利用Ecopath模型评价鲢鳙放养对千岛湖生态系统的影响

“保水渔业”是中国控制"水华"暴发等生态灾变的措施之一，其结果存在较大的不确定性。在浙江省的新安江水库（千岛湖），"保水渔业"的实施带来了水质改善和渔业增产的双重效果。但在生态系统自组织层面，这种人工干预手段引起的生态系统结构化效应的研究，尚未真正展开。基于2008-2010年千岛湖的生态和渔业资源调查数据，应用EwE （V6.6）构建了2010年千岛湖生态系统的Ecopath模型，并将其与2004和2016年的模型进行对照，分析了千岛湖生态系统在鲢、鳙鱼放养下的变化。千岛湖生态系统在3个年份均为4个整合营养级，营养能流分布成典型的金字塔型，且营养流总量中流向碎屑的占比很大，营养级Ⅰ、Ⅱ的能量被利用得不够充分；除鲢、鳙鱼外大部分鱼类的生物量逐渐下降，浮游植物和碎屑的生物量增多；系统的初级生产力和规模得到了一定提升，但总体的能量转换效率有所降低。在一些和系统成熟度、复原力和稳定性密切相关的参数方面，总初级生产量/总呼吸量增加，Finn氏循环指数和Finn氏平均路径长度逐渐降低，3个年份的连接指数（CI）分别为0.223、0.219、0.263，系统杂食指数（SOI）分别为0.087、0.102和0.131。研究分析表明，长期的鲢、鳙鱼放养使千岛湖的食物网结构发生了较大的变动，生态系统的营养交互关系不够复杂，成熟度和稳定性有所下降。千岛湖作为一个由水库发展而来的淡水水体，食物网关系本身就较为简单。因此，未来需要避免过多的人为干扰，并基于生态学原理更系统地进行修复工作。     

黄河口邻近海域生态系统能量流动与三疣梭子蟹增殖容量估算

增殖放流是渔业资源养护的重要手段, 生态系统与放流种类能流格局的变化研究,是进行增殖容量评估的研究基础.根据2012和2013年黄河口邻近海域的资源调查数据,构建了黄河口邻近海域6、8、10月的Ecopath模型,比较分析了3个月份该海域生态系统能量流动的变化,初步评估了三疣梭子蟹的增殖容量.结果表明： 黄河口邻近海域生态系统的能量流动主要在营养级I～III之间进行,营养级IV以及以上的能量流动较小.6月第I营养级整合系统流动的比例最高,8月最低.第II营养级整合系统流动的比例8月最高,6月最低.三疣梭子蟹相对能量流动和绝对能量流动均是第III营养级最高,三疣梭子蟹的营养级3月平均为3.28.黄河口邻近海域生态系统有较高的剩余生产量,6月最高、8月最低,系统的总初级生产量/总呼吸(TPP/TR) 3个月份分别为5.49、2.47、3.01,总初级生产量/总生物量(TPP/B)分别为47.61、33.30、29.78,同时具有较低的循环指数(FCI：0.03～0.06),黄河口邻近海域生态系统处于脆弱的不稳定期.系统的能量转换效率为7.3%～11.5%;渔获物的平均营养级8月和10月有所下降,3个月份分别为3.23、2.97和2.82;总捕捞效率8月最高,6月最低.在黄河口邻近海域8月Ecopath模型基础上,初步评估三疣梭子蟹的增殖容量为1.5115 t·km^-2.     

基于Ecopath模型的千岛湖生态系统结构和功能分析

为探索千岛湖生态系统现状及其历史变化, 根据2016年千岛湖的渔业资源与生态环境调查数据, 构建了千岛湖生态系统的 Ecopath 模型, 综合分析系统的能量流动过程、营养级结构和生态系统总体特征。2016年千岛湖 Ecopath 模型由18个功能组组成, 有效营养级范围为1—3.41, 牧食食物链的能量流动占系统总能量的56%。系统杂食指数(SOI)、联结指数(CI)、Finn循环指数分别为0.13, 0.26和5.15%。千岛湖与其他湖泊和水库比较, 其生态系统的各功能组的聚合度较高, 联结程度较为紧密, 物质再循环比例较高, 系统较为成熟。但千岛湖的系统总流量较低为24698.27 t/(km2·a), 总初级生产量与总呼吸量的比值为6.51, 表明系统总体规模较小且仍处于发展阶段。根据千岛湖生态系统历年变化趋势分析: 千岛湖生态系统的总体规模有变大趋势, 稳定性和复杂性有所增强, 但营养交互关系变弱, 系统抵抗外界干扰的能力仍较低。同时, 千岛湖生态系统的初级生产者转化效率较低, 食物网趋于简单, 应采取适当的管理措施, 以保障千岛湖生态系统的健康发展。     

New trophic indicators and target values for an ecosystem-based management of fisheries

In the present study, we tested five trophic indicators and we demonstrated their usefulness to assess the environmental status of marine ecosystems and to implement an ecosystem approach to fisheries management (EAFM). The tested indicators include the slope of the biomass spectrum, the mean trophic level (MTL), the marine trophic index (MTI) and two newly developed indicators, the high trophic level indicator (HTI) and the apex predator indicator (API). Indicators are compared between current state and potential reference situations, using as case studies: the Celtic Sea/Bay of Biscay, North Sea and English Channel ecosystems. Trophic spectra are obtained from Ecopath models while reference situations are estimated, simulating with EcoTroph and Ecosim different fishing pressures including three candidate scenarios for an EAFM. Inter-ecosystems assessments are done using Ecopath models, simulations outputs and scientific surveys data to assess the current states of the studied ecosystems, contrast the reference situations and analyze the responses of all indicators. Sensitivity analyses are also conducted on the main simulation parameters to test the robustness of the chosen indicators. Ecosystems specific targets for EAFM are proposed for the five trophic indicators estimated from whole-ecosystem models, while in the Celtic Sea/Bay of Biscay ecosystem targets are proposed for the MTL (=3.85) and HTI (48%) estimated from standard bottom-trawl surveys. The HTI is proposed to be relevant for survey data and the API is recommended using whole-ecosystem models. We conclude that HTI and API show trends in ecosystems health better than MTI.     

柳树对水体氮素的去除率及其吸收动力学

在水培条件下,研究了2种柳树(Salix integra)无性系(“一支笔”和“微山湖”)对模拟富营养化水体中氮素的吸收状况,并采用常规耗竭法探讨了柳树幼苗根系对NH4+-N、NO3--N的吸收动力学特征.结果表明:2种柳树无性系对低浓度模拟富营养化水体中总氮的去除率均达90％以上,是高浓度情况下的2倍;对低浓度模拟污水中总磷的去除率达80％,高浓度下则达92％,且“一支笔”对总氮、总磷的吸收效果优于“微山湖”;2种柳树无性系对氮素的吸收均表现为水体中营养物质浓度越高,去除效果越好;只有NH4+-N或NO3--N存在时,“微山湖”的最大吸收速率和亲和力高于“一支笔”;当有其他氮源影响时,2种柳树无性系对NH4+-N和NO3--N的吸收效率则下降至50％;研究表明,柳树对富营养化水体的生态修复作用较强,是进行面源污染生态修复的优良树种.     

南海北部生态系统食物网结构、能量流动及系统特征

根据20072008年在南海北部(107°00'120°00'E、17°00'23°30'N)进行的海洋生态综合调查数据,应用Ecopath with Ecosim软件构建了南海北部生态系统的生态通道模型,并通过模型分析了南海北部海洋生态系统的食物网结构、能量流动和系统的总体特征,并简要总结过度捕捞生态系统的基本特征。结果表明,南海北部海洋生态系统以捕食食物链为主要能流通道,初级生产者是系统能量的主要来源。各功能群的营养级范围为13.99,哺乳动物占据了最高的营养层,平均渔获物营养级为2.93。利用生态网络分析,系统的能量流动主要有6级,来自初级生产者的能流效率为12.6%,来自碎屑的转换效率为10.4%,平均能量转换效率为11.5%。系统连接指数(Connectance Index,CI)和系统杂食指数(System Omnivory Index,SOI)分别为0.290和0.239;Finn’s循环指数(Finn’scy cling index,FCI)和系统平均路径长度(Finn’s mean path length,MPL)分别为4.380和2.476;总初级生产力/总呼吸为2.596,综合研究表明当前南海北部海洋生态系统处于不成熟阶段。     

Coral–algal phase shifts alter fish communities and reduce fisheries production

Anthropogenic stress has been shown to reduce coral coverage in ecosystems all over the world. A phase shift towards an algae‐dominated system may accompany coral loss. In this case, the composition of the reef‐associated fish assemblage will change and human communities relying on reef fisheries for income and food security may be negatively impacted. We present a case study based on the Raja Ampat Archipelago in Eastern Indonesia. Using a dynamic food web model, we simulate the loss of coral reefs with accompanied transition towards an algae‐dominated state and quantify the likely change in fish populations and fisheries productivity. One set of simulations represents extreme scenarios, including 100% loss of coral. In this experiment, ecosystem changes are driven by coral loss itself and a degree of habitat dependency by reef fish is assumed. An alternative simulation is presented without assumed habitat dependency, where changes to the ecosystem are driven by historical observations of reef fish communities when coral is lost. The coral–algal phase shift results in reduced biodiversity and ecosystem maturity. Relative increases in the biomass of small‐bodied fish species mean higher productivity on reefs overall, but much reduced landings of traditionally targeted species.     

Combined effects of global climate change and regional ecosystem drivers on an exploited marine food web

Changes in climate, in combination with intensive exploitation of marine resources, have caused large‐scale reorganizations in many of the world's marine ecosystems during the past decades. The Baltic Sea in Northern Europe is one of the systems most affected. In addition to being exposed to persistent eutrophication, intensive fishing, and one of the world's fastest rates of warming in the last two decades of the 20th century, accelerated climate change including atmospheric warming and changes in precipitation is projected for this region during the 21st century. Here, we used a new multimodel approach to project how the interaction of climate, nutrient loads, and cod fishing may affect the future of the open Central Baltic Sea food web. Regionally downscaled global climate scenarios were, in combination with three nutrient load scenarios, used to drive an ensemble of three regional biogeochemical models (BGMs). An Ecopath with Ecosim food web model was then forced with the BGM results from different nutrient‐climate scenarios in combination with two different cod fishing scenarios. The results showed that regional management is likely to play a major role in determining the future of the Baltic Sea ecosystem. By the end of the 21st century, for example, the combination of intensive cod fishing and high nutrient loads projected a strongly eutrophicated and sprat‐dominated ecosystem, whereas low cod fishing in combination with low nutrient loads resulted in a cod‐dominated ecosystem with eutrophication levels close to present. Also, nonlinearities were observed in the sensitivity of different trophic groups to nutrient loads or fishing depending on the combination of the two. Finally, many climate variables and species biomasses were projected to levels unseen in the past. Hence, the risk for ecological surprises needs to be addressed, particularly when the results are discussed in the ecosystem‐based management context.     

基于Ecopath模型的崂山湾人工鱼礁区生态系统结构和功能研究

基于2014—2016年青岛崂山湾人工鱼礁区的生物资源调查数据,利用Ecopath with Ecosim(EwE)软件构建崂山湾人工鱼礁区生态系统生态通道模型(Ecopath),系统分析了崂山湾人工鱼礁区生态系统的能量流动规律和结构特征,估算了栉孔扇贝的养殖容量。该模型由17个功能组组成,基本涵盖了崂山湾人工鱼礁区生态系统能量流动的主要过程。生态网络分析表明,生态系统各功能组的营养级范围为1.0—4.255,星康吉鳗占据了营养级的最高层。能量流动主要有5级,各营养级平均能量传递效率为10.8%,其中来自初级生产者的能量效率为9.8%,来自碎屑的传递效率为10.9%;系统总流量为14256.510 t km~(-2) a~(-1),其中68%的能量来自碎屑供给;系统的总初级生产量/总呼吸量为1.127,系统联结指数为0.293,杂食指数为0.333,表明崂山湾人工鱼礁区生态系统成熟度较高,食物网结构较复杂,系统内部稳定性较高。关键种指数分析结果显示,许氏平鲉具有较高的关键指数和相对总影响,表明其可能在当前生态系统中扮演重要的生态角色。吊笼养殖栉孔扇贝生态容纳量为189.679 t/km~2,在维持生态系统平衡和稳定的前提下,当前现存量最大可增加18.55%。