Anthropogenic factors and habitat complexity influence biodiversity but wave exposure drives species turnover of a subtropical rocky inter‐tidal metacommunity          下载免费PDF全文

Christopher P. Bloch  Brian T. Klingbeil 《Marine Ecology》2016,37(1):64-76

Coastal ecosystems are complex and species rich, but are vulnerable to degradation from a variety of anthropogenic activities. Nevertheless, information on inter‐tidal community composition in the Caribbean Basin and at other oceanic sites is lacking. Such information is essential to developing a more comprehensive understanding of rocky inter‐tidal systems and their responses to global change. The goals of this study were to determine the relative importance of environmental (wave power density, wave height), habitat (e.g. algal cover, slope, complexity of rock surfaces) and anthropogenic (distance to roads, population density) factors associated with the structure of local assemblages at multiple shore heights and the regional metacommunity of mobile invertebrates on oceanic rocky inter‐tidal habitats. Environmental characteristics associated with habitat complexity (algal cover, rock surface complexity) and human population density were most strongly associated with abundance and biodiversity of invertebrates. Species richness was positively correlated with surface complexity, but abundance was negatively correlated with both surface complexity and per cent algal cover. By contrast, abundance of invertebrates was positively correlated with human population density, and diversity was negatively correlated with human population density. Abundance of invertebrates was greatest in the mid inter‐tidal zone, whereas diversity was greatest in the lower inter‐tidal zone. Metacommunity structure was Gleasonian, but the gradient along which species turnover occurred was correlated with measures of wave exposure, rather than anthropogenic activity. Unlike in previous studies, mostly at mainland sites, human activity primarily altered dominance patterns of communities, while having relatively little effect on species richness or composition.  相似文献   

Description of the vessel traffic within the north Pelagos Sanctuary: Inputs for Marine Spatial Planning and management implications within an existing international Marine Protected Area     

《Marine Policy》2016

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Fishers’ knowledge indicates short-term temporal changes in the amount and composition of catches in the southwestern Atlantic     

《Marine Policy》2016

The scarcity of data on fish catches difficult management of small-scale fisheries in developing countries. This study applies fishers’ knowledge to investigate temporal changes in the amount (biomass) and composition (major ecological categories) of fishing resources exploited by small-scale coastal fisheries in the southeastern Brazilian coast. Four hypotheses were investigated: (1) The amount of fish caught reported by fishers would decrease over time. (2) Older fishers would report higher fish catches than younger fishers. (3) Recent interviews would mention large-sized predators less often. (4) Recent interviews would mention less high valued fishing resources. Interviews with 421 fishers in 36 communities in the southeastern Brazilian coast were analyzed, covering a time span of 14 years, from 1995 to 2009. The hypothesis 1 was confirmed, 3 was partially confirmed, while 2 and 4 were not confirmed. Fishers’ age was unrelated to all variables. The results from fishers’ interviews indicated the temporal trends of: (1) a decrease in the biomass of fish caught; (2) an increase in the occurrence of smaller fish and invertebrates in the catch; (3) an increase of high value fishing resources; and (4) maintenance of large predators. The first two indicators suggest excessive fishing, but the later indicators (3 and 4) suggest that the socioecological system of the southeastern Brazilian coast had not yet undergone major ecological shifts.  相似文献   

反渗透海水淡化技术现状和展望     

高从堦  周勇  刘立芬 《海洋技术学报》2016,(1):1-14

反渗透膜技术于20世纪60年代取得突破性进展,促使反渗透海水淡化在近50年间高速发展,淡化产能自20世纪90年代起激增.海水反渗透(SWRO)淡化已成为目前投资最省、成本最低的利用海水制备饮用水的过程.文中主要对海水反渗透淡化的发展状况进行了介绍,如膜和组件的改进,关键设备高压泵和能量回收装置效率的提高,多种工艺过程的不断发展,包括预处理和后处理的新工艺,以及对环境的影响和相应对策等.反渗透技术的发展也推动了其他膜分离技术的进步,并扩展其应用领域.预计在不久的将来,膜技术在海水淡化和水再利用、扩大和保护水资源、循环经济、清洁生产、改造传统产业、节能减排及提高人民生活水平等方面发挥的作用会越来越显著.  相似文献   

1980—2018年黄河上游气候变化及其对生态植被和径流量的影响   总被引：3，自引：0，他引：3       下载免费PDF全文

叶培龙  张强  王莺  徐丽丽  韩林君  李蓉 《大气科学学报》2020,43(6):967-979

黄河上游是黄河流域最重要的水源涵养地和产流区,对黄河流域的水资源安全、生态环境和粮食安全有决定性的意义。近年来在西北地区气候暖湿化的背景下,黄河上游气候生态水文等问题受到了各方的高度关注。本文利用卫星遥感数据、格点融合数据和水文监测数据,分析了黄河上游气候的多尺度变化特征及其对植被和径流量的影响。结果表明：1）1980-2018年黄河上游暖湿化趋势呈现全区域较一致的气候特征,温度增加率为0.023℃/a,降水增加率为1.09 mm/a,但同时又存在明显的区域差异性,湟水流域至甘肃中部降水增加最显著,宁蒙荒漠地带增温趋势最明显,2000年以来整个黄河上游降水明显增加。2000年后汇流区与流径区的蒸散发明显增加,但源头区南部波动减少。2）当前的暖湿化有利于黄河上游植被生长,1999年以来汇流区和源头区部分区域的植被增加率达到0.04/（10 a）;从长期趋势看,源头区、汇流区植被指数与上年降水呈显著正相关关系,而流径区植被指数与当年降水相关性显著;降水对黄河上游流域植被具有明显的改善作用,而温度对其影响较复杂,各区域不同的植被类型是导致降水、温度、蒸散影响存在差异的可能原因。3）1980-2018年唐乃亥站和兰州站的年径流量均呈减少趋势,但1998年以来两站的年径流量明显增加,兰州站年径流量的增加率是唐乃亥站的近3倍。长期趋势表明,唐乃亥站年径流量与当年降水呈显著正相关关系,兰州站年径流量与当年降水、蒸散的相关系数均明显低于唐乃亥站;从年际波动看,降水是决定年径流量的最主要影响因子,而生态植被、冻土退化、水储量变化及社会活动等因素对径流量的影响也不容忽视。该研究为科学应对黄河上游生态保护及实现黄河流域高质量发展提供了参考依据。  相似文献   

柴达木盆地盐尘暴及其资源生态环境影响   总被引：1，自引：1，他引：0       下载免费PDF全文

张西营  李雯霞  耿鋆  苗卫良  李永寿  唐启亮  陈亮  袁小龙  郭晓宁  王钰  才仁扎西 《盐湖研究》2020,28(1):11-17

在干旱和半干旱地区,盐尘暴是一种常见的极端气象灾害。柴达木盆地频发的沙尘暴实质上就是盐尘暴。柴达木盆地盐尘暴已经对区域大气、土壤、植被、人类健康乃至全球气候变化都产生了不同程度的影响。由于柴达木盆地盐尘暴中可溶盐成分来源复杂,尽管目前对其形成过程和机制还缺乏深刻理解,但人类的资源开发活动对盐尘暴显然具有促进作用。有必要从系统的角度来考虑柴达木盆地盐尘暴对区域乃至全球的影响,这对于区域生态环境的正确评估和后期恢复治理具有重要意义。  相似文献   

Morphological and sedimentary impacts and recovery on a mixed sandy to pebbly seabed exposed to marine aggregate extraction (Eastern English Channel,France)     

Sophie Le Bot  Robert Lafite  Matthieu Fournier  Agnès Baltzer  Michel Desprez 《Estuarine, Coastal and Shelf Science》2010

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Breaking wave loads at vertical seawalls and breakwaters     

Giovanni Cuomo  William Allsop  Tom Bruce  Jonathan Pearson 《Coastal Engineering》2010

This paper presents recent advances in knowledge on wave loads, based on experimental work carried out in the CIEM/LIM large flume at Barcelona within the framework of the VOWS (Violent Overtopping by Waves at Seawalls) project. Both quasi-static and impact wave forces from the new data set have been compared with predictions by empirical and analytical methods. The scatter in impact forces has been found to be large over the whole range of measurements, with no existing method giving especially good predictions. Based on general considerations, a simple and intuitive set of prediction formulae has been introduced for quasi-static and impact forces, and overturning moments, giving good agreement with the new measurements. New prediction formulae have been compared with previous measurements from physical model tests at small and large scale, giving satisfactory results over a relatively wide range of test conditions. The time variation of wave impacts is discussed, together with pressure distribution up the wall, which shows that within experimental limitations the measured pressures are within existing limits of previous study.  相似文献   

Scaling wave impact pressures on vertical walls     

Giovanni Cuomo  William Allsop  Shigeo Takahashi 《Coastal Engineering》2010

It is widely recognized that the use of Froude similarity for scaling up wave impact pressures recorded during physical model tests may lead to over-estimation of impact maxima. Based on reviewing historical work dating back to the 30s and further developments in the 60s and 80s, a general method is presented that is suitable for scaling up impact pressures and rise times measured during small scale physical model tests. The method accounts for the effect of air leakage and is applicable to most wave impact loads. The model is applied to scale wave impact pressures on vertical walls and similar structures, and consistent correction factors for the Froude scaling law are derived.  相似文献   

Variability of temperature,salinity and tidally‐averaged density in the middle estuary of the St Lawrence     

Langley R. Muir 《大气与海洋》2013,51(4):320-336

Abstract

Surveys in the Middle Estuary of the St Lawrence have yielded a data base consisting of more than 15,000 T‐S pairs distributed over 62 13‐h profiling stations. Although the T‐S curves at each station are remarkably linear, the variability of the slopes and intercepts of the lines is considerable. The means and standard deviations of the temperature and salinity at each individual station are not explicable in terms of linear combinations of the parameters for location in the Estuary, the upstream water properties, the phase of the spring‐neap cycle and the tidal energies.

It is shown that the tidally‐averaged density structure is separable into horizontal and vertical components and that its vertical variation over the whole Estuary may be explained by any one of three different functional forms. However, its horizontal variation is not explicable in terms of linear combinations of the parameters mentioned in the paragraph above.

Plots of the horizontal variations in temperature, salinity or density may only be meaningful if the data are collected synoptically, and even then cannot be considered to be accurate over time‐scales longer than one tidal cycle.  相似文献