长江口及其毗邻海域鱼类群落优势种的生态位宽度与重叠

根据“北斗号”调查船2006年6月、8月和10月在长江口及其毗邻海域进行渔业资源底拖网调查的资料,通过相对重要性指数确定鱼类群落优势种,对优势种的生态位测度指标及季节变化进行分析.结果表明： 3航次的优势种共有10种,它们的生态位宽度和生态位重叠指标呈现出明显的季节性变化,通过Bray-Curtis相似性聚类与非度量多维标度(MDS)分析可分为两组.第一组为鳀鱼、鳄齿鱼、发光鲷,其生态位宽度和生态位重叠指标夏季大于秋季,呈现出由夏季到秋季从长江口及其毗邻海域向外部深水区移动的趋势;第二组为带鱼、矛尾虾虎鱼、细条天竺鲷、小黄鱼、刺鲳、白姑鱼、七星底灯鱼,其生态位宽度和生态位重叠指标秋季大于夏季,呈现出由夏季到秋季从黄海南部和东海北部水域向长江口及其毗邻海域移动的趋势.这两组鱼类不同的移动趋势与其生态习性和环境因素有关.     

Influence of changes in salinity and light intensity on growth of phytoplankton communities from the Schelde river and estuary (Belgium/The Netherlands)

In the Schelde continuum, a succession in the phytoplankton community is observed along the transition from the river to the freshwater tidal reaches of the estuary and from the freshwater to brackish reaches of the estuary. The goal of this study was to experimentally evaluate the contribution of changes in salinity and light climate to this succession. In summer 2000 and in spring 2001, phytoplankton communities from the river, the freshwater tidal reaches and the brackish reaches of the estuary were incubated under high or low light intensities and exposed to a change in salinity. HPLC analysis was used to evaluate the response of different algal groups to changes in light intensity and salinity. When incubated at a light intensity corresponding to the mean underwater light intensity of the freshwater tidal reaches, growth of phytoplankton from the river as well as from freshwater tidal reaches was significantly lower than when incubated at a light intensity corresponding to the mean underwater light intensity of the river. The phytoplankton community from the freshwater tidal reaches did not appear to be better adapted to low light intensities than the phytoplankton community from the river. Although diatoms were expected to be less sensitive to a reduction in light intensity than green algae, the opposite response was observed. Freshwater and brackish water phytoplankton were negatively affected by respectively an increase or decrease in salinity. However, the effect of salinity was not strong enough to explain the disappearance of freshwater and brackish water phytoplankton between a salinity of 0.5 and 10 psu, suggesting that other factors also play a role. In the freshwater phytoplankton communities from the river and the freshwater tidal reaches, green algae and diatoms responded in a similar way to an increase in salinity. In the brackish water phytoplankton community, fucoxanthin displayed a different response to salinity than lutein and chlorophyll a.     

长江口北支浮游植物群落结构周年变化特征

2010年10月至2011年9月对长江口北支水域的浮游植物进行周年调查,共采集到183种（包括变种和变型）,隶属于7门60属,其中硅藻门种类最多,有35属137种,占浮游植物总种类数的75%。周年优势种为具槽直链藻、中肋骨条藻、条纹小环藻、两栖颤藻、小伪菱形藻双楔变种、颗粒直链藻和小环藻未定种。本次调查中,季节间浮游植物的丰度差异不显著（P〉0.05）,但各月间浮游植物丰度差异显著（P〈0.05）,全年丰度在2.83×10^3～6.18×10^4cells/L之间,其中6月的丰度最高,1月的丰度最低,全年的平均丰度为1.73×10^4cells/L。Pearson相关性分析显示,浮游植物丰度与硝酸盐浓度显著正相关（P〈0.05）,与氨氮浓度极显著正相关（P〈0.01）,含氮营养盐对浮游植物的影响明显。     

The role of salinity in structuring the fish assemblages in a tropical estuary

The present study describes the seasonal changes of the fish species composition in three areas of the main channel of the Caeté River estuary, Brazil. The fish faunas of each habitat differed in density, biomass and species composition. Mean fish density and biomass for the Caeté River estuary channel was 0·25 individuals m⁻² and 0·9 g m⁻² respectively. Analysis of catch data showed that the number of species, total density and total biomass differed significantly between areas and seasons. For the most important species, the mean density of Cathorops spixii, Aspredinichthys filamentosus, Aspredo sp. 2, Pimelodus blochii, Pseudauchnipterus nodosus and Macrodon ancylodon , differed significantly between seasons while the mean density of Stellifer rastrifer , Stellifer microps, Aspredo aspredo , Aspredo sp. 1 and Cynoscion acoupa did not. The mean biomass of these species, with exception of S. microps and Aspredo sp. 1, also differed significantly between seasons. In the Caeté estuary seasonal salinity fluctuations appeared to be the main factor that structured the fish assemblage in the entire estuarine system. At least 85% of the species captured by the artisanal and subsistence fisheries in the Bragantine region required estuarine conditions to complete their life cycle.     

长江河口潮间带鱼类群落的时空变化

根据2006年3-11月每月在长江口4个潮间带站点的36网次鱼类采样数据,分析了该水域鱼类群落组成的时空变化特征.结果表明：本次调查采获鱼类55种,隶属20科,其中,鲤科鱼类最多,有18种,占总种数的32.7%,虾虎鱼科其次,有8种,占14.5%,石首鱼科4种,占7.3%;调查水域潮间带鱼类群落可分为口内淡水区鱼类群落和河口咸淡水区鱼类群落2组,河口咸淡水区鱼类的物种多样性比口内淡水区略低,其中,口内淡水区以油似鳊和鳊等淡水鱼类为优势种,河口咸水区以斑尾刺虾虎鱼、鲻和棘头梅童等咸淡水鱼类为优势种;二组间鱼类种类组成的平均相异性为80.75%,23种鱼类对平均相异性的累积贡献率>90%,主要贡献来自油鲻、斑尾刺虾虎鱼、棘头梅童鱼、似鳊、红狼牙虾虎鱼、鲫、鳊和长蛇鮈等;春季的研究区鱼类群落丰度与夏、秋两季均存在一定程度的差异,而夏、秋两季间的差异相对较小.就单组鱼类群落丰度而言,水温对其季节变化的影响较盐度大,而盐度对整个河口鱼类群落的影响较水温大.     

福建漳江口红树林湿地沉积物中四种重金属的空间分布特征

对漳江口红树林湿地沉积物中4种重金属(Pb、Cd、Ni、Fe)含量空间分布的研究表明,漳江口红树林湿地沉积物中Pb、Fe含量较高,Cd、Ni含量相对较低;林内沉积物的Pb、Cd含量显著高于林外沉积物;在垂岸方向上,表层沉积物中除Ni外其它三种元素含量均表现出从林外到林内增加的趋势;在垂直梯度上,四种元素含量均随着沉积物深度增加而逐渐降低。     

Nitrogen sequestration capacity of two salt marshes from the Tagus estuary

The role of salt marshes as nitrogen sink is examined taking into consideration the seasonal variation of above and belowground biomass of Spartina martima and Halimione portulacoides in two marshes from Tagus estuary, Pancas and Corroios, and the degradation rates of belowground litter. Total nitrogen was determined in plant components, decomposing litter and sediment. Biomass was higher in Corroios, the saltier marsh, with 7190 g m⁻² y⁻¹ dw of S. maritima and 6593 g m⁻² y⁻¹ dw of H. portulacoides and the belowground component contributed to 96% and 90% of total biomass, respectively. In the other marsh, Pancas, belowground biomass contributed to 56% and 76% of total biomass for S. maritima and H. portulacoides, respectively. Litterbag experiment showed that between 25% and 50% of nitrogen is lost within the first month and remained relatively constant in the next four months. Slower decomposition is observed in sediments with higher nitrogen concentration (max. 0.7% N in the saltier marsh). Higher concentrations of N were found in the sediment upper layers. Considering the sediment-root system, most of the nitrogen is stored in the sediment compartment and only about 1–4% of the total N was found in the roots. Considering these results, Tagus salt marshes act as a sink for nitrogen.     

辽河口盐地碱蓬湿地景观破碎化及驱动机制

湿地景观破碎化的加剧严重影响了湿地生物多样性保护和湿地生态系统服务功能的维持,本研究以辽河口盐地碱蓬(Suaeda salsa)湿地为研究对象,基于GIS平台构建1985—2019年间湿地景观数据库,定量分析湿地景观破碎化特征及其驱动因素。结果表明:1985—2019年间,辽河口盐地碱蓬湿地呈退化趋势,具体表现为湿地面积萎缩,湿地景观破碎化加剧。盐地碱蓬湿地面积在1988年达到最大值4158.81 hm~2,景观聚集度较高,此后,湿地景观破碎度出现先增大后减小再增大的波动变化,2003年和2019年盐地碱蓬湿地景观破碎化最为严重,破碎度分别达到5.90和7.89;影响辽河口盐地碱蓬湿地景观破碎化主要驱动因素为人为开发活动和水文过程;景观破碎化的整体上升趋势与道路修建、农田开发、水产养殖、径流量和输沙量有较好的空间对应关系,道路修建、农田开发和水产养殖面积的增加以及年径流量的减少是导致盐地碱蓬湿地景观破碎化的主导因素。     

近岸典型生态系统大型底栖动物的次级生产力——以瓯江口、洞头列岛为例

为更好了解和估算河口及岛屿生态系统大型底栖动物次级生产力的情况,以近岸两个典型生态系统河口-瓯江口、岛屿-洞头列岛为例,于2015年4月和10月在该海域进行大型底栖动物调查,采用3种Brey经验模型对大型底栖动物次级生产力进行估算,并分析次级生产力与环境因子的关系。结果表明:(1)以去灰干重(ash-free dry weight,AFDW)计,Brey经验公式估算瓯江口和洞头列岛海域年均次级生产力分别为0.48 g(AFDW)m~(-2)a~(-1)和0.70 g(AFDW)m~(-2)a~(-1),Brey模型估算瓯江口和洞头列岛海域年均次级生产力分别为0.51 g(AFDW)m~(-2)a~(-1)和1.55 g(AFDW)m~(-2)a~(-1),Brey模型估算瓯江口和洞头列岛海域年均次级生产力分别为0.25 g(AFDW)m~(-2)a~(-1)和0.99 g(AFDW)m~(-2)a~(-1)。(2)3种经验模型反映大型底栖动物年均次级生产力空间分布趋势一致:瓯江口海域有1高值区,位于瓯江口南部;洞头列岛海域有2高值区,分别位于洞头本岛东北部的三盘岛与花岗岛之间和东黄岛东南部的岛屿之间。(3)瓯江口海域大型底栖动物年均次级生产力主要贡献种为双鳃内卷齿蚕Aglaophamus dibranchis、长吻沙蚕Glycera chirori、异蚓虫Heteromastus filiforms、焦河篮蛤Potamocorbula ustulata、薄云母蛤Yoldia similis、圆筒原盒螺Eocylichna braunsi,它们对次级生产力的贡献率超54.2%;洞头列岛海域大型底栖动物年均次级生产力主要贡献种为双鳃内卷齿蚕、异蚓虫、薄云母蛤、绒毛细足蟹Raphidopus ciliatus、隆线强蟹Eucrate crenata、脑纽虫Cerebratulina sp.、红狼牙鰕虎鱼Odontamblyopus rubicundus,它们对次级生产力的贡献率超57.1%。(4)次级生产力与环境因子的相关性分析显示化学需氧量、悬浮物和表层沉积物中值粒径是影响瓯江口海域大型底栖动物年均次级生产力的重要环境因子,而环境因子与洞头列岛海域大型底栖动物年均次级生产力相关关系不显著。(5)瓯江口海域Brey经验公式与Brey模型估算结果基本一致,洞头列岛海域Brey经验公式与Brey模型估算结果基本一致。     

黄河口不同氮基质碱蓬种子萌发及幼苗生长对盐分及氮输入的响应

2014年4-11月,选择黄河入海口北部滨岸高潮滩的碱蓬湿地为研究对象,基于野外原位氮负荷增强模拟试验(N0,无额外氮输入;N1,低氮输入;N2,中氮输入;N3,高氮输入),获取相应的不同氮基质种子(S0,S1,S2和S3),以研究其发芽率以及幼苗生长状况对不同盐分胁迫和氮浓度交互作用的响应。结果表明,不同氮负荷影响下碱蓬成熟种子中的氮含量整体表现为S2S0S1S3,中氮输入更利于种子中氮养分的累积。盐分和氮交互作用下4种氮基质种子的发芽率总体表现为S2S1S0S3(P0.05),S2在不同盐分胁迫下的发芽率最高,幼苗的生长状况也最好。随着盐分的增加,4种氮基质种子的发芽率及幼苗生长状况均受到一定程度的抑制,但较低的盐分有助于其幼苗长度的增长,且随着氮输入量的增加这种抑制作用可得到一定程度缓解。盐分胁迫、氮浓度和种子类型作为单独因素出现时对碱蓬的发芽率、幼苗长度、鲜重和干重均产生显著影响,除幼苗长度受氮浓度和盐分胁迫交互作用的影响达到显著水平外(P0.05),其他因子交互作用对诸生态指标的影响并不明显。研究发现,不同氮输入处理不仅改变了原生环境碱蓬种子的氮含量,而且也使这些具备不同氮基质的种子对不同盐分胁迫与氮浓度环境具有不同的生态适应对策,中氮输入下的碱蓬种子(S2)无论在萌发率还是在幼苗生长状况上均优于其他氮基质的种子。未来,随着黄河口新生湿地氮养分供给的不断增加,当湿地氮养分达到中氮水平时,将更有利于碱蓬种子的萌发以及幼苗的生长,当氮养分达到更高水平时,碱蓬种子的萌发以及幼苗生长可能会受到一定程度的抑制。