Climate change: A potential risk to cage culture and genetic structure of native fisheries in fish cage‐installed inland lakes

Fish cage aquaculture (FCA) in lakes is a viable climate change (CC) mitigation approach; however, deficiencies in monitoring, early warning and risk planning could threaten its sustainability. Thus, the present study focused on examining the experiences with CC and its risks to cage fish culture, and phenotypic structure of a typical endemic fishery in fish cage‐installed (FCI) and fish cage‐free (FCF) lakes. Using a structured questionnaire, fisherfolks of typical FCI and FCF lakes in southwestern Nigeria were consulted for their local experiences regarding CC variables, effects on cage aquaculture and the occurrence of caged fish in their fish catches. For phenotypic structure analysis, size cohorts of cage‐cultured (CCU) and wild‐caught (WC) Oreochromis niloticus from FCI (CC_UFCI and WCFCI), and WC from FCF (WCFCF) were obtained and analysed for phenotypic differences (p < .05) and mix‐up through cluster/linkage analysis. Respondents experienced unpredictable climatic conditions, increased rainfall fluctuations and declining rainfall (86.4; 47.1%, 50.0; 64.7%, 100.0; 88.2%, in FCI and FCF lakes, respectively), indicating that CC affects cage culture, induces cage damage and floods, and results in caged fish escapes (40.9; 35.3%, 81.8; 11.8%, 95.5; 41.2% in FCI and FCF lakes, respectively), while caged fishes occur in fisherfolks’ catches (63.6% FCI). Phenotypically, WCFCF and WCFCI were similar, but differed from CC_UFCI for pre‐dorsal length. WCFCF and WCFCI differed for caudal peduncle lengths. In addition, some individuals of CC_UFCI clustered with WCFCI and WCFCF, rather than their population cohorts. Climate change impacts on FCA lakes have implications regarding caged fish escapes. Phenotypic structures indicated a possible mix‐up of caged and wild O. niloticus populations. Thus, monitoring, control and surveillance (MCS) of cage culture in lakes is necessary, and development of genetic markers for endemic species would also facilitate MCS.     

新型渠道清淤技术与设备研究

国家重点水利工程南水北调工程、东调南下工程、引黄济青续建工程等建成后,部分干线渠道除调水外还要承担排涝泄洪的任务,泥沙淤积在所难免。根据南水北调东线工程混凝土衬砌输水渠道清淤,研制了一种通过吸泥系统、泥浆输送系统完成清淤疏浚任务的高度自动化的潜水疏浚机,可以接收岸上人员的指令或者自主判断水下淤泥的分布情形,并以此决定在水下的行走方式,实现转弯、避碍,控制自身在水中的方位。这种小型清淤设备可以应用于渠道、湖泊、航道的环保清淤、水库清淤、沉砂池清淤、河道治理等。同时这种清淤设备还能做到在水下清淤疏浚过程中不引起环境的二次污染,不造成断流,具有高效、节能、方便操作、劳动强度小,适应作业范围宽及低成本等优点。     

我国城市河湖水生态环境评价体系构建与实证分析

参考国内外相关研究成果,在全面掌握我国城市河湖水生态环境现状与问题的基础上,采用层次分析法、隶属度函数计算等分析方法,建立了城市河湖水生态系统的评价指标体系与评价标准,并以江苏省为例,利用历史数据以及监测资料,对城市河湖水生态环境现状进行了实证分析。结果表明,所构建的评价指标体系能够对城市河湖水生态环境进行较为全面的分析,可为城市河湖水污染综合治理和城市生态建设提供科学依据与实证参考。     

离散Hopfield神经网络在湖库营养状态评价中的应用——以全国24个湖库富营养化等级评价为例

基于离散Hopfield神经网络联想记忆特性,建立了湖库富营养化等级综合评价模型,对全国24个湖库进行富营养化等级综合评价,并与文献投影寻踪法、评分指标法和LM-BP网络法的评价结果进行比较。结果表明:①离散Hopfield神经网络运用于湖库营养化等级评价具有简单、直观,容易实现等优点,其评价结果令人满意;②一般离散Hopfield神经网络并非适用于任何富营养化等级评价,当评价对象单项指标(因子)间存在较大差异时,对象将得不到正确的评价。     

卫星测高数据筛选方法研究——以 Jason-3 数据和洪泽湖为例

针对卫星测高数据质量在湖库地区不稳定问题,提出一种基于数据质量评价、筛选提取水位的方法。使用Jason-3卫星测高数据,选取数据质量不稳定的洪泽湖地区为例进行实验。结果表明,该方法在改善数据精度方面明显优于传统方法,提取的测高水位与实测水位间相关系数从传统方法的0.11提高到0.59,均方根误差也从2m减少到0.5m,使得Jason-3数据用于湖库水位监测时具有较高的可信度。此外,对于那些数据质量不好的周期,提取的水位精度普遍不高,基于数据质量评价结果将它们舍去,可进一步提高了整体的监测精度,相关系数可提高到0.9,均方根误差减少到0.19m,这对于为无资料湖库构建精确的库容曲线具有重要意义。     

云南典型高原湖泊富营养化及其生态修复研究

始于70年代末80年代初的湖泊富营养化问题,严重阻碍了云南社会经济发展,继而引起了人们极大地关注。已有的研究从富营养化特征、机制、演化以及生态、工程修复等方面进行了相关探究,其1980—2010年湖泊水体总磷、总氮、透明度、叶绿素、生化需氧量及营养状况指数等均指示和记录了近30年来云南典型高原湖泊富营养化特征及演化过程。在系统总结前人研究成果的基础上、基于云南高原湖泊富营养化的典型性与差异性、富营养化演化及其修复现状的背景下认为:近年来富营养化水体水质好转大多只是季节性或区域性迹象,云南高原湖泊整体上乃处于持续的富营养化和污染状态,部分湖泊因为周边农业用地和建设的扩展已经导致湖泊处于不可恢复状态,抚仙湖、阳宗海等湖泊周边因开发需水量大,导致湖泊水位出现快速下降和湖容大量减少。进一步对云南高原典型富营养化湖泊开展更大时间尺度的研究,特别是湖泊变化机理的研究和趋势预警的升级是今后努力的重点和方向。     

国外湖泊管理和保护的经验及其启示

在世界范围内,湖泊在经济社会发展中发挥着重要作用.然而,由于我国对湖泊的盲目开发利用和在湖泊管理中的缺位和错位,导致了湖泊状况不断恶化.深入分析了美国、澳大利亚、欧盟和日本的湖泊保护和管理的经验,包括法制方面、管理体制方面和管理措施方面等不同之处,可借鉴并转化为对我国的启示.     

Spatio-temporal variability of diatom assemblages in surface sediments of Lake Peipsi

The modern diatom assemblages in surface sediments of large and shallow Lake Peipsi sensu stricto (2611 km²; maximum depth 12.9 m) in north-eastern Europe (Estonia) were studied. Ordination techniques were used to identify physical environmental parameters (grain size of sediment, water depth and distance from the shore) that explain the distribution of diatoms in the lake. Diatom species distribution and concentration in surface sediment showed large variations (concentrations varied from 3.3 × 10⁶ to 149 × 10⁶ g⁻¹ dry weight). The texture of surface sediments and concentration of diatoms are highly correlated (p ≤ 0.05), thus suggesting that the relocation of cohesive particles (silt) due to wind and wave actions affects the spatial variations of diatoms in surface sediments. The diatom data set analysed in the 1970s, and samples taken in 2006 showed some perceptible changes in the composition and concentrations of the diatom assemblages over this time period. However, main dominant diatom taxa have not changed during more than 25 years.     

基于分形几何理论的河湖结构连通性评价方法

基于分形几何理论与方法,针对河湖的结构连通性,利用分形意义上的分形维数和分枝维数概念,给出了一种流域(或区域)河湖结构连通性的评价方法。运用构造的简单河网结构模型,通过计算河湖覆盖度、分形维数和分枝维数来验算和评价了常州市主城区的河湖结构连通性,并与湖西区对比,结果表明,常州市主城区的分形维数和河湖覆盖度均大于湖西区,分枝维数均在1.50左右,常州市主城区的河湖结构连通性水平高于湖西区,两者流域地貌均处于侵蚀发育阶段的壮年期。     

河湖长制下跨界河湖联合管理保护对策研究——以太湖为例

以太湖流域为例,通过文献整理、现场调研、座谈交流等方式,梳理太湖流域生态环境现状和管理情况,总结太湖流域联合管理保护经验,分析太湖流域联合管理保护方面存在的不足。在此基础上,从推进流域整体管理保护立法、出台跨界河湖联防联控指导意见、统一规划、统一标准、加强河湖保护和治理协同作业、以水定产、绿色发展等方面,提出加强太湖流域联合管理保护的对策建议,以期能对提升太湖流域跨界综合管理与河湖长制推行水平有所帮助。