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1.
Short sediment cores from two gulfs, Monche Bay and Kunchast Bay, of Lake Imandra (Kola Peninsula, northern Russia) were analysed for sediment chemistry and chironomid head capsule remains. Monche Bay has been receiving metals from the Severonikel copper-nickel smelter since the late 1930's. Kunchast Bay was selected in the remotest lake basin as an internal reference site. There were no pronounced changes in the chironomid assemblages with the beginning of slight metal contamination of Kunchast Bay. Based on the reconstructed environmental variables and chironomid assemblages, three developmental stages were distinguished from the chironomid fauna history of Monche Bay: (1) A natural development stage; (2) the early warning stage; and (3) the developing crises stage. During the first period, the changes in the chironomid fauna reflect an anthropogenically undisturbed assemblage, with Micropsectra insignilobus dominating (17–23%). The changes during the second period reflect the initial phase of anthropogenic succession associated with the beginning of metal pollution. The main species showed opposite distributional patterns in this period: the abundance of M. insignilobus decreased, whereas the abundance of Chironomus, Procladius and Sergentia coracina increased. At the same time, maximal numbers were attained for species richness (45) and Shannon-Weaver diversity (4.85) of chironomid assemblages, and the highest head capsule concentration (75 head capsules · g–1 of dry sediment). The third period was characterized by a major shift in the faunal assemblages, from M. insignilobus to other dominant species, including Chironomus (22–44%), Procladius (10–30 %) and S. coracina (15–18%). Besides fauna changes, assemblages of the third period are distinguished by the occurrence of mouthpart deformities in Chironomus head capsules. 相似文献
2.
Calorific value, lipid content and radioactivity of common species from Hornsund, Southwest Spitsbergen 总被引：1，自引：0，他引：1
In the summer of 1981 the common flora and fauna of 28 species from Hornsund were collected, and the energy value, lipid content and global activity determined. It was found that the plants had low energy values, varying from 12.26 ± 0.42 kJ g−1 dry weight to 15.45 ±1.00kJ'dry weight. The highest values in animals were noted in Liparis liparis (Pisces) 22.15 ± 0.89 kJg−1 dry weight, and Sagitta elegans (Chae-tognatha) 20.64 ± 0.49kJg−1 , the lowest being in Orchomene minuta (Amphipoda) 11.30 ± 0.74kJg−1 d.w. The lipid contents in the species studied were mostly low, the mean range from lowest to highest being 1.37-8.60% for plants and 7.14–31.93% for animals, and they were proportional to the energy value. Both the energy values and lipid contents were comparable to those in similar species from other waters. The global fi activity in the organisms analysed was not high; at the same time plants had a higher content of radioactive isotopes, 1.97-61.9pCi g−1 d.w., than animals, 5.2-17.8pCi g−1 d.w. 相似文献
3.
Aruna Srivastava Corresponding author B. N. Nagpal Rekha Saxena Vas Dev S. K. Subbarao 《International journal of geographical information science》2013,27(1):91-98
This paper reports research to predict the distribution of An. minimus, a malaria vector in forest fringe areas using GIS to support precision surveys for malaria control. Because An. minimus is a forest‐associated species, generalized thematic maps (1:6?000?000) of forest cover, soil type, altitude, rainfall and temperature were used. Digitization, overlaying, integration and analysis of thematic maps were done using Arc/Info 8.1 NT and Arc/View 3.2 (GIS, ESRI) software. GIS delineated favourable areas for An. minimus where the species is likely to be found, and precision surveys can be conducted. Precision field surveys in selected locations of favourable/non‐favourable areas were carried out. The species could be found in all locations designated as a favourable area and was absent in non‐favourable areas. In two districts, one where the species is reported to have disappeared in the early 1950s and the other where it was not reported in earlier surveys, GIS helped in precision surveys, and An. minimus was found. The technique can quickly cover vast and inaccessible areas and is easy to duplicate in other parts of the world to assist cost‐effective control of malaria. It can also delineate areas favourable for any species of flora and fauna to help precision surveys. 相似文献
4.
Karabash (52°2 N, 60°10 E) is a copper smelting town in the southern Ural Mountains of Russia. The town is affected by sulphur dioxide emissions and deposition of metal-rich particulates from the smelter, acid drainage from old mine workings, and leachates from disused waste dumps and tailings dams. The close proximity of houses to these sources of pollution is of concern to human health and has devastated terrestrial vegetation in the environs. The environmental impact of the smelter on lakes in the area has been assessed using chironomids. Short sediment cores were taken from 16 lakes within a 50 km radius of the smelter and the composition of the chironomid fauna from the bottom of each core, representing conditions prior to the commissioning of the smelter in 1910, was compared with the present chironomid fauna in the surface sediments. Redundancy analysis (RDA) showed that changes in the chironomid fauna of most lakes were driven by trophic change, independent of the industrial activity. Lakes and ponds adjacent to the smelter and waste dumps, which directly receive contaminated waters were devoid of macro- and mesofauna and flora, but there is no evidence that other lakes have been severely impacted by smelter emissions. Local geology ensures that the lakes are well-buffered to the effects of acid deposition which will limit the bioavailability of metals in the water column and sediment. 相似文献
5.
本文记述了四川万县盐井沟和巫山大庙山原期夷平面上的喀斯特洞穴及其动物群。论证了山原期夷平面的剥夷时期为新第三纪;洞穴生成时期为上新世;其堆积为更新世。并对万县盐井沟动物群的时代及所属层位提出了讨论。 相似文献
6.
H.J.B. Birks D.T. Monteith N.L. Rose Vivienne J. Jones Sylvia M. Peglar 《Journal of Paleolimnology》2004,31(4):411-431
Twenty-four lakes on Svalbard were sampled for palaeolimnological studies and are described in terms of their geographical location, catchment characteristics, water chemistry, and flora. No sediment could be retrieved from one of the lakes. There is a close correlation, as detected by redundancy analysis, between lake-water chemistry and catchment variables, particularly bedrock geology and geographical location for 23 lakes. The flora of the lake catchments is statistically related, as shown by canonical correspondence analysis, to bedrock geology, climate (geographical location), and nutrient status (bird impact). Modern pollen assemblages from eleven lakes contain 2–25% far-distance extra-regional pollen. The modern local and regional pollen depositions are dominated by Oxyria digyna, Poaceae, Saxifraga, Salix, and Brassicaceae pollen. 相似文献
7.
8.
A late Holocene diatom stratigraphy of Bottom Pond (37°05′S, 12°17′W) was studied and interpreted to infer paleolimnological
and climate changes on Tristan da Cunha, South Atlantic. The diatom flora of Bottom Pond is dominated by meroplanktonic Aulacoseira alpigena and A. distans and a benthic/epiphytic flora including Achnanthes spp., Naviculadicta spp., Eunotia taxa and Frustulia rhomboides. The flora also includes an important terrestrial and aerophytic component, consisting of several Diadesmis spp., Navicula lapidosa, Nitzschia terrestris and some Pinnularia spp., at times dominating the flora. Peaks of high terrestrial diatom abundances and low abundances and concentrations of
Aulacoseira spp., correspond to periods of increased magnetic susceptibility and are interpreted to be the result of increased catchment
erosion and/or precipitation leading to enhanced in-wash of species living in the soils around the lake. The diatom record
of Bottom Pond most likely registers both local responses to increased erosion in the catchment as well as climatic change
of a more regional character. Comparisons with the geochemical record in 2nd Pond on Nightingale Island show a correspondence
between the two data sets at 2,000–1,750 cal yrs BP, most likely evidence of increased precipitation in the Tristan da Cunha
region. The Tristan da Cunha archipelago is situated at the northern limit of the Southern hemisphere west wind belt and stronger
and/or a northward shift of the westerlies, are probably the main causes of the precipitation changes. 相似文献
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11.
Invertebrates in salt lakes of the Bolivian Altiplano 总被引：2，自引：0，他引：2
W. D. Williams T. R. Carrick I. A. E. Bayly J. Green D. B. Herbst 《International Journal of Salt Lake Research》1995,4(1):65-77
Based upon a short reconnaissance (March 1991), the chemicalnature and principal invertebrate fauna of seven saline lakes on the Altiplano of southern Bolivia are discussed (Lago de Uru-uru, Pastos Grandes, Lago Ramiditas, Lago Hedionda, Lago Cañapa, Laguna Colorado, pool at L. Colorado). Salinities ranged between 4.4 and 156 g L–1. The fauna was depauperate. Except at the lowest salinities (<5 gL–1), rotifers were absent. At high salinities (>50 g L–1), onlyArtemia, Boeckella poopoensis, ephydrids and a dolichopodid were present. 相似文献
12.
9000 years of chironomid assemblage dynamics in an Alpine lake: long-term trends, sensitivity to disturbance, and resilience of the fauna 总被引：2，自引：0，他引：2
Subfossil chironomid analysis was applied to a sediment core from Sägistalsee, a small lake at present-day tree-line elevation in the Swiss Alps. During the whole 9000-year stratigraphy the chironomid fauna was dominated by taxa typical of alpine lakes. Major faunistic trends were caused by changes in accumulation rates of three taxa, namely Procladius, Stictochironomus, and Tanytarsus lugens-type. In the early Holocene Procladius was the dominant taxon. In younger samples, Stictochironomus tended to have as high or higher abundances and both taxa showed an increase in accumulation rates. A possible cause of this succession is the decrease of lake-water depth due to infilling of the lake basin and changes in associated limnological parameters. The immigration of Picea (spruce) at ca. 6500 cal. 14C yrs BP and the resulting denser woodlands in the lake's catchment may have promoted this trend. During three phases, from ca. 70–1450, 1900–2350, and 3500–3950 cal. BP, remains of Procladius, Stictochironomus, and Tanytarsus lugens-type are absent from the lake sediment, whereas other typical lake taxa and stream chironomids show no change in accumulation rate. Together with sediment chemistry data, this suggests that increased oxygen deficits in the lake's bottom water during these intervals caused the elimination of chironomids living in the deepest part of the lake. All three periods coincide with increased human activity in the catchment, as deduced from palaeobotanical evidence. Therefore, enhanced nutrient loading of the lake due to the presence of humans and their livestock in the catchment is the most likely cause of the increased anoxia. The chironomid fauna reacted the same way to intensive pasturing during the last ca. 1500 years as to Bronze Age clear-cutting and more moderate pasturing during the Bronze, Iron, and Roman Ages, suggesting that alpine lake ecosystems can be extremely sensitive to human activity in the catchment. On the other hand, the chironomid assemblages show a considerable amount of resilience to human disturbance, as the chironomid fauna reverted to the pre-impact stage after the first two periods of human activity. In recent years, even though pasturing decreased again, the chironomid fauna has only partly recovered. This is possibly due to other human-induced changes in the lake ecosystem, e.g., the stocking of the lake with fish. The chironomid stratigraphy is difficult to interpret climatologically as the strongest changes in chironomid-inferred temperatures coincide with periods of intensive human activity in the catchment. 相似文献
13.
D.S. Shafer M.H. Young S.F. Zitzer T.G. Caldwell E.V. McDonald 《Journal of Arid Environments》2007,69(4):633-657
Interrelated, biotic (flora and fauna) and abiotic (pedogenesis and hydrology) processes were examined at four sites (30, and approximately 1000–3000, 7000–12 000, and 125 000 years before present) in the northern Mojave Desert. Data collected at each included floral and faunal surveys; soil texture, structure, and morphology; and soil hydraulic properties. Separate measurements were made in shrub undercanopy and intercanopy microsites. At all sites, shrubs made up greater than 86 percent of total perennial cover, being least on the youngest site (4 percent) and most on the 7000–12 000-year-old site (31 percent). In the intercanopy, winter annual density was highest on the 1000- to 3000-year-old site (249 plants/m2) and lowest on the oldest site (4 plants/m2). Faunal activity, measured by burrow density, was highest on the 1000–3000- and 7000–12 000-year-old sites (0.21 burrows/m2) and density was twice as high in the undercanopy versus the intercanopy. Burrow density was lower at the two oldest sites, although density was not statistically greater in the undercanopy than intercanopy. At the older sites, the soil water balance was increasingly controlled by Av horizons in intercanopy soils in which saturated hydraulic conductivity (Ksat) decreased 95 percent from the youngest to the oldest site. No significant reduction in Ksat in undercanopy soils was observed. Decreases in the intercanopy sites correlated with decreases in annual plant density and bioturbation, suggesting these processes are interrelated with surface age. 相似文献
14.
V. J. Jones N. Solovieva A. E. Self S. McGowan P. Rosén J. S. Salonen H. Seppä M. Väliranta E. Parrott S. J. Brooks 《Journal of Paleolimnology》2011,46(1):123-137
A consequence of predicted climate warming will be tree-line advance over large areas of the Russian tundra. Palaeolimnological
techniques can be used to provide analogues of how such changes in tree-line advance and subsequent retreat affected lake
ecosystems in the past. A Holocene sediment core taken from Kharinei Lake (Russia) was dated radiometrically and used for
multi-proxy analyses with the aim of determining how climate and tree-line dynamics affected the productivity, community structure,
carbon cycling and light regime in the lake. Pollen and macrofossil analyses were used to determine the dates of the arrival
and retreat of birch and spruce forest. C:N ratios and percent loss-on-ignition were used to infer past changes in sediment
organic matter. Visible-near-infrared spectroscopy and diatom analysis were used to infer past changes in lake-water carbon.
Algal pigments and aquatic macrophytes were used to determine changes in lake productivity and light. Chironomids together
with remains of the aquatic flora and fauna were used to provide information on past July temperature and continentality.
Lake sedimentation was initiated shortly before 11,000 cal. years BP, when both chironomid- and pollen-inferred temperature
reconstructions suggest higher summer temperatures than present, between 1 and 2°C warmer, and lake productivity was relatively
high. A few trees were already present at this time. The spruce forest expanded at 8,000 cal. year BP remaining in the vicinity
of the lake until 3,500 cal. year BP. This period coincided with a high concentration of organic material in the water column,
and relatively high benthic productivity, as indicated by a high benthic: planktonic diatom ratio. After tree-line retreat,
the optical transparency of the lake increased, and it became more open and exposed, and was thus subject to greater water-column
mixing resulting in a higher abundance of diatom phytoplankton, especially heavily silicified Aulocoseira species. The colder climate resulted in a shorter ice-free period, the lake was less productive and there was a loss of aquatic
macrophytes. Increased wind-induced mixing following forest retreat had a greater influence on the lake ecosystem than the
effects of decreasing organic matter concentration and increased light penetration. 相似文献
15.
Javier Alcocer Alfonso Lugo Elva Escobar Malinali Sánchez 《International Journal of Salt Lake Research》1996,5(3):261-274
Totolcingo (El Carmen), a large and now episodically filled playa lake in the east-ernmost portion of the Mexican Plateau, filled with water in 1993. Water persisted for just one month (May). Alkaline (pH 10), saline (K25 up to 30,000S/cm) waters, dominated by NaHCO3 and Na2CO3, characterized the lake. The fauna was depauperate. The components of the fauna wereEphydra (Hydropyrus)hians Say (ephydrid),Limnodrilus hoffmeisteri Claparède (tubificid), andBerosus sp. (Coleoptera). The species in the lake were widely dispersed and typical inhabitants of saline lakes. Possible reasons for the depauperate fauna include (a) overall physical and chemical conditions, (b) unpredictable hydrology, and (c) the short (one month) inundation period prevented colonization. 相似文献
16.
The wreck of the Sea Venture on Bermuda reefs in 1609 initiated continuous habitation by humans on these islands. Colonization brought significant changes to the native and endemic flora of Bermuda. Original floral diversity was low, due to the effects of isolation and lack of previous anthropogenic influences. Two dominant endemic components of the flora, Bermuda cedar (Juniperus bermudiana) and Bermuda palmetto (Sabal bermudana), were extensively utilized by the colonists. Cedar was used for housing, furniture, shipbuilding and export, while the palmetto was used for roof thatch, basketry, food and drink. Exploitation of these species occurred to such extent that the General Laws of Bermuda included resolutions protecting them as early as 1622. Later, in the period between 1946 and 1951, two accidentally introduced scale insects eliminated 95% of the existing cedar population.While the flora and geography of upland habitats on Bermuda have been drastically modified by humans, the peat marsh basins have remained relatively unaffected. From the peats of one of these, Devonshire Marsh, a 9-m core was extracted for pollen analysis and to evaluate the potential for further study. The pollen record below 1.6 m indicated very little change in the native and endemic flora of Bermuda, but above that depth statistically significant changes in the relative abundances of pollen of Bermuda cedar and Bermuda palmetto are noted. Relative abundances of both species decreases significantly above this depth. This decrease is interpreted to represent the arrival of colonists and their impact on the cedar and palmetto populations. A second decrease in relative abundance of Bermuda cedar is recorded above 0.7 m. This reflects the scale infestation and decimation of the remaining cedar population. Coincident with decreases in cedar and palmetto are increases in relative abundance of Poaceae and Asteraceae, indicative of cleared land and the spread of weedy taxa. A radiocarbon date of 520±70 yr BP at a depth of 1.7 m and major changes in relative abundance of palynomorphs in proximity to the marsh surface allows their interpretation as a record of human impact on the endemic flora of Bermuda.This is the 19th in a series of papers published in this special AMQUA issue. These papers were presented at the 1994 meeting of the American Quaternary Association held 19–22 June, 1994, at the University of Minnesota, Minneapolis, Minnesota, USA. Dr Linda C. K. Shane served as guest editor for these papers. 相似文献
17.
Response of alpine chironomid communities (Lake Chuna, Kola Peninsula, northwestern Russia) to atmospheric contamination 总被引：1，自引：0，他引：1
A short sediment core from the deepest part of an alpine lake (Lake Chuna, Kola Peninsula, northwestern Russia), covering about the past 200 yrs of sediment accumulation, was analysed for chironomid head capsule remains. The lake has been receiving acidic precipitation and heavy metals loading from the atmosphere since the 1940's. A total of 22 chironomid taxa were recorded. The most important taxa were typical elements of oligotrophic lakes, i.e.Micropsectra insignilobus, Paratanytarsus penicillatus, Stictochironomus spp. and Heterotrissocladius marcidus. Based on the cluster analyses results for the reconstructed environmental variables and chironomid communities, three developmental stages were distinguished from the lake history: (1) Natural ontogeny stage (before ~1945); (2) Initial stage of anthropogenic ontogeny (~1945-~1982); and (3) Anthropogenic ontogeny stage (~1982-~1996). During the first period, the changes in the chironomid fauna were characterized as an anthropogenically undisturbed community, with M. insignilobus dominating (46-66%). The changes during the second period reflected the initial phase of anthropogenic succession associated with the beginning of acidification and heavy metal pollution. The main species showed opposite distributional patterns in this period; the abundance of the group M. insignilobus/Stictochironomus spp. decreased, whereas the abundance of P. penicillatus/H. marcidus increased. The third period was characterized by a major shift in the faunal assemblages, from M. insignilobus to other dominant species including P. penicillatus (19-30%). The increases of Orthocladiinae relative abundance and total organic content in the uppermost sediment layers may be explained by a decrease in lake productivity. The decreases of cold-stenothermal taxa Stictochironomus spp. and M. insignilobus in the uppermost sediment layers can be explained by the global warming during the 20th century. The lake ecosystem is likely to be affected by both inputs of airborne contaminants and climate changes. 相似文献
18.
为理解准噶尔盆地东南缘绿洲-荒漠交错带土壤动物群落特征,采用国际通用采样方法在2010年4月、7月、9月及11月中旬对该交错带不同生境土壤动物群落进行了调查研究,比较分析了该区土壤动物群落组成、多样性及其季节动态特征。结果表明:①共采集到大、中小型土壤动物9 788只,隶属于4门12纲32目,其中甲螨目、弹尾目、中气门目和前气门目为优势类群,常见类群有垫刃目、鞘翅目幼虫、膜翅目、无气门目、缨翅目和双翅目幼虫,优势类群和常见类群占群落总个体数的96.27%,其他22类群均属于稀有类群,只占总捕获量的3.73%。②在不同生境土壤动物群落组成、个体数量及多样性都表现出了明显的时空变异（P<0.05）,其类群数高低顺序为自然林＞防护林＞牧草地＞灌木林＞耕地＞菜瓜地＞荒草原＞荒漠,而个体数量顺序为菜瓜地＞耕地＞牧草地＞防护林＞自然林＞荒草原＞灌木林＞荒漠。③不同生境土壤动物的垂直分布具有明显的表聚特征,即从地表向下,随着土壤深度的增加土壤动物个体数量逐渐减少。④在不同生境土壤动物个体数量表现出了明显季节变化,其高低顺序为冬季＞秋季＞春季＞夏季。研究结果为进一步开展干旱区绿洲-荒漠生态系统土壤动物生态学的研究奠定了基础。 相似文献
19.
A fairly diverse and abundant diatom flora is associated with remains of Mammut americanum at the Shelton Mastodon Site in northern Oakland County, Michigan. The most abundant elements of this flora are species commonly recorded from late-glacial deposits in North America and Europe. The nearest modern analogues of this flora are assemblages deposited in small lakes in the high arctic and present day periglacial environments. Based on the diatoms present, the most probable depositional habitat was the margin of a moderately alkaline (pH>7.0) and moderately productive pond which existed under arctic conditions. 相似文献
20.
Svetislav S. Krsti? Wolfgang Zech Igor Obreht Zorica Svir?ev Slobodan B. Markovi? 《Journal of Paleolimnology》2012,47(1):113-124
This study presents changes in diatom flora assemblage composition, TOC, TOC/N and biogenic opal in a 450 cm core of Lake
Panch Pokhari, Central Nepal (4,050 m asl), indicating Late Quaternary environmental fluctuations. Four Diatom Zones (DZ) were detected, with two major changes. The first one was found in ~430 cm depth (~14.8 cal. kyr BP), where the original
flora characterized by Navicula digitulus Hustedt, Pinnularia rhombarea Krammer, P. aff. viridiformis var. minor Krammer, Encyonema silesiacum (Bleisch) D. G. Mann, Cymbopleura naviculiformis (Auerswald) Krammer and Nitzschia sp. was fully replaced by an assemblage consisting of Aulacoseira alpigena (Grunow) Krammer, Diatoma hyemalis (Roth) Heib., Tabellaria flocculosa (Ehrenberg) Kützing, Brachysira brebissonii Ross and Pinnularia subgibba Krammer, creating a stable diatom assemblage for ~8 kyr (DZ3). The second change was found at ~70 cm (~2.1 cal. kyr BP) when
increased nutrient inputs lead to emergence of new taxa such as Fragilaria construens var. subsalina Hustedt, F. tenera (W. Smith) Lange-Bertalot, Eunotia cf. pseudopapilio Lange-Bertalot and M. N?rpel-Schempp and Gomphonema subclavatum Grunow. In order to evaluate the past environmental conditions in the Lake Panch Pokhari, the detected diatom taxa were subjected
to analyses of their autecological preferences and dominance within the specific assemblage. We also assumed that TOC/N ratios
>10 indicate accelerated erosion due to the strengthening of the Summer Monsoon starting at ~14.8 and between 13.7 and 12.8 cal.
kyr BP. Monsoon intensity was most pronounced during the Early Holocene and at the beginning of the Late Holocene. The fluctuations
of TOC and TOC/N in the Late Glacial sediments seem to correlate temporally and climatically with oscillations in the Northern
Atlantic region. 相似文献