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Understanding species distributions, and how they change in space and time, is vital when prioritising conservation or management initiatives. We assessed the distribution and density patterns of common dolphins (Delphinus sp.), bottlenose dolphins (Tursiops truncatus) and Bryde’s whales (Balaenoptera edeni) in the Hauraki Gulf, New Zealand. Dedicated boat-based surveys were conducted in the inner Hauraki Gulf (IHG) and off Great Barrier Island (GBI) during 2010–2012. Generalised linear models were used to investigate temporal changes in relative densities and kernel density estimation was implemented to examine spatial trends. Common dolphins were widely distributed during all seasons, with higher densities observed during winter and spring in the IHG but during autumn off GBI. There was inter-annual variation in Bryde’s whale distribution, with high densities recorded off GBI in 2011. Bottlenose dolphins were infrequently sighted in the IHG but regularly encountered off GBI, with the highest densities during spring and summer. 相似文献
2.
新疆希勒库都克铜钼矿区岩浆混合作用: 来自锆石U-Pb年代学的证据 总被引：7，自引：6，他引：1
新疆北部富蕴县内希勒库都克铜钼矿区的花岗闪长岩及其包体岩相学、矿物化学和岩石地球化学特征及野外地质特征显示其为岩浆混合作用的结果。本文获得花岗闪长岩及其中暗色微粒包体玄武安山玢岩、细粒辉长闪长岩锆石U-Pb年龄为326.8±2.1Ma、327.6±2.4Ma、329.3±2.3Ma,年龄值基本一致,这一结果从年代学角度为花岗闪长岩及其中暗色微粒包体的岩浆混合作用成因提供证据。偏酸性的花岗闪长质与偏基性玄武安山质岩浆混合作用形成了331.9±2.1Ma的安山玢岩脉。 相似文献
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J. Elizabeth Jackson Michael G. Yost Catherine Karr Cole Fitzpatrick Brian K. Lamb Serena H. Chung Jack Chen Jeremy Avise Roger A. Rosenblatt Richard A. Fenske 《Climatic change》2010,102(1-2):159-186
Illness and mortality related to heat and worsening air quality are core public health concerns associated with climate change projections. We examined the historical relationship between age- and cause-specific mortality rates from 1980 through 2006 and heat events at the 99th percentile of humidex values in the historic period from January 1, 1970 to December 31, 2006 in the greater Seattle area (King, Pierce and Snohomish counties), Spokane County, the Tri-Cities (Benton and Franklin counties) and Yakima County; the relative risks of mortality during heat events were applied to population and climate projections for Washington State to calculate number of deaths above the baseline (1980–2006) expected during projected heat events in 2025, 2045 and 2085. Three different warming scenarios were used in the analysis. Relative risks for the greater Seattle area showed a significant dose-response relationship between heat event duration and daily mortality rates for non-traumatic deaths for persons ages 45 and above, typically peaking at four days of exposure to humidex values above the 99th percentile. The largest number of projected excess deaths in all years and scenarios for the Seattle region was found for age 65 and above. Under the middle warming scenario, this age group is expected to have 96, 148 and 266 excess deaths from all non-traumatic causes in 2025, 2045 and 2085, respectively. We also examined projected excess deaths due to ground-level ozone concentrations at mid century (2045–2054) in King and Spokane counties. Current (1997–2006) ozone measurements and mid-twenty-first century ozone projections were coupled with dose-response data from the scientific literature to produce estimates overall and cardiopulmonary mortality. Daily maximum 8-h ozone concentrations are forecasted to be 16–28% higher in the mid twenty-first century compared to the recent decade of 1997–2006. By mid-century in King County the non-traumatic mortality rate related to ozone was projected to increase from baseline (0.026 per 100,000; 95% confidence interval 0.013–0.038) to 0.033 (95% CI 0.017–0.049). For the same health outcome in Spokane County, the baseline period rate of 0.058 (95% CI 0.030–0.085) was estimated increase to 0.068 (95% CI 0.035–0.100) by mid-century. The cardiopulmonary death rate per 100,000 due to ozone was estimated to increase from 0.011 (95% CI 0.005–0.017) to 0.015 (0.007–0.022) in King County, and from 0.027 (95% CI 0.013–0.042) to 0.032 (95% CI 0.015–0.049) in Spokane County. Public health interventions aimed at protecting Washington’s population from excessive heat and increased ozone concentrations will become increasingly important for preventing deaths, especially among older adults. Furthermore, heat and air quality related illnesses that do not result in death, but are serious nevertheless, may be reduced by the same measures. 相似文献
4.
Julia G. Harenčár Greg A. Lutgen Zac M. Taylor Norah P. Saarman Jennifer M. Yost 《Estuaries and Coasts》2018,41(8):2356-2367
Seagrass populations are in decline worldwide. Eelgrass (Zostera marina L.), one of California’s native seagrasses, is no exception to this trend. In the last 8 years, the estuary in Morro Bay, California, has lost 95% of its eelgrass. Population bottlenecks like this one often result in severe reductions in genetic diversity; however, this is not always the case. The decline of eelgrass in Morro Bay provides an opportunity to better understand the effects of population decline on population genetics. Furthermore, the failure of recent restoration efforts necessitates a better understanding of the genetic underpinnings of the population. Previous research on eelgrass in California has demonstrated a link between population genetic diversity and eelgrass bed health, ecosystem functioning, and resilience to disturbance and extreme climatic events. The genetic diversity and population structure of Morro Bay eelgrass have not been assessed until this study. We also compare Morro Bay eelgrass to Bodega Bay eelgrass in Northern California. We conducted fragment length analysis of nine microsatellite loci on 133 Morro Bay samples, and 20 Bodega Bay samples. We found no population differentiation between the remaining beds in Morro Bay and no difference among samples growing at different tidal depths. Comparisons with Bodega Bay revealed that Morro Bay eelgrass contains three first-generation migrants from the north, but Morro Bay remains considerably genetically differentiated from Bodega Bay. Despite the precipitous loss of eelgrass in Morro Bay between 2008 and 2017, genetic diversity remains relatively high and comparable to other populations on the west coast. 相似文献
5.
Wild rice (Zizania spp. L.) is a North American native grain with spiritual and dietary significance to many native people. Wild rice is also an important aquatic plant that provides critical habitat to wetland and aquatic wildlife. Past distribution of wild rice in North America is poorly understood, largely because of the limited taxonomic resolution of Poaceae pollen. A novel technique for detecting diagnostic Zizania silica phytoliths allows unambiguous identification of this taxon in lake sediments. We need to better understand modern depositional patterns of phytoliths in lake sediments, however, before attempting detailed paleoreconstructions. We analyzed distributions of diagnostic Zizania and other Poaceae phytoliths in modern sediments from three lakes with variable percent cover of wild rice and a non-wild rice control lake in central Minnesota. Absolute counts of phytoliths per gram sediment were achieved using an exotic diatom marker. Non-Zizania short-cell phytoliths, i.e. phytoliths from wetland grasses Phragmites australis and Muhlenbergia glomerata, dominate the assemblages in all lakes. Most Poaceae short-cell phytoliths appear to be derived locally, with little evidence for regional inheritance from eolian or alluvial processes. Because of anatomical differences in decay of plant debris and other taphonomic issues, Zizania inflorescence rondel phytoliths were most abundant, with morphotypes from other parts rarely encountered. Even in sediments under the densest wild rice stands, Zizania phytoliths contributed a maximum of 9 % to total Poaceae phytolith abundance. Lake morphology also affects the depositional pattern of phytoliths in modern sediments, so coring locations should be considered carefully. At least 500 phytoliths should be counted to detect a sufficient number of wild rice phytolith morphotypes. Diagnostic Zizania phytoliths are a reliable tool for wild rice detection in paleolake sediments. 相似文献
6.
Until recently, vessel collisions with small cetaceans were presumed rare, mainly as a consequence of limited reporting. Observations on dolphin wound healing from propeller strike injuries also remain scarce. We present an extreme case of a bottlenose dolphin (Tursiops truncatus) with multiple propeller wounds, including a penetration to the bone, where survival was possible for at least 23 days post injury. We used photographic records in conjunction with field observations to describe wound progression in the absence of treatment. Considering the severity of the wounds, it was surprising that the injuries were not immediately fatal. A practical solution remains to be found for the problem of odontocete vessel collisions, in particular for small highly mobile species using neritic waters. In view of the ongoing problem in the Hauraki Gulf and, indeed, worldwide, we recommend continued evaluation of cases and reporting of incidents, in addition to investigations into mechanisms that may reduce the risk of occurrence of vessel collisions with cetaceans. 相似文献
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Potentially active volcanoes of Peru-Observations using Landsat Thematic Mapper and Space Shuttle imagery 总被引：1，自引：1，他引：0
Landsat Thematic Mapper (TM) images and Space Shuttle color photograph have been used to make a synoptic study of the volcanoes of southern Peru (14°–17° S), the northernmost portin of the Central Volcanic Zone (CVZ 14°–28° S) of the Andes. Apart from providing consistent coverage, the chief merit of the TM for this study has been the spatial resolution provided by the 30-m pixel size. The optimal 20-m resolution, variable lighting and viewing geometry, and stereo capability of the Shuttle photography provided an invaluable ancilliary data set. At the resolution available, subtle glacial-morphological features such as valley and terminal moraines can be confidently identified, and these features have been used to determine the relative ages of volcanoes. Volcanoes have been classified as potentially active if they have; (i) a well-preserved summit crater, (ii) pristine lava flow texture and morphology, (iii) flank lava flows with low albedo, and (iv) evidence of postglacial (<10 000 years) activity. Eight major volcanoes are postulated to be potentially active. Most are large, dominantly andesitic, composite cones with edifice heights of up to 2500 m; some of which threaten nearby settlements. One of them, Sabancaya, was active as recently as July 1988. Other, little-known, postglacial volcanic features include Huaynaputina, site of a major explosive rhyolitic eruption in 1600 a.d., and several fields of monogenetic scoria cones and lava flows. The active volcanic front is some 200 km east of the Peru-Chile trench, and the volcanoes lie on a trenchparallel trend oblique to the EW subduction. This narrow volcanic zone is thought to reflect the steep dip of the Nazca plate through the zone of magma generation. The break in the trend of the volcanic front in the northern extremity of the volcanic zone is thought to reflect the complexity of the crustal stress field above a major segment boundary in the subducting plate. The fields of mafic monogenetic centers also occur in this region. In comparison with the southern part of the CVZ, the general paucity of older volcanic edifices north of 17° S suggests a more recent onset of volcanism north of this latitude probably resulting from the oblique subduction of the Nazca ridge and the consequent northward migration of its intersection with the Pere-Chile trench. This, coupled with the lack of any large silicic caldera systems and youthful dacite domes, like those found further south, suggest that there are real differences between the volcanic evolution of different parts of the CVZ. 相似文献
8.
西秦岭凤太矿集区丝毛岭金矿床地质地球化学特征 总被引：1，自引：0，他引：1
西秦岭凤太矿集区丝毛岭金矿床位于八卦庙造山型金矿床西侧5km左右,是一个新探明的剪切带型金矿。其成矿作用过程可分为早期石英-绢云母-硫化物阶段、中期多金属-硫化物阶段和晚期碳酸盐阶段。对早、中期的石英流体包裹体测试结果表明,丝毛岭金矿床成矿流体以富CO2、中温、低盐度为特征,总体上属于中温低盐度CO2-H2O体系,流体包裹体类型的多样性是流体不混溶性的产物。从早阶段到主成矿阶段成矿流体的温度、压力和盐度均有降低,硫逸度增高,有利于金的沉淀富集。H、O、S、C同位素研究结果,以及与八卦庙金矿床的对比分析表明,二者的成矿流体具有相似性和同源性,都是以深部来源为主的多源流体。由于丝毛岭金矿床产出的层位高于八卦庙金矿床,其成矿环境相对开放。 相似文献
9.
Analyses of surface and seepage waters from selected floodwater retarding structures in west-central Oklahoma, U.S.A. show the salinity of seepage to be several times greater than that of the impounded waters. The increases in concentration of the several chemical components are not proportional. This phenomenon appears to be caused largely by simple solution, which is closely related to the chemical character of the geologic formation that provides the reservoir site and the earth fill of the dam. Concentration of certain chemical components in the seepage water progressively decreases as the structure ages. This is probably a function of depletion, which is related to the amounts and solubility of the parent materials subjected to solution. In contrast, the concentration of certain other components, such as iron and calcium, increases with time. The chemical activities within the accumulating mud on the bottom of the reservoir apparently cause these increases. 相似文献
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