Aquatic insects associated with two morphologically different submerged macrophytes, <Emphasis Type="Italic">Lagarosiphon ilicifolius</Emphasis> and <Emphasis Type="Italic">Vallisneria aethiopica</Emphasis>, in small fishless ponds

The study assessed the composition and abundance of insect assemblages associated with two submerged macrophytes, Lagarosiphon ilicifolius and Vallisneria aethiopica, in fishless ponds. Six ponds were used, with each plant occurring singly in two ponds, whilst the remainder had both plants. The insects were sampled using a 500-μm mesh. The number of insect taxa, diversity and total abundance on Lagarosiphon were greater than on Vallisneria when the plants occurred in separate ponds. In ponds comprising both plants, the total insect abundance on Lagarosiphon was greater than on Vallisneria. In all ponds, anisopteran naiads were dominant. Hemicordulia, Diplacodes and Trithemis made up 36.2, 27.1 and 15.2%, respectively, of the total number of insects on Lagarosiphon in single plant ponds. Trithemis was the only odonate in ponds comprised exclusively of Vallisneria and made up 68.7% of insects. In ponds that were cultured with both plants, four anisopteran taxa, Hemicordulia, Diplacodes, Trithemis and Tramea, were collected. In single plant ponds, the body-size class distribution of naiads on Lagarosiphon was characterised by a broader range, with significantly greater numbers of smaller and larger size classes than on Vallisneria (Kolmogorov–Smirnov test, P < 0.05). The study shows that in fishless waters, epiphytic insect assemblages may differ between the two plant species, especially when they are widely separated in space, probably due to greater predator–prey interactions on Vallisneria than on Lagarosiphon. The two plants may also differentially affect water physicochemical conditions, which may possibly influence insect ovipositing behaviour, and so affect insect community assemblage.     

The effect of plant density on epiphytic macroinvertebrates associated with a submerged macrophyte,Lagarosiphon ilicifolius Obermeyer,in Lake Kariba,Zimbabwe

The effect of variations in the density of a submerged macrophyte, Lagarosiphon ilicifolius, on epiphytic macroinvertebrate community structure in the shallow waters of a sheltered bay of Lake Kariba were investigated. The body size class distributions of a mayfly, Cloeon (Ephemeroptera: Baetidae), and the damselfly family, Coenagrionidae, were also assessed with respect to variation in vegetation density. Macroinvertebrates were sampled from low-, moderate- and high-density beds of L. ilicifolius. There were no significant differences in individual taxon and total macroinvertebrate abundances, macroinvertebrate richness and diversity with respect to vegetation density. In all three density categories the functional feeding group (FFG) composition was dominated by collector-gatherers and collector-filterers. The abundance of the two FFGs did not change significantly within each, as well as among, the three vegetation-density categories (ANOVA, p > 0.05). The largest size class of Cloeon occurred only in high-density beds, whereas the largest coenagrionid individuals were obtained from low- and moderate-density beds and were absent from high-density beds. The results suggest that variation in the density of Lagarosiphon does not affect epiphytic macroinvertebrate community structure, but does affect body-size distributions of macroinvertebrate taxa, probably by affecting predator-prey interactions.     

Aquatic macrophytes, macroinvertebrate associations and water levels in a lowland Tasmanian river

Aquatic macrophytes are a common habitat for macroinvertebrates and may occupy depth zones in the littoral region of lowland rivers. Studies have indicated that different species of macrophyte typically support different assemblages, abundances and numbers of species of macroinvertebrates. This has often been attributed to differences in the dissectedness of stems and leaves of the macrophytes, resulting in differences in the surface area and/or the number of microhabitats available to invertebrates. I set out to measure the abundance and taxonomic richness and to describe the macroinvertebrate assemblages associated with three species of aquatic macrophyte in a pool in the Macquarie River, Tasmania and to examine responses of these variables to changes in water levels over summer. The macrophyte species sampled wereMyriophyllum simulans/variifolium, Triglochin procera} and Eleocharis sphacelata, each one differing in the dissectedness of its stems and leaves and its location in the littoral zone. Whereas the greatest abundance of macroinvertebrates was found associated in all months (i.e. at all water levels) with the structurally complex and shallowest macrophyte species, Myriophyllum, the number of taxa associated with this species was in several cases lower than for the structurally simpler and deeper water Triglochin and Eleocharis. While water depth and total plant biomass of samples were often correlated with invertebrate abundance and richness, these relationships were different for each macrophyte species. Of the nine most common invertebrate taxa collected from all samples, the abundances of more than half showed consistent differences among macrophyte species across months, two showed differences among macrophytes, but with an interaction with month and two showed no differences among macrophytes. There were major differences in the invertebrate assemblages associated with each macrophyte species in any one month, however, there was also a large turnover of taxa associated with the species of macrophytes from one month to the next. Changes in water level and concomitant changes in environmental variables are suggested as factors influencing the invertebrate fauna in the littoral zone of the pool of the Macquarie River. It is thus important for river managers to be aware that species of macroinvertebrates are not evenly distributed across species of macrophyte and that water levels and their influence on macrophytes as invertebrate habitat may play an integral part in determining the abundance, richness and assemblage of invertebrates in rivers.     

A primary study on relationships between subfossil chironomids and the distribution of aquatic macrophytes in three lowland floodplain lakes,China

Aquatic macrophytes act as an important substrate for zoobenthos-supporting midge communities (chironomids) that can be used for reconstructing past environmental change. This study selected three macrophyte-dominated lakes in the middle reach of the Yangtze floodplain (central China), to identify relationships between macrophyte characteristics (i.e. communities, richness and biomass) and subfossil chironomid assemblages. One-way ANOSIM tests illustrated that there were significant differences in chironomid community compositions between lakes. Most chironomid taxa were not selective of dominant macrophyte species, but Corynoneura species were found to be associated with the development of Vallisneria as revealed by SIMPER analysis. Multivariate analyses indicate that submerged plant biomass, water depth and secchi depth, conductivity and the concentration of HCO₃ ^? were significantly correlated with midge compositions. Overall, this study corroborates the existing opinions that chironomid species show little selectivity to plant type but are significantly influenced by plant density. As an exception to this general trend, we found strong associations between Corynoneura chironomid larvae and Vallisneria macrophytes, prompting the need for future experimental studies to confirm this association.     

Environmental gradients determining the distribution of benthic macroinvertebrates in Lake Takkobu, Kushiro wetland, northern Japan

Effects of environmental variables on the distribution of benthic macroinvertebrates inhabiting sediments were studied at 25 sites along the shoreline of Lake Takkobu in the Kushiro wetland of northern Japan in summer 2003. During the last decade, the lake’s status has undergone a drastic shift from clear water dominated by submerged macrophytes to turbid water dominated by phytoplankton. The canonical correspondence analysis showed that four environmental variables explained the significant variation in the macroinvertebrate species composition: submerged plant biomass, bottom sediment organic matter content (OMC), distance from the mouth of the Takkobu River, and bottom-layer pH. Five species of Chironomidae [Chironomus sp. (except plumosus group), Psectrocladius sp., Corynoneura sp., Parachironomus sp. arcuatus group, and Zavreliella sp.] occurred in sites with relatively lower pH and a high submerged plant biomass, whereas three species of Tubificidae (Tubifex tubifex, Aulodrilus limnobius and Aulodrilus sp.) and two of Chironomidae (Nanocladius sp. and Monodiamesa sp.) occurred in sites with high pH and little vegetation. The three Tubificidae species also preferred organic-rich sediments. Irrespective of aquatic vegetation, Sphaerium sp. (Bivalvia) and Monodiamesa sp. (Chironomidae) occurred in low-OMC sites, whereas Tanypus sp. (Chironomidae) preferred high-OMC sites. The number of macroinvertebrate taxa showed the highest correlation with the number of submerged plants, suggesting that macroinvertebrate species richness was related mostly to submerged plant species diversity in this lake. The quantity and species richness of submerged plants and OMC are thus important determinants of the community structure of macroinvertebrates inhabiting sediments in Lake Takkobu.     

Redescription of Vorticella oceanica Zacharias, 1906 (Ciliophora: Peritrichia) with notes on its host, the marine planktonic diatom Chaetoceros coarctatum Lauder,1864

The late-spring quantitative relationship between epiphyton and macroinvertebrates was analyzed on the basis of units of colonizable plant surface of Typha angustifolia, Phragmites australis and Nuphar lutea (floating leaves) in the shallow euthrophic Lake Loosdrecht (the Netherlands), with a high seston load. The non-predatory chironomid larvae (Glyptotendipes viridis, Endochironomus albipennis, Pentapedilum sordens, Cricotopus sylvestris agg.) dominated among the macroinvertebrate taxa, controlling the diversity and resemblance of macroinvertebrate assemblages. There was a gradient in functional feeding groups among the chironomids from continuous filtering of the seston to prevailing utilization of epiphyton. We found no direct relationship between the total macroinvertebrate abundance and the epiphyton mass on the plants surface. We attribute this to the filter feeding-strategy of the most abundant species, Glyptotendipes viridis, that utilizes seston in the eutrophicated lake.     

Macroinvertebrates associated with submerged macrophytes: sample size and power to detect effects

When planning and conducting ecological experiments, it is important to consider how many samples are necessary to detect differences among treatments with acceptably high statistical power. An analysis of statistical power is especially important when studying epiphytic macroinvertebrate colonization of submerged plants because they exhibit large plant-to-plant variability. Despite this variability, many studies have suggested that epiphytic macroinvertebrates preferentially colonize plants based on plant architecture type (broad versus dissected leaves). In this study, we calculated the power and number of samples necessary to detect differences in epiphytic macroinvertebrate abundance (numbers and biomass) among five species and two architecture types of macrophytes in a lake in MI, U.S.A. Using power analysis, we found that we had very high power to detect the differences present between macroinvertebrate abundance by architecture type and by macrophyte species (power = 1.000 and 0.994; effect sizes = 0.872 and 0.646, respectively. However, to detect very small differences between the two architecture types and the five plant species, we determined that many more samples were necessary to achieve similar statistical power (effect size = 0.1–0.3, number of samples = 60–527 and 36–310, respectively; power = 0.9). Our results suggest that macroinvertebrate abundance does in fact vary predictably with plant architecture. Dissected-leaf plants harbored higher abundances of macroinvertebrates than broad-leaf plants (ANOVA, density p = 0.001, biomass p < 0.001). This knowledge should allow us to better design future studies of epiphytic macroinvertebrates.     

Benthic macroinvertebrates associated with four species of macrophytes

Benthic macroinvertebrates associated with four species of macrophytes (Nymphoides peltata, Ceratophyllum demersum, Polygonum amphibium and Carex sp.) were investigated during two growing seasons (2001 and 2002) in the slow-flowing Čonakut Channel in the Kopački rit Nature Park in Croatia. A total of 31 macroinvertebrate taxa were found. C. demersum, a submerged plant with dissected leaves, supported the highest macroinvertebrate abundance, almost seven times more than N. peltata, a floating plant with undissected leaves, which harboured the lowest abundance during the research period. Chironomidae larvae (50–83%) and Oligochaeta (14–46%) were the most abundant groups recorded on all macrophyte species. Water-level fluctuation, because of its influence on the appearance and growth of aquatic vegetation, and the trophic state of water within the macrophyte stands seemed to be the main factors which affected the taxonomic composition and abundance of macroinvertebrates.     

The influence of large water level fluctuations and hurricanes on periphyton and associated nutrient storage in subtropical Lake Okeechobee,USA

The abundance, community structure and nutrient content of periphyton, and the host plant taxa Chara, Hydrilla, Potamogeton, Vallisneria and Scirpus were studied in Lake Okeechobee, USA. Water levels were generally high during the study period (August 2002–January 2006), but substantial fluctuations occurred. All host plant biomass was seasonally variable but only Vallisneria biomass was spatially variable. All submerged plant beds disappeared after the passage of two hurricanes in September 2004, and a third hurricane passed over the lake in October 2005. Periphyton assemblages were statistically separated most by substrate and then by season. Prior to the hurricanes, annual maxima of periphyton biovolumes and those of summer submerged plant coverage coincided. During all study years, the diatom taxa dominated periphyton total biovolumes. Periphyton biomass was generally highest during the summer or prior to the hurricanes (in the case of epiphytes) and was spatially variable in the case of both Scirpus and Vallisneria. Epiphytic nutrient contents within each host plant group seasonally varied except for nitrogen and carbon in the Vallisneria epiphytes. Epipelic nutrient contents were spatially variable and seasonally variable for carbon. Nutrient contents in epipelon were significantly higher than that in Scirpus epiphytes and were similar but lower among all epiphytic communities. The total annual areal potential epiphytic phosphorus storage extrapolated during this study (2.0 × 10⁻⁴ metric tons ha⁻¹ year⁻¹) was underestimated because storage estimates for epipelon, Chara and Hydrilla-associated epiphytes were omitted. The Chara and Hydrilla-associated epiphytic nutrient storage values were omitted because of limited data, whereas the epipelic data may have not been spatially representative. For periphyton biovolume, host substrate type, water level fluctuation and hurricane impacts on host substrates appear to be more important than seasonal variation in such factors as temperature and nutrients. Epiphytic nutrient storage appears to be influenced most by water level fluctuation and hurricane-related impacts, while the host substrate type appears to be a less important factor than it is for periphyton biovolume. Maximum periphyton biomass and high nutrient storage in shallow subtropical and tropical eutrophic lakes may only occur at consistently lower water levels and during infrequent periods of disturbance, which enhance host substrate colonizable area.     

Taxonomic and size structures of phytophilous macroinvertebrate communities in Vallisneria and Trapa beds of the Hudson River, New York

Phytophilous macroinvertebrates (PMI) were sampled from the surfaces and surrounding water of two aquatic plant species, Vallisneria americana and Trapa natans, which have substantially different morphologies. It was expected that the plants would harbor invertebrate communities of different structure. Total density of PMI was consistently greater in Vallisneria than inTrapa, e.g. 6× greater per m³ water and 21× greater per m² leaf surface in August. Each macrophyte harbored taxa that were either significantly more abundant or present only with that macrophyte; the herbivore Galerucella nymphaceae (Coleptera: Chrysomelidae) was abundant on Trapa. Vallisneria harbored 34 taxa vs. 40 taxa in Trapa, but similarity was low (Morisita's C=0.55–0.66). Predaceous invertebrates were more prevalent in Trapa than in Vallisneria, as were larger individuals. Both PMI communities exhibited shifts in size distribution between July and August. Standing crop of Trapa was 3× greater than forVallisneria. These two macrophyte beds clearly support PMI communities of different taxonomic and size structure, which is believed to be related to the differences in macrophyte morphology.     

The effect of turbidity state and microhabitat on macroinvertebrate assemblages: a pilot study of six shallow lakes

Shallow lakes can occur in two alternative stable states, a clear-water state and a turbid state. This is associated with separate assemblages of fish, zooplankton and plants. Little is known about whether macroinvertebrate assemblages differ across both stable states. This study investigated this in a connected set of three turbid and three clear-water shallow lakes. To overcome confounding effects of differences in spatial structure of macrophytes in turbid and clear-water lakes, we sampled three microhabitats that occurred in both alternative stable states: open water, sago pondweed (Potamogeton pectinatus) and reed (Phragmites australis). Univariate analyses indicated no differences in the number of organisms, taxon richness or diversity between turbid and clear-water lakes. Multivariate analysis, however, showed significant differences in the macroinvertebrate community structure of both stable states. Nine taxa explained a significant amount of the variation between both lake types, of which seven preferred the clear-water lakes. The number of organisms and the taxon richness were higher in reed than in the other microhabitats, but diversity and evenness did not differ among the microhabitats. Multivariate analyses could separate all three microhabitats. Eight taxa, mainly detritus feeders and collector–gatherers, explained most of the variation in the data and preferred the reed microhabitat. The effects of stable state (6.8% explained variance) and microhabitat (13.1% explained variance) on the macroinvertebrate assemblages were largely independent from each other (1.5% shared variance). Although macroinvertebrates are not implemented in the initial theory of stable states, our results show clearly different assemblages across both stable states.     

Zonation of submerged macrophyte vegetation in Lake Kariba,Zimbabwe and its ecological interpretation

The submerged vegetation of Lake Kariba is described in relation to degree of slope (lake morphometry), depth and light transparency. The direct gradient analysis technique — canonical correspondence analysis and the TWINSPAN classification programs were used to analyse the data set. The western end of the lake with low transparency has a low species diversity (with Vallisneria aethiopica dominating). Species diversity increases with increased transparency in the other parts of the lake. The classification revealed monospecific communities for all species as well as mixed communities with Lagarosiphon as the associate species with the broadest distribution. The ordination revealed a first axis strongly related to depth and transparency gradients and the second axis related to slope. Vallisneria aethiopica has a growth form adapted to grow in shallow areas subjected to wave action. Potamogeton octandrus also growing in shallow areas is restricted to sheltered areas. Lagarosiphon ilicifolius precluded from the shallow exposed areas grows at medium depth but has a growth form adapted to tap light at the surface. Najas pectinata and Ceratophyllum demersum are adapted to grow in deep water.Abbreviations CCA Canonical correspondence analysis     

Biodiversity and Structure of Macroinvertebrate Communities Along a Small Permanent Salinity Gradient (Meurthe River,France)

Changes in the macroinvertebrate community were investigated over 10 months at four sites along a 19 km salinity gradient (0.21–2.60 g l⁻¹) in a sixth-order stream, the Meurthe River, northeastern France. Abiotic characteristics other than salinity were similar between the sites. Macroinvertebrate taxonomic richness decreased by 30% downstream of the 1.4 g l⁻¹ sites while diversity, evenness or total abundance of taxa did not change along the gradient. In terms of functioning, a slight change in relative abundances of invertebrate feeding groups followed the salinity gradient. Eight invertebrate assemblages occurred within specific salinity distributions were identified. The exotics Gammarus tigrinus, Dreissena polymorpha, Corbicula fluminalis and Corophium curvispinum, were more abundant at the highest salinity site. These results suggest that rising salinity concentrations drastically affect the species composition, including favouring exotic species.     

Inferring past zooplanktivorous fish and macrophyte density in a shallow lake: application of a new regression tree model

1. Eutrophication has a profound effect on the biological structure and function of shallow lakes, altering the composition and abundance of submerged macrophyte and fish assemblages. Relatively little is known, however, about decadal to centennial‐scale change in these important aspects of shallow lake ecology. 2. Established palaeolimnological inference models are limited to reconstructing a single variable. As macrophyte and zooplanktivorous fish abundance exert dual and interacting controls on cladoceran assemblages a single variable inference model may contain significant error. To obviate this problem, we applied a new cladoceran‐based multivariate regression tree (MRT) model to cladoceran subfossil assemblages from dated cores from a small shallow lake (Felbrigg Lake, U.K.) to assess long‐term change in fish and submerged macrophyte abundance. Plant macrofossil, chironomid and mollusc subfossil assemblages were also analysed to track changes in biological structure and function and to evaluate the inferences of the MRT model. 3. Over the 200+ year period covered by the sediment cores, there was good agreement in the timing and nature of ecological change reflected by the plant macrofossil, mollusc, chironomid and cladoceran data. The sediment sequence was divided into three dated zones: c. 1797–1890, c. 1890–1954 and c. 1954–present. Prior to 1890 plant‐associated mollusc, cladoceran and chironomid assemblages indicated a species‐rich macrophyte community; a scenario confirmed by the plant macrofossil data. From c. 1890 to 1954 macrophyte‐associated species of all three invertebrate groups remained abundant but the proportion of pelagic cladocerans rose. Post‐1954 mollusc and chironomid assemblages changed to sediment associated detrital feeders and the proportion of pelagic cladoceran taxa increased further. 4. The cladoceran‐based MRT model indicated a long period of stability, c. 1790–1927, characterised by abundant submerged macrophytes and zooplanktivorous fish. From c. 1927 to 1980, the MRT model inferred a decline in zooplanktivorous fish density (ZF) but relative stability in August macrophyte abundance. From 1980 to 2000, an increase in zooplanktivorous fish was inferred tallying well with available data on the fish population (since the 1970s), which indicated extirpation of perch in the 1970s and a subsequent increase in the rudd population. The model inferred little change in August macrophyte abundance until post‐c. 1980 at which point it indicated a decline. The surface sediment assemblage was placed in MRT group A, where submerged plants are absent or very rare in late summer in good agreement with current conditions at the site. 5. The MRT model, applied here for the first time, appears to have successfully tracked changes in macrophyte abundance and ZF over the last 200 years at Felbrigg Lake. The inferences agreed with historical observations on the fish community and the supporting palaeolimnological data. Given that multiple structuring forces shape most biological communities, the application of a model capable of allowing for this represents a significant advance in palaeolimnology.     

Effects of elevated turbidity on shallow lake fish communities

Synopsis We compared the fish communities of two shallow lakes in the lower Waikato River basin, North Island, New Zealand, to determine the effects of elevated suspended solids (SS) and collapse of submerged macrophytes. Lake Waahi was turbid (20–40 g m^-3 SS) and devoid of submerged macrophytes whereas Lake Whangape was clearer (5 g m^-3 SS) and dominated by submerged macrophytes. The lakes had similar fish species richness and had nine major species in common; representing eight families including Anguillidae, Retropinnidae, Galaxiidae, Eleotridae, Mugilidae, Ictaluridae, Poeciliidae, and Cyprinidae (two species). The only major fish that was absent from Lake Waahi was a lacustrine form of the common smelt, Retropinna retropinna, which disappeared after the lake became turbid in the late 1970s. CPUE, condition, and size of most species in Lake Waahi were similar to, or greater than, those in Lake Whangape. Lake Whangape clearly exceeded Lake Waahi only for CPUE of two species. Within Lake Whangape two species displayed significantly greater condition, and one species greater size, in a turbid arm of the lake than in the main basin. Apart from lacustrine Retropinna retropinna, the fish in these lakes appear well adapted to cope with, or to avoid, the direct toxic effects of suspended and settleable solids on sensitive early developmental stages. In Lake Waahi loss of cover and food provided by submerged macrophytes appears to have been compensated for by increased turbidity and an associated increase in the biomass of the mysid, Tenagomysis chiltoni (a major prey item).     

3种种植方式下沉水植物恢复效果研究

恢复沉水植物是受污染水体生态修复与重建的有效措施之一,人工快速大面积恢复沉水植物的方法是关键。选取杭州西湖西进区域茅家埠和浴鹄湾近岸水域,分别采用扦插法、沉栽法和播种法对沉水植物菹草、苦草和黑藻进行种植。研究表明：运用沉栽法种植的菹草存活率比用播种法种植的存活率高71.1%;运用扦插法种植的苦草比沉栽法和播种法的存活率分别高84.3%和87.8%;运用扦插法种植的黑藻比用播种法种植的存活率高69%;3种种植方式下最终的单株植物生物量间无显著差异。     

Macroinvertebrate communities in Phragmites australis (Cav.) Trin. ex Steud. reed beds and open bank habitats in central victorian streams in Australia

Reed invasion is a common phenomenon of open streams with disturbed riparian vegetation in river catchments. Knowledge of the effects of such vegetation change on aquatic communities is fundamental to river management. Macroinvertebrate fauna in Phragmites australis (Cav.) Trin. ex Steud. and open bank habitats were examined in three rivers in central Victoria in order to understand the effect of such littoral habitat on macroinvertebrates. Data were analysed using Partially Nested Factorial ANOVA with season, river and habitats as main effects. Habitat structure had a significant effect (p<0.05) on macroinvertebrate species richness, however this was not seasonally consistent across the three rivers. There was a significant increase (p<0.05) in macroinvertebrate taxa richness in Phragmites habitats during winter and spring seasons. Total abundance of taxa showed no consistent significant differences in the two habitats. Results of Canonical Analysis of Principle Coordinates indicated significant differences (p<0.05) in macroinvertebrate assemblages between Phragmites and bare bank habitats in all seasons. Habitat selection by taxa could be related to the microphysical environment of the habitats. This study suggests that reed beds create important littoral habitat structures which support diverse macroinvertebrate assemblages.     

高邮湖大型底栖动物群落结构及影响因素

跨流域调水工程沿线调蓄湖泊生态状况直接决定工程能否顺利实施。基于2018年4和9月高邮湖底栖动物调查数据,对底栖动物区系组成、群落结构及主要影响因子进行了研究。调查期间共鉴定出底栖动物42种,隶属3门7纲22科;软铗小摇蚊（Microchironomus tener）、霍甫水丝蚓（Limnodrilus hoffmeisteri）、齿吻沙蚕（Nephtys sp.）、苏氏尾鳃蚓（Branchiura sowerbyi）、厚唇嫩丝蚓（Teneridrilus mastix）为调查期间优势物种,相对丰度分别为24.0%、17.7%、8.1%、7.2%和6.5%;两次调查期间底栖动物优势物种组成存在较大差异。密度、物种丰度、香浓指数在4月份显著高于9月份;非度量多维标度排序（NMDS）和多响应置换过程（MRPP）从群落层面证实了两次调查期间底栖动物群落结构的差异性。指示物种分析表明,软铗小摇蚊、霍甫水丝蚓和有栉管水蚓（Aulodrilus pectinatus）是造成两次调查底栖动物群落差异的关键物种。基于距离的冗余分析（dbRDA）表明,高邮湖底栖动物群落在4月份主要受硅酸盐和总磷影响;9月份主要受水深和叶绿素a影响。     

Composition of aquatic invertebrates associated with macrophytes in Lake Tonle Sap,Cambodia

Faunal composition of aquatic invertebrate communities associated with submerged parts of several species of macrophytes were studied in different areas in littoral Lake Tonle Sap in Cambodia, with special reference to those in root systems (interrhizon) of a free-floating water hyacinth (Eichhornia crassipes). Nine phyla of invertebrates were collected, of which oligochaetes, shrimps and Limnoperna mussels were abundant along with meiobenthic crustaceans. The macrophyte-associated invertebrates in Lake Tonle Sap might be unique in having abundant sessile animals, such as sponges, bryozoans and Limnoperna mussels. The Limnoperna mussels attached to macrophytes were more abundant in offshore and inundated forest than in secluded vegetational stands toward the shoreline. It suggests that water movement can be an important factor determining the distribution and abundance of the sessile animals by controlling larval dispersions and might be associated with the hydrological characteristic of the lake, i.e., the lake opens to the large Mekong River with drastic seasonal changes in water level.     

Diet composition and prey preference of tench, Tinca tinca (L.), common bream, Abramis brama (L.), perch, Perca fluviatilis L. and roach, Rutilus rutilus (L.), in two contrasting gravel pit lakes: potential trophic overlap with wildfowl

The abundance of benthic macroinvertebrate taxa and the relative abundance of zooplankton taxa were compared with the diet of bream, tench. perch and roach from two gravel pit lakes during May-July 1986 and 1987. Significant food preferences were demonstrated between species and between lakes. Chironomid pupae dominated the macroinvertebrate diet of perch, roach, ate predominantly either Spirogyra sp. (St Peters Lake) or Daphniu hyalina (Main Lake).
The Main Lake, bream fed largely upon chironomid larvae and the bivalve Sphuerium but in St Peters Lake they positively selected a variety of less abundant benthic invertebrate taxa. Bream switched from benthos to zooplankton in the Main Lake in 1986. Tench ate large numbers of Aselhs and showed positive selection of various macroinvertebrate prey in St Peters but ate D. hjulim in Main Lake. Tropic overlap for chironomids and other macroinvertebrate prey was demonstrated between perch, bream and tench, and potentially with wildfowl which used the gravel pits for breeding and wintering.