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111.
Spatial distribution of the pomacentrids on Singapore reefs was assessed visually, while temporal change was studied within permanent quadrats established on a patch reef between 4 Jul and 30 Nov 1989. Partitioning of space, both horizontally and vertically, on the reef was observed in 15 species. The population of territorial damselfishes on the reef flat was less stable than on the reef slope over time, due to the seasonal occurrence of dense stands of the brown macroalgae, Sargassum. Space was found to be a limiting factor at the reef flat due to the high density of pomacentrids found there. Food resource was the limiting factor on the reef slope, where low light intensity due to sedimentation and lack of suitable substrate inhibited turf algal growth. Multi-specific recruitment of juveniles occurred in April and between mid-October and early November. 相似文献
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Connell DP Withum JA Winter SE Statnick RM Bilonick RA 《Journal of the Air & Waste Management Association (1995)》2005,55(5):559-573
One-hour average ambient concentrations of particulate matter (PM) with an aerodynamic diameter < 2.5 microm (PM2.5) were determined in Steubenville, OH, between June 2000 and May 2002 with a tapered element oscillating microbalance (TEOM). Hourly average gaseous copollutant [carbon monoxide (CO), sulfur dioxide (SO2), nitrogen oxide (NOx), and ozone (O3)] concentrations and meteorological conditions also were measured. Although 75% of the 14,682 hourly PM2.5 concentrations measured during this period were < or = 17 microg/m3, concentrations > 65 microg/m3 were observed 76 times. On average, PM2.5 concentrations at Steubenville exhibited a diurnal pattern of higher early morning concentrations and lower afternoon concentrations, similar to the diurnal profiles of CO and NO(x). This pattern was highly variable; however, PM2.5 concentrations > 65 microg/m3 were never observed during the mid-afternoon between 1:00 p.m. and 5:00 p.m. EST. Twenty-two episodes centered on one or more of these elevated concentrations were identified. Five episodes occurred during the months June through August; the maximum PM2.5 concentration during these episodes was 76.6 microg/m3. Episodes occurring during climatologically cooler months often featured higher peak concentrations (five had maximum concentrations between 95.0 and 139.6 microg/m3), and many exhibited strong covariation between PM2.5 and CO, NO(x), or SO2. Case studies suggested that nocturnal surface-based temperature inversions were influential in driving high nighttime concentrations of these species during several cool season episodes, which typically had dramatically lower afternoon concentrations. These findings provide insights that may be useful in the development of PM2.5 reduction strategies for Steubenville, and suggest that studies assessing possible health effects of PM2.5 should carefully consider exposure issues related to the intraday timing of PM2.5 episodes, as well as the potential for toxicological interactions among PM2.5, and primary gaseous pollutants. 相似文献
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Chlorinated paraffins (CPs), as technical mixtures of polychlorinated alkanes (PCAs), are ubiquitous in the environment. CPs tend to behave in a similar way to persistent organic pollutants (POPs), leading several countries to impose regulations on the use of CPs. In this article, we review the literature on the properties of CPs, the current analytical tools available to determine CPs in various types of environmental matrices, and concentrations found in the environment. In particular, concentrations of CPs in environmental compartments including air, water, sediments, biota, human food products and human tissues are summarized. Priorities for future research are: improvements in analytical methodologies (reducing the complexity of the analysis, producing reference materials and performing interlaboratory studies); determining background levels of chlorinated paraffins in the environment and human populations (this question should be answered using quality assured analytical tools allowing the intercomparison of data); and investigating the sources of CPs to the environment and to humans. 相似文献
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IntroductionYard maintenance equipment is potentially dangerous, and some of the more frequency used equipment (e.g., lawn mowers) has been extensively studied. However, the extent of lawn trimmers as a source of injury has not previously been explored.MethodsData from the Consumer Product Safety Commission's National Electronic Injury Surveillance System were used to estimate the number of patients treated in U.S. emergency departments for lawn trimmer-related injuries. Injury rates were calculated according to age, sex, and race, and characteristics of the injury event were determined.ResultsAn estimated 81,907 injuries involving a lawn trimmer occurred from 2000–2009. The incidence generally increased over time. Men, people aged 40–49, and Caucasians were the groups most likely to be injured. The most commonly injured body part was the head, specifically the eye, accounting for 42.5% of the injuries. Contusions and abrasions were the most common type of injury to the head, but lacerations were the most common injury to the extremities, and strains/sprains were the most common injury to the trunk.DiscussionAlthough previous research on lawn trimmers has focused exclusively on injuries to the eyes, the results of the current study show that such injuries are one component of the problem. Because most of the injuries were due to foreign objects, it is important that the use of adequate safety gear be emphasized when operating lawn trimmers.Impact on IndustryResults suggest that lawn trimmer design changes and better safety education for trimmer use can reduce the rate of injury and reverse the current trend. 相似文献
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Michael Stat Jeffrey John Joseph D. DiBattista Stephen J. Newman Michael Bunce Euan S. Harvey 《Conservation biology》2019,33(1):196-205
Monitoring communities of fish is important for the management and sustainability of fisheries and marine ecosystems. Baited remote underwater video systems (BRUVs) are among the most effective nondestructive techniques for sampling bony fishes and elasmobranchs (sharks, rays, and skates). However, BRUVs sample visually conspicuous biota; hence, some taxa are undersampled or not recorded at all. We compared the diversity of fishes characterized using BRUVs with diversity detected via environmental DNA (eDNA) metabarcoding. We sampled seawater and captured BRUVs imagery at 48 locales that included reef and seagrass beds inside and outside a marine reserve (Jurien Bay in Western Australia). Eighty-two fish genera from 13 orders were detected, and the community of fishes described using eDNA and BRUVs combined yielded >30% more generic richness than when either method was used alone. Rather than detecting a homogenous genetic signature, the eDNA assemblages mirrored the BRUVs’ spatial explicitness; differentiation of taxa between seagrass and reef was clear despite the relatively small geographical scale of the study site (∼35 km2). Taxa that were not sampled by one approach, due to limitations and biases intrinsic to the method, were often detected with the other. Therefore, using BRUVs and eDNA in concert provides a more holistic view of vertebrate marine communities across habitats. Both methods are noninvasive, which enhances their potential for widespread implementation in the surveillance of marine ecosystems. 相似文献
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S. W. Jeffrey 《Marine Biology》1974,26(2):101-110
Phytoplankton pigments at a coastal station off Sydney, Australia, were studied by cellulose thinlayer chromatography. The chromatographic procedure distinguished chlorophylls a, b and c, chlorophyllide a, pheophytin a and pheophorbide a, and the major carotenoids carotene, astaxanthin, fucoxanthin, peridinin, diadinoxanthin and neoxanthin. Chlorophyllide a and pheophorbide a were the most significant chlorophyll-a degradation products in the water column, chlorophyllide a coming from chlorophyllase activity of senescent diatoms, and pheophorbide a from faecal pellets of copepods. Chlorophyll c occurred in every sample, even where there was no trace of chlorophyll a. Because of the greater chemical and biological stability of chlorophyll c compared to chlorophyll a, high chlorophyll c:a ratios result from a large proportion of senescent or detrital material in the samples. Determining the position of patches of copepods, diatoms, green algae and dinoflagellates in the water column was easily done by noting the presence of definitive pigments on the chromatograms. 相似文献
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