鱼类生物群落对太子河流域土地利用、河岸带栖息地质量的响应

河流生态系统的退化是多空间尺度环境因子作用的结果。探讨不同尺度环境因子及水生生物之间的作用关系,识别影响水生生物群落完整性的尺度问题,是有效开展水生生物保护的基础。基于2009年对太子河流域15个样点的鱼类、河岸带栖息地质量评价,结合遥感影像解译的太子河流域土地利用情况(包括流域尺度和河段尺度),研究鱼类完整性指数(F-IBI)与两种尺度土地利用、栖息地质量参数之间的关系。结果表明太子河上游地区河岸栖息地质量较好,下游地区由于农业用地、城镇用地比例的增加河岸栖息地质量明显下降。F-IBI与自然用地比例呈正相关,与农业、城镇用地比例呈负相关。农业用地对F-IBI的影响体现在流域尺度,而城镇用地在两种尺度上都存在显著影响。相比于农业用地,城镇用地相同比例的增加会导致F-IBI更快的下降。底质、水质状况、人类活动强度是显著影响F-IBI的栖息地质量评价参数。3项参数均随农业和城镇用地比例增加而降低,农业用地主要在流域尺度上对3项参数产生影响,城镇用地主要影响底质和水质状况2项参数,而在两种尺度上的影响相差不大。     

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.     

The value of plant functional groups in demonstrating and communicating vegetation responses to environmental flows

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Spatial variation in ciliate communities with respect to water quality in the Delhi NCR stretch of River Yamuna,India

The River Yamuna emerges from Saptarishi Kund, Yamunotri and merge with River Ganges at Allahabad, India. Anthropogenic stress has affected the water quality of the river Yamuna drastically in the stretch traversing Delhi and its satellite towns (National Capital Region, NCR). In the present study, effect of water quality on the microbial life in the River Yamuna was analyzed using ciliate communities (Protista, Ciliophora) as bio-indicators. Water samples were collected from six sampling sites chosen according to the levels of pollution along the river and water quality was analysed using standard physicochemical factors. As the river traverses Delhi NCR, water quality deteriorates considerably as indicated by the Water Quality Index at the selected sampling sites. Seventy-four ciliate species representing nine classes were recorded. Based on the Shannon diversity index, maximum species diversity was found at the point where the river enters Delhi. The saprobity index showed the river water was beta-mesosaprobic when the river enters Delhi and alpha-mesosaprobic at downstream sites after the first major drain outfall. Significant relationship between the spatial variation in ciliate communities and abiotic parameters indicate that ciliates can be used as effective bioindicators of pollution in the River Yamuna.     

Vertical distribution of Microcystis population in the regulated Nakdong River, Korea

The vertical distribution of a bloom-forming Microcystis population was studied based on the relevant limnological parameters obtained from the lower Nakdong River (Mulgum) during the summer of 1994. Over three months (late June to late September), a high abundance of Microcystis population (mean ± SD, 2.9 ± 8.4 × 10⁵ cells ml⁻¹, n = 40) and algal biomass (mean ± SD, chlorophyll a, 131 ± 346 μg l⁻¹, n = 31) was persistent throughout the entire water column (0–5 m, n = 11). The vertical distribution of carbon content was uneven, with a high concentration near the surface zone (mean ± SD, total, 7.9 ± 7.8; Microcystis, 5.2 ± 8.3 μg C ml⁻¹, n = 15). Incorporating limnological and meteorological factors, a diel study of the vertical distribution of Microcystis showed that the chlorophyll a concentration was highest near the surface zone on a calm night (wind velocity, <2 m s⁻¹, 2300–700) but was evenly distributed on a windy day (>4 m s⁻¹, 1100–1900). Among many possible factors, wind velocity may have played an important role in controlling the vertical distribution of Microcystis in the lower Nakdong River. Received: July 12, 1999 / Accepted: November 15, 1999     

赣江流域土地利用方式对河流水质的影响

赣江是鄱阳湖的最大支流,是鄱阳湖水污染物的主要来源,查明流域土地利用方式对赣江水质的影响和鄱阳湖的水环境保护具有重要意义。基于2012年对赣江7个主要支流NH+4-N、TP、CODMn和DO浓度的每月测定结果,通过不同空间尺度和土地类型等级划分,利用相关分析和冗余分析研究土地利用方式对赣江流域河流水质的影响。研究结果表明,子流域的土地利用方式对TP的影响大于缓冲区;对CODMn的影响在丰水期大于缓冲区,在枯水期小于缓冲区;对NH+4-N的影响在丰水期与缓冲区接近,在枯水期小于缓冲区;DO受土地利用方式的影响较小。水田中的丘陵水田是赣江水体TP和丰水期CODMn的主要来源;平原水田是枯水期CODMn的主要来源。居民建设用地中的城镇用地是赣江水体TP、NH+4-N和丰水期CODMn的主要来源,农村用地是CODMn的主要来源。水域中的水库坑塘是赣江水体TP和丰水期NH+4-N、CODMn的主要来源。     

石羊河流域土地覆被空间演化及驱动机制

基于石羊河流域1998年、2002年、2006年、2010年NDVI、夜间灯光数据和TM影像提取的土壤信息,以城市地表人工覆被系统为基础,计算流域土地覆被指数(Land-Cover Index,LCI),利用小波分析、空间变差函数和间隙度指数等方法构建测度模型,分析了石羊河流域地区十多年来的土地人工覆被空间演化过程和格局,然后利用回归拟合方程找出影响地区土地覆被变化的驱动机制。结果表明:LCI大范围分布受地形限制,高值区(城镇用地区域)值越来越高,而低值区(植被覆盖区域)值在2002年形成了峰值后下降,即地区城镇化水平显著提高的同时,林草覆盖率缓慢变好,并且逐渐形成区域簇群,同时地区城镇化水平受人为因素的影响较大,植被覆盖度受自然因素的影响较大。     

Diet overlap among two Asian carp and three native fishes in backwater lakes on the Illinois and Mississippi rivers

Bighead and silver carp are well established in the Mississippi River basin following their accidental introduction in the 1980s. Referred to collectively as Asian carp, these species are filter feeders consuming phytoplankton and zooplankton. We examined diet overlap and electivity of Asian carp and three native filter feeding fishes, bigmouth buffalo, gizzard shad, and paddlefish, in backwater lakes of the Illinois and Mississippi rivers. Rotifers, Keratella spp., Brachionus spp., and Trichocerca spp., were the most common prey items consumed by Asian carp and gizzard shad, whereas crustacean zooplankton were the preferred prey of paddlefish. Bigmouth buffalo diet was broad, including both rotifers and crustacean zooplankton. Dietary overlap with Asian carp was greatest for gizzard shad followed by bigmouth buffalo, but we found little diet overlap for paddlefish. Diet similarity based on taxonomy correlated strongly with diet similarity based on size suggesting filtration efficiency influenced the overlap patterns we observed. Although rotifers were the most common prey item consumed by both bighead and silver carp, we found a negative relation between silver carp CPUE and cladoceran density. The competitive effect of Asian carp on native fishes may be forestalled because of the high productivity of Illinois and Mississippi river habitats, yet the potential for negative consequences of Asian carp in less productive ecosystems, including Lake Michigan, should not be underestimated.     

Historical presence of the sturgeon Acipenser sturio in the Rhône basin determined by the analysis of ancient DNA cytochrome b sequences

Sturgeon disappeared from the Rhône River in the mid 70’s without certitude about which species it was and about the existence of a sympatry between European sturgeon, Acipenser sturio, and Adriatic sturgeon, A. naccarii, in this watershed. In order to reach a reliable specific determination of this extinct sturgeon population, archaeozoological remains of the Jardin d’Hiver in Arles city, on the Rhône river banks, were genetically analysed, following strict criteria of authentication for the ancient DNA work. The rich collection of Arles sturgeon bone remains stems from human activities between the 6th and the 2nd Century BC. Sequences of 86 bp of the cytochrome b gene were obtained on four bones, from different anatomical parts of the fish and from different archaeological layers. All gave A. sturio diagnostic sequences. This preliminary analysis is an essential first step in the project of sturgeon reintroduction in the Rhône River. Thus, further analyses on a larger sample are necessary to comfort this result and to solve the question of sympatry with A. naccarii.     

Dinoflagellate cyst distribution in marine surface sediments off West Africa (17–6°N) in relation to sea-surface conditions, freshwater input and seasonal coastal upwelling

An organic-walled dinoflagellate cyst analysis was carried out on 53 surface sediment samples from West Africa (17–6°N) to obtain insight in the relationship between their spatial distribution and hydrological conditions in the upper water column as well as marine productivity in the study area.Multivariate analysis of the dinoflagellate cyst relative abundances and environmental parameters of the water column shows that sea-surface temperature, salinity, marine productivity and bottom water oxygen are the factors that relate significantly to the distribution patterns of individual species in the region.The composition of cyst assemblages and dinoflagellate cyst concentrations allows the identification of four hydrographic regimes; 1) the northern regime between 17 and 14°N characterized by high productivity associated with seasonal coastal upwelling, 2) the southern regime between 12 and 6°N associated with high-nutrient waters influenced by river discharge 3) the intermediate regime between 14 and 12°N influenced mainly by seasonal coastal upwelling additionally associated with fluvial input of terrestrial nutrients and 4) the offshore regime characterized by low chlorophyll-a concentrations in upper waters and high bottom water oxygen concentrations.Our data show that cysts of Polykrikos kofoidii, Selenopemphix quanta, Dubridinium spp., Echinidinium species, cysts of Protoperidinium monospinum and Spiniferites pachydermus are the best proxies to reconstruct the boundary between the NE trade winds and the monsoon winds in the subtropical eastern Atlantic Ocean. The association of Bitectatodinium spongium, Lejeunecysta oliva, Quinquecuspis concreta, Selenopemphix nephroides, Trinovantedinium applanatum can be used to reconstruct past river outflow variations within this region.