Distribution of filter-feeding caddisflies (Trichoptera) and plankton drift in a Swedish lake-outlet stream

The objectives of this investigation were to relate the longitudinal distribution of filter-feeding caddisflies to quality and quantity of seston, and to document factors facilitating coexistence among filter-feeding species, in a 4th-order lake-outlet stream in central Sweden. A sharp decline in abundance and biomass of filtering caddisflies was evident within 1 km from the lake outlet following negative power functions. In contrast to particulate organic carbon, significant reductions of both phytoplankton and zooplankton biomass, especially some large species, were recorded between the lake-outlet and 1.9 km downstream. Differences in longitudinal and temporal distribution provide evidence of resource partitioning between filtering species included.     

热带－亚热带森林中猕猴的食性

采用跟踪观察法对热带－亚热带森林中的猕猴种群的食性及其与植被类型的关系进行了调查,结果表明,猕猴主要选择季雨林或次生季雨林为其觅食场所,栖息地植物的地理分布和种类直接影响其食性,猕猴对植物各部位的采食频度随植物生长期而变化．     

Factors influencing the longitudinal distribution of larval Hydropsychidae (Trichoptera) in a southern Appalachian stream system (U.S.A.)

The influence of physical habitat variables and suspended particulate organic matter (seston) on the distribution and production of eight species of larval Hydropsychidae was studied along a 6.4 km section of a southern Appalachian stream. Samples were collected at six stations encompassing stream orders 1–4 and an elevation range of 610 m. Multivariate analysis of covariance (using time as the covariable) and discriminant function analysis were used to examine habitat differences between the sampling stations due to the following variables: current velocity; coarse benthic detritus; substrate composition (by particle size); substrate heterogeneity; degree-days; and diel temperature fluctuation. The associations of these variables with the abundance (and production) of larval hydropsychids was also examined using the same statistical procedures. The six sampling stations represented three or four distinct habitats based on patterns of change in the variables along the stream continuum. Diel temperature fluctuation, median substrate particle size, the proportion of sand substrate, and substrate heterogeneity were most closely associated with the overall difference between the sampling stations. Hydropsychid species distribution along the stream system followed subfamily lines, i.e., Arctopsychinae and Diplectroninae were more abundant and productive in the upper 4.5 km of the stream, while Hydropsychinae were dominant in the lower 1.9 km. Diel temperature fluctuation was the habitat variable most highly correlated with patterns of hydropsychid abundance and production. The longitudinal pattern of species distribution, i.e., larger particle feeding Arctopsychinae being replaced downstream by smaller particle feeding Hydropsychinae, also coincided with the distribution of seston particle size classes along the stream. Mean seston particle size generally declined downstream, as particles <42 µm increased in relative abundance while those between 43 µm and 5 mm decreased. Temperature, seston, and substrate composition all undoubtedly exerted an important influence on the distribution and production of Hydropsychidae and other filter feeding insects in this stream. The validity and generality of these results depend upon the scope of the sampling effort. Conclusions drawn from data collected over the entire range (and limits) of a species' distribution are more sound than those based on data from a limited area.     

Feeding habits and dietary overlap of Naididae (Oligochaeta) from a bog stream

Feeding habits and dietary overlap of three species of naidid oligochaetes (Chaetogaster diastrophus, Dero digitata, Dero nivea) were studied during June 1982–December 1983 from a bog stream in Wisconsin, USA. Chaetogaster diastrophus primarily ingested diatoms, while D. digitata and D. nivea primarily ingested detritus. Dietary overlap was substantial (97–98%) between D. digitata and D. nivea using the dietary overlap coefficient. Dietary overlap between C. diastrophus and D. digitata was 58–62% and that between C. diastrophus and D. nivea was 51–55%. Dietary differences existed between the three species in the percentage of each major food type and diatom genera ingested, selective ingestion or avoidance of diatom genera and in the size classes (length and/or volume) of diatoms consumed. These data suggest temporal coexistence of these species may possibly be due to complex food resource partitioning, although in this habitat, C. diastrophus, D. digitata, and D. nivea did not exhibit concurrent peak abundances; thus, interspecific competition for food was minimized.     

Emergence of some caddisflies (Trichoptera) from a wooded stream in southern Ontario

Twenty-eight species of nine families of caddisflies (Trichoptera) were identified in 170 samples taken over an 8-month period from five emergence traps placed on a second-order, forested, cold-stenothermal stream on the Niagara Escarpment, Ontario, Canada.A mean of 980.9 caddisflies m^–2 of streambed was obtained over the entire sampling period. Eleven common species accounted for 92.8% of the total emergence with specific proportions ranging from 23.8% (Wormaldia moesta) to 0.11 % (Rhyacophila sp.). The use of various kinds of traps in other studies and their effects on the detection of species composition and abundance are discussed and compared with the present study.Although the distributions of all the common species were invariant over time, four species showed low to high degrees of patchiness in the streambed; the other seven common species were uniformly distributed. However, a large residual variance suggested a subtle mechanism of microhabitat selection by the larvae and (or) pupae, not detectable by even the small emergence traps used.Both sexes of 15 species, only males of 4 and only females of 9 species were collected. Eight of the eleven common species showed significant departures from a balanced sex ratio and five exhibited a protandry of from 1 to 3 weeks. Neither this study nor others have been able to establish a predictable pattern of sex ratios in Trichoptera.The emergence periods and patterns of the eleven common species are described and compared with other studies. Of these common species, one emerged in the spring, seven during the summer and three during the late summer or early fall. Ten species had a short emergence period with a distinct peak and a significantly skewed pattern. One species,Parapsyche apicalis, exhibited a prolonged emergence period, no distinct peak and a significantly platykurtotic² pattern. With the exception ofLepidostoma sp. A, the emergence patterns of the common species were unimodal.     

长江口中国花鲈食性分析

中国花鲈(Lateolabrax maculatus)是长江口重要的经济鱼类之一。根据2010年7月至10月在长江口崇明东滩团结沙和东旺沙水域采集到的胃含物样品,对中国花鲈的摄食习性进行了研究。结果表明,从中国花鲈胃含物中共鉴定出6类27种饵料生物,其多样性指数H’值为2.484,均匀度指数J’为0.7535,优势指数D为0.1262。采用百分比相对重要性指数(IRI%)和综合指标优势指数(Ip)分析的结果较一致,鱼类是长江口中国花鲈夏季主要食物,其百分比相对重要性指数(IRI%)和综合指标优势指数(Ip)分别为82.63%和94.48,鮻(Liza haematocheila)为优势饵料生物(IRI%=41.89,Ip=53.20)。团结沙和东旺沙中国花鲈食性差异较大,主成分分析(PCA)表明鲚属(Coilia spp.)、舌虾虎鱼(Glossogobius giuris)、脊尾白虾(Exopalaemoncarinicauda)和雷伊著名团水虱(Gnorimosphaeroma rayi)是造成这种差异的主要饵料生物种类。     

Feeding of an Iberian stream cyprinid assemblage: seasonality of resource use in a highly variable environment

Food resource use by seven cyprinids from an Iberian stream was analysed over 9 months. Differences in food resource use were found both between species and within species between seasons. Plant material was a more important food for carp, nase, goldfish and barbel than for gudgeon, roach and chub, irrespective of the season. Chironomid larvae were the staple animal food for the former five species throughout the year. Roach and chub, especially the latter, displayed large seasonal variations in prey use, with chironomid larvae only being important during autumn. Ephemerellid nymphs and ephemeropteran imagos dominated the animal diet of chub during spring and summer, respectively. Dipteran adults and Formicidae were the most important prey for roach during spring and summer, with other common prey being ephemerellid nymphs and hydropsychid larvae. Food resource overlap among the three dominant species (roach, barbel and chub) displayed a large seasonal variation. High overlaps were observed during autumn when these species used the same resources. During summer overlaps were much lower with each species specialising on different prey. The remaining less abundant species had large diet overlaps amongst themselves and with barbel, over all seasons. It is suggested that morphological constraints, habitat partitioning and temporal changes in food resource limitation may be involved in producing these patterns of food resource use.     

Instar sizes,life cycles,and food habits of five Rhyacophila (Trichoptera: Rhyacophilidae) species from the Appalachian Mountains of South Carolina,U.S.A.

The larval head widths at each instar, life cycles, and food habits of late instars were determined for five species of Rhyacophila from two Appalachian mountain streams in South Carolina, U.S.A. Rhyacophila acutiloba Morse & Ross was univoltine with two cohorts, one emerging in the spring and another presumably emerging in early autumn. Rhyacophila fuscula (Walker), R. nigrita Banks, and R. carolina Banks were apparently multicohort, univoltine species with extended flight periods. Rhyacophila minor Banks was univoltine with a spring emergence. All species were predaceous and consumed mainly Plecoptera nymphs and Trichoptera larvae.     

The effects of low concentrations of particulates from paper mill effluent on the macroinvertebrate community of a fast-flowing stream

The effects of a paper mill effluent on the macroinvertebrate community were assessed for the riffle areas of a large fast-flowing stream, the lower reaches of the Saranac River of northern New York State, U.S.A. The effluent caused few changes in dissolved oxygen concentration, pH, biochemical oxygen demand, temperature or nutrient content; however, significant differences in transmitted light, concentrations of particulates and accumulated debris on the substrate were observed. A moderate decrease in invertebrate diversity correlated with increased levels of particulates and substrate debris. An analysis of the response of invertebrate functional groups revealed the effluent had little effect on the density of gathering collector organisms. The functional groups most severely reduced in density were the filtering collectors and scrapers. Predators showed a moderate reduction in density in response to the effluent. The alterations in invertebrate densities were attributed largely to the alterations in seston and substrate caused by the introduction of particulates composed mainly of paper fiber and inert dye.     

In situ measurements of net primary production in a Colorado mountain stream

Six stations were established on a Colorado mountain stream, and net primary productivity was measured in situ during all seasons. For 24-hour periods the dissolved oxygen and temperature of the water were electronically monitored over an undisturbed 1 x 1 m section of rubble bottom enclosed by a large plastic dome tightly fitted to the substrate. A submerged pump maintained a current within the dome, and the whole apparatus was submerged below the stream level. The bottom community net metabolism varied between heterotrophy and autotrophy with no correlations with altitude, season, light, water chemistry, and temperature. Readings were all very low and ranged from -27.38 to 35.59 grams of carbon fixed per square meter per year. There were no correlations between biomass of the bottom fauna and net community productivity.Contribution No. 71, University of Colorado Limnology Laboratory     

Variation in the summer diet of age-0 brown trout in a regulated mountain stream

We describe the age-0 brown trout (Salmo trutta) collected from a mountain stream downstream from a reservoir in June, July, and August 1990. Sample sites were 1, 12, and 20 km downstream from the reservoir at elevations of 2840, 2600, and 2230 m above mean sea level. The mean length of fish in the samples increased with downstream progression and from June through August. Zooplankton predominated the diet of fish collected in June from the most upstream sampling site, while Diptera larvae predominated the diet of fish from more downstream sampling sites in June. In July and August, the diet of fish from the upstream site was predominated by Diptera larvae, while the diet of fish from the other two sites was predominated by Ephemeroptera nymphs. Variation in diet among sampling sites and sampling months was related not only to increasing fish sizes over the summer but also to the availability of zooplankton flushed from the reservoir.     

Macroinvertebrate drift in a Rocky Mountain stream

An extensive series of drift collections from a Rocky Mountain stream was used to investigate quantitative patterns in the taxonomic composition of drift throughout spring, summer and fall for 1975–1978. Drift was estimated by drift rate, the number of organisms drifting past a point per 24 h; and by drift density, the numbers of organisms collected per 100 m³ of water sampled.Drift densities were up to ten times greater by night than by day, and 24 h drift densities for the total fauna approached 2000 per 100 m³ in June–July, declining to <500 by autumn. Ephemeroptera, and especially Baetis, dominated the drift. Drift rates were greatest in late spring, around 10⁶ per 24 h, which are among the highest values reported for small trout streams. Drift rates declined to <10⁵ during the summer, and shifts in the taxonomic composition are described.Multiple regression analysis of the relationship between drift rate and density, and the independent variables discharge, benthic density and temperature, showed that discharge typically was a significant predictor of 24 h drift rate, usually the best single predictor. In contrast, 24 h drift density most frequently was independent of discharge, indicating that this measure tends to correct for seasonal variation in discharge, as suggested in the literature. However, this was not invariably true. Drift density significantly correlated with benthic density in five of eight taxa inspected, thus seasonal declines in the benthos probably accounted for parallel declines in drift density.     

Use and partition of space and resources by two coexisting Rhyacophila species (Trichoptera) in a high mountain stream

Life history, distribution, drift and food habits of two coexisting Rhyacophila species, Rhyacophila evoluta and Rhyacophila intermedia were studied in a high mountain stream in the Pyrénées.The life histories of both species took two years downstream and three years upstream. Several generations and a large range of larval instars permanently coexisted in the river.Slight temporal segregation of the life histories and differences in size and food habits of the coexisting larvae partially reduced the interspecific competition and allowed an optimal use of space. Instars IV of R. evoluta and V of R. intermedia, which had the most similar biological characteristics had the same microdistribution when they lived alone but used different habitats when they coexisted.     

Stable isotope analysis of macroinvertebrates and their food sources in a glacier stream

1. Food sources and trophic structure of the macroinvertebrate community along a longitudinal gradient were examined in a glacier stream of the Swiss Alps (Val Roseg). Analysis of multiple stable isotopes (δ¹³C and δ¹⁵N) and measurement of C : N ratios were used to differentiate between allochthonous and autochthonous organic matter.
2. Although isotopic signatures of algae varied widely among sites and dates, it was possible to discriminate between allochthonous and autochthonous food sources using a site-specific approach.
3. Dominant food sources of herbivorous invertebrates in all main channel sites were epilithic diatoms and the filamentous gold alga Hydrurus foetidus . Allochthonous organic matter was of some importance only in a groundwater-fed stream close to the floodplain margin.
4. Seasonal changes in the δ¹³C signature of the macroinvertebrates corresponded with seasonal changes in δ¹³C of the gold alga H. foetidus . This indicated that the energy base remains autochthonous throughout the year.
5. Because of limited food sources, feeding plasticity of the invertebrate community was high. Both grazers and shredders fed predominantly on algae, whereas gatherer-collectors seemed to be omnivorous.
6. The overall enrichment of δ¹⁵N was 2.25‰ ( r ²=0.99) per trophic level. On a gradient from the glacier site to a downstream forested site trophic enrichment was constant but variation in δ¹⁵N within trophic levels decreased.     

The metabolism of organic matter in the hyporheic zone of a mountain stream, and its spatial distribution

Community respiration in hyporheic sediments (HCR) was studied in a characteristic riffle-pool-sequence of a mountain stream. HCR activity at the riffle site strongly exceeded that at the corresponding pool site with a mean ratio of 5.3. The vertical distribution of HCR activity was homogeneous in the pool, while there was a distinct maximum in the uppermost layer in the riffle. Similarly, the spatial distribution of certain fractions of particulate organic matter (POM), and their turnover, was largely determined by stream morphology. Mean annual HCR per unit area of stream bed was estimated as 1.71 g O₂ m⁻² d⁻¹. Hence, HCR contributes significantly to total heterotrophic activity in streams, thus enhancing the relative importance of heterotrophic processes in running waters containing hyporheic zones.     

Diurnal shifts in use of summer habitat by age-0 brown trout in a regulated mountain stream

Diurnal shifts in habitat use by age-0 (< 50 mm total length) brown trout (Salmo trutta) were observed from June to July 1989 and 1990 in low-gradient (< 1% channel slope) reaches of Douglas Creek, Medicine Bow National Forest, Wyoming. Fish were visually located during day and night, and water depth, water velocity, distance from the stream edge, substrate, habitat type, and cover were determined at each location. The fish were found predominantly in locations with slow water velocities in stream-margin and backwater-pool habitats. They were observed in slower water, closer to the stream edge at night than during the day.     

Abundance patterns of filter-feeding Caddisflies (Trichoptera : Hydropsychidae) and seston in a Montana (U.S.A.) lake outlet

The abundance patterns of four species of net-spinning caddisflies (Trichoptera : Hydropsychidae) were studied in a Montana (U.S.A.) lake outlet stream. Total Hydropsychidae reached very high densities (X > 1400 / 0.2 m²) near the lake outfall but declined precipitously downstream. Abundance patterns generally agree with a published model of filter-feeder / seston interactions in lake outlets. Larval densities were greater on moss-covered substrates and one species occupied habitats of lower water velocity compared to other species. Seston concentrations increased downstream contrary to expectation. Nutrient quality of seston may be important in predicting abundance of stream filter-feeders.     

Egg characteristics and oviposition behaviour of the aquatic insect orders Ephemeroptera,Plecoptera and Trichoptera in New Zealand: a review

The abundance and distribution of aquatic insects may be controlled by factors at any stage of the life cycle. To understand the potential role of factors affecting egg and adult stages and oviposition, basic information on egg characteristics and oviposition behaviour is required. However, published information on New Zealand Ephemeroptera, Plecoptera and Trichoptera (EPT) is scattered and very limited. This review compiles current knowledge of New Zealand EPT egg characteristics and oviposition behaviour using published information and unpublished observations. Where direct observations are lacking, information on closely related species overseas, and inferences based on female morphology, are included. Eggs show a variety of physical characteristics that may influence egg retention, transport and distribution. Oviposition behaviour is highly selective among some taxa, but appears generalist among others, though the latter may still require specific cues. Identifying and providing for adult, egg and oviposition requirements may be fundamental to re-establishing EPT populations in restored aquatic habitats.     

Feeding habits and trophic levels of Mediterranean fish

The estimation of fractional trophic levels(TROPHs) is essential for the management offisheries resources as well as for quantifyingthe ecosystem effects of fishing. We gatheredall available information concerning thefeeding habits of 332 fish stocks, belonging to146 species, 59 families and 21 orders,throughout the Mediterranean Sea, and estimatedtheir TROPH values. The latter ranged from 2.0to 4.5 and the following functional trophicgroups were identified: (a) pure herbivores (TROPH = 2.0–2.1, mean = 2.02, SD = 0.03),which were very rare and represented by Siganus luridus, Siganus rivulatus andSarpa salpa, all of which feed on red,brown, green and blue-green algae; (b)omnivores with a preference for vegetablematerial (2.1 < TROPH < 2.9, mean = 2.5,SD = 0.12), but feeding on other prey, such assponges, hydrozoans, anthozoans, polychaetes,ostracods, isopods, amphipods and copepods. This type of omnivore was very rare among thecases reviewed; (c) omnivores with a preferencefor animal material (2.9 < TROPH < 3.7,mean = 3.4, SD = 0.19) feeding on a wide variety ofprey (e.g., algae, foraminifera, brachyurans,balanoids, ascidians, amphipods,appendicularians, annelids, isopods,gastropods, cnidarians, ophiurids, polychaetes,cladocerans, mysids, euphausids, fish larvae,cephalopods). They were the most numerous andwere mainly represented by species of thefamilies Blenniidae, Bothidae, Centracanthidae,Gobiidae, Labridae, Lotidae, Macrouridae,Mullidae, Ophidiidae, Soleidae, Triglidaeand Engraulidae; and (d) carnivores witha preference for large decapods, cephalopodsand fish (3.7 < TROPH < 4.5). They werethe next most abundant group among the casesreviewed. They were mainly represented byspecies of the families Dalatiidae, Lophiidae,Scombridae, Scyliorhinidae, Synodontidae,Torpedinidae, Merlucciidae, Xiphiidae andZeidae. This group was divided into twosubgroups: one exhibiting a preference fordecapods and fish (3.7 < TROPH < 4.0,mean = 3.85, SD = 0.09) and another one exhibitinga preference for fish and cephalopods (4.0 相似文献