摘要:

AbstractThe diel emergence patterns of 16 chironomid species from a Berkshire lake are characterized. A study of these patterns and those described previously in the literature indicate that the diel pattern for any chironomid species can often be predicted on the basis of the Tribe to which it belongs. Chironomini spp. usually emerge at dusk or at night. Macropelopiini spp. and Metrioenemini spp. characteristically emerge during daylight but the former peak in the morning and the latter peak in the afternoon. Orthocladiini and Tanytarsini spp. exhibit more varied patterns although bimodalism is a frequent feature. The phylogenetic conservatism in the diel patterns displayed implies that these patterns became established early during chironomid evolution, and are, therefore, plesiomorphic.

ISSN:0020-9309    

DOI:10.1002/iroh.19900750501

出版商:Akademie Verlag, Berlin    

年代:1990

数据来源: WILEY

摘要:

AbstractIngestion of fluorescent particles by natural protozoan assemblage was studied in the Řimov Reservoir (Southern Bohemia) from April to October, 1987. Attached and free‐living bacterial abundance, proportion of active bacteria, density of suspended particles and biomass of cladocerans were also monitored.Heterotrophic nanoflagellates (HNF; 5–12.8 102ml−1) were the dominant bacterial micrograzers during the spring period and consumed 3 to 9% of the total bacteria per day. After the spring phytoplankton bloom maximum densities of suspended particles and attached bacteria (up to 28% of the total counts) were found. Development of cladocerans in May sharply decreased the proportion of attached bacteria and kept them below 5% of the total counts.All the studied components of plankton except Cladocera decreased during the clearwater phase. The most significant drop was observed in the numbers of protozoans, and they were negligible for bacterial elimination. Bacterial losses during that time apparently were due to cladoceran grazing.During the summer period, ciliates (15–142 ml−1) were mostly dominant micrograzers, and protozoan community grazing increased up to 21% of bacterial standing stock per day. The proportion of active bacteria was strongly correlated with protozoan grazin

ISSN:0020-9309    

DOI:10.1002/iroh.19900750502

出版商:Akademie Verlag, Berlin    

年代:1990

数据来源: WILEY

摘要:

AbstractIn short‐run experiments herring larvae at the end of the yolk sac stage (SL6.5 to 8.5 m) were fed with maize and potato starch to investigate the effect of particle size on food selection. About 20% of the larvae ingested these particles during the experiments.In the case of maize starch (3 to 26 μm grain size) the size classes from 14 to 25 μm and in the case of potato starch (5 to 80 μm) the size classes larger than 29 μm were preferred. The highest numbers of ingested grains per larva were 150 maize starch grains and 57 potato starch grains.The selective uptake of these size classes leads to the conclusion that planktonic organisms in this size range—in other words mostly protozoans—may play an important role as a first food source of herri

ISSN:0020-9309    

DOI:10.1002/iroh.19900750503

出版商:Akademie Verlag, Berlin    

年代:1990

数据来源: WILEY

摘要:

AbstractTwo Jordanian sandy beaches, one at the northern end and the other at the southern end near the Saudi‐Jordanian border, were examined during November 1984 to October 1985. Sediments of the South station were made of coarser sand than the North station. In general, low organic carbon and calcium carbonate levels were found at both stations. A total of 15839 animals representing 45 taxa were collected from both stations. Major differences in community structure were found between the two stations. An average density of 7981/m2, 39 taxa. an average diversity value of 1.78 and an evenness of 0.37 were characteristic of the South station. Lower number of taxa (39) and density (818/m2) were found on the North station. However, the average diversity (3.18) and evenness (0.74) were higher. Using the biological index value of MCCLOSKEY (1970), the archiannelidSaccocirrussp. was the most dominant species at the South station and the bivalveTellina pernaat the North statio

ISSN:0020-9309    

DOI:10.1002/iroh.19900750504

出版商:Akademie Verlag, Berlin    

年代:1990

数据来源: WILEY

摘要:

AbstractResearch into endangered species of fish and cyclostomes, as well as their living environment, are prerequisite to determining species protection measures.Relevant ecological research was carried out in three streams in the trout and grayling region; the environmental conditions were recorded, and the populations characterised.Consequently the following suggestions for the protection of the streams dealt with in this research can be made.

ISSN:0020-9309    

DOI:10.1002/iroh.19900750505

出版商:Akademie Verlag, Berlin    

年代:1990

数据来源: WILEY

摘要:

AbstractPopulation densities and generation time of heterotrophic bacteria were estimated in water and sediments of fish ponds used for polyculture, monoculture and traditional systems of fish farming over a period of two and a half years. Spatial differences in microbial densities in the ponds were related to the organic loadings of the farm site and farm management. A number of environmental factors such as nitrogen, dissolved organic carbon, bicarbonate and phosphate of water were found to be responsible for the seasonal changes of heterotrophic bacteria in these ponds.

ISSN:0020-9309    

DOI:10.1002/iroh.19900750506

出版商:Akademie Verlag, Berlin    

年代:1990

数据来源: WILEY

摘要:

AbstractComparative‐morphological analysis of the structure of the Cladocera of the superfamily Sidoidea ( = Ctenopoda) comprising the families Sididae and Holopediidae, compared with representatives of other groups: Chydoroidea (=Anomopoda), Limnadiiformii (= Conchostraca), Polyphemiformii (Polyphemiformes (= Onychopoda) and Leptodoriformes (= Haplopoda)) and Branchipodiones (Branchipodiformes (= Anostraca) and Triopiformes (= Notostraca)) is made. The main parameters and structures important in functional‐morphological and ecological aspects are considered: including dimensions of the body, its form and proportions, the complex eye, swimming antennae, body covers, thoracic limbs, the postabdomen. In distinction from all crustaceans under consideration in the Sididae and the Polyphemiformii organs contributing to rapid manoeuvrable swimming, soaring and good orientation in the environment received the prevailing development in evolution: antennae, stabilizing appendages of the posterior part of the body, the eye, etc. All this predetermined elaboration of the life strategy in these forms mainly aimed, especially in the Sididae, at active avoidance of predation combined with elements of passive protection (imperceptibility attained by various methods). Representatives of the Sididae, including planktonicDiaphanosoma, well survive in water bodies with the intensive press of predation. All others, including the Holopediidae, clearly possess the passive protection (development in localities inaccessible to predators, imperceptibility, protective structures on the body surface, et

ISSN:0020-9309    

DOI:10.1002/iroh.19900750507

出版商:Akademie Verlag, Berlin    

年代:1990

数据来源: WILEY

摘要:

AbstractResting cell formation in algae and cyanobacteria is one of the strategies developed for withstanding adverse environmental conditions. This note informs about the different capacities of such resting cells to germinate after long‐term dark preservation at 4 °C inAnabaena variabilis(Cyanobacteria, Cyanophyta) andHaematococcus lacustris(Chlorophyta, Volvocale

ISSN:0020-9309    

DOI:10.1002/iroh.19900750508

出版商:Akademie Verlag, Berlin    

年代:1990

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19900750509

出版商:Akademie Verlag, Berlin    

年代:1990

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19900750511

出版商:Akademie Verlag, Berlin    

年代:1990

数据来源: WILEY