research vessel The Odyssey. Total Cr levels were measured in 361 sperm whales collected from 16 regions around the globe detectable levels ranged from 0.9 to 122.6 μg Cr g tissue⁻¹ with a global mean of 8.8 ± 0.9 μg g⁻¹. Two whales had undetectable levels. The highest levels were found in sperm whales sampled in the waters near the Islands of Kiribati in the Pacific (mean = 44.3 ± 14.4) and the Seychelles in the Indian Ocean (mean = 19.5 ± 5.4 μg g⁻¹). The lowest mean levels were found in whales near the Canary Islands (mean = 3.7 ± 0.8 μg g⁻¹) and off of the coast of Sri Lanka (mean = 3.3 ± 0.4 μg g⁻¹). The global mean Cr level in whale skin was 28-times higher than mean Cr skin levels in humans without occupational exposure. The whale levels were more similar to levels only observed previously in human lung tissue from workers who died of Cr-induced lung cancer. We conclude that Cr pollution in the marine environment is significant and that further study is urgently needed.     

Factors diminishing the effectiveness of phosphorus loading from municipal effluent: critical information for TMDL analyses

Factors that diminish the effectiveness of phosphorus inputs from a municipal wastewater treatment facility (Metro) in contributing to phosphorus levels and its availability to support algae growth in a culturally eutrophic urban lake (Onondaga Lake, NY) were characterized and quantified. These factors included the bioavailability and settling characteristics of particulate phosphorus from this effluent, the dominant form (70%) of phosphorus in this input, and the plunging of the discharge to stratified layers in the lake. Supporting studies included: (1) chemical and morphometric characterization of the phosphorus-enriched particles of this effluent, compared to particle populations of the tributaries and lake, with an individual particle analysis technique; (2) conduct of algal bioavailability assays of the particulate phosphorus of the effluent; (3) conduct of multiple size class settling velocity measurements on effluent particles; and (4) determinations of the propensity of the discharge to plunge, and documentation of plunging through three-dimensional monitoring of a tracer adjoining the outfall. All of these diminishing effects were found to be operative for the Metro effluent in Onondaga Lake and will be integrated into a forthcoming phosphorus "total maximum daily load" analysis for the lake, through appropriate representation in a supporting mechanistic water quality model. The particulate phosphorus in the effluent was associated entirely with Fe-rich particles formed in the phosphorus treatment process. These particles did not contribute to concentrations in pelagic portions of the lake, due to local deposition associated with their large size. Moreover, this particulate phosphorus was found to be nearly entirely unavailable to support algae growth. While substantial differences are to be expected for various inputs, the effective loading concept and the approaches adopted here to assess the diminishing factors are broadly applicable.     

New measurements of cyanobacterial toxins in natural waters using high performance liquid chromatography coupled to tandem mass spectrometry

The presence and levels of the cyanobacterial toxins microcystin-LR, anatoxin-a, and cylindrospermopsin were measured in various Wisconsin waters where algal nuisance or bloom conditions were noted. Out of 74 samples analyzed, 36 had detectable levels of microcystin-LR (49%), and four had detectable levels of anatoxin-a (5%). Cylindrospermopsin, the toxin produced by Cylindrospermopsis (a warm water species that has been moving its range northward, including to Wisconsin), was not detected in the field samples tested. Concentrations of microcystin-LR ranged from 1.2 to 7600 microg L(-1). Anatoxin-a ranged from 0.68 to 1750 microg L(-1), which is the highest concentration reported from around the world. Cyanobacterial toxins, because of their high potency, deserve continued scrutiny by resource managers and public health officials responsible for recreational waters.     

Unusual sources of aluminium and heavy metals in potable waters

Aluminium in water supplies derives from natural sources and from the use of Al₂(SO₄)₃ in water treatment. Heavy metals such as Pb, Cu, Zn and Cd can be added to water from pipework and solder. However, it is apparent that AI and other metals in potable waters can derive from deposits on pipe walls which can be subsequently mobilised when the supply and/or treatment process is changed. Concentrations of Al in domestic supply water of the Llanbrynmair area have been shown to increase from 1 g to 50 g L^–1 during its 18 km journey along the water main. Similarly, Pb concentrations in a public building in the Aberystwyth area are found to be extremely elevated due to the metal's mobilisation from encrustations occurring on the copper pipework.     

The importance of agricultural yield elasticity for indirect land use change: a Bayesian network analysis for robust uncertainty quantification

ABSTRACT

A major barrier to realising biofuels’ climate change mitigation potential is uncertainty concerning carbon emissions from indirect land use change (ILUC). Central to this uncertainty is the extent to which yields can respond dynamically to increased demand for agricultural commodities. This study examines the elasticity of soybean and corn yields in the USA for 1990–2017 using Bayesian network models to robustly quantify uncertainty. The central finding is that a single parameter value for yield elasticity does not adequately represent the effects of technology, policy and price pressures through time. The models demonstrate the limiting role of technological progress as well as farmers’ capital investment in response to system shocks. Results suggest evaluation of parameter uncertainty alone is unlikely to capture a full range of future ILUC scenarios and reiterate the need for ILUC studies to use probabilistic approaches as standard to robustly inform climate change mitigation policies.     

Prevention of neural tube defects in curly-tail mice by maternal administration of vitamin A

Various doses of vitamin A were administered on day 9 of pregnancy to the pregnant curly-tail mouse, a mutant, 60 per cent of which have neural tube defects (NTD). There was a reduction in the incidence of NTD in the fetuses with all doses used. The effect was maximal with 5 mg/kg; it was also marked, but to a lesser degree, with 10 and 20 mg/kg and minimal with 1 mg/kg. The implications of these findings in the mouse to the prevention of NTD in humans by preconception vitamin supplementation are discussed.     

A SIMPLE TECHNIQUE FOR ESTIMATING ABSORPTION AND SCATTERING COEFFICIENTS1

ABSTRACT: Results from five different test systems, which include a wide range of optical conditions, indicate credible estimates of the values of the absorption and scattering coefficients can be calculated from paired measurements of Secchi disc transparency and the diffuse attenuation coefficient. The diagnostic utility of the estimates in identifying components and processes that regulate light penetration is demonstrated for three different cases. The simple estimation technique is valuable in the analysis of existing data bases that lack comprehensive optical information to develop and evaluate alternate models for light penetration and to establish the experimental needs of future field programs to support lake management efforts.