Re-creating missing population baselines for Pacific reef sharks

Sharks and other large predators are scarce on most coral reefs, but studies of their historical ecology provide qualitative evidence that predators were once numerous in these ecosystems. Quantifying density of sharks in the absence of humans (baseline) is, however, hindered by a paucity of pertinent time-series data. Recently researchers have used underwater visual surveys, primarily of limited spatial extent or nonstandard design, to infer negative associations between reef shark abundance and human populations. We analyzed data from 1607 towed-diver surveys (>1 ha transects surveyed by observers towed behind a boat) conducted at 46 reefs in the central-western Pacific Ocean, reefs that included some of the world's most pristine coral reefs. Estimates of shark density from towed-diver surveys were substantially lower (<10%) than published estimates from surveys along small transects (<0.02 ha), which is not consistent with inverted biomass pyramids (predator biomass greater than prey biomass) reported by other researchers for pristine reefs. We examined the relation between the density of reef sharks observed in towed-diver surveys and human population in models that accounted for the influence of oceanic primary productivity, sea surface temperature, reef area, and reef physical complexity. We used these models to estimate the density of sharks in the absence of humans. Densities of gray reef sharks (Carcharhinus amblyrhynchos), whitetip reef sharks (Triaenodon obesus), and the group "all reef sharks" increased substantially as human population decreased and as primary productivity and minimum sea surface temperature (or reef area, which was highly correlated with temperature) increased. Simulated baseline densities of reef sharks under the absence of humans were 1.1-2.4/ha for the main Hawaiian Islands, 1.2-2.4/ha for inhabited islands of American Samoa, and 0.9-2.1/ha for inhabited islands in the Mariana Archipelago, which suggests that density of reef sharks has declined to 3-10% of baseline levels in these areas.     

Passive air sampling for persistent organic pollutants: introductory remarks to the special issue

There have been a number of developments in the need, design and use of passive air samplers (PAS) for persistent organic pollutants (POPs). This article is the first in a Special Issue of the journal to review these developments and some of the data arising from them. We explain the need and benefit of developing PAS for POPs, the different approaches that can be used, and highlight future developments and needs.     

The effects of subchronic exposure to NeemAzal T/S on zebrafish (Danio rerio)

The objective of the study was to investigate the subchronic effects of the insecticidal preparation NeemAzal T/S at concentrations of 3, 10 and 30?mg/L on the mortality, growth and histopathology of juvenile zebrafish (Danio rerio), as well as its related effects on selected indices of oxidative stress during a 28-day toxicity test. The juvenile growth toxicity test was performed according to OECD Guidelines 215 (Fish, Juvenile Growth Test). The results of this study indicate that these tested concentrations of NeemAzal T/S (containing 1% of the active ingredient azadirachtin A) affect fish growth and have a negative influence on the indices of oxidative stress in the juvenile stage of zebrafish, as well as cause mild histopathological changes in liver tissue.     

生产体系对肉产品(主要是猪肉)品质的影响

肉产品的技术、营养和感官品质在屠宰前后可能会受到多种交互作用因素的影响.从文献来看,以创造猪肉可持续生产体系为目标的各种变革,通常对肉的最终pH值没有影响或影响较小.一些研究表明,可持续生产体系降低了猪肉的持水能力.与常规饲养体系相比,户外生产被认为更能增加猪肉的剪切力值.肉色的影响因素很多,这些因素可能导致猪肉颜色更暗、色素含量增加,或猪肉颜色更浅淡、结构有所变化.在使用含有多不饱和脂肪酸饲料的生产体系中,肉产品所含类脂的不饱和性更强,肉产品的营养价值更高.一句话,必须考虑各因素间的组合效应如:饲养、生产体系、遗传型、性别和宰前处理等对肉品质量的影响.     

The influence of production systems on meat quality, with emphasis on pork

Technological, nutritional, and sensory meat quality may be influenced by multiple interacting factors before and after slaughter. Reviewing the literature, it can be seen that alterations aimed at creating more sustainable production systems for pig meat generally have either no effect or a lowering effect on the ultimate pH value of the meat. Some studies indicate reduced water-holding capacity in sustainably produced pork. Outdoor production may be expected to increase further the shear force of the meat compared to conventional systems. The color may be affected in different ways, leading to either darker, more pigmented meat or paler, structurally effected meat. The more unsaturated profile of the lipids in meat produced in a system that includes feeds containing polyunsaturated fatty acids is favorable with respect to the nutritional quality of the meat. To conclude, the combinatory effects of, for example, feeding, production systems, genotype, sex, and preslaughter treatments, have to be addressed.     

Prescribed burns and wildfires in Colorado: impacts of mitigation measures on indoor air particulate matter

Wildfires and prescribed burns are receiving increasing attention as sources of fine particulate matter (PM2.5). The goal of this research project was to understand the impact of mitigation strategies for residences impacted by scheduled prescribed burns and wildfires. Pairs of residences were solicited to have PM2.5 concentrations monitored inside and outside of their houses during four fires. The effect of using air cleaners on indoor PM2.5 was investigated, as well as the effect of keeping windows closed. Appropriately sized air cleaners were provided to one of each pair of residences; occupants of all of the residences were asked to keep windows shut and minimize opening of exterior doors. Additionally, residents were asked to record all of the activities that may be a source of particulate matter, such as cooking and cleaning. Measurements were made during one prescribed burn and three wildfires during the 2002 fire season. Outdoor 24-hr average PM2.5 concentrations ranging from 6 to 38 microg/m3 were measured during the fires, compared with levels of 2-5 microg/m3 during background measurements when no fires were burning. During the fires, PM2.5 was < 3 microg/m3 inside all of the houses with air cleaners installed. This corresponds with a decrease of 63-88% in homes with the air cleaners operating when compared with homes without air cleaners. In the homes without the air cleaners, measured indoor concentrations were 58-100% of the concentrations measured outdoors.     

Monitoring microbial biomass and respiration in different soils from the Czech Republic--a summary of results

The microbial biomass (Cbio), respiration (basal respiration (BR) and potential respiration (PR)), and derived indices for 520 independent soil samples of 117 different soils from the Czech Republic were statistically analysed. The broad range of soil samples allowed the stepwise breakdown of the database into six reasonable categories of soil: arable soils, loamy grassland soils, sandy grassland soils with weak organic matter content, sandy grassland soils with moderate organic matter content, forest soils with moderate organic matter content, and forest organic soils with rich organic matter content. Because soil microbiology lacks benchmarking values, the ranges of the microbial characteristics for these categories were stated and are presented here. The separation into soil groups narrowed the ranges enough to be useful for comparative purposes. The groups displayed significant differences in basal microbial parameters. The lowest microbial biomass was found in arable soils and grassland sandy soils with weak organic matter content. The highest microbial biomass was shown by loamy grassland soils and organic forest soils. Respiration displayed similar results to the microbial biomass. The derived indices revealed less significant differences confirming their inner-standard nature. The relationships between the soil contamination and microbial parameters were not explored because of the confounding effect of soil organic matter. However, it was not shown by the category of grassland sandy soils with weak organic matter content suggesting they could be especially suitable for the biomonitoring of harmful effects of chemicals on soil microorganisms.     

Comparison of differences between copper bioaccumulation and biosorption

Biological methods for wastewater treatment are becoming more accepted all over the world. The method, which makes use of accumulating abilities of living cells, is called bioaccumulation. In contrast with it, biosorption takes advantage of sequestering capabilities of dry or dead cells, which is technologically advantageous. The differences between bioaccumulation and biosorption of copper from model solutions were studied in this work. Application of living algal cells has some disadvantages. Copper significantly damages the surface of living cells, which results in partial loss of cell-binding abilities and release of accumulated copper back into solution. The binding capacity of living cells is significantly lower than that of dead cells. There is also a possibility of desorption and reuse of biomass in case of biosorption.     

A whole-plant mathematical model for the phytoextraction of lead (Pb) by maize

Phytoextraction is a technology that uses plants to remove heavy metals from contaminated soils. Although it is economically attractive compared to other methods, little attention has been paid to the mathematical modeling of the mechanisms involved. In this work, we simulate the phytoextraction of Pb using a mechanistic system dynamics modelling approach and the physiology model of maize (Zea mays) as a model system as it is a good Pb accumulator and translocator. Simulation results showed that precipitation is the most important mechanism related to the uptake of Pb from the ground. The most important model parameters have been identified through sensitivity analysis.