Spectroscopy properties and optimization for the detection of mercury（Ⅱ） with series hydroxyl-porphyrins

结合紫外分光光度法研究系列羟基卟啉与汞离子的显色反应,并优化其检测条件.在pH=7.5的条件下,以N,N-二甲基甲酰胺（DMF）作为溶剂,加入0.4 mL表面活性剂Tween-80,系列羟基卟啉与Hg2＋发生配位反应,发现其最大吸收峰与卟啉环上（meso）位苯基对位上的羟基数目相关.热力学研究表明,单羟基卟啉化合物对Hg2＋检测效果最好,形成1∶1配位化合物,检测限可达0.042μg.L-1,且在0—50 mg.L-1范围内符合比尔定律.     

Evidence for broadcast spawning as well as brooding in the scleractinian coral Pocillopora damicornis

The reproductive activity of 88 colonies of Pocillopora damicornis at Rottnest Island, Western Australia, was examined over 12 mo (20 August 1988 to 20 August 1989). Larvae were found close to the three new moons of February, March and April, 1989, but in large numbers only during March; 67% of all corals produced larvae. There was no obvious connection between gametogenesis and the production of brooded larvae; however, those corals which did not produce, larvae also did not produce ova but did produce, sperm, and must be considered male colonies. All colonies which produced ova went on to produce planulae. Spermatogenesis occurred throughout the year, but oogenesis occurred between September 1988 and April 1989. Dramatic declines in the percentage of polyps containing eggs and sperm occurred in early February and early April 1989. On these dates the amount of lipid in the tissue of the corals decreased, which suggests that the decline in the percentage of polyps with sperm and eggs was not due to the gametes being resorbed by the polyps. Therefore, P. damicornis at Rottnest Island appears to be both a brooder and a broadcaster with asexual reproduction through brooded larvae and sexual reproduction through spawning of gametes. This accounts for earlier evidence in the literature that some input from sexual reproduction had been occurring in the populations of P. damicornis at Rottnest Island. There is no direct evidence for spawning, as broadcasting of gametes has not been observed, but the indirect evidence provides a strong argument for the existence of this dual reproduction.     

The fly-and-social foraging hypothesis for diurnal migration: why American crows migrate during the day

Most migratory species migrate at night, and the benefits associated with nocturnal migration have been well reviewed; however, less attention has been paid to the benefits associated with diurnal migration. There are two theories for diurnal migration: (1) diurnal migration allows for the use of thermals and therefore reduces energy loss, and (2) the fly-and-forage hypothesis, which suggests that diurnal migrants can search for prey and forage as they migrate. We investigated whether American crows (Corvus brachyrhynchos) engage in the fly-and-forage strategy of diurnal migration as they migrated north in the spring. We tracked eight radio-tagged crows as they migrated hundreds of kilometers in the spring to determine if they were diurnal migrants, whether they migrated with conspecifics, whether they stopped to forage, and if they did stop, whether they forage with conspecifics. All crows migrated during the day, and while on several occasions crows were seen migrating in close association with conspecifics, all crows were also observed migrating alone. On average, crows migrated approximately 300 km the day they left their wintering grounds, and over the course of this day, they stopped twice and foraged at these locations for 35 min. On all but one occasion, the stops made during migration were to forage with groups of conspecifics. While the fly-and-forage hypothesis for diurnal migration has primary been applied to raptors, many diurnal migrants forage socially, and the presence of foraging conspecifics and/or heterospecifics may be a significant benefit in locating food resources and ultimately migrating during the day.     

Genomic erosion in a demographically recovered bird species during conservation rescue

The pink pigeon (Nesoenas mayeri) is an endemic species of Mauritius that has made a remarkable recovery after a severe population bottleneck in the 1970s to early 1990s. Prior to this bottleneck, an ex situ population was established from which captive-bred individuals were released into free-living subpopulations to increase population size and genetic variation. This conservation rescue led to rapid population recovery to 400–480 individuals, and the species was twice downlisted on the International Union for the Conservation of Nature (IUCN) Red List. We analyzed the impacts of the bottleneck and genetic rescue on neutral genetic variation during and after population recovery (1993–2008) with restriction site-associated sequencing, microsatellite analyses, and quantitative genetic analysis of studbook data of 1112 birds from zoos in Europe and the United States. We used computer simulations to study the predicted changes in genetic variation and population viability from the past into the future. Genetic variation declined rapidly, despite the population rebound, and the effective population size was approximately an order of magnitude smaller than census size. The species carried a high genetic load of circa 15 lethal equivalents for longevity. Our computer simulations predicted continued inbreeding will likely result in increased expression of deleterious mutations (i.e., a high realized load) and severe inbreeding depression. Without continued conservation actions, it is likely that the pink pigeon will go extinct in the wild within 100 years. Conservation rescue of the pink pigeon has been instrumental in the recovery of the free-living population. However, further genetic rescue with captive-bred birds from zoos is required to recover lost variation, reduce expression of harmful deleterious variation, and prevent extinction. The use of genomics and modeling data can inform IUCN assessments of the viability and extinction risk of species, and it helps in assessments of the conservation dependency of populations.     

Individual boldness affects interspecific interactions in sticklebacks

Within populations of many species, individuals that are otherwise similar to one another in age, size or sex can differ markedly in behaviours such as resource use, risk taking and competitive ability. There has been much research into the implications of such variation for intraspecific interactions, yet little investigation into its role in influencing interspecific interactions outside of a predator–prey context. In this study, we investigated the role of individual-level behavioural variation in determining the outcomes of interactions between two ecologically similar fishes, the threespine and ninespine sticklebacks (Gasterosteus aculeatus and Pungitius pungitius). Experiment 1 asked whether individuals of both species were consistent in their expression of two behaviours: activity in novel surroundings and latency to attack prey. For each behaviour, focal individuals were assayed twice, 10 days apart. Performances were positively correlated between exposures, suggesting behavioural consistency within individuals, at least over this timescale. Experiment 2 revealed not only differences in habitat use described both by species-level variation, with ninespines spending more time in vegetated areas, but also by individual differences, with more active individuals of both species spending more time in open water than in vegetation. Experiment 3 revealed that when heterospecific pairs competed for prey, bolder individuals consumed a greater share, irrespective of species. These findings suggest that individual-level variation can facilitate overlap in habitat use between heterospecifics and also determine the outcomes of resource contests when they meet. We discuss how this might vary between populations as a function of prevailing selection pressures and suggest approaches for testing our predictions.     

Biogeochemical consequences of a changing Arctic shelf seafloor ecosystem

Unprecedented and dramatic transformations are occurring in the Arctic in response to climate change, but academic, public, and political discourse has disproportionately focussed on the most visible and direct aspects of change, including sea ice melt, permafrost thaw, the fate of charismatic megafauna, and the expansion of fisheries. Such narratives disregard the importance of less visible and indirect processes and, in particular, miss the substantive contribution of the shelf seafloor in regulating nutrients and sequestering carbon. Here, we summarise the biogeochemical functioning of the Arctic shelf seafloor before considering how climate change and regional adjustments to human activities may alter its biogeochemical and ecological dynamics, including ecosystem function, carbon burial, or nutrient recycling. We highlight the importance of the Arctic benthic system in mitigating climatic and anthropogenic change and, with a focus on the Barents Sea, offer some observations and our perspectives on future management and policy.     

Fire Regimes and Tree Growth in Low Rainfall Jarrah Forest of South-west Australia

Regular fuel reduction burning is an important management strategy for reducing the scale and intensity of wildfires in south-west Australian native forests, but the long term effects of this on tree and stand growth are not well understood. Five fire treatments, including application of frequent and infrequent low intensity burns, and 25 years of fire exclusion, were applied to small (4 ha) experimental plots in a low rainfall mixed jarrah (Eucalyptus marginata) and marri (Corymbia calophylla) forest to investigate the effects of these treatments on tree stem diameter growth, stand basal area increment and tree mortality. Mean tree stem growth measured over 20 years was lowest in the long unburnt treatment compared with the burn treatments, although surface soil nutrient levels were generally higher in the unburnt treatment, suggesting these sites may be moisture limited. There was no clear pattern of the effects of the burn treatments, including the number of fires and the interval between fires, on tree stem growth, stand basal area increment, crown health or mortality. These factors were strongly influenced by dominance condition, with dominant and co-dominant trees growing most and suppressed trees growing least and experiencing the highest mortality levels. There was no evidence of deteriorating tree or stand health that could be attributed to either regular low intensity burning or to a long period (25 years) of fire exclusion.