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1.
The life cycles of Isoperla grammatica, Amphinemura sulcicollis and Nemoura hesperiae are studied in a Northern Italy stream, sited in the Apennines. The three species show a univoltine life cycle and their development coincides approximately in the same period of the year, although the one of I. grammatica is longer. Possible egg dormancy could exist in the A. sulcicollis and N. hesperiae life cycles, but this needs to be proved. The three taxa show a spring flight period in the study area. Growth is almost constant through the life cycle, except in A. sulcicollis in which an increase is observed at the end of the development. N. hesperiae exhibits a faster growth than the other species. In addition, in this paper, the nymph of N. hesperiae is described and designed for the first time.  相似文献   

2.
Resource dynamics and detritivore production in an acid stream   总被引:2,自引:0,他引:2  
1. Life history patterns and production of eight shredder‐detritivore species were studied in relation to the detritus dynamics of a small acidic stream in England. Mean annual detritus inputs (direct and lateral sources combined) were approximately 400 g m?2 year?1 and showed significant seasonal and annual variation. 2. Detritus standing stock did not increase significantly during times of high input, reflecting low retention efficiency. However, the mean detritus standing stock was relatively large (108 g m?2) reflecting a slow decomposition rate typical of acid streams. 3. Four species were univoltine with highly synchronous patterns of emergence and recruitment (Leuctra inermis, Leuctra hippopus, Capnia vidua and Amphinemura sulcicollis). Two species were univoltine with extended patterns of emergence and recruitment (Nemoura cinerea, Potamophylax cingulatus). Leuctra nigra was apparently semivoltine, while Protonemura meyeri showed two successive cohorts in the second year of the study, suggesting either bivoltinism or cohort splitting. 3. Secondary production of the dominant shredders was 1.67 g m?2 year?1 in 1997 and 1.99 g m?2 year?1 in 1998, which is low compared with other small European streams. This was probably because of an impoverished invertebrate community and poor food quality associated with acid conditions. Food availability probably did not account for the low production as the detritus standing stock far exceeded the estimated shredder ingestion of 42–50 g m?2 year?1. 4. Despite low overall shredder production, species‐specific production was high, possibly because of competitive release in this species‐poor acid stream. Periods of high production and growth showed no relationship with detritus availability but were closely related to life history.  相似文献   

3.
Takao Shimizu 《水生昆虫》2013,35(4):203-208
Three closely related species from Japan are treated and defined as composing the Amphinemura flavostigma group (Okamoto, 1922). One species, A. nikkoensis, is described as new to science. Two already known species, A. flavostigma and A. monotuberculata (Kawai, 1956), are redescribed, while the female of the latter is described for the first time. Another species, A. tetraspinosa Kawai, 1960, is regarded as a subjective synonym of Nemoura flavostigma Okamoto, 1922.  相似文献   

4.
Abstract. 1. The post-emergence lateral migration of both sexes of eight stonefly species was examined in a dystrophic, fourth-order forest river in eastern Finland.
2. For this purpose, 7351 stonefly adults were collected with eighteen trunk funnels positioned in rows of six at distances of approximately 1, 15 and 60 m from the river. A further 1880 adults were also caught from the vegetation of the bank zone by sweep netting and with slit traps.
3. The species could be grouped into two types with respect to migration distance: Isoperla difformis, I.grammatica and Leuctra fusca tended to stay in the bank area, whereas Nemoura flexuosa, N.avicularis, Amphinemura borealis, L.hippopus and N.cinerea tended to disperse into the forest, so that the majority were found some distance away from the shore.
4. The males of the leuctrids, N.flexuosa and N.cinerea migrated farther than the females.
5. The sex ratio was significantly biased in all species except N.flexuosa. The isoperlids, leuctrids and A.borealis showed a significant predominance of females in the trunk funnel catches, but males were significantly dominant in N.avicularis and N.cinerea. The material caught by other methods reversed the ratio for I.difformis and N.avicularis. Comparison of the sex ratios of the species with other reports revealed marked variation and deviation from unity, much of which could be attributed to bias introduced by the sampling methods.
6. Lateral migration seems to be the first phase in the colonization cycle, although the latter as such was not studied here. Adults of Euholognatha species migrate farther than those of Systellognatha, a difference of which may be due to their ability to feed as adults.  相似文献   

5.
Feeding habits of the Euholognathan stoneflies Nemoura hesperiae and Amphinemura sulcicollis are studied in a little stream located in northern Italy. The former fed mainly on coarse particulate organic matter (CPOM), together with detritus, while the latter fed principally on detritus and, in a lower concern, on CPOM. Thus they can be catalogued fundamentally as shredder and collector‐gatherer, respectively. Shifts in diet composition were detected in relation to size in both taxa. Probably niche overlapping does not exist despite both species having similar size and nymphal development duration, and coinciding in time. This work supports that, though functional feeding groups are very useful, they should not be inferred from related species or higher taxonomical levels. Even intra‐population differences and ontogenetic shifts should be considered in fine scale studies.  相似文献   

6.
A total 14 streams located in the Tatra Mts (Slovakia) were investigated. The studied river basins have different deforestation range (0–45.5%) influenced by windstorm. Daily and annual water temperature suggested that in streams overflowing through the area deforested by windstorm the temperature was higher than in selected non-disturbed streams. Higher average nutrient concentrations in samples from these streams are connected with nutrient mobilization from disturbed forest soils after the windstorm. Most of the damaged streams have higher trophic status, including POM and biofilms. The growth of the most abundant larvae increases with deforestation. Growth of species Leuctra rauscheri, Protonemura Montana, and Perlodes intricatus correlates with the sum of daily temperatures over a given time interval. Growth of species Brachyptera seticornis, Leuctra autumnalis and Isoperla sudetica are affected by stream trophy.  相似文献   

7.
P. P. Harper 《Hydrobiologia》1973,41(3):309-356
The life-histories of seven species of Nemouridae and two of Leuctridae have been investigated in Southern Ontario. Eleven sampling stations were chosen to illustrate the range of temperature conditions found in local streams.The Nemouridae and Leuctridae make up most of the stonefly fauna of the upstream cooler stations, but their numerical importance decreases considerably downstream.There is a definite seasonal succession of the species: Soyedina aallicularia, Prostoia completa and Shipsa rotunda appear in late spring, Nemoura trispinosa, Amphinemura delosa} and A. nigritta in early summer, Leuctra tenuis in midsummer and A. linda in late summer. L. ferruginea emerges throughout most of the summer, at least in the headwater streams.All the species are univoltine, except L. ferruginea which is usually semivoltine. Most Nemouridae, A. spp., P. completa and S. rotunda undergo a long embryonic diapause, whereas N. trispinosa and S. vallicularia develop directly. The nymphal development of N. trispinosa was compared in three streams; although the general pattern is similar, the growth is much more synchronized in the warmest station. There appears to be 16 nymphal instars in this species. L. ferruginea was common in seven stations; in the coolest, the life-cycle lasts two years, but in the warmest, many specimens succeed in completing their cycle in one year.
Résumé Les cycles vitaux de sept espèces de Nemouridae et deux espèces de Leuctridae ont été étudiés dans onze ruisseaux du Sud de l'Ontario; ces stations d'échantillonnage représentent la gamme des températures des ruisseaux de cette région.Les Nemouridae et les Leuctridae constituent la majeure partie de la faune des Plécoptères dans les stations froides de l'amont. Cependant, leur importance décroît de façon significative dans les stations plus en aval.On reconnaît une succession bien définie des espèces durant l'année: Soyedina aallicularia, Prostoia completa et Shipsa rotunda apparaissent à la fin du printemps, Nemoura trispinosa, Amphinemura delosa et A. nigritta au début de l'été, Leuctra tenuis au milieu de l'ete et A. linda à la fin de l'été. L. ferruginea emerge pendant presque toute la saison chaude, du moins dans les stations de l'amont.Toutes ces espèces sont univoltines, sauf L. ferruginea qui est ordinairement semivoltine. La plupart des Nemouridae, soient A. spp., P. completa et S. rotunda doivent compléter une longue diapause embryonnaire, alors que N. trispinosa et S. vallicularia se développent directement. On a comparé la vie larvaire de N. trispinosa dans trois ruisseaux: bien que l'essentiel de la biologie soit semblable dans les trois cas, on remarque un plus grand synchronisme de la croissance dans la station la plus en aval. Il semble y avoir 16 stades larvaires chez cette espèce. L. ferruginea était abondante dans sept stations; dans la plus froide, le cycle vital dure deux ans, alors que dans la plus chaude, plusieurs specimens arrivent a boucler leur cycle en un an.
  相似文献   

8.
Peter Zwick 《Hydrobiologia》1990,194(3):207-223
Upstream oviposition flights of several Plecoptera species of the genera Leuctra, Nemoura, Isoperla and Siphonoperla along the Breitenbach, Hesse, Germany are inferred from 1. oviposition occuring upstream from emergence areas; 2. size differences and size-shifts between emerging and egg-laying females; 3. concentration of oviposition in upstream sections of the emergence area. The last point relies on direct catches of egg-laying females with sticky traps, and on over-representation of old, mature females in upstream emergence traps towards the end of, or even after actual emergence periods. Criteria for age class discrimination of the respective taxa are described. The validity of the present and of other indirect evidence for directed adult flights and the significance of adult upstream displacement are discussed. Optical orientation cues are suggested. Females of Leuctra prima and Siphonoperla torrentium are shown to gain 25–50% dry weight by feeding in the terrestrial environment; general information indicates many other Plecoptera may be similar in this respect. Terrestrial adult life is shown to last for 3–8 weeks. This long time, evidence of important flight activity and feeding together suggest that the terrestrial phase is spent as an active adult, the inevitable risks of which may form an important control of population dynamics.  相似文献   

9.
1. The flight behaviour of adult merolimnic insects was studied on the first order limestone stream Leutra (Thuringia, Germany) using sticky traps. The focus of the present study was on testing the colonisation cycle hypothesis of Müller (1954) and on the small-scale dispersal of adult merolimnic insects. 2. A high number of sticky traps was used to guarantee a proper statistical analysis of the data and exclude effects of the heterogeneous environment on flight behaviour. 3. The flight behaviour of Leuctra hippopus, Nemoura cambrica, Nemoura flexuosa, Protonemura nitida, Protonemura praecox (Plecoptera), and Baetis rhodani (Ephemeroptera) was studied. 4. Specific flight corridors were observed for P. praecox, Nemoura spp., L. hippopus and B. rhodani. 5. Comparison of the catches on sticky traps set perpendicular to the water showed no significant flight upstream in any of the taxa studied. Thus, the results do not support the hypothesis of the colonisation cycle.  相似文献   

10.
The effect of brown trout (Salmo trutta L.) on invertebrate drift density was examined in three previously fish-free springbrooks. Drift density was studied during the day following the sequential introduction of: 1) empty cages, 2) cages containing trout, and 3) empty cages. Each period lasted three whole days, and drift density was measured at daytime and night-time every day. Control drift density was determined using empty cages in two similar springbrooks.Night-time drift density of large Gammarus pulex L. (>3.9 mg DW ind–1) decreased compared to that of smaller size-groups following trout introduction, and was significantly lower (p<0.05) than the pre-introductory level after the trout had been removed again.The daytime drift density of large G. pulex remained unchanged, as did both daytime and night-time drift density of smaller size-groups of G. pulex, and the other taxa investigated (Leuctra hippopus (Kempny), Leuctra nigra (Olivier), Amphimura sp., Nemoura flexuosa Aubert, and Baetis rhodani (Pict.)). No significant changes in drift density were observed in two control springbrooks.  相似文献   

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