共查询到20条相似文献，搜索用时 539 毫秒
1.
2.
Lewis SE Schaffelke B Shaw M Bainbridge ZT Rohde KW Kennedy K Davis AM Masters BL Devlin MJ Mueller JF Brodie JE 《Marine pollution bulletin》2012,65(4-9):280-291
Herbicide residues have been measured in the Great Barrier Reef lagoon at concentrations which have the potential to harm marine plant communities. Monitoring on the Great Barrier Reef lagoon following wet season discharge show that 80% of the time when herbicides are detected, more than one are present. These herbicides have been shown to act in an additive manner with regards to photosystem-II inhibition. In this study, the area of the Great Barrier Reef considered to be at risk from herbicides is compared when exposures are considered for each herbicide individually and also for herbicide mixtures. Two normalisation indices for herbicide mixtures were calculated based on current guidelines and PSII inhibition thresholds. The results show that the area of risk for most regions is greatly increased under the proposed additive PSII inhibition threshold and that the resilience of this important ecosystem could be reduced by exposure to these herbicides. 相似文献
3.
Cuauhtemoc Franco Ochoa Edgar Mendoza Baldwin Rodolfo Silva Casarín Gabriel Ruiz Martínez 《洁净——土壤、空气、水》2012,40(9):920-925
Pollution, habitat modification, and species migration are some of the results of human activities on natural environments which can be mitigated or compensated with proper planning. Irresponsibility or ignorance in planning coastal projects too often produces damage to natural systems which can be unpredictable and sometimes irrevocable. The specific site analyzed in this paper is the Cuautla littoral sub‐system which was originally a lagoon that diverted river water to other lagoons and estuaries, thus irrigating the Mexican Marismas Nacionales system, in the states of Nayarit and Sinaloa, Mexico. In the 1970s social and economic considerations motivated the construction of a small breaching canal from the sea to the lagoon. The subsequent growth of this channel was unforeseen and has produced an irreversible impact not only in the sub‐system but probably in the entire area of Marismas Nacionales. A lack of understanding of the present balances in the damaged system and of the impacts the changing morphology has on future change has created the need to study this area using numerical hydrodynamic simulation. The present distribution of water in the sub‐system was established and the governing processes were detected. By means of an analytical estimation of equilibrium conditions it was found that if nothing is done, the channel will continue eroding and the ecosystem will continue to degrade. Only by understanding the dramatic perturbations caused by the construction of the channel to the hydrologic and morphologic equilibriums can there be any hope of rescuing the ecosystem, including its human activities. 相似文献
4.
Impacts of land-use and climate changes on ecosystem productivity and carbon cycle in the cropping-grazing transitional zone in China 总被引：4，自引：0，他引：4
GAO Zhiqiang LIU Jiyuan CAO Mingkui LI Kerang & TAO Bo Institute of Geographic Sciences Natural Resources Research Chinese Academy of Sciences Beijing China 《中国科学D辑(英文版)》2005,48(9):1479-1491
Terrestrial ecosystems are both a carbon source and sink, therefore play an important role in the global carbon cycle that act as a link of interactions between human activities and climate changes[1,2]. Climate change impacts ecosystem carbon cycle through af- fecting biological processes, e.g. plant photosynthesis, respiration, and soil carbon decomposition. Land-use change directly modifies the distribution and structure of terrestrial ecosystems and hence the carbon storage and fluxes. Usi… 相似文献
5.
Reinaldo L. Bozelli Adriano Caliman Rafael D. Guariento Luciana S. Carneiro Jayme M. Santangelo Marcos P. Figueiredo-Barros Joo J.F. Leal Adriana M. Rocha Letícia B. Quesado Paloma M. Lopes Vinicius F. Farjalla Claudio C. Marinho Fabio Roland Francisco A. Esteves 《Limnologica》2009,39(4):306-313
Human activities are exposing freshwater ecosystems to a wide range of stressors, whose direct and indirect effects can be alleviated or exacerbated through interactive effects with dynamic environmental drivers. This study used long-term data from two Neotropical lacustrine freshwater systems (Batata Lake, an Amazonian floodplain lake and Imboassica lagoon, an Atlantic coastal lagoon) subjected to different kinds of environmental fluctuations (i.e., flood pulse and sandbar opening) and anthropogenic impacts (i.e., siltation and eutrophication). Our objective was to determine whether the effects of human perturbations are contingent on modifications of important biotic and abiotic characteristics through environmental variability. For both ecosystems, environmental variability consistently interacted with anthropogenic perturbations to alter most of the variables analyzed, such as nutrient dynamics, chlorophyll-a concentration, zooplankton and benthic invertebrate species richness, and temporal community stability, which indicates that interactive effects between environmental variability and anthropogenic perturbations may impact a myriad of ecosystem properties. Furthermore, the nature of these interactive effects was highly dependent on the variable considered and on the ecosystem analyzed. For example, at Imboassica lagoon, sandbar openings interacted synergistically with trophic state to increase the phosphorus concentration in the water column. At Batata Lake, flooding generally alleviated the negative effects of siltation on species richness by both diluting inorganic suspended material concentration and by promoting local recruitment from the regional species pool. Such results indicate that our ability to understand and predict the outcome of anthropogenic impacts on inland aquatic systems can be hampered if we consider human stressors as “static” phenomena disconnected from dynamic interactions with major local environmental drivers. 相似文献
6.
7.
Lagoons interspersed within wetlands are expected to increase the residence time of the flow in the system which, in turn, will lead to enhanced pollutant removal thus ensuring a good ecological status of the ecosystem. In this study, lagoons interspersed in vegetated wetlands have been mimicked in the laboratory to develop a theoretical model to establish the impact three major driving parameters (the vegetation density surrounding a lagoon, the depth aspect ratio [length vs. depth] of the lagoon and the circulating flow – through the Reynolds number) have on determining the residence time of the flow in the lagoon. The results indicate that, according to the maximum free available area of the flow, the presence of vegetation (Juncus maritimus) decreases the residence time. In addition, an increase in the Reynolds number of the circulating flow in the wetlands also resulted in a decrease in the lagoon residence time. Nevertheless, lagoon residence times were found to depend on the depth of the lagoon, with deeper lagoons having higher residence times. The length of the lagoon, however, was found not to affect the residence time. High lagoon residence times in either natural or constructed wetlands are desirable because they enhance pollutant removal from the water. Although, if the residence times are too long, this may lead to anoxic water conditions that could in fact threaten the wetland's ecosystem. 相似文献
8.
9.
湖泊渔业研究:进展与展望 总被引：4，自引：3，他引：1
作为一种传统产业,渔业在我国经济社会发展中具有不可缺失的重要地位.而渔业作为湖泊最重要的功能之一,其资源变动是湖泊生态系统演变的重要影响因子,同时湖泊渔业资源的变动和退化也是对环境变化最直接的响应.自1980s以来,随着湖泊水环境的改变,湖泊渔业资源衰退趋势明显,中上层浮游生物食性鱼类在鱼类群落中占优势,鱼类资源小型化、低龄化现象严重.本文以湖泊渔业发展的历程为切入口,系统阐述人类活动及湖泊环境变化对渔业资源及生态系统的影响,厘清现阶段湖泊水环境管理、湖泊生态系统修复、湖泊渔业可持续发展等关系,展望我国湖泊渔业的发展前景及新型模式. 相似文献
10.
Shilong PIAO Xinping ZHANG Anping CHEN Qiang LIU Xu LIAN Xuhui WANG Shushi PENG Xiuchen WU 《中国科学:地球科学(英文版)》2019,(10)
The increased frequency of climate extremes in recent years has profoundly affected terrestrial ecosystem functions and the welfare of human society. The carbon cycle is a key process of terrestrial ecosystem changes. Therefore, a better understanding and assessment of the impacts of climate extremes on the terrestrial carbon cycle could provide an important scientific basis to facilitate the mitigation and adaption of our society to climate change. In this paper, we systematically review the impacts of climate extremes(e.g. drought, extreme precipitation, extreme hot and extreme cold) on terrestrial ecosystems and their mechanisms. Existing studies have suggested that drought is one of the most important stressors on the terrestrial carbon sink, and that it can inhibit both ecosystem productivity and respiration. Because ecosystem productivity is usually more sensitive to drought than respiration, drought can significantly reduce the strength of terrestrial ecosystem carbon sinks and even turn them into carbon sources. Large inter-model variations have been found in the simulations of drought-induced changes in the carbon cycle, suggesting the existence of a large gap in current understanding of the mechanisms behind the responses of ecosystem carbon balance to drought, especially for tropical vegetation. The effects of extreme precipitation on the carbon cycle vary across different regions. In general, extreme precipitation enhances carbon accumulation in arid ecosystems, but restrains carbon sequestration in moist ecosystems. However, current knowledge on the indirect effects of extreme precipitation on the carbon cycle through regulating processes such as soil carbon lateral transportation and nutrient loss is still limited. This knowledge gap has caused large uncertainties in assessing the total carbon cycle impact of extreme precipitation. Extreme hot and extreme cold can affect the terrestrial carbon cycle through various ecosystem processes. Note that the severity of such climate extremes depends greatly on their timing, which needs to be investigated thoroughly in future studies. In light of current knowledge and gaps in the understanding of how extreme climates affect the terrestrial carbon cycle, we strongly recommend that future studies should place more attention on the long-term impacts and on the driving mechanisms at different time scales.Studies based on multi-source data, methods and across multiple spatial-temporal scales, are also necessary to better characterize the response of terrestrial ecosystems to climate extremes. 相似文献
11.
Alexandra C. Oliver Rob C. Jamieson Kathryn A. Smith Julia A. Cantelon Barret L. Kurylyk 《水文研究》2024,38(5):e15144
Coastal eutrophication poses an increasing risk to ecosystem health due to enhanced nutrient loading to the global coastline. Submarine groundwater discharge (SGD) represents a significant pathway for nitrate-nitrogen (NO3-N) transport to the coast, but diffusive SGD transport is difficult to monitor directly, given the low flux rates and expansive discharge areas. In contrast, focused SGD from intertidal springs can potentially be sampled and directly gauged, providing unique insight into SGD and associated contaminant transport. Basin Head is a coastal lagoon in Prince Edward Island, Canada that is a federally protected ecosystem. Nitrate-nitrogen is conveyed from agricultural fields in the contributing watershed to the eutrophic lagoon via intertidal groundwater springs and groundwater-dominated tributaries. We used several field methods to characterize groundwater discharge, nutrient loading, and in-channel mixing associated with intertidal springs. The tributaries and intertidal springs were gauged and sampled to estimate a representative summer nitrate load to the lagoon. Our analysis revealed that NO3-N export to the lagoon through tributaries and springs throughout summer 2023 was on average 401 kg N/month, with the combined spring loading comparable in magnitude to the combined tributary loading. We collected thermal infrared and visual imagery using drone surveys and found spatial overlap between cold-water plumes from the spring discharge and macroalgae blooms, indicating the local thermal and ecosystem impacts of the focused SGD. We also mapped the electrical resistivity (salinity) distribution in the water column around one large spring with electromagnetic geophysics at different tidal stages to reveal the three-dimensional spring plume dynamics. Results showed that the fresher spring water floated above the saline lagoon water with the brackish plume oriented in the direction of the tidal current. Collectively, our multi-pronged field investigations help elucidate the hydrologic, thermal, and nutrient dynamics of intertidal springs and the cascading ecosystem impacts. 相似文献
12.
生态功能区划是我国正在开展的一项关于资源与环境管理的重大基础性工作.生态功能区划的理论和方法是当前生态学、环境科学、地理学等学科面临的一项新的热点课题.本文首先讨论了生态功能区划的概念,从认识区划看,生态功能区划属于生态系统区域划分的范畴,从实践的角度,则强调人文活动对生态系统可持续能力产生的影响,指出自然生态区不是生态功能区,生态功能区须反映人类的利用和价值判断.生态功能区划,不单是以自然要素或自然系统的"地带性分异"为基础,更是以生态系统的等级结构和尺度原则为基础,用生态系统完整性的评价测量人类活动对生态系统的影响,将生态功能区划的科学基础落在"基于生态系统的管理"平台上.文章提出了基于流域的我国生态功能区划的初步思想,讨论了区划的原则和方法,建立了生态系统完整性评价和功能区划分的指标体系.其基本内容是,认识并按照生态系统的自然边界划分生态系统单元;进行生态系统完整性评价;在此基础上划分不同的生态功能区,确定主导生态功能. 相似文献
13.
The Paul do Boquilobo is an important wetland ecosystem classified by Unesco as a MAB Biosphere reserve also awarded Ramsar site status, representing one of the most important habitats for the resident nesting colony of Cattle Egret (Bulbucus ibis). Yet owing to its location, it suffers from human induced impacts which include industrial and domestic effluent discharges as well as agricultural land use which have negatively impacted water quality. The current study reports the results obtained from the introductory monitoring programme of surface water quality in the Nature Reserve to emphasize the detrimental impact of the anthropogenic activities in the water quality of such an important ecosystem. The study involved physicochemical and biotic variables, microbial parameters and biological indicators. Results after 3 years of monitoring bring to evidence a poor water quality further impaired by seasonal patterns. Statistical analysis of data attributed water quality variation to 3 main parameters – pH, dissolved oxygen and nitrates, indicating heavy contamination loads from both organic and agricultural sources. Seasonality plays a role in water flow and climatic conditions, where sampling sites presented variable water quality data, suggesting a depurative function of the wetland. 相似文献
14.
The European water framework directive (WFD) aims at achieving good ecological status of water bodies, which implies assessment of their current ecological quality status in respect to defined reference (pristine) conditions. In this paper, two historical biodiversity datasets (from 1920s and 1950s) and results from the recent inventory are used to trace the long-term changes of the macrozoobenthos in the eutrophic boreal lagoon of the Baltic Sea.In comparison of datasets the highest congruence was obtained for molluscs and malacostracan crustaceans, which also had a similar level of taxonomic emphasis between studies. Considering inconsistencies in methodology and taxonomic determination, only few species extinctions in these groups did likely occur during the last 100 years. Two amphipod species (Gammarus pulex and Gammarus lacustris) were not found during the recent survey, whereas five new species of this taxonomic group occurred in the lagoon since 1950s. The causes of these extinctions remain unclear; however displacement by established new amphipods cannot be excluded. Theodoxus fluviatilis was recently recorded in the very restricted area of the lagoon, while in earlier studies the species was mentioned as common and widely distributed in the water body. On the other hand, 10 gastropod species and 9 bivalves were reported for the first time in the lagoon and most likely have been overlooked in earlier surveys. Approximately 10% of the species have their origin outside the Baltic Sea basin and the number of invasions considerably exceeds the number of likely extinctions. Assessment scheme of such changes is unclear following WFD guidelines, therefore elaboration of a framework for evaluation of the alien species diversity in a context of local biodiversity should attain more effort when implementing the WFD. 相似文献
15.
Holocene salinity fluctuations of the East Korean lagoon related to sea level and precipitation changes 
下载免费PDF全文
下载免费PDF全文 Detailed diatom records within core sediments from Maeho Lagoon along the Eastern coast of South Korea revealed that the ecological dynamics of the lagoon during the Holocene were associated with relative sea level and regional precipitation. Accelerator mass spectrometry (AMS) 14C dating indicates that sediment accumulation began prior to 8300 cal. year BP, and that the lagoon formed around 8000 cal. year BP. The salinity level of the lagoon increased until 5000 cal. year BP, and then decreased. Long‐term trends in salinity were dependent upon changes in sea level: periods of high salinity in the lagoon were generally coincident with periods of high sea levels along the east coasts of Korea and Japan. On the other hand, multicentennial‐scale fluctuations in diatom assemblages and magnetic susceptibility (MS) suggest that a 400 year fluctuation in salinity was regulated by changes in precipitation in the area of this lagoon. Changes in the westerly jet stream, controlled by variation in solar irradiance, had an important influence on precipitation volume in South Korea, suggesting that the patterns of the westerly jet stream fluctuate on a 400 year cycle. 相似文献
16.
《国际泥沙研究》2021,36(6):756-769
Coastal lagoons are particularly vulnerable to climate change, in particular, Sea Level Rise (SLR) due to their shallowness. Lake Burullus provides a variety of socio-economic services as the second largest coastal lagoon in Egypt. Recently, it has experienced significant ecological deterioration. Thus, its ecosystem is fragile in the face of anthropogenic induced changes. The main objective of the current study is to investigate the climate change impacts on characteristics of Lake Burullus. A depth averaged hydro-ecological modeling system, MIKE21, was applied to develop an eco - hydrodynamic model for the lake. The developed model was calibrated and verified for two successive years: July 2011–June 2012 and July 2012–June 2013. The model simulations exhibited good agreement with the measurements during the calibration and verification processes. Six different Regional Climate Models (RCMs) were compared, using six different statistical metrics, to determine the most accurate one for the study area. The required meteorological input, including surface air temperature, precipitation, and evaporation were derived from the selected RCM. The meteorological input was extracted for two different years in the 21 st century considering one Representative Concentration Pathways (RCPs) scenario, based on the Intergovernmental Panel on Climate Change (IPCC) 5th Report. Regional SLR projections for the Mediterranean Sea for the selected RCP scenario and the two studied years were obtained. These future climate change estimates were used to modify the validated model of the lake. A sensitivity analysis was applied to assess effect of future climatic conditions and SLR, separately. The results revealed that the lake water depths will increase and it will be warmer and more saline. Significant spatial variability of the studied parameters under climate change forcing is expected. Consequently, climate change is going to restrict the lake's ability to preserve the present-day species. An urgent management plan involving adaptation works, should be implemented to reduce such potential species losses in Egyptian lagoons. 相似文献
17.
顾及生态安全格局的流域生态保护红线划定及管控研究——以云南杞麓湖流域为例 总被引：1，自引：0，他引：1
生态保护红线划定是保障国土空间生态安全的重要举措,对保持生态系统的完整性,实现可持续发展具有重要意义.本文基于生态系统服务功能和生态敏感性对杞麓湖流域进行生态安全格局体系的构建,并开展精细化的生态保护红线划定研究,并进一步结合无人机航拍影像及实地调研成果,构建管控路径.得到结论:(1)水源涵养、水土保持、生物多样性、洪水调蓄重要性评价中的极重要区域叠加得到生态系统服务功能极重要区.者湾河、长沙河、大沙河及沟谷密度较大的山区敏感性最高,坝区整体生态敏感性较高.(2)一级生态保护红线范围包括生态极重要区域、生态极敏感区域及湖泊岸线、水库.二级生态保护红线范围包括环湖生态缓冲区、山区林地生态缓冲区及以河流为主的生态廊道.三级生态保护红线范围为生态协调区,土地覆盖以农田为主.(3)一级生态保护红线范围内的生态极敏感区应采取相关生态修复技术进行生态功能的保护.二级生态保护红线范围以生态保护为重点,保持该区域的生态环境质量.三级生态保护红线范围通过生态修复进行整体优化,提高生态环境承载能力. 相似文献
18.
Flow regimes have been severely altered by climate change and human activities in recent decades, which has led to ecological degradation in rivers. This study proposes an analogy analysis-based framework, coupled with the Pettitt test, the indicators of hydrological alteration and the range of variation approach, which were used to distinguish the different effects. This framework was applied to the Sha River, a typical river in North China, to test its effectiveness. The results show that: (i) human disturbance had larger effects on pre-flood flow magnitude, the timing, frequency and duration of high and low pulse, and the flow change rate; (ii) climate change mainly influences the magnitude of flood and post-flood flows, and of extreme events; and (iii) the probability of high alteration from the target frequency increased by 69.7% due to the combined impacts. These results can provide valuable references for water resource and aquatic ecosystem management. 相似文献
19.
湖沼学是研究内陆水体的多学科整合科学——兼论我国湖沼学发展面临的挑战与机遇 总被引：1，自引：0，他引：1
湖沼学是研究内陆水体的多学科交叉综合性科学,自从Forel F.A.于1892年首次对湖沼学做出定义以来已有近130年历史.湖沼学的主要分支学科包括地质湖沼学(包括古湖沼学)、物理湖沼学、化学(生物地球化学)湖沼学和生物湖沼学.湖沼学的关键自然属性是通过跨学科的整合,从水生态系统水平综合分析相关过程与机理,并对生态系统变化进行预测.因此,湖泊学也是支撑水资源与生态系统保护、管理与修复的核心科学.然而,目前我国湖沼学发展面临分支学科发展不平衡、研究碎片化等问题,而人类活动加剧和气候变化对内陆水体生态系统的影响及管理对策是湖沼学研究面临的挑战与机遇.我国湖沼学研究亟需围绕人类活动、气候变化的影响,重点开展以下几个方面的工作:1)水动力与水文地貌特征变化及其环境生态效应; 2)营养盐和有机质生物地球化学循环及其环境生态效应; 3)食物网结构与功能; 4)外来入侵物种的影响与控制对策; 5)与水环境有关的传染病防治; 6)地表水生态评价; 7)生态系统演变机理与退化生态系统修复等. 相似文献
20.
The net ecosystem services value in mainland China 总被引：1，自引：0，他引：1
Protection of the ecological environment is an effective strategy for maintaining ecosystem health,improving provision of ecosystem services,and increasing human well-being.However,traditional calculations of the value of ecosystem services(VES)provide weak guidance because they ignore the costs of these services,leading to economically inefficient strategies.To understand the difference between VES and the net ecosystem services value(NES,after subtracting costs from VES)and to improve evaluations of ecosystem services,we estimated NES for mainland China(including farmland,grassland,forest,and wetland).NES totaled 10.0×10~3RMB ha~(-1)yr~(-1)in 2014,which is only 35.1%of the corresponding VES.Grassland NES was–0.7×10~3RMB ha~(-1)yr~(-1),in contrast with a positive grassland VES.NES of farmland,grassland,forest,and wetland in2014 totaled 7.2×10~(12)RMB,accounting for 27.0%of China’s GNP.Recent Chinese planning based on VES emphasizes forest conservation and ignores the conservation of other important ecosystems,such as grassland,leading to a continuing loss of China’s natural capital.Due to regional differences in economic conditions,resource endowments,and geographical characteristics,VES and NES differ among regions.To maximize the ecological benefits from conservation,it is necessary to account for these differences by comparing strategies based on NES,thereby choosing projects that maximize both economic and ecological benefits.To maintain the ecological balance,ecological restoration and socioeconomic activities should account for the costs of providing ecosystem services.This is essential to minimize the costs and maximize the benefits of projects. 相似文献