新疆博斯腾湖浮游细菌丰度对富营养化及咸化的响应

本文以地处干旱地区我国最大的内陆淡水湖——博斯腾湖为研究对象,于2010年6月,在博斯腾湖大小湖区共选取23个采样点,采用表面荧光显微镜直接计数法( FDC)研究了水体中浮游细菌丰度的空间分布规律及其与环境因子的关系.结果表明:博斯腾湖水体中总氮(TN)浓度在0.26-1.45 mg/L之间变动(均值0.91 mg/L...     

太湖梅梁湾冬末春初浮游动物时空变化及其环境意义

根据１９９８年２－３月完全原庆湖梅梁湾地区水环境综合调查,对有关浮游动物时空情况进行了分析,这次调查共设７个点,湾口上的Ｊ２,Ｊ４与湾内的Ｊ６,Ｊ７均是分５层采样,共分无风,小风和大风３次天气过程,每次过程采集２到３次样品与记录。结果显示,太湖梅梁湾地区浮游生物中枝角类和桡足类的生物量与水温变化关系密切,水温越高,生物量越高,温度相同时,其生物量与透明度呈正比。     

太平洋褶柔鱼冬生群资源丰度变动对ENSO事件的响应研究

太平洋褶柔鱼为大洋性经济鱼种,具有一年生命周期,其资源变动受气候和海洋环境条件的显著影响。本研究根据日本提供的2003-2012年太平洋褶柔鱼冬生群体的渔业统计数据,结合产卵场环境数据以及尼诺指数ONI（定义为Niño 3.4区海表温度距平值）,分析不同气候条件下（厄尔尼诺和拉尼娜）太平洋褶柔鱼冬生群体产卵场海表温度（SST）、叶绿素a（Chl-a）浓度以及适宜产卵面积（SSA）的变动情况及对其资源丰度（CPUE）的影响。结果表明,太平洋褶柔鱼冬生群体产卵场SST、Chl-a浓度和SSA具有明显的季节性变化。相关分析表明,各年CPUE与Chl-a浓度以及SSA具有显著的正相关关系（p<0.05）,但与SST相关性不显著（p>0.05）。此外,厄尔尼诺和拉尼娜事件通过驱动太平洋褶柔鱼冬生群体产卵场SSA和关键海域（25°-29°N,122.5°-130.5°E）内的Chl-a空间分布和大小变化,从而改变其资源丰度,但影响作用随各异常事件的强度不同而变化,具体表现为：发生弱强度厄尔尼诺事件时,产卵场SSA较高,Chl-a浓度处于较低水平,导致资源补充量处于较低水平,CPUE降低;发生中等强度厄尔尼诺事件时,产卵场SSA较低,但Chl-a浓度处于较高水平,导致资源补充量增加,CPUE处于上升水平;发生中等强度拉尼娜事件时,产卵场SSA和Chl-a浓度均处于较高水平,资源补充量显著增加,CPUE显著升高。研究表明,厄尔尼诺和拉尼娜事件对太平洋褶柔鱼冬生群体产卵场摄食孵化环境和资源丰度变动具有显著影响。     

基于不同环境因子的中西太平洋鲣鱼资源丰度灰色预测模型构建

鲣Katsuwonus pelamis广泛分布于各大洋热带和亚热带海域,其中以中西太平洋资源量最为丰富。综合评价环境因子对鲣鱼资源量的影响,构建科学的资源预报模型可为我国可持续合理开发该鱼种提供参考。本研究利用1998—2013年中西太平洋渔获量数据,以单位捕捞努力量渔获量(CPUE)为资源相对丰度指标,利用灰色关联方法分析鲣鱼资源相对丰度与环境因子之间的关联度,选取合适的环境因子,并基于不同环境因子构建不同的灰色预测模型对鲣鱼资源相对丰度进行预测,比较选择最优模型。结果表明, 中西太平洋鲣鱼的产量逐年递增,而CPUE在年间有着较大的波动。灰色关联分析认为,海表面温度与CPUE的平均关联度最大,其次为Nino3.4区海表温度距平值,其他的环境因子与CPUE的关联度较小。基于多环境因子的预测模型中,包含所有因子(海表面温度、海表面高度、叶绿素质量浓度a和Nino3.4区海表温度距平值)的模型M1有着最佳的拟合效果,实际值与预测值的相对误差为6.475 2,相关系数为0.687 4;而基于单一环境因子的预测模型中,去除11月SST数据的模型S2有着最佳的拟合效果,实际值与预测值的相对误差为7.419 2,相关系数为0.791 0。相比多环境因子的预测模型,单一环境因子预测模型有着较高的稳定性,实际值与预测值直接相关性也较高,可以作为中西太平洋鲣鱼资源相对丰度预报的最优模型。     

Annual cycle of zooplankton abundance and species composition in Izmit Bay (the northeastern Marmara Sea)

The monthly abundance, biomass and taxonomic composition of zooplankton of Izmit Bay (the northeastern Marmara Sea) were studied from October 2001 to September 2002. Most species within the zooplankton community displayed a clear pattern of succession throughout the year. Generally copepods and cladocerans were the most abundant groups, while the contribution of meroplankton increased at inner-most stations and dominated the zooplankton. Both species number (S) and diversity (H′) were positively influenced by the increase in salinity of upper layers (r = 0.30 and r = 0.31, p < 0.001, respectively), while chlorophyll a was negatively affected (r = −0.36, p < 0.001). Even though Noctiluca scintillans had a significant seasonality (F_11,120 = 8.45, p < 0.001, ANOVA), abundance was not related to fluctuations in temperature and only chlorophyll a was adversely correlated (r = −0.35, p < 0.001). In general, there are some minor differences in zooplankton assemblages of upper and lower layers. A comparison of the species composition and abundance of Izmit Bay with other Black Sea bays reveals a high similarity between them.     

Regular habitat switch as an important feeding strategy of an opportunistic seabird species at the interface between land and sea

During deteriorated prey availability, purely pelagic, specialised seabird species have to alter their feeding strategy by extending foraging radii and/or time spent at sea or reducing feeding intervals of chicks. In contrast, more generalised species such as the opportunistic black-headed gull (Larus ridibundus) breeding at the German North Sea coast, can be assumed to react on prey shortages by switching foraging habitats. The coastal zone of the German North Sea provides a rich habitat mosaic consisting of the offshore zone, tidal flats and terrestrial habitats. Thus, we expected distinct temporal and spatial patterns of habitat switch in accordance with prey availability and environmental constraints. We carried out ship-based and aerial surveys as well as dietary analyses and observations on flight activity. We found a significant switch from terrestrial to marine feeding sites both on a daily basis (related to tidal cycle) and over the whole breeding season. Most likely, the latter switch is the result of lower prey availability in the terrestrial habitats and an increasing quality (in terms of prey abundance and energy intake) of the marine area. While there was only moderate variability in habitat use among different years, we revealed significant differences in the diet of birds from different colonies. The high dietary plasticity and flexible feeding strategy, switching between terrestrial and marine prey is certainly of major importance for the success of an opportunistic avian top predator in a complex coastal zone. It is suggested that – compared to situations elsewhere – the number of breeding pairs of black-headed gulls in the German North Sea coast are still stable due to the switch of foraging habitats performed by individuals in this region.     

基于改进线性光谱分离模型的植被覆盖度反演

线性光谱分离技术可以有效地提取像元水平上植被或其他端元(影像中的地物)的相对百分比,但是目前该技术在多光谱宽波段影像数据应用中,由于波段数量、波段宽度等的限制,估算精度离定量研究的水平仍有一定差距。鉴于此,本文提出了一种改进的线性光谱分离方法,该方法在对影像进行土地覆盖分类基础上进行分离,一方面同类土地覆盖类型内同种地物的光谱变异相对较小,更有利于端元选取;另一方面,分影像的地物种类数量明显少于整幅影像,更容易满足模型的适用条件,从而突破了波段数量限制,同时使地物光谱分离更具针对性,经过验证,该方法较传统分离方法相比植被覆盖度的反演精度可提高6.4%,用该方法实现了研究区的植被覆盖度的定量反演并对研究区植被覆盖度的空间结构进行了分析。     

Depth-stratified community zonation patterns on Gulf of Alaska rocky shores

Vertical zonation patterns have been considered ubiquitous in intertidal ecosystems but questions remain about their generality for individual taxonomic groups and over broad spatial scales, and whether they continue into adjacent shallow subtidal habitats. Taxon richness, invertebrate abundance, and macroalgal biomass were examined in the summer of 2003 along a vertical gradient in the rocky intertidal and shallow subtidal habitats around Kodiak Island, Kachemak Bay, and Prince William Sound, all within the Gulf of Alaska. Replicate samples of benthic organisms were taken in the high (～ 7 m), mid (～ 4 m) and low (～ 0 m) intertidal (relative to MLLW), and at 1, 5, 10 and 15 m water depths at three sites in each region, and identified to the lowest possible taxonomic level. Our primary goals were to assess (1) how estimates of taxon richness, invertebrate abundance, and macroalgal biomass vary among intertidal heights and subtidal depths and (2) how general these patterns are when considered across the Gulf of Alaska. Our results show that when all invertebrates were considered together, most of the variation in taxon richness was accounted for by differences among depths (i.e. intertidal heights and subtidal depths) (～ 51%), and among replicate samples within each depth (～ 26%). Little to none of the variation was accounted for by differences among sites within each region (～ 1%) or among regions themselves (～ 0%). When considered across the Gulf of Alaska, total taxon richness and organism abundance were greatest in the low intertidal/shallow subtidal and decreased with increasing height/depth. When separated by phylum and examined together with macroalgae, variation in abundance and/or biomass among depths was significant and accounted for most of the variability. Differences among regions and sites within each region were not significant and accounted for little to none of the variance. Because the pattern of zonation varied among sites within each region, it reduced the generality of a single zonation pattern for the Gulf of Alaska. Likewise, when community composition was compared among depths, geographic regions and sites within each region using multivariate analyses, vertical zonation patterns were evident at a regional scale, but high variability in these patterns among sites within each region reduced the generality of these patterns.     

Grain size, geochemistry, magnetic susceptibility: Proxies in identifying sources and factors controlling distribution of metals in a tropical estuary, India

The aim of this study is to understand the various sources and factors controlling the abundance and distribution of the metals through the analyses of selected metals (iron, manganese, chromium, copper, zinc and cobalt), sand, silt, clay, organic carbon and magnetic susceptibility of the surface sediments of Zuari estuary in three different seasons. Total suspended matter (TSM) concentration and salinity of near surface and bottom waters were also measured. The study undertaken for three seasons, based on 18 selected stations all along the estuary, indicated that the concentration of most of the metals were comparatively higher during pre-monsoon than in monsoon and post-monsoon seasons. Further, along the length of the estuary, high concentrations were observed at lower middle and lower estuary and also at few stations at the upstream end. Salinity, distribution of TSM, size of the sediment, organic matter, geomorphological setup, fresh water input from land and release of industrial waste within the estuary played a role in distribution and concentration of metals. Magnetic measurements indicated the dominance of haematite like minerals and helped in understanding the source and depositional processes.