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The dependencies between the abundance of Chironomus f. l. plumosus and bream (Abramis brama) net catches in a lowland reservoir (Zegrzyński Reservoir, central Poland)

Prus P.

Oceanological and Hydrobiological Studies

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2009

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Vol. 38, No.3

15-30

EN

Chironomus f. l. plumosus larvae, a valuable food of bream (Abramis brama (L.)), dominate in the benthos of the extra-littoral zone of the shallow, lowland, eutrophic Zegrzyński Reservoir. Bream is the dominant fish species in this reservoir, making up to 80% of total net catches. During eight years of studies, very regular Chironomus population dynamics were noted in the lotic part of the central, broad basin of the reservoir. There were usually two peaks of the abundance: the higher one in spring, and the much lower one in late summer. Both peaks of Chironomus abundance positively correlated with commercial net catches of bream in the reservoir in particular years. The total bream catch per year in the reservoir studied also correlated positively with the average yearly abundance of Chironomus. The correlation between Chironomus abundance and bream occurrence (measured by commercial net catches) in the reservoir studied suggests that this environment is used by bream mainly as a feeding ground. In the years with a low spring Chironomus peak of abundance, the bream leave the reservoir, searching for food in its inflows - two large, lowland rivers. This corresponds to much lower catches noted in the reservoir in the years of low Chironomus abundance.

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Cytogenetic characteristic of species of the Chironomus genus (Diptera, Chironomidae) from Lake Łuknajno Biosphere Reserve (northwest Poland)

Jabłońska-Barna I., Michailova P.

Oceanological and Hydrobiological Studies

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2009

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Vol. 38, No.2

77-81

EN

The cytotaxonomic characteristics of two species of the Chironomus genus from Lake Łuknajno (northwest Poland) were determined: Chironomus nuditarsis Strenzke, 1959 with the chromosome arm combinations of AB, CD, EF, and G (the "thummi" cytocomplex), and Camptochironomus tentans (Fabricius, 1805) with the chromosome arm combinations of AB, CF, DE, and G. A heterozygous inversion in arm F of the Chironomus nuditarsis chromosomes was detected. The polymorphism of Camptochironomus tentans as a homozygous inversion in arms A and E and a heterozygous inversion in arm F were revealed.

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Insecticidal activity - a new bioactive property of the cyanobacterium Fischerella

Becher Paul G., Juttner Friedrich

Polish Journal of Ecology

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2006

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Vol. 54, nr 4

653-662

EN

Cyanobacterial biofilms serve as food and as shelter for benthic invertebrates, such as juvenile insects. Chironomids are often the most frequently found and abundant insect larvae in freshwater ecosystems. As a consequence of high grazing pressure, effective defence mechanisms can be expected in biofilm-forming organisms. The presence of chemical defence was studied in detail in 12 axenic and monoxenic cyanobacterial species. Flakes of cyanobacterial biofilms were offered to Chironomus riparius (Meigen) over a period of 8 days. Mortality and body-length of the surviving animals were used as indicators for the toxicity of the cyanobacteria and their suitability as food. Toxicity and inhibition of larval growth were found for several cyanobacteria tested. Fischerella sp. (ATCC 43239) was the most active and caused 100% mortality in Chironomus larvae within 24 h. Mortality was also high (87%) for larvae fed with Aphanothece sp. Moderate toxicity (40-60% mortality) was found for Calothrix sp. (PCC 7507), C. braunii Bornet et Flahault, C. thermalis (Schwabe) Hansgirg and a cyanobacterium of the LPP group designated JU 5. Mortality of 7-33% was observed for Calothrix parietina (Nageli) Thuret, Oscillatoria brevis (Kutzing) Gomont, Cylindrospermum sp., Nostoc sp., Calothrix anomala Mitra and a cyanobacterium of the LPP group designated 5 KB. Differences depending on the cyanobacterial food offered were also seen in the lengths of surviving larvae. Fischerella sp. (ATCC 43239) was studied in more detail to chemically characterize the observed insecticidal activity. The insecticidal activity could be extracted with 60% aq. methanol from the fresh biomass and caused 100% mortality in Chironomus. A literature survey was performed on the bioactive compounds so far isolated and characterized from Fischerella and related Stigonematales. It is noticeable that no insecticidal activity has been shown for any of these compounds yet. The newly found insecticidal property of Fischerella may lead to the identification of bioactive compounds which may be important as a chemical defence against insect grazers.

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Influence of the population density and the amount of food on Chironomus plumosus (L.) and Tubificidae. Laboratory experiments

Kajak Z., Prus P.

Polish Journal of Ecology

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2004

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Vol. 52, nr 1

47-53

EN

The aim of this paper has been to examine experimentally the importance of the density of larvae and of the addition of the food for Chironomus and Tubificidae using selected parameters and indices of their populations. Increase of the density of Chironomus plumosus larvae (0.5-50.0 thousands ind. m^-2) in laboratory experiments resulted in the decrease of emergence of imagos, number of tube apertures (3.5-0.4 apertures ind.^-1), and in the lower rate of tubes building. The addition of the food (powdered dry daphnids or food tablets for aquarial fish) had only slight effect on tube numbers but it decreased clearly the getting out of larvae from tubes (probably due to improved feeding conditions inside tubes). It had also a slight negative effect on the survival of larvae. Numbers and individual growth of Tubificidae were positively dependent on the addition of the food (also in the form of naturally dead Chironomus larvae) and negatively - on the density of Chironomus

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Seasonal and year-to-year variation of numbers of Chironomus plumosus L. and Tubificidae in a lowland reservoir : regularities, causes, mechanisms

Kajak Z., Prus P.

Polish Journal of Ecology

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2003

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Vol. 51, nr 3

339-351

EN

During 9 years of studies very regular Chironomus population dynamics was stated in a eutrophic, lowland dam reservoir. There were usually two peaks of the abundance: the higher one at spring (up to 80 thousands ind. m^-2) and the much lower in autumn. The duration of the spring Chironomus generation was about 3 weeks. The constant presence of young larvae during the summer did not result in the high total abundance of larvae, mainly due to the strong predation of fish and swallows on various stages of Chironomus. The smaller predators pressure in the spring (due to fish breeding) and in the autumn (due to lower temperatures) resulted in the mentioned two peaks. The spring peak abundance was positively correlated with the chlorophyll concentration in water (feeding resource for larvae) and negatively with the water flow. There was also negative correlation of the water flow and the chlorophyll concentration, as well as abundance of Chironomus and Tubificidae during the vegetation season (April-October). Tubificidae correlated strongly positively with the spring Chironomus numbers (with a month lag). The slight positive correlation of these benthic components abundance occurred for the whole vegetation season. Tubificidae occurred in generally high numbers up to 400 thousands m^-2, but various in different years, and with no regular changes during the season.

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Field experiment reveals no relation between substrate composition and Chironomus abundance

Kajak Z., Prus P.

Polish Journal of Ecology

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2001

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Vol. 49, nr 1

19-27

EN

In the field experiment no relation between organic matter content (0-83%) in substrates provided and Chironomus plumosus (L.) abundance was found. Numbers of larvae and their age structure were usually similar on the mineral substrate and various bottom sediments but sometimes differed up to 2-3 times (at the same site and date of sampling); there was howerver no correlation with the quality of substrate. This indicates that the feeding of Chironomus plumosus did not depend on the bottom deposit the larwae lived in, but mostly on sedimenting tripton, which formed a thin layer on the top of substrates provided. Also mutual relations of individuals and the period of exposure of the sediment (from 3 weeks to few months) did not matter. Very high abundance of Ch. plumosus (up to 90 thousands ind. m^-2) found already after 3 weeks exposition in the sediment initially without that species indicates a very high growth potential of the Chironomus population at the study site.

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Effects of the density of larvae and type of substrate on Chironomus plumosus L. (Diptera: Chironomidae) population. Laboratory experiments

Kajak Z., Prus P.

Polish Journal of Ecology

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2001

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Vol. 49, nr 4

369-378

EN

Strong dependence of larval tube numbers on the population density, the condition of larvae and feeding situation occurred, but no correlation with the type of substrate was found. Numbers of larval tubes per individual were on the average 2.6 times lower at high (20 and 40 thousands ind. m^-2) than at low (2 - 2.5 thousands ind. m^-2) initial densities of larvae. They fluctuated strongly, but only at low densities, indicating the very high activity of larvae; high densities probably restrained this activity. The grown up larvae succeeded in finishingtheir full development in the mineral substrate with the tiny (<0.1 mm) layer of the natural mud at the top of it. No conical nettings (inside larval tubes) for food filtration were observed. The larvae fed mostly on the internal walls of their tubes; sometimes they also collected particles from the surface of the substrate (especially of substrates poor in the organic matter), after the food was furnished. The emergence of imagines depended on the larval density but quite differently than the numbers of tubes. The threshold for the decreased tube numbers per individual was between 2.5 and 20 thousands individuals m^2, while that for the emergence of imagines - between 20 and 40 thousands individuals m^2.