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1.
枝角类作为淡水湖泊生态系统中的初级消费者之一,对生存环境的改变极为敏感.本文分析了太湖西、中和东部等湖区的钻孔沉积物、表层沉积物以及春夏秋季活体枝角类的组成与丰度.结果表明:活体枝角类组成以象鼻溞(Bosmina spp.)为优势种,秋季枝角类属种数量最多.太湖不同生态型湖区表层沉积物枝角类组成均以象鼻溞为优势种,其中西部与中心湖区的枝角类组成与丰度较为相似,种类单一,枝角类绝对丰度高;东部湖区枝角类属种较为丰富,绝对丰度低,优势种由浮游种象鼻溞以及沿岸种圆形盘肠溞(Chydorus sphaericus sl)和西方笔纹溞(Graptoleberis testudinaria)等种属构成.百年以来,太湖枝角类组成与丰度随着营养水平增加而改变,富营养指示种(Bosmina longirostris)丰度的增加与贫营养指示种(Bosmina longispina)丰度的下降,响应了湖区生态环境的演变过程.1970s末期,太湖西部与中心湖区在进入富营养化阶段,枝角类组成单一,象鼻溞占有绝对优势,与东部湖区相比,沿岸种、底栖种稀少.东部湖区在1960s以后,枝角类属种数量增加,但丰度下降,响应了1960s以来该区域营养水平提高、沉水植被生物量增加以及沼泽化加剧的环境过程.  相似文献   

2.
We aimed to demonstrate different input of organic and inorganic carbon, nitrogen and phosphorus from three main groups of primary producers (phytoplankton, charophytes and vascular submerged macrophytes) to respective lake sediments. Studies were carried out in one eutrophic and two mesotrophic lakes. Samples of sediments were taken from profundal and from littoral zones, the latter divided into such overgrown by charophytes and others covered by vascular submerged macrophytes. We applied a stoichiometric approach to illustrate variable functional carbon to nutrients relationships. Among profundal sediments, the lowest organic to inorganic carbon ratio was found in sediments from the eutrophic lake due to precipitation of calcium carbonate during algal blooms. Extremely low inorganic carbon input to profundal sediment of one of the mesotrophic lakes may be explained by low phytoplankton production but also by dissolution of once deposited calcium carbonates. Charophyte-dominated littoral sediments contained significantly more inorganic carbon than other littoral and profundal sediments. Comparison of stoichiometric ratios between plant standing crop and underlying littoral sediments showed significant enrichment of sediments in nitrogen manifested by reduction of organic carbon to total nitrogen ratio during plant decomposition taking place both in charophyte and in vascular plant stands. We also attempted to divide phosphorus pool in sediments into organic P and calcium-bound P present in charophyte stands and in profundal sediments of eutrophic lake. In the former, calcium-bound P was estimated at 17–19 % of the total P pool while in profundal sediments it amounted 42 % of the total P. This difference suggests that calcium carbonate settling during algal blooms in a eutrophic lake may be more effective in P trapping than calcite encrustations covering charophyte plants in littoral sites. In conclusions, we underline the need of considering often neglected inorganic fractions of carbon and phosphorus to get better insight into carbon and nutrient burial in lake sediments.  相似文献   

3.
The distribution of benthic invertebrates and their subfossil remains was examined within the basin of De Waay, a dimictic, eutrophic lake in the Netherlands. We focused on Chironomidae, but also report the abundances of 11 invertebrate groups that potentially produce chitinous remains that are preserved in the fossil record, although their remains could only be identified at a coarser taxonomic resolution. Most living invertebrates sampled in different seasons were constrained to the littoral zone, with the exception of a few taxa (Ceratopogonidae, Chaoborus flavicans, and Chironomus) that are adapted to low oxygen conditions in the seasonally anoxic profundal zone. In contrast, assemblages of invertebrate remains in lake surface sediments were similar in the entire lake basin, suggesting that considerable numbers of invertebrate remains are transported and redeposited off-shore in Lake De Waay, due to its steep bathymetry. These results indicate that a single sediment sample obtained from the centre of this lake contains subfossil invertebrate remains originating from the entire lake basin. In Lake De Waay, the majority of taxa found in the living assemblages were identified as remains in lake surface sediments, at least for the Chironomidae that could be identified at a similar taxonomic level in living and subfossil assemblages. Of the total 44 chironomid taxa found in Lake De Waay, 35 taxa occurred in the living assemblages and 34 taxa occurred in the subfossil assemblages. Thirty chironomid taxa occurred both as living and subfossil specimens, and on average these 30 taxa represent 94% of the specimens encountered in a sediment sample. Five rare chironomid taxa present as living larvae were not detected in the subfossil assemblages. Conversely, eight rare and four common chironomid taxa were found in subfossil remains, but not in living assemblages. Our results indicate that subfossil assemblages in surface sediment samples provide spatially integrated and representative samples of the living assemblage. However, a combined approach examining both the living benthic invertebrate fauna and invertebrate remains in lake surface sediments will potentially give a more complete and detailed overview of benthic invertebrates in a lake ecosystem than an approach based exclusively on one of these groups.  相似文献   

4.
Biological assemblages are affected by both environmental and spatial processes. Spatial autocorrelation can be specially marked in discrete ecosystems patchily distributed over a large region (e.g., lakes arranged in districts). Lake typologies are exclusively based on environmental features, but we hardly know to what extent spatial patterns can hinder their implementation. We analysed the role of environmental factors and spatial autocorrelation in shaping littoral macroinvertebrate communities of 51 mountain lakes from a large Spanish region in order to test: 1) the suitability of the variables currently used to construct typologies; 2) the influence of spatial patterns on typology implementation. Biologically meaningful types of lakes were created and described by means of cluster analysis (Jaccard index) and multiple discriminant analysis. Water permanence, substrate type and vegetation were the main drivers of the assemblage composition. The cluster analysis and Mantel tests showed that spatial patterns did not generally hamper recognizing lake types. Only in the district with lakes closest to each other (Sanabria Natural Park), spatial autocorrelation was strong enough to overcome the effects of some factors (substrate type), but not others (water permanence).  相似文献   

5.
微塑料作为新型环境污染物正日益受到人们密切关注,为探索微塑料在鄱阳湖流域的污染状况,以鄱阳湖流域"五河"入湖口的沉积物为研究对象,分别在3个水文周期(平水期、丰水期和枯水期)选择6个典型区域采集沉积物进行分析.采用浮选分离方法及金相显微鉴定技术,分析鄱阳湖"五河"入湖口沉积物中微塑料的类型、丰度和表面形貌等特征,旨在揭示鄱阳湖沉积物中微塑料的空间分布规律及不同水位期的动态变化.研究结果显示微塑料的类型有碎片类、发泡类、薄膜类和纤维类,其中主要以碎片类微塑料为主,所占百分比为51.95%;70%的微塑料粒径<1 mm,微塑料(<5 mm)的平均丰度为811.11 n/kg,6个样点的微塑料丰度值表现为朱港 > 吴城 > 渡头乡 > 龙口 > 瑞洪镇 > 南矶山.6个样点的微塑料丰度值与鄱阳湖水位动态均具一致性,在枯水期所占比例最高,达到44.41%;平水期次之,达到31.52%;丰水期所占比例最低,仅占24.07%.不同水期、不同样地存在不同程度的微塑料污染问题警示人们要重视塑料垃圾的排放及其污染问题,以减少对湖泊、河流等湿地生态环境的影响.  相似文献   

6.
Algae which bloom in open water and accumulate in the littoral zones may affect the biogeochemical cycle of phosphorus in eutrophic lakes. To determine such effects, a part of the lakeshore with little allochthonous nutrient input in Taihu Lake, China was selected for this field study. Distinct differences in sedimentary P forms were found among the different littoral subzones. The surface sedimentary total phosphorus (TP) content was 655 mg/kg in the eulittoral subzone and 631 to 641 mg/kg in the infralittoral subzone. Both were much higher than that in the profundal zone (410 mg/kg). Calcium‐bound P (Ca‐P) was significantly correlated to exchangeable P (Ex‐P), and they both had the highest contents in the infralittoral subzone and the lowest in the profundal zone. The aluminum‐ and iron‐bound P (Al‐P, Fe‐P) contents decreased from land to water along the ecotone section. Lower Fe/P ratios and higher Al‐P/Fe‐P ratios appeared in the infralittoral subzone, as compared with the profundal zone. This suggested that the accumulated algae could lead to a great deposit of P in the littoral zones. However, the active sedimentary P form transformation in the littoral zones would also result in a partial release of the accumulated P to the overlying water.  相似文献   

7.
Gusakov  V. A. 《Water Resources》2001,28(1):94-104
Data on the abundance, horizontal distribution, and the seasonal dynamics of the dominant species and the entire group Cyclopoida in the meiobenthos of the open littoral and profundal of the Rybinsk Reservoir are presented. The probability that the passive and active migrations of cyclops in the reservoir are controlled by the natural (transsedimentational activity of hydrodynamic processes) and human-induced factors (artificial water level control) is discussed.  相似文献   

8.
To understand how littoral biota respond to anthropogenic disturbances, limnologists seek to detect the scale at which patterns and processes occur. We conducted an extensive study on the shoreline phytobenthos of Lake Garda (Italy) with the following main objectives: (i) to examine the importance of urbanization for species distribution within a set of hierarchical spatial scales (101–104 m), and then (ii) to test the spatio-temporal interactions on a reduced set of scales (101–102 m, and 101–102 days). Results showed that most of the variation in most abundant species and habitat characteristics occurred at the spatial scale of 101–102 m. Species richness was positively related with microheterogeneity, but the relationship occurred only at low urbanization and not at highly-urbanized sites where artificial shores were less heterogeneous. The similarity of species assemblages was regulated by two interacting processes, one operating at a fine spatial scale (102 m), reflecting the physical-habitat requirements of the species, and the other one operating at a broader scale (104 m) in relation to the N–S nitrogen gradient. Overall, time explained 73 % of the total variation of species assemblages, space 7 %, and 20 % was explained by the interaction between space and time (the patch scale, 10s of m, and area scale, 100s of m, interacted with the finest temporal scale, 10s of days). This interaction might be explained by the process of species recruitment operating at different rates at the two spatial scales. Since the largest variation in species assemblages was at the temporal scale (due to the seasonal succession of phytobenthos), we recommend collecting at least one sample per season when monitoring littoral habitats.  相似文献   

9.
The habitat and diet variation of the common carp (Cyprinus carpio) were studied in Lake Banyoles (Catalonia, Spain). Carp was the second most abundant species offshore and used more the littoral in spring and deep bottoms in winter. The diet of carp was based on detritus, amphipods (Echinogammarus sp.), phantom midge larvae (Chaoborus flavicans), diatom mucilages, and plant debris. Amphipods and phantom midge larvae were much more important in diet than previous studies found, because of their greater availability in this lake. Among the carp inhabiting deep waters, there was size-dependent variation in diet, with smaller carp selecting more meiobenthos (cladocerans, ostracods, and small chironomids) and larger carp preying on profundal macrobenthos (phantom midge larvae and large chironomids). Roach (Rutilus rutilus) and carp dominated in abundance the non-littoral zone of the lake and showed resource partitioning, with roach being a more efficient zooplanktivore and carp being more able to prey on hard material (plant seeds, mollusks, and ostracods).  相似文献   

10.
Arcellinida (testate lobose amoebae) were examined from 22 surface-sediment samples collected from homogenous environments in eastern Canadian lakes (Lac du Castor Blanc, SW Quebec; Oromocto Lake, SW New Brunswick) to: 1) evaluate the faunal consistency of assemblages within the targeted environments; and, 2) assess the Arcellinida assemblage response evident in samples collected from Oromocto Lake in 2010 CE (n = 10) and 2012 CE (n = 6) to inter-annual changes in environmental conditions. Cluster analysis and detrended correspondence analysis (DCA), redundancy analysis (RDA), and Bray-Curtis Dissimilarity Matrix (BCDM) were used to identify the dominant arcellinidan assemblages, determine physicochemical controls over the Arcellinida distribution, and assess the assemblages’ faunal homogeneity, respectively. Cluster analysis, DCA, and BCDM results revealed two distinct and relatively homogenous arcellinidan assemblages: 1) Lac du Castor Blanc Assemblage; and 2) Oromocto Lake Assemblage, which could further be subdivided into Oromocto Lake 2010 CE (OL10), and 2012 CE (OL12) sub-assemblages. RDA results showed that 65.6% of the variance in the arcellinidan distribution could be attributed to four significant parameters; sand size fraction (32.1%), calcium (29.2%), manganese (2.7%), and organic content (1.5%). The OL10 and OL12 sub-assemblages aligned well with the respective sample collection dates of 2010 CE and 2012 CE, with proportions of the healthy-lake-indicating Diffluggiid taxa being higher in OL12, likely due to a concurrent slight increase in substrate organic content in the 2012 CE sediments. Our results confirm the faunal homogeneity of assemblages in limnologically similar environments, and demonstrate the rapid response of Arcellinida assemblages to changes in lake conditions at inter-annual time scales.  相似文献   

11.
The evolutions of diatom floras and the total phosphorous (TP) concentrations in the historical period were reconstructed for two lakes, Longgan and Taibai in the middle Yangtze River,based on high resolutional fossil diatom study from two sediment cores and an established regional diatom-TP transfer function. The TP concentration in Longgan Lake changed slightly in the range of 36-62 μg/L and kept its middle trophic level in the past 200 years. The changes of diatom assemblages reflect a macrophyte-dominated history of the lake. During the nineteenth century, the lake TP concentration increased comparatively, corresponding to the increase in abundance of benthic diatoms. The progressive increase of epiphytic diatoms since the onset of the twentieth century indicates the development of aquatic plants, coinciding with the twice drops of water TP level. The TP concentration in Taibai Lake kept a stable status about 50 μg/L before 1953 AD, while diatoms dominated by facultative planktonic Aulacoseira granulata shifted quickly to epiphytic diatom species, indicating a rapid expansion of aquatic vegetation. During 1953-1970 AD, the coverage of aquatic plants decreased greatly inferred by the low abundance of epiphytic diatoms as well as declined planktonic types, and the reconstructed TP concentration shows an obvious rising trend firstly, suggesting the beginning of the lake eutrophication. The lake was in the eutrophic condition after 1970, coinciding with the successive increase of planktonic diatoms. The comparison of the two lakes suggests the internal adjustment and purification function of aquatic plants for nutrients in water. The discrepancy of TP trends in the two lakes after 1960 reflects two different patterns of lake environmental response to human disturbance. Sediments in Taibai Lake clearly recorded the process of lake ecological transformation from the macrophyte-dominated stage to the algae-dominated stage. The limits of TP concentration (68-118 μg/L) in the transitional state can be considered as the critical value between the two stable ecosystems. Further work will be necessary to provide more evidence from the sediments in more eutrophic lakes for the primary inference. The reconstructive TP level and the inference of aquatic plants from fossil diatoms in different lakes, as well as their comparison provide a scientific basis for ecological restoration of eutrophic lakes in research regions.  相似文献   

12.
The evolutions of diatom floras and the total phosphorous (TP) concentrations in the historical period were reconstructed for two lakes, Longgan and Taibai in the middle Yangtze River, based on high resolutional fossil diatom study from two sediment cores and an established regional diatom-TP transfer function. The TP concentration in Longgan Lake changed slightly in the range of 36–62 μg/L and kept its middle trophic level in the past 200 years. The changes of diatom assemblages reflect a macrophyte-dominated history of the lake. During the nineteenth century, the lake TP concentration increased comparatively, corresponding to the increase in abundance of benthic diatoms. The progressive increase of epiphytic diatoms since the onset of the twentieth century indicates the development of aquatic plants, coinciding with the twice drops of water TP level. The TP concentration in Taibai Lake kept a stable status about 50 μg/L before 1953 AD, while diatoms dominated by facultative planktonic Aulacoseira granulata shifted quickly to epiphytic diatom species, indicating a rapid expansion of aquatic vegetation. During 1953–1970 AD, the coverage of aquatic plants decreased greatly inferred by the low abundance of epiphytic diatoms as well as declined planktonic types, and the reconstructed TP concentration shows an obvious rising trend firstly, suggesting the beginning of the lake eutrophication. The lake was in the eutrophic condition after 1970, coinciding with the successive increase of planktonic diatoms. The comparison of the two lakes suggests the internal adjustment and purification function of aquatic plants for nutrients in water. The discrepancy of TP trends in the two lakes after 1960 reflects two different patterns of lake environmental response to human disturbance. Sediments in Taibai Lake clearly recorded the process of lake ecological transformation from the macrophyte-dominated stage to the algae-dominated stage. The limits of TP concentration (68–118 μg/L) in the transitional state can be considered as the critical value between the two stable ecosystems. Further work will be necessary to provide more evidence from the sediments in more eutrophic lakes for the primary inference. The reconstructive TP level and the inference of aquatic plants from fossil diatoms in different lakes, as well as their comparison provide a scientific basis for ecological restoration of eutrophic lakes in research regions.  相似文献   

13.
14.
Zoobenthic communities were used to indicate the trophic state of three mountain lakes of western Switzerland. In these lakes, the macrobenthos was constituted mainly by oligochaetes and chironomid larvae;Tubifex tubifex was the most abundant worm species. In Lakes Lioson and Hongrin, the abundance of zoobenthos did not change or increased slightly with depth andStylodrilus heringianus was present. In Lake Chavonnes, zoobenthos decreased strongly with depth and it consisted mainly ofTubifex tubifex. These data, compared with those from other oligotrophic lakes, indicated that Lake Chavonnes was eutrophic whereas Lakes Lioson and Hongrin were oligotrophic. However, Lake Hongrin—an artificial lake made in 1968—constituted a special case. Its water comes in part from mountain rivers and in part from Lake Geneva. Consequently, some benthic species of Lake Geneva have colonized Lake Hongrin and its water is warmer than in a typical mountain lake.   相似文献   

15.
太湖枝角类微化石的初步研究   总被引:1,自引:1,他引:0  
湖泊沉积物中的枝角类微化石能够在一定程度上反映历史时期水体中的枝角类种群动态,从而具有重要的环境指示意义.通过对太湖(马山附近)沉积物中枝角类微化石的初步研究,尝试反演了所研究湖区近百年来水体环境的演化过程.并对枝角类种群动态的驱动因素进行了分析.从沉积物中共鉴定出10属14种枝角类,其中象鼻溞属占绝对优势,相对丰度平均值高达95.4%尖额潘属次之为4.2%;盘肠潘属以及其他枝角类不到1%.研究结果显示,随沉积深度自下而上变化,喜好富营养水体环境的B.longtrostris cornuta和A.rectangula的丰度逐渐增加,而偏贫-中营养环境的A.intrmedia的丰度则逐渐下降,表明水体营养水平处于逐渐上升的过程,其中表层3cm以上枝角类绝对丰度的急剧下降和A.intermedia 的完全消失表明,20世纪80年代末期以来水体急剧富营养化;另外枝角类敞水区种类与沿岸带种类的数量比(肌)随沉积深度的变化也在一定程度上反映了太湖水深,水面积的变化以及20世纪80年代末期以来的水体富营养化状况.研究结果同时也表明,20世纪60年代以前,自然环境条件为影响枝角类种群动态的主控因素,此后人类活动的影响越来越明显并最终成为枝角类种群动态的决定性因素.  相似文献   

16.
Within the shallow littoral zones of lakes, periphyton is an essential component, representing an important source of primary production and a food resource for herbivores. Periphytic communities are abundantly inhabited by meiofaunal organisms, which are mostly dominated by nematodes. During the last 3 decades, consumer–resource interactions between herbivore consumers and periphytic components (mainly algae) have been intensively studied. Although whole grazer community and single species effects on periphyton are known from field and laboratory experiments, the importance of single, dominant grazer taxa in direct comparison to whole community impacts is unknown. To investigate the continuity of grazing effects of a single, dominant macrograzer (Theodoxus fluviatilis, Gastropoda, Prosobranchia) on epilithic meiofauna and algae with respect to the whole grazer community, a temporally structured field experiment was carried out in Lake Erken (Sweden). Grazer impacts on periphytic algae and meiofauna were tested by controlling macrograzer access to littoral periphyton communities for 8 weeks in an exclosure/enclosure experimental design. Overall, the results showed macrograzer presence to have temporally constant, strongly negative effects on algal biomass as well as meiofaunal abundance and community composition. Moreover, T. fluviatilis alone accounted for up to 80% of the grazing effects, indicative of their ability to regulate periphytic communities in lakes. The present study yields new insights into the effects of a single grazer species and stressed temporal patterns of consumer–resource interactions in freshwater lakes.  相似文献   

17.
18.
浅型富营养湖泊的生态恢复——五里湖水生植被重建实验   总被引:30,自引:4,他引:26  
李文朝 《湖泊科学》1996,8(Z1):1-10
依据浅型湖泊生态系统的多稳定态理论,在富营养湖泊治理过程中,当外来污染得到有效控制时,通过人工重建水生植被可以加速湖泊的生态恢复。在五里湖中,挺水植物和浮叶植物都能很好地生长,水底光照不足是沉水植物难以生长的主要原因。在自然条件下建成了永久性挺水植物群落和浮叶植物群落,在人工控制的围隔环境中改善了水底光照条件,建成了沉水植物群落。但这些沉水植物仍不能渡过夏季,主要原因是湖水过深和水温较高,降低水位和建造人工浅滩可为五里湖沉水植被恢复创造有利条件。本研究可为富营养水体的水质控制和植被恢复提供多种实用技术,但在水生植被的结构与环境功能等方面仍需开展深入的定量研究。  相似文献   

19.
We analyzed cladoceran remains in dated sediment cores from four lakes in Nova Scotia, Canada, to assess the potential effects of climate warming, acidic deposition, and a major fish kill caused by copper sulphate poisoning on assemblage composition and Bosmina size structure. In three of the four lakes, we observed a decline in Daphnia in the early 20th century that might be indicative of limnological changes in response to acidic deposition or increased fish predation. The appearance of the softwater zooplankter Holopedium glacialis in Hirtle Lake ~1995 might be linked to declining aqueous [Ca], a consequence of acidic deposition. No shifts in subfossil Cladocera were identified in this study that could be linked to climate warming. The application of copper sulphate as a fish poison to Trefry Lake (the lake was later re-stocked with trout fry) in 1938 resulted in dramatic and persistent changes in the cladoceran assemblage, where littoral Cladocera declined in relative abundance and small, pelagic Bosmina increased. In addition, we observed a reduction in the mean body size of Bosmina in post-1938 sediments, suggesting that planktivorous fish abundance increased and/or predatory copepods and other invertebrate predators decreased. No recovery of Cladocera to pre-disturbance conditions was observed. Overall, our data suggest that acidic deposition and calcium decline may have had a modest impact on the cladoceran communities in these lakes, but the effects of copper sulphate poisoning on the food web in Trefry Lake were widespread, and still persist over 70?years following this intervention.  相似文献   

20.
盐湖中的矿物沉积记录着丰富的环境气候变化信息,是古环境研究的重要对象.在无地表径流补给的盐湖中,其矿物组成及沉积特征与有地表径流补给的湖泊相比是否有一定的特殊性,是值得探讨的问题.采集巴丹吉林沙漠33个不同矿化度地下水补给型湖泊的表层沉积物和10个地表风积砂样品,通过X衍射的方法,分析样品的矿物组成.结果显示:湖泊表层沉积物主要为石英、长石、辉石、云母等碎屑矿物,部分湖泊含有少量的碳酸盐和氯化物盐类矿物.湖泊沉积物的矿物组成与湖水矿化度的关系较为密切,淡水湖仅分布碎屑矿物,微咸水湖含有碎屑矿物和碳酸盐类矿物,盐湖含有碎屑矿物、碳酸盐类矿物和氯化物.风积砂样品中主要为碎屑矿物,占总矿物含量的90%,对湖泊沉积物的矿物组成影响较大,但对湖泊沉积物中的盐类矿物没有贡献,表明湖泊表层沉积物中盐类矿物主要是自生作用形成的.虽然本地区湖泊边缘的沉积物中盐类矿物种类相对较少并且含量较低,但其盐类矿物组成与分布能够响应湖水矿化度的变化,其环境指示意义与有径流补给的盐湖相同,可以指示其湖水的盐度.因此,可以从巴丹吉林沙漠地下水补给型湖泊沉积的盐类矿物中提取相应的古环境信息,用于恢复古气候和古环境的研究.  相似文献   

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