On the fauna of chironomidae (Diptera) of the Hrazdan Basin (Armenia)

A faunistic review of larvae and pupae of chironomid midges (Diptera, Chironomidae) from 15 habitats in the Hrazdan River valley (Armenia) is presented. The revealed fauna includes 40 species from 20 genera and 6 families and tribes. Diploid chromosome numbers are specified for 24 species from 13 genera and 4 subfamilies; 23 species from 14 genera and 4 subfamilies are reported from the region for the first time. Predominant oligotrophic status is confirmed for most of the reservoirs studied.     

On the chironomid (Diptera,Chironomidae) fauna in Lake Sevan

An annotated list of the chironomid species collected in Lake Sevan in the first 10 days of October 2006 and 2007 is presented. Chironomid species were identified by the aquatic stages of their development (larvae and pupae) and imagoes. The list includes 26 species, among which nine species were recorded in the lake for the first time. Altogether, 53 species of chironomids have been recorded in Lake Sevan.     

Chironomids fauna (Diptera, Chironomidae) in some waterbodies and watercourses of Mongolia

An annotated list of chironomid species from some waterbodies and watercourses of Mongolia identified by an imaginal developmental stage is presented. The list includes 97 species of 39 genera and 5 subfamilies: Tanypodinae (6 species), Diamesinae (1), Prodiamesinae (2), Orthocladiinae (33), and Chironominae (55). Of all found chironomid imagos, 11 species have been earlier identified for the Mongolian fauna, the other 86 species have been registered for the first time. The largest number of species has been recorded in Lake Sangiyn-Dalai—28; in Lake Ugiy and River Ider—19 species. In the rest of the lakes, the number of recorded species varies from 18 to 10 species, and in rivers, from 13 to 2. Most of the species are boreal and widespread. The number of Paleoarctic species amounts to 44 and Holarctic species amounts to 49.     

Fauna of chironomids (Diptera,Chironomidae) of the Kama River Basin

An annotated list of chironomid species is presented for the watercourses and waterbodies of the Kama River Basin, which covers the territories of Perm krai, Sverdlov oblast’, Kirov oblast’, the Udmurt Republic, and the Republic of Bashkortostan. The list includes 253 species of 107 genera and 6 subfamilies: Podonominae (2 species), Tanypodinae (35), Diamesinae (10), Prodiamesinae (4), Orthocladiinae (92), and Chironominae (110). Eighty one of these species were defined under the imagoes.     

Contrasting effects of an invasive crayfish (Procambarus clarkii) on two temperate stream communities

1. The effects of omnivorous exotic species on native communities are often difficult to predict because of the broad diets and behavioural flexibility of the omnivore, and the diverse abiotic and biotic characteristics of invaded systems. We investigated experimentally the effects of a gradient of density of the introduced, omnivorous red swamp crayfish Procambarus clarkii (Decapoda: Cambaridae) on two stream communities in southern California, U.S.A. 2. The Ventura River is a clear, flowing stream with a cobble substratum, with abundant algae but low densities of large invertebrates, small herbivores and snails. The Santa Ynez River at the time of the study consisted of a series of drying pools underlain by sand, with abundant charophytes, large predatory invertebrates and herbivores, including snails. 3. In the Ventura River, periphyton biomass and inorganic sediment decreased with increasing crayfish abundance, but in the Santa Ynez River, periphyton and sediment were unrelated to crayfish densities. 4. In the Ventura River, the biomass and density of all benthic invertebrates combined, chironomids, micropredators, the meiofauna (chydorid cladocerans, copepods and ostracods), and specific predatory and herbivorous taxa, as well as taxon richness, were negatively related to crayfish density. In the Santa Ynez River, the biomass and average body size of benthic invertebrates, predatory invertebrates, herbivores and chironomids, but not total invertebrate density or taxon richness, were negatively related to crayfish density. 5. Fewer large predatory invertebrates and snails (Physella gyrina) in both streams, and baetid mayflies in the Ventura River, were visible at night in channels where crayfish were abundant. Snails responded to crayfish by moving above the water line in the Santa Ynez River, but not in the Ventura River. 6. We suggest that the same omnivore had different effects on these neighbouring streams because of crayfish predation on large invertebrates in the Santa Ynez River and the scarcity of such prey in the Ventura River, leading to increased crayfish grazing on periphyton, and reductions in periphyton‐associated invertebrates, in the Ventura River.     

Feeding chronology and habits of Alosa spp. (Clupeidae) juveniles from the lower Hudson River estuary, New York

Synopsis Feeding habits of juvenile alewife, A. pseudoharengus, blueback herring, A. aestivalis, and American shad, Alosa sapidissima, were examined over a 24 h period at an inshore location on the lower Hudson River. Feeding periodicity differed by species: alewives showed no diel differences, whereas shad fed least intensively near dawn and herring least intensively at night. Alewives fed primarily on chironomids and the amphipod Corophium lacustre, shad on Formicidae and larval chironomids, and herring on chironomids and copepods. Diel variation in prey selection was evident. Dietary overlap was generally greatest between alewife and herring and least between shad and herring.     

Data on the fish species composition in Nyukzha River (Olekma Tributary) and its basin

Results of investigation of the ichthyofauna of Nyukzha River (Lena basin), its tributaries (Jeltula, Nerunga (Malaya Nrunna), and Ogyngli), and lakes of this system are presented. The list of fishes revealed in this region includes 12 species belonging to seven families and five orders. The problem of the taxonomic status of a number of species in the area under study is discussed.     

Laboratory investigation on community composition, emergence patterns and biomass of wood-inhabiting Chironomidae (Diptera) from a sandy lowland stream in Central Europe (Germany)

Wood-inhabiting chironomid communities were investigated from June 1998 to July 1999 by laboratory rearing of randomly collected submerged branches from a headwater and mid-reach site of a sandy lowland stream, separated by an impoundment used for fishery purposes. Total annual emergence (males and females) from headwater samples was higher (2551 ind m^–2 y^–1) compared to the mid-reach (1576 ind m^–2 y^–1), which could be due to disturbances caused by frequent impoundment openings resulting in high discharge events. Chironomid community from branches comprised three subfamilies, with Orthocladiinae (18 species, 2189 ind m^–2 y^–1) clearly predominating at the headwater (total of 36 species). Mid-reach samples (total of 48 species) showed similar emergent numbers of Orthocladiinae (19 species, 786 ind m^–2 y^–1) and Chironominae (26 species, 764 ind m^–2 y^–1). Tanypodinae were caught very rarely in the laboratory emergence (12 ind m^–2 y^–1 at both sites). Shannon-Wiener diversity index for the mid-reach chironomid community was higher (2.52) than for the headwater community (1.68). Chironomid species composition on woody debris was similar between stream sites, with a Sørensen index of 0.75, but showed different dominance structures indicated by a Wainstein index of 0.26. Total adult biomass (in the manner of dry mass) during the study period was higher for wood-dwelling chironomids from the headwater (158.2 mg m^–2 y^–1) compared to the mid-reach (123.8 mg m^–2 y^–1), but individual biomass was higher for mid-reach chironomids (0.079 mg ind^–1 vs. 0.062 mg ind^–1 at the headwater), indicating the predominance of larger species. Total biomass of wood-inhabiting chironomids in the investigated lowland stream was low compared to other field emergence studies, which could be attributed to the laboratory approach for investigating the emergence from a single substrate type (submerged wood) instead of the integrative field surveys where chironomids from all habitats were caught. Main reason for the lack of chironomid species closely associated to wood in this sandy lowland stream could be infrequent but episodic disurbances caused by the anthropogenic induced highly fluctuating discharge regime of the downstream study site.     

A new mermithid nematode in imagos of Cladopelma collator (Townes) (Diptera: Chironomidae) eclosing from waterways in northern Minnesota

Octomyomermis connellyi n. sp. (Nematoda: Mermithidae) is described from the hemocoel of male and female imagos of Cladopelma collator (Townes) eclosing from Lake Ozawindib and from Gulsvig Landing in the upper Mississippi River in northern Minnesota. The species is distinguished from the other species in the genus. Included is a list of the other 9 adequately described members of the genus Octomyomermis that have been reported from the United States (California and Minnesota), Argentina, Russia, and Zambia. Bionomics and anomalies of the new species are addressed.     

Species composition,abundance and emergence phenology of midges (Deiptera: Chironomidae) in a brown-water stream of West-Central Alberta,Canada

Sixteen floating, box type emergence traps, each covering 0.1 m², were placed along 150 m of a third-order stretch of the Bigoray River, a slow-flowing, vegetation-choked, brown-water muskeg stream. Effects of trap design, trap shading, length of sampling interval, and stream velocity on the number of midges caught was examined. Of the 112 species of Chironomidae caught, 32 species made up 90% of the catch and their emergence phenology is described in detail. There were more rare species than expected from Preston's lognormal distribution. Percentage of Bigoray species belonging to Tanypodinae, Orthocladiinae, Chironomini and Tanytarsini was 18%, 43%, 20%, and 19%, and was compared with 27 other studies on lotic chironomids. During the 140-day emergence period an average of 19.3 × 10³ chironomids emerged per square meter of stream. Based on changes in male:female ratios throughout a species emergence period, it was postulated that 30% of the Bigoray chironomid species were univoltine, 50% were bivoltine, and 20% were trivoltine.     

Diets of four sympatric species of Etheostoma (Pisces: Percidae) from southern Indiana: interspecific and intraspecific multiple comparisons

Synopsis The diets of four species of Etheostoma (E. spectabile, E. caeruleum, E. flabellare and E. nigrum) were investigated from ten Order 3 streams in the White River drainage of southern Indiana. All species fed mainly on insect larvae, primarily chironomids, ephemeropterans and plecopterans. Dietary proportions, as frequency of occurrence, were compared using cluster analysis based on matrices of values of Spearman rank correlation, Schoener index, Jaccard association, and Pearson's r. Certain species and, in some cases, stream pairs within species clustered closely in all analyses or in three of the four. Most clusters do not show closer intraspecific than interspecific similarity and specific streams had more influence than species in forming the logic of some clusters. It can be concluded that these fishes are opportunistic predators.     

Chironomids of Italian rice fields

Studies on chironomids of Italian rice fields began in 1914, but a comprehensive faunistic picture of Italian rice field chironomids was provided only by COCCHI in 1966. In 1988 and 1989 field research south of Verona (northern Italy) permitted us to confirm the results of COCCHI regardingC. sylvestris andChironomus spp., and to increase the number of known species of Italian rice field chironomids. The list of species which are injurious to rice is similar to that of other European countries, with the exception ofHarnischia falcata andTanytarsus sp. The type and period of damage is different for certain species (e.g. Cricotopus sylvestris) in Italy in comparison to other countries. A few agrotechnical steps are recommended to control pest species. The finding of the parthenogenetic speciesParatanytarsus grimmii in lab. aquaria used for rearing purposes is documented.     

Laboratory investigation on community composition, emergence patterns and biomass of wood-inhabiting Chironomidae (Diptera) from a sandy lowland stream in Central Europe (Germany)

Wood-inhabiting chironomid communities were investigated from June 1998 to July 1999 by laboratory rearing of randomly collected submerged branches from a headwater and mid-reach site of a sandy lowland stream, separated by an impoundment used for fishery purposes. Total annual emergence (males and females) from headwater samples was higher (2551 ind m^–2 y^–1) compared to the mid-reach (1576 ind m^–2 y^–1), which could be due to disturbances caused by frequent impoundment openings resulting in high discharge events. Chironomid community from branches comprised three subfamilies, with Orthocladiinae (18 species, 2189 ind m^–2 y^–1) clearly predominating at the headwater (total of 36 species). Mid-reach samples (total of 48 species) showed similar emergent numbers of Orthocladiinae (19 species, 786 ind m^–2 y^–1) and Chironominae (26 species, 764 ind m^–2 y^–1). Tanypodinae were caught very rarely in the laboratory emergence (12 ind m^–2 y^–1 at both sites). Shannon-Wiener diversity index for the mid-reach chironomid community was higher (2.52) than for the headwater community (1.68). Chironomid species composition on woody debris was similar between stream sites, with a Sørensen index of 0.75, but showed different dominance structures indicated by a Wainstein index of 0.26. Total adult biomass (in the manner of dry mass) during the study period was higher for wood-dwelling chironomids from the headwater (158.2 mg m^–2 y^–1) compared to the mid-reach (123.8 mg m^–2 y^–1), but individual biomass was higher for mid-reach chironomids (0.079 mg ind^–1 vs. 0.062 mg ind^–1 at the headwater), indicating the predominance of larger species. Total biomass of wood-inhabiting chironomids in the investigated lowland stream was low compared to other field emergence studies, which could be attributed to the laboratory approach for investigating the emergence from a single substrate type (submerged wood) instead of the integrative field surveys where chironomids from all habitats were caught. Main reason for the lack of chironomid species closely associated to wood in this sandy lowland stream could be infrequent but episodic disurbances caused by the anthropogenic induced highly fluctuating discharge regime of the downstream study site.     

Chironomids as Bioindicators in Acidified Streams: A Contribution to the Acidity Tolerance of Chironomid Species with a Classification in Sensitivity Classes

In 12 forest brooks differing in acidity (pH-values from 2.79 to 6.89) chironomids were sampled to establish their acid-tolerance based on their occurrence in a certain pH range. Some taxa were found only at pH values higher than pH 6.0, others not below pH 5.5. A relatively high number of species could tolerate periodical pH values below 4. Only a few species were limited to high pH. Using these results, 25 species were classified according to their acid-sensitivity. The suitability of these species for the assessment of the acidity-state of running waters was tested. The study demonstrates that chironomids are qualified bioindicators for assessment of the acidity-state within technical water quality monitoring. It is recommended that the classified chironomid species be added to the list of macroinvertebrate acidity indicators.     

Species composition and structure of macrozoobenthos in Lake Sevan during the period of its increased water level

A list of macroinvertebrate species recorded in the zoobenthos in Lake Sevan in 2007 and 2010 is presented. The list includes 38 species, 14 of which have been found in the lake for the first time. Chironomid larvae and pupae are the most diverse (27 species) in the macrozoobenthos of the lake. In Bolshoi Sevan, the maximum biomass of macrozoobenthos (24.82 g/m²) was recorded in the sublittoral; in Malyi Sevan the maximum biomass (14.31 g/m²) was recorded in the profundal. In 2010 chironomids dominated by biomass in the sublittoral (48.9 and 60.3%, respectively). The benthos in the littoral was dominated by oligochaetes (50.2%).     

Selective predation by four darter (Percidae) species on larval chironomids (Diptera) from a Mississippi stream

We determined seasonal foraging modes of four sympatric darter species, Etheostoma lynceum, E. stigmaeum, E. swaini and Percina nigrofasciata, from Beaverdam Creek, Mississippi (USA) at two scales of taxonomic resolution: (1) chironomid prey identified to family and (2) chironomid prey identified to genus/species. When chironomids were identified to family, high proportional similarity (PS) and low niche breadth (NB) values suggested the darters fed opportunistically on a relatively small number of available prey taxa. In contrast, when chironomids were identified to genus/species, concordant low PS and NB values suggested the darters fed like classic specialists, selecting a small number of prey taxa relative to prey availability in the resource base. The darters selected just one to four chironomid taxa from 52 available taxa across seasons. Our study shows that the scale of taxonomic resolution used to identify darter prey may influence the characterization of darter foraging modes.     

Fungal and oomycete parasites of Chironomidae,Ceratopogonidae and Simuliidae (Culicomorpha,Diptera)

Members of the families Chironomidae (chironomids or non-biting midges), Ceratopogonidae (ceratopogonids or biting midges) and Simuliidae (simulids or blackflies) are ubiquitous dipterans of the infraorder Culicomorpha. They are extremely diversified in ecological strategies. Their larvae play major roles in aquatic food webs as detritivores or predators, whereas their adults can be general predators (Chironomidae), hemolymphagous or hematophagous predators (Ceratopogonidae and Simuliidae) or pollinators. Both larval and adult stages are commonly infected by bacteria, viruses, protists, nematodes, true fungi and oomycetes. These phylogenetically diverse assemblages of microorganisms can simultaneously infect multiple species of chironomids, ceratopogonids and simulids, and each host may become trophically interrelated with other hosts by sharing their parasites. Here, we review the information on fungal and oomycete parasites of these dipteran groups with special reference to the natural regulation of host populations, the impact of parasitism in food webs, and the potential of these parasites as biocontrol agents.     

The realized food niches of three species of stream-dwelling triclads (Turbellaria)

SUMMARY. 1. The diet of Phagocata vitta, Crenobia alpina and Polycelis felina in a Welsh stream was examined, using a serologicat technique, at monthly intervals over 18 months.
2. For each triclad species, dietary composition changed little with time or increasing body size, and overall feeding intensity was greatest in summer and least in winter.
3. Alt species fed most heavily on oligochaetes, chironomids and Gammarus. Phagocata vitta fed lightly on Plecoptera, Trichoptera and Ephemeroptera whilst the other two triclad species fed substantially on the first two of these prey categories.
4. Food niche breadth indices indicated a wide diet for all species with some specialization in some months. Electivity indices showed positive electivity for oligochaetes and chironomids by all species and for Plecoptera by C. alpina and P. felina .
5. Diets overlapped and none had a food refuge: therefore the potential for interspecific competition for food exists.     

Distribution of chironomids in the littoral zone of Lake Texoma,Oklahoma and Texas

Lake Texoma in southcentral Oklahoma was formed by the impoundment of the Washita and Red Rivers. The Red River is more highly saline than the Washita and creates a complex salinity gradient across the reservoir. Populations of chironomids were monitored with multiple-plate samplers in areas of high (34–113 mg l^–1 Cl^–), intermediate (35–60 mg l^–1 Cl^–) and low (4–27 mg l^–1 Cl^–) salinity during the spring and summer of 1978. Food availability, temperature, salinity and wind direction influenced the distribution of the 14 genera and at least 22 species of chironomids which colonized the multiple-plate samplers. Filter-feeders attained their highest densities in the river-arm stations where levels of particulate organic matter (POM) were high. Algal grazers attained their highest densities in the clear intermediate area where the plates of the samplers were covered with algal mats. Most of the genera believed to be feeding primarily on POM decreased in density as the temperature and density of Glyptotendipes sp. rose. Certain species were restricted to either the Red River arm or the Washita River arm and this is probably a reflection of different salinity tolerances.     

Diet of the leeches Erpobdella octoculata (L) and Helobdella stagnalis (L) in a lotic habitat subject to organic pollution

SUMMARY 1. A study of the diet of E. octoculata (L) and H. stagnalis (L) using a serological technique was carried out in a lot ic habitat subject to organic pollution and seasonal sewage fungus growth.
2. The results indicate that E. octoculata consumed predominantly Chironomidae and Oligochaeta, while H. stagttalis had a less pronounced prey preference, consuming rather similar proportions of chironomids, oligochaetes, Asellus and gastropod snails.
3. At enriched sites, E. ocioculata consumed relatively more chironomids and fewer oligochaetes, while H. stagnalis took more gastropods and fewer chironomids.
4. Seasonal differences were noted in the diet of both leeches with chironomids predominating chiefly from April to August, and molluscs, oligochaetes and Asellus at other times of the year. Intra-specific differences (on a weight-age basis) were only seen for E. octoculata , small forms consuming chiefly oligochaetes and larger ones concentrating on chironomids.