A survey of airborne algae and cyanobacteria within the indoor environment of an office building in Kuala Lumpur,Malaysia

This study investigates the occurrence of airborne algae and cyanobacteria (AAC) within the indoor environment of an office building in Kuala Lumpur, Malaysia. Samples of air, wall scrapings and soils of potted plants were collected from various sites within the building and surrounding areas. In addition, AAC were collected by exposing a culture medium to the indoor air. Based on the cultured material, 14 taxa of AAC consisting of cyanobacteria such as Phormidium angustissima and Chroococcus minor and chlorophytes such as Chlorella vulgaris and Chlorococcum humicola were recorded. The surrounding areas of the building recorded the highest occurrence (75%) of AAC. Within the building, the highest occurrence of AAC (45%) was recorded on the lower ground floor, an area exposed to the outdoor environment. Some of the AAC recorded were also detected in the wall scraping and soil samples. Areas with heavy human movement appeared to have high occurrence of AAC. Human movement appeared to be an important factor in affecting the dispersal of the AAC.     

Algal biofilms on tree bark to monitor airborne pollutants

Algae are used in biomonitoring systems to detect water or soil pollution. So it is conceivable to establish a biomonitoring system for the detection of airborne pollutants (ozone and particulate matter (PM-10)) in urban habitats by algae. Autotrophic biofilms are widely present, cover nearly every exposed surface, especially tree bark and consist of a large variety of species of algae, cyanobacteria and fungi. To explore the diversity of green algae at different air pollution monitoring sites we choose trees with different structures of bark at three locations in and near Leipzig. We compared the measured levels of air pollution with the algal species and communities present. The sites differed in the quality and amount of airborne pollutants, among which we concentrated on ozone and particulate matter (PM-10). The collection sites were Leipzig-Centre, Leipzig-West and a forest area east of Leipzig (Collmberg). Autotrophic biofilms were collected, algae cultures established and taxonomic and morphological studies were carried out with light microscopy. Green algae were present on tree bark at all sites and forty-eight different algal species and cyanobacteria were isolated. Preliminary results suggested a correlation between pollutants and occurrence of some specific algal species and the specific algal assemblages at a given site. It is concluded that this could provide the basis for a biomonitoring system involving aero-terrestrial algae for the detection of airborne pollutants. Presented at the International Symposium Biology and Taxonomy of Green Algae V, Smolenice, June 26–29, 2007, Slovakia.     

Movement patterns and habitat use of three declining littoral fish species in a north-temperate mesotrophic lake

We explored patterns of habitat use and movement of three declining fish species intolerant to eutrophication in a north-temperate (Minnesota, USA) glacial lake: the blackchin shiner Notropis heterodon, blacknose shiner Notropis heterolepis, and banded killifish Fundulus diaphanus. We marked individuals with elastomer tags and estimated movement distances of recaptured individuals. Estimated home ranges for all species ranged from 3,264 to 19,525 m², which covered 0.8 and 5.0% of our study lake’s total littoral area. Individuals of all species traveled to opposite ends of the lake over periods of time as short as 24 h. Using Geographic Information System (GIS) overlays and generalized additive models, we found fish species occurrences to be positively associated with macrophyte biovolume greater than 20% and with a high probability of occurrence of Chara. The magnitude of main and interaction effects varied among years and species. Overall, blackchin shiner occurrence was most strongly associated with biovolume. In other species by year combinations, biovolume and Chara explained varying degrees of variance in fish probability of occurrence. Our results suggest that controlling lake eutrophication and protecting of refuge areas of dense macrophytes and Chara may be needed to conserve these species.     

Keratinolytic Fungi in Egyptian Soils

The frequency of occurrence of keratinolytic fungi in seventy soil samples, collected from different sites in Upper Egypt and in the coastal area of the Mediterranean, was determined by baiting with human and animal hairs and pigeon feathers. Twenty-one species, in addition to an unidentified species, which belong to sixteen genera were collected. Chrysosporium indicum, C. tropicum, C. keratinophilum, and Microsporum gypseum were the most frequent fungal species recovered from the baited soils. The soil samples collected from the salt marshes of the coastal Mediterranean area were completely free from any keratinolytic fungi, whereas the soil samples collected from cultivated soils contributed species, ranging from one to four species.     

荒漠草原盐沼湿地苦豆子土壤细菌群落构建机制及其影响因素

【背景】荒漠草原盐沼湿地是陆地生态系统的重要组成部分,土壤水分和盐分变化是影响该生态系统土壤细菌群落构建的重要因素。【目的】土壤细菌群落构建是由确定性和随机性主导的连续生态过程,阐明荒漠草原盐沼湿地土壤细菌群落的构建机制对于加深微生物作为关键生态系统因子重要性的理解具有积极意义。【方法】以宁夏中部典型荒漠草原盐沼苦水湖湿地为研究对象,对近湖边（near the lake,NL）和远离湖边（far from the lake,FL）苦豆子群落土壤理化特性进行测定并结合土壤细菌高通量测序分析。【结果】NL和FL样地具有明显的水盐梯度变化,NL样地土壤pH、含水量和电导率均显著高于FL样地;变形菌门、放线菌门、厚壁菌门、拟杆菌门和黏菌门是研究区域土壤细菌群落的优势菌门,变形菌门相对丰度随水盐梯度上升而升高,放线菌门和厚壁菌门相对丰度则随之下降,门下成员大多与水盐变化具有明显的相关性;此外,FL样地土壤细菌网络则具有稳定的网络关系;随着NL样地向FL样地的延伸,土壤细菌群落由随机过程主导,并且受pH、电导率和环境变量的影响。【结论】荒漠草原盐沼湿地水分和盐分的变化改变了土壤细菌群落结构;土壤细菌群落通过生态位占据等策略提高逆境下的生存能力;细菌群落构建是随机过程和确定性过程组成的连续统一体,同样受环境变化的影响。本结果揭示了荒漠草原盐沼湿地细菌群落结构和相互关系对环境变化的响应特征,同时阐明了该区土壤细菌群落的构建机制及影响因素,也为相关科学研究提供了一定理论参考。     

夏季故宫养心殿空气中真菌的调查与分析

【目的】在无法实现洁净环境的古建筑内,文物易遭受霉菌的破坏,尤其是在闷热的夏季。探明空气中真菌的种类对文物、游客的安全具有重要意义。【方法】采用自然沉降法与撞击法对夏季养心殿正殿内代表性的6个取样位置的气生真菌进行培养并进行ITS1 rDNA序列分析。【结果】利用自然沉降法测得气生真菌22种,以枝孢属(Cladosporium)、曲霉属(Aspergillus)和青霉属(Penicillium)为优势类群,在2个位置(佛堂二层与西暖阁)空气真菌污染超标;而撞击法测得100余种,腐生营养型真菌比例较高,优势类群为链格孢属(Alternaria)、Cladosporium、木霉属 (Trichoderma)、根霉属(Rhizopus)、Aspergillus和Penicillium,所有6个位置均超标。通过对环境因子与真菌多样性的相关性分析发现,养心殿内真菌丰度与温度、湿度及悬浮颗粒物有着密切关系。在相对湿度较低的6月,温度对丰度影响较大;高湿度时,悬浮颗粒物与湿度对真菌丰度影响更大。丝状真菌的丰度与小粒径悬浮颗粒物、相对湿度存在显著正相关,而空气中的酵母菌与温度相关性更高。【结论】本研究对养心殿正殿空气中真菌的种属进行了鉴定,并分析了与环境因子的相关性,为预防、开放展览以及修缮提供了科学依据。     

Direct observations on the sublittoral marine algae of Argyll,Scotland

Summary The distribution with depth of sublittoral marine algae has been investigated at 11 sites on the west coast of Scotland. More than half of the species found were confined to the sublittoral zone. The greatest variety of species was found in shallow water at sites sheltered from excessive turbulence. With increasing depth the number of species found steadily decreased. There was no evidence of a specifically distinct algal flora confined to deeper water. No algae were found deeper than 36 m below ELWS at any site, but the lower limit of algal growth was reduced to 9 m in a turbid water loch and to 3 m at a site where the herbivorous echinoderm Ophiocomina nigra was abundant. Fairly distinct algal communities were found on different substrates. The major communities recognised underwater were algae attached to stable substrata, algae attached to unstable substrata and epiphytic on other algae, especially on the stipes of Laminaria hyperborea. On stable rock in areas subject to water movement L. hyperborea forest was the dominant vegetation whereas on unstable substrata and in sheltered localities L. saccharina was dominant.     

Estimation of soil algal biomass in salinized irrigation land: a comparison of culture dilution and chlorophyll a extraction methods

Two representative methods for quantitative estimation of soil algae, the culture dilution method and chlorophyll a extraction, were compared using soil samples collected from irrigation land in the flood plain of the River Ili, Kazakhstan, where the distribution of soil algae had been studied in the previous year. The estimate by the culture dilution method was almost the same as in the previous year, except for one site, which was enclosed by shrubs of sakusaul, Haloxylon aphyllum (Minkw.) Iljin. The important role of wind in transport of airborne algal cells was pointed out. There was a significant correlation (p<0.001) between the logarithm of the number of colonies by the culture dilution method andthe logarithm of the concentration of chlorophyll a, when data from all samples were analyzed. However, no significant correlation was observed with the data of cropland sites alone. Furthermore, the seasonal variations of both values at each site did not necessarily agree with each other. One reason for the inconsistency may have been the over estimation of chlorophyll a caused by inclusion of litter from vascular plants. Other reasons may relate to differences between the methodologies. The density of soil algae estimated by culture dilution reflects the algal biomass in a certain previous period of time. Therefore, it is suggested that the method is suitable for spatial, but not for seasonal studies. This revised version was published online in August 2006 with corrections to the Cover Date.     

Arbuscular mycorrhizal fungi associated with sedges on the Tibetan plateau

The arbuscular mycorrhizal (AM) status of nine dominant sedge species and the diversity of AM fungi in Tibetan grassland were surveyed in the autumn of 2003 and 2004. Most of the sedge species and ecotypes examined were mycorrhizal, but Carex moorcroftii and Kobresia pusilla were of doubtful AM status, and Kobresia humilis was facultatively mycorrhizal. This is the first report of the mycorrhizal status of eight of the nine sedge species examined. Intraradical vesicles and aseptate hyphae were the structures most frequently observed. Appressoria, coils, and arbuscules were found in the roots of a few sedge species. A strong negative correlation was found between soil organic matter content and the extent of mycorrhizal colonization. Using trap cultures, 26 species of AM fungi belonging to six genera, Glomus, Acaulospora, Paraglomus, Archaeospora, Pacispora, and Scutellospora, were isolated from the soil samples collected. The frequency of occurrence of different taxa of AM fungi varied greatly. Glomus and Acaulospora were the dominant genera, and Acaulospora scrobiculata was the most frequent and abundant species. The species richness of AM fungi was 2.73 in the study area. Species richness and diversity index differed among the sedge species but were not correlated with soil factors such as pH, available P, or organic matter content.     

Tardigrade Distribution in a Medium-sized City of Central Argentina

The distribution and abundance of tardigrades in the city of General Pico (Argentina) are analyzed from samples collected during autumn and spring 2001. Sample sites included paved urban locations with different traffic intensities, non-paved periurban places, and places with peculiar conditions such as the city industrial area and the bus station. Trees of the same species were selected in each area and from each of them nine subsamples of lichens and/or moss, 11 mm in diameter, were taken with steel corers. The diversity, density and relative abundance of tardigrades was recorded and analyzed. Sampling sites were ordinated and classified with PCA and clustering. The number total of species collected in the research was 5. The maximum number of species per site and per tree was 4. The species recorded were: Echiniscus rufoviridis, Milnesium cf. tardigradum, Ramazzottius oberhaeuseri, Macrobiotus areolatus and an undescribed species of the genus Macrobiotus. The average density was approximately 10 specimens per cm² and the maximum values reach over 50 specimens per cm². R. oberhaeuseri and M. cf. tardigradum were the most frequent species. R. oberhaeuseri dominates in periurban areas with high suspension dust and very exposed to the sun. M. cf. tardigradum dominates on paved streets with intense vehicle traffic. Results supported the hypothesis of the relationship between air quality and tardigrade diversity.     

A preliminary survey of the arbuscular mycorrhizal status of grassland plants in southern Tibet

We report for the first time the arbuscular mycorrhizal (AM) status of native plant species and AM fungal diversity in the grasslands of southern Tibet. A total of 51 soil samples were collected from the rhizospheres of the dominant plant species, and AM fungal structures were observed in 18 (82%) of 22 plant species examined. Vesicles and aseptate hyphae were the structures most frequently observed in the plant roots. After trap culture for 5 months, 25 AM fungal taxa were identified in the soil samples collected, of which nine belonged to Glomus, ten to Acaulospora, one to Entrophospora and five to Scutellospora. The frequency of occurrence of different genera and species varied greatly. Glomus was the dominant genus, and the most frequent and abundant species was Glomus mosseae. Over the whole sampling area, spore density in the rhizosphere soil of different host plant species ranged from 2 to 66 per 20 g air-dried soil. Overall AM fungal species richness was 2.10 and species diversity was 2.35. AM fungal diversity was also compared among the four different land use types (farmland and normal, disturbed and highly disturbed montane scrub grassland). Spore densities in the farmland and normal grassland were much higher than in the grasslands that had been degraded to varying degrees. The species richness in normal grassland was the highest of the four land use types examined. Species diversity varied from 1.99 to 0.94 and was highest in normal grassland, intermediate in degraded grassland and farmland, and lowest in the highly disturbed grassland.     

Keratinolytic fungi in Egyptian soils

The frequency of occurrence of keratinolytic fungi in seventy soil samples collected from different sites in Upper Egypt and in the coastal area of the Mediterranean and baited with human and animal hair and pigeon feathers was determined.Twenty-one species in addition to an unidentified species, which belong to sixteen genera were collected.Chrysosporium indicum, C. tropicum, C. keratinophilum andMicrosporum gypseum were the most frequent fungal species recovered from baited soils.The eight soil samples collected from the salt marshes of the coastal Mediterranean area were completely free from any keratinolytic fungi, whereas the sixty-two soil samples collected from cultivated soils contributed a species ranging from one to four species.     

Animal associations with the dominant species of shallow water macrophytes along the coastline of the Vestfold Hills,Antarctica

Benthic grab samples, taken through core holes in sea-ice 1983, returned eight species of marine macrophytes which had associated fauna on at least one sample. A total of 24 animal taxa were found on these eight macrophytes. Phyllophora antarctica had a significantly greater biomass of attached fauna per unit of macrophyte biomass than any of the other seven species. It also had the greatest variety of epiphytic fauna (21 taxa). Phyllophora antarctica was the only macrophyte collected from comparatively protected Ellis Fjord, apart from filamentous algae, including Cladophora subsimplex and Geminocarpus austrogeorgiae, which were found in the most landward basin. It therefore played an important role in the ecology of the fjord. Palmaria decipiens was commonly collected at more exposed coastal sites and was dominant in Long Fjord, characterized here as intermediate in terms of water movement. Sixteen animal taxa were collected from this macrophyte with the greatest numbers being found in July and August. Only four animal taxa were collected from Iridaea cordata. The other five macrophyte species from which epiphytic animals were collected (Porphyra endiviifolium, Plocamium cartilagineum, Desmarestia menziesii, Himantothallus grandifolius and Cladophora subsimplex had animals associated with them on less than half the occasions when they were found.     

Arbuscular fungi and mycorrhizae (Glomales) of the Hel Peninsula,Poland

In the years 1985–1989, the occurrence of arbuscular fungi and mycorrhizae on the Hel Peninsula (Poland) was investigated with the help of 45 soil and root samples collected under 20 plant species of eight families. Except for Zea mays, the other plant species were from uncultivated sites. All soil samples contained spores of arbuscular fungi, of which about 45% were of the genus Glomus. Acaulospora spp. preferred members of the Cupressaceae. Spores of Gigaspora occurred rarely and only in two plant families. Glomus spp. were most frequently associated with plants of the Rosaceae, and species of Scutellospora were found at markedly higher frequencies among roots of plants of the Gramineae and Cupressaceae. A total of 29 spore-forming species and Glomus tenue (a fungus recognizable by its distinctive infections) were found. The most frequently recovered fungus, Glomus tenue, was present in roots of 56.8% of examined plants. Of the spore-forming fungi, the most frequently isolated spores were those of Scutellospora dipurpurascens, then Glomus constrictum, Acaulospora 61, and Glomus microcarpum. The overall spore density in examined samples averaged 99.8 in 100 g dry soil in the range 1 to 547, and was highest in a sample taken from around roots of Festuca arundinacea. The dominant fungi forming spores in sampled soils were Glomus constrictum, Glomus microcarpum, and Scutellospora dipurpurascens. The average species density was 3.9 in 100 g dry soil in the range 1 to 10, and was highest in Corynephorus canescens, Rosa canina, and Thuja occidentalis. Levels of colonization by arbuscular fungi ranged from 0.0 to94.0% (mean 23.3%) of the root length and were highest in Festuca arundinaceae and Zea mays.     

林火对植物根围丛枝菌根真菌多样性的影响

林火是森林生态系统的一种主要干扰因子,以青岛市三标山林火迹地为研究对象,采集荆条(Vitex negundo)、胡枝子(Lespedeza bicolor)、花木蓝(Indigofera kirilowii)、青花椒(Zanthoxylum schinifolium)和野青茅(Deyeuxia arundinacea)5种优势植物根围土壤,研究不同林火强度对丛枝菌根(AM)真菌多样性的影响。结果表明,AM真菌侵染率和孢子密度随火灾强度的加强而降低;非过火区植物根围土壤中,分离鉴定出AM真菌3属11种,轻度过火区分离鉴定出AM真菌3属10种,中度过火区分离鉴定出AM真菌3属9种,重度过火区分离鉴定出AM真菌3属8种。过火区AM真菌种丰度低于非过火区。过火区和非过火区AM真菌的重要值和优势种不同,非过火区植物根围的优势种是地球囊霉(Glomus geosporum)、台湾球囊霉(G.taiwanensis)、分支巨孢囊霉(Gigaspora ramisporophora)、极大巨孢囊霉(Gi.gigantean)、福摩萨球囊霉(G.formosanum)、悬钩子球囊霉(G.rubiforme)、柯氏无梗囊霉(Acaulospora koskei)和松蜜无梗囊霉(A.thomii);轻度过火区植物根围的优势种是地球囊霉和台湾球囊霉;中度过火区的是台湾球囊霉和地球囊霉(野青茅除外);重度过火区植物根围的优势种是地球囊霉。不同强度的过火区对AM真菌群落组成有不同程度的影响。认为林火降低植物根围土壤中AM真菌多样性。     

Can macrophytes be useful in biomanipulation of lakes? The Lake Zwemlust example

Lake Zwemlust (area 1.5 ha, Z_m 1.5 m) has been the object of an extensive limnological study since its biomanipulation involving removal of planktivorous fish (bream) in March 1987 and emptying of the lake. In the subsequent summer period of 1987 the Secchi depth increased to the lake bottom (2.5 m), compared withca 30 cm in the earlier summers. The reaction of submerged macrophytes to improving under-water light climate was rapid. In summer 1987, besides the introducedChara globularis, 5 species of submerged macrophytes occurred and colonized 10% of the lake area. In 1988 and 1989 only quantitative changes were observed; new species did not appear, but the area colonized by macrophytes increased by 7 and 10 times, respectively.Elodea nuttallii was dominant among the macrophytes andMougeotia sp. among the filamentous green algae. Their abundance, contributed to transient N-limination of phytoplankton causing a persistent clear water phase in 1988 and 1989, unlike in 1987 when zooplankton grazing contributed chiefly to the water clarity. Laboratory bioassays on macrophytes confirmed nitrogen limitation.     

Culturable Airborne Bacteria in Outdoor Environments in Beijing,China

Airborne bacteria are important biological components of bioaerosol and play an important role in ecosystem. Bacteria at a high concentration in the atmosphere can result in biological air pollution and all kinds of diseases. In this study, a systematical survey on the culturable airborne bacteria was carried out for 1 year at three sites in Beijing urban area. Results showed that concentrations of culturable bacteria ranged from 71 colony forming units (CFU)/m³ to 22,100 CFU/m³, and the mean was 2,217 CFU/m³. Bacterial concentrations at the human activity-enriched site (RCEES) and the highly trafficked site (XZM) were virtually the same point. They were significantly higher than those at the greener site (BBG). Significant variation in bacterial concentrations in different seasons was observed at RCEES and XZM with higher concentrations in summer and autumn. In a single day, significantly lower concentrations were detected at 13:00 hours through all sampling sites. In this study, 165 species in 47 genera of culturable bacteria were identified. Micrococcus was one of the most dominant bacterial groups and contributed to approximately 20∼30% of the total bacterial concentration, followed by Staphylococcus, Bacillus, Corynebacterium, and Pseudomonas. The bacterial species with a high concentration percentage included Micrococcus luteus and Micrococcus roseus.     

Relation between nematode communities and trophic state in southern Swedish lakes

The aim of this study was to examine whether littoral nematode community patterns are shaped by lake trophic state. It was hypothesized that trophic level is associated negatively with the proportion of omnivores and positively with the percentages of bacterial feeders, but not at all with the diversity, abundance, and biomass of freshwater nematodes. Sediment samples were taken at littoral sites of eight southern Swedish lakes of different trophy in spring and autumn 2007. Trophic level was found to strongly influence species richness, as oligotrophic and mesotrophic lakes supported the greatest species numbers, whereas nematode abundance, biomass, and Shannon index were unaffected. Furthermore, our results indicated effects on the nematode community’s trophic structure, with a larger proportion of predatory nematodes in oligotrophic and mesotrophic lakes but no differences in the other feeding types (bacteria, algae and suction feeders, omnivorous species). Multivariate analysis indicated a shift in species compositions along the threshold from mesotrophic to eutrophic conditions, with the presence of Tobrilus gracilis, Monhystera paludicola, Brevitobrilus stefanskii, and Ethmolaimus pratensis related to the latter. Nematode communities in oligotrophic and mesotrophic lakes were characterized by a similar species composition, with pronounced occurrences of Eumonhystera longicaudatula, Semitobrilus cf. pellucidus, Prodesmodora circulata, and Rhabdolaimus terrestris. Overall, the results suggested that lake trophic state is a major factor structuring littoral nematode communities, although intra-lake variations might be of importance as well.     

乐安河—鄱阳湖湿地植物群落特征及其优势植物对重金属Cu、Pb、Cd的富集

选择乐安河—鄱阳湖湿地典型植物群落,采用重要值方法评价各样点植物群落特征并筛选出典型优势植物,通过室内理化测试分析不同生境中优势植物植株及其根区土壤中重金属Cu、Pb、Cd的含量;采用生物富集系数(BCF)方法评价不同优势植物对重金属Cu、Pb、Cd的富集特性。结果表明:研究区湿地植物以草本为主,在各样点共发现124种物种,包括蕨类植物2科2属2种,种子植物40科97属122种,并从中筛选出羊蹄、红蓼、鼠曲草、紫云英、苎麻等5种富集能力较强的优势植物;植物根区土壤中的Cu、Cd含量均超过土壤环境质量三级标准,而且Cu、Cd的最高含量分别为824.03、5.03 mg·kg-1;不同优势植物对Cu、Pb、Cd等3种重金属元素中的1种或2种表现出较强的富集能力,其中优势物种红蓼对Cu具有较强的富集能力,含Cu量最高为148.80 mg·kg-1,另一种优势物种鼠曲草对三种元素的生物富集系数均较高,且对Cd的最高富集含量为15.17 mg·kg-1,对Cd的生物富集系数最高值为19.14,高于其他植物10倍以上,鼠曲草对重金属Cd具有富集植物的基本特征,且对Cu和Cd具有共富集特征并具有较高的耐性,紫云英、羊蹄等对Cd的富集能力也较强。上述5种优势植物种群对鄱阳湖湿地Cu、Pb、Cd等重金属污染物的生态修复具有一定参考价值,可作为鄱阳湖湿地重金属污染修复植物的选择对象。     

Bloom formation of Gloeotrichia echinulata and Aphanizomenon flos-aquae in a shallow,eutrophic, Danish lake

Over a period of four years, the seasonal periodicity of dominant phytoplankton species in a shallow, eutrophic Danish lake changed markedly. Cyanophytes prevailed during the summer period of all four years. In the first three years, species of Microcystis, Anabaena and Aphanothece dominated, whereas in the fourth year of investigation, these algae were replaced by Gloeotrichia echinulata (J. E. Smith) Richter and Aphanizomenon flos-aquae (L.) Ralfs. The most striking environmental differences in the fourth year as compared with the previous three years, were an increase in tranparency, from about 0.5 meter in 1989–1991 to more than 2 metres preceding the summer maximum in 1992, and a simultaneous occurrence of low oxygen concentrations. A collapse of the fish population was followed by an increased proportion of large Cladocerans in the zooplankton. Improved light conditions at the bottom and grazing pressure from large Cladocerans favoured growth of the large colony forming blue-green algae, Gloeotrichia echinulata and Aphanizomenon flos-aquae. These species germinate from resting spores in the sediment and are able to sustain some growth there before migration to the lake water. The transfer of algal biomass from the bottom sediment to the water phase was accompanied by a marked increase in concentrations of particulate phosphorus and nitrogen in the entire lake.