Urban Stream Rehabilitation: A Design and Construction Case Study

/ This paper describes the fundamental design features, and construction methods and sequence, of a rehabilitation project on a small suburban creek in Moscow, Idaho, USA. A meandering channel pattern was reestablished for approximately 280 m of straightened, dredged channel, a new floodplain was excavated, and the new riparian zone was replanted. The new stream channel was sized to accommodate an estimated natural bankfull discharge ( approximately 5.6 cms), and floodplain design attempted to match the conveyance of the old enlarged channel (14-20 cms). The project was coordinated by a local nonprofit environmental organization, and the design and construction were tailored to donated materials and a largely volunteer labor force. A high-magnitude flood event (ca. 50-year recurrence interval) six months after construction had no significant impact on the newly constructed channel and revetments, but underscored the need for important detailing of the structures. The use of volunteer labor, while entailing certain benefits, complicates project planning and construction. The most general lesson learned from this project is that sponsoring agencies and clients need to be informed of the many steps and sequencing of properly constructed, complex stream rehabilitation projects as well as the high time and cost requirements for these tasks. KEY WORDS: Stream corridor restoration; Channel design; Streambank revetments     

Length polymorphism at the avpr1a locus is correlated with male reproductive behavior in a natural population of prairie voles (Microtus ochrogaster)

Laboratory studies have shown that vasopressin can influence sociosexual behavior through its action on the vasopressin 1a receptor (V1aR). There is substantial evidence that the length of a microsatellite in the gene (avpr1a) encoding for the V1aR can affect social attachment to females and paternal behavior in male prairie voles under laboratory conditions. However, previous field studies of prairie voles have failed to detect a strong effect of the length of a male’s avpr1a allele on their sociosexual behavior, but these studies are typically much shorter than the average prairie vole breeding lifespan. We examined the relationship between male avpr1a microsatellite allele length and sociosexual behavior in a natural population of prairie voles for 15 weeks, closer to the lifespan of prairie voles in nature. Contrary to predictions, we found that males with the longest avpr1a microsatellite alleles were significantly more likely to sire offspring with more than one female and to sire offspring that survived until trappable age than males with the shortest avpr1a microsatellite allele lengths. This relationship was the strongest for males with the longest tenure on the study site. As in previous field studies, we did not find evidence of a relationship between a male’s avpr1a genotype and any index of social behavior including male residency status or the number of females with which males associate. This is the first study to support the hypothesis that a male’s avpr1a genotype is a factor underlying variation in the genetic mating system of prairie voles under natural conditions.     

Temporal separation of two fin whale call types across the eastern North Pacific

Fin whales (Balaenoptera physalus) produce a variety of low-frequency, short-duration, frequency-modulated calls. The differences in temporal patterns between two fin whale call types are described from long-term passive acoustic data collected intermittently between 2005 and 2011 at three locations across the eastern North Pacific: the Bering Sea, off Southern California, and in Canal de Ballenas in the northern Gulf of California. Fin whale calls were detected at all sites year-round, during all periods with recordings. At all three locations, 40-Hz calls peaked in June, preceding a peak in 20-Hz calls by 3–5 months. Monitoring both call types may provide a more accurate insight into the seasonal presence of fin whales across the eastern North Pacific than can be obtained from a single call type. The 40-Hz call may be associated with a foraging function, and temporal separation between 40- and 20-Hz calls may indicate the separation between predominately feeding behavior and other social interactions.     

Incorporating health outcomes into environmental justice research: The case of children's asthma and air pollution in Phoenix,Arizona

Asthma is a health condition that is also an environmental justice issue. Using an environmental justice frame, this paper explores socio-demographic, indoor hazard, and air quality factors that contribute to disparities in asthma hospitalizations. Multivariate Poisson regression models predicting asthma hospitalizations at the zip code level are employed to examine the case of metropolitan Phoenix, Arizona (AZ). Controlling for socio-demographics, indoor hazards, and toxic releases from industry, ozone was the strongest predictor of asthma hospitalizations. This paper contributes to the project of inserting health measures into quantitative environmental justice studies.     

Can rare positive interactions become common when large carnivores consume livestock?

Livestock populations in protected areas are viewed negatively because of their interaction with native ungulates through direct competition for food resources. However, livestock and native prey can also interact indirectly through their shared predator. Indirect interactions between two prey species occur when one prey modifies either the functional or numerical responses of a shared predator. This interaction is often manifested as negative effects (apparent competition) on one or both prey species through increased predation risk. But indirect interactions can also yield positive effects on a focal prey if the shared predator modifies its functional response toward increased consumption of an abundant and higher-quality alternative prey. Such a phenomenon between two prey species is underappreciated and overlooked in nature. Positive indirect effects can be expected to occur in livestock-dominated wildlife reserves containing large carnivores. We searched for such positive effects in Acacia-Zizhypus forests of India's Gir sanctuary where livestock (Bubalus bubalis and Bos indicus) and a coexisting native prey (chital deer, Axis axis) are consumed by Asiatic lions (Panthera leo persica). Chital vigilance was higher in areas with low livestock density than in areas with high livestock density. This positive indirect effect occurred because lion predation rates on livestock were twice as great where livestock were abundant than where livestock density was low. Positive indirect interactions mediated by shared predators may be more common than generally thought with rather major consequences for ecological understanding and conservation. We encourage further studies to understand outcomes of indirect interactions on long-term predator-prey dynamics in livestock-dominated protected areas.     

Species diversity reduces parasite infection through cross-generational effects on host abundance

With growing interest in the effects of biodiversity on disease, there is a critical need for studies that empirically identify the mechanisms underlying the diversity-disease relationship. Here, we combined wetland surveys of host community structure with mechanistic experiments involving a multi-host parasite to evaluate competing explanations for the dilution effect. Sampling of 320 wetlands in California indicated that snail host communities were strongly nested, with competent hosts for the trematode Ribeiroia ondatrae predominating in low-richness assemblages and unsuitable hosts increasingly present in more diverse communities. Moreover, competent host density was negatively associated with increases in snail species richness. These patterns in host community assembly support a key prerequisite underlying the dilution effect. Results of multigenerational mesocosm experiments designed to mimic field-observed community assemblages allowed us to evaluate the relative importance of host density and diversity in influencing parasite infection success. Increases in snail species richness (from one to four species) had sharply negative effects on the density of infected hosts (-90% reduction). However, this effect was indirect; competition associated with non-host species led to a 95% reduction in host density (susceptible host regulation), owing primarily to a reduction in host reproduction. Among susceptible hosts, there were no differences in infection prevalence as a function of community structure, indicating a lack of support for a direct effect of diversity on infection (encounter reduction). In monospecific conditions, higher initial host densities increased infection among adult hosts; however, compensatory reproduction in the low-density treatments equalized the final number of infected hosts by the next generation, underscoring the relevance of multigenerational studies in understanding the dilution effect. These findings highlight the role of interspecific competition in mediating the relationship between species richness and parasite infection and emphasize the importance of field-informed experimental research in understanding mechanisms underlying the diversity-disease relationship.     

Exploring the conservation status of an endangered coastal plant over the last nine years: a case study in Andalusia,Spain

Human pressure has been exponentially growing during recent decades in coastal areas, which have led to drastic losses of biodiversity in coastal ecosystems. The current conservation status of many coastal plant species is directly related to a lack of environmental criteria in the urban planning of coastal areas over recent decades. This study aimed to evaluate the evolution, over the last 9 years, of the conservation status of various populations of the endangered plant Glaucium flavum, exploring the extent to which human pressure and different management strategies practiced in the coastal areas where the populations are established have affected the conservation status of the species. The populations analysed have evolved in a different manner over the last 9 years, as have their threat factors, and a relationship was evident between their conservation status and the evolution of these different threat factors. Our results indicate that an appropriate planning of local management actions, such as the installation of walkways or the successful eradication of invasive species, may be determinant factors for successful conservation of the coastal vegetation. The presence of species that are sensitive to slight changes in the ecosystem, and the main factors that govern the plant performance of these species, must be given full consideration in decision-making processes of coastal planning and management.     

农药引起的两栖动物脑部的变化：亚致死浓度的毒死蜱如何直接影响神经发育

农药虽然可以控制病虫害,但其广泛使用造成自然环境的污染,致使非靶标生物暴露于农药污染环境中。即使低浓度农药暴露也会直接或间接影响水生生物群落。前期人工池塘(中宇宙)研究结果表明痕量毒死蜱(chlorpyrifos, CPF)可改变蝌蚪体态和神经发育。造成这个结果的原因可能为：1)CPF暴露的直接影响;2)农药造成了浮游动物数量下降扰乱食物网。为了明确原因,我们在CPF耐受浮游动物存在的情况下,考察了CPF对两栖动物发育的影响,这种浮游动物是不同营养级别水生生物群落的重要组成部分。豹蛙(Lithobates pipiens)蝌蚪饲养在中宇宙的环境,经过变态期,环境中含有0或1 μg/L CPF,或CPF敏感型浮游动物Daphnia pulex。CPF发育期暴露致使蝌蚪蜕变时视顶盖、延髓、间脑相对更宽,而这一结果与中宇宙中浮游动物种群无关。因此,CPF直接影响大脑发育,与不同营养级别的群落的无关。至于身体形态方面,CPF对无CPF敏感型浮游动物的中宇宙中饲养的蝌蚪蜕变形态没有影响,但在没有CPF污染时,蝌蚪身体形态对浮游动物种群数量很敏感。研究表明,生态水平的低剂量有机磷农药暴露可直接影响脊椎动物的神经发育。 精选自Sara J. McClelland, Randall J. Bendis, Rick A. Relyea, Sarah K. Woodley. Insecticide-induced changes in amphibian brains: How sublethal concentrations of chlorpyrifos directly affect neurodevelopment. Environmental Toxicology and Chemistry,2018,37:2692–2698.
详情请见 https://doi.org/10.1002/etc.4240