Advancing Africa’s Great Lakes research and academic potential: Answering the call for harmonized,long-term,collaborative networks and partnerships

The African Great Lakes (AGL) have rich fisheries and are renowned “biodiversity hotspots”. Consequently the AGL and the ecosystem services they provide, underpin the welfare and livelihoods of over 50 million people across 10 countries. Despite the recognized importance of the AGL, these vital ecosystems and their livelihood support systems are threatened by numerous anthropogenic stressors at local, regional, and global scales. Past and continued efforts to address critical challenges on these lakes are often short-term, parochial, disparate, and uncoordinated resulting in a lack of comprehensive and comparable scientific data and inadequate resources to influence evidence-based policy. Over the past two decades, several international workshops, conferences and scientific publications have identified the need for collaboration, knowledge sharing, and harmonization of research and management as key elements to enhance conservation efforts in the AGL. In this commentary, we introduce the African Center for Aquatic Research and Education (ACARE), which aims to strengthen research and provide the scientific evidence needed to make informed decisions related to sustainable fisheries and aquatic resource management in the AGL. To do this, ACARE will administer a highly collaborative network of experts with three long-term goals: (1) strengthen global and regional research partnerships; (2) establish transboundary and inter-jurisdictional lake advisory groups; and (3) build capacity of freshwater scientists through experiential education and public engagement.     

3D-modelling of Lake Kivu: Horizontal and vertical flow and temperature structure under spatially variable atmospheric forcing

With the increasing extraction of methane from Lake Kivu, there is a growing need to evaluate the effect of such operations on the lake’s permanent density stratification. This requires understanding of the spatial structure and variability of flow velocities and constituents in Lake Kivu. In this study, we develop a 3D hydrodynamic model of Lake Kivu, set-up within DELFT3D at a 750 m grid spacing and forced by COSMO-CLM atmosphere model results at a 2.8 km grid spacing. Validation shows that the model correctly reproduces the generation and breakdown of the temperature stratification in the upper mixed layer and predicts flow velocity magnitudes and directions similar to measurements both at the surface and at greater depth. Analysis of currents reveals a surface current pattern with two clockwise circulations, one around the whole lake and a smaller one in the northern part, with velocities around 0.1 m/s. This pattern is consistently present over an (ensemble-)averaged day, both in the wet and in the dry season, while day-by-day variations are large. Time-averaged deep currents are found to be a few mm/s at maximum. However, the variations can be substantial, with standard deviations up to 2 cm/s for the currents at 220 m depth, attributed to internal seiches. The temperature stratification, present during the entire wet season, is found to first break down in the dry season in the southern part of the lake. This is explained by the spatial differences in the wind stress and the evaporation heat fluxes during the dry season.     

鄱阳湖控制工程对自然保护区生态环境的影响

鄱阳湖是长江流域的一大淡水湖泊，其水旱灾害相当频繁，长期以来，国家和地方政府十分重视鄱阳湖洪涝灾害的治理研究工作，逐步形成了以鄱阳湖控制工程为代表的治理方案，该控制工程实施后，其水位将常年维持在16．0－18．0m之间，这将直接淹没16．0m以下的然状态下随着枯洪季节在而变化形成的的草滩、沼泽和浅水洼地等独特湿地自然景观，其自然环境将发生变化，使湖泊水域增大，洲滩，湿地大面积减少，从而对国家级鄱阳湖候鸟自然保护区生态环境带来严重不利影响。     

松嫩平原湖泡湿地浮游植物调查与研究

松嫩平原扎龙、向海国家级自然保护区是我国中温带最完整的湿地生态系统。本文以扎龙、向海、莫莫格、查干泡湿地保护区为例,对湿地浮游植物的种类组成和数量变化进行了详细调查与研究。     

国内湖泊水质污染及富营养化治理

湖泊水质污染及生态恢复是我国当前水环境保护所面临的主要问题。在国内湖泊富营养化防治调研的基础上,对我国重点治理的“三湖”水环境状况及治理对策进行了总结与分析,提出国内湖泊治理存在的问题和对策,以及官厅水库水污染防治应注意的问题。     

Lake-Level Change and Water Balance Analysis at Lake Qinghai,West China during Recent Decades

Lake Qinghai, the largest saline lake with an area of 4,260 km² (2000) and average depth of 21 m (1985) in West China, has experienced severe decline in water level in recent decades. This study aimed to investigate water balance of the lake and identify the causes for the decline in lake level. There was a 3.35-m decline in water level with an average decreasing rate of 8.0 cm year⁻¹ between 1959 and 2000. The lake water balance showed that mean annual precipitation between 1959 and 2000 over the lake was 357 ± 10 mm, evaporation was 924 ± 10 mm, surface runoff water inflow was 348 ± 21 mm, groundwater inflow was 138 mm ± 9 and the change in lake level was −80 ± 31 mm. The variation of lake level was highly positively correlated to surface runoff and precipitation and negatively to evaporation, the correlation coefficients were 0.89, 0.81 and −0.66, respectively. Water consumption by human activities accounts for 1% of the evaporation loss of the lake, implying that water consumption by human activities has little effect on lake level decline. Most dramatic decline in lake level occurred in the warm and dry years, and moderate decline in the cold and dry years, and relatively slight decline in the warm and wet years, therefore, the trend of cold/warm and dry climate in recent decades may be the main reasons for the decline in lake level.     

Initial appraisal of water quality of Lake Santa Ana,Mexico

Lake Santa Ana is located in the Mexican central plateau, a semiarid region characterized by low rainfall and high evaporation rates. Because of the area's climatic conditions, most of its few existing lakes and reservoirs are ephemeral, with significantly reduced surface areas during the dry season. Mexican authorities currently pay little or no attention to these special aquatic ecosystems. As a consequence, several of these waterbodies are severely degraded in regard to both water quantity and quality. As a result, this report describes Lake Santa Ana as a case study. Several water quality parameters, including physicochemical, microbiological and heavy metal concentrations, were measured at eight sampling sites in the lake, and four sites in the lake basin, in 2005. Some dissolved ions were also analysed in 2007 in the lake, and in a well located close to the lake, in order to evaluate possible interactions between groundwater and surface waters. These study results indicate that the lake does not have significant interactions with groundwater in the local aquifer. Most of the measured water quality parameters do not meet the international suggested standards for inland surface waters to sustain aquatic life, and preserve the habitat for both endemic and migratory waterfowl. Loss of aquatic habitats puts at risk the value of the central portion of Mexico as a migratory route for North American waterfowl species.     

Mitigating cyanobacterial blooms: how effective are ‘effective microorganisms’?

This study examined the effects of ‘Effective Microorganisms (EM)’ on the growth of cyanobacteria, and their ability to terminate cyanobacterial blooms. The EM was tested in the form of ‘mudballs’ or ‘Bokashi‐balls’, and as a suspension (EM‐A) in laboratory experiments. No growth inhibition was observed for a laboratory strain of Microcystis aeruginosa and for M. aeruginosa from the field at the recommended dosage of 1 EM‐mudball per square‐metre (≈0.1–0.3 g L^?1). Cyanobacteria were inhibited only at very high concentrations (5–10 g L^?1 cyanobacteria), and a bloom was reduced, being attributed to the high amount of clay and high water turbidity. For these high dosage treatments, the dissolved oxygen concentration dropped initially to very low levels, with longer incubation indicating that nutrients were released from the material. The EM‐A suspension appeared ineffective in hampering cyanobacterial growths at recommended usage concentrations. EM‐mudballs released phosphate (160 μg P g^?1) and metals (aluminium, copper, traces of lead and lanthanum). The results of this study did not support the hypothesis that EM are effective in preventing cyanobacterial proliferation or in terminating blooms, thereby suggesting lake restoration by ‘Effective Microorganisms’ is not a convincing eutrophication control option.     

基于组合赋权的湖泊健康评价物元分析模型

湖泊生态系统的健康是人与自然和谐相处及可持续发展理念的重要体现。通过建立湖泊健康评价物元分析模型,并改进其指标权重的计算,以离差平方和准则将层次分析法、熵值法及主成分分析法3种赋权方法取得的权重结合得到最优组合赋权,应用到某地5个湖泊进行湖泊健康评价。根据当地湖泊具体情况,选取12个详细指标建立评价体系与评价标准,通过模型计算得出结果显示5个湖泊中4个湖泊评价结果为优,一个评价结果为良,湖泊总体健康状况良好。因此该模型用于湖泊健康评价是非常有效的。     

森林植被改善对鄱阳湖流域径流和输沙过程的影响

以河流基流为切入点,研究流域植被调节径流、水土保持等微观作用影响大中型河流湖泊径流过程和水沙过程宏观效应的机理。鄱阳湖流域60年来天然降水没有发生趋势性变化。流域森林覆盖率由34.73%上升到63.00%,植被质量改善,赣江等入湖河流基流增加83 m~3/s,河流输沙量减少。2000年以后和2000年以前相比较,枯水期降水径流系数增大,年流量过程平坦化,一定程度上减小洪灾风险,有利于水资源利用和生态环境保护。2001年以后进入鄱阳湖泥沙平均每年减少1 007×10~4t;出湖泥沙增加314×10~4t。因此,鄱阳湖入江水道由淤积转变为冲刷,但出湖流量过程没有趋势性变化。