scholarly journals Openness of Fish Habitat Matters: Lake Pelagic Fish Community Starts Very Close to the Shore

Water ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3291
Author(s):  
Karlos Moraes ◽  
Allan T. Souza ◽  
Mojmír Vašek ◽  
Daniel Bartoň ◽  
Petr Blabolil ◽  
...  

Fish communities differ significantly between the littoral and the pelagic habitats. This paper attempts to define the shift in communities between the two habitats based on the European standard gillnet catch. We sampled the benthic and pelagic habitats from shore to shore in Lake Most and Římov Reservoir (Czech Republic). The 3 m deep pelagic nets were spanned across the water body at equal distances from two boundary points, where the depth was 3.5 m. The benthic community contained more fish, more species, and smaller individuals. The mild sloped littoral with a soft bottom attracted more fish than the sloping bank with a hard bottom and less benthos and large Daphnia. The catch of the pelagic nets was dominated by eurytopic fish—rudd (Scardinius erythrophthalmus) and roach (Rutilus rutilus) in Most and bleak (Alburnus alburnus) in Římov. With the exception of one case where overgrown macrophytes extended the structured habitat, the largest shift from the benthic to the pelagic community was observed only in the first pelagic gillnet above the bottom depth of 3.5 m. Open water catches were relatively constant with small signs of decline towards the middle of the lake. The results indicate that the benthic gillnet catch is representative of a very limited area and volume, while most of the volume is dominated by the pelagic community. This has important consequences for the assessment of the community parameters of the whole lake following the European standards for gillnet sampling design.

2008 ◽  
Vol 53 (4) ◽  
Author(s):  
Kálmán Molnár ◽  
Gábor Cech ◽  
Csaba Székely

AbstractDuring a survey on myxosporean parasites of cyprinid fishes in Hungary, Myxobolus infections were found in the cartilaginous rays of the gill filaments in roach (Rutilus rutilus) and bleak (Alburnus alburnus). Myxobolus spp. causing the infections were studied by morphological, histological and molecular methods. Small plasmodia surrounded by chondrocytes contained relatively few spores which differed from each other and from the known Myxobolus spp. both in their morphology and 18S rDNA sequences. Both species, described as M. feisti sp. nov. and M. susanlimae sp. nov., are characterised by a specific cartilaginous histotropism.


1989 ◽  
Vol 46 (6) ◽  
pp. 995-1001 ◽  
Author(s):  
Josef Wanzenböck ◽  
Fritz Schiemer

Larval and juvenile fish of roach (Rutilus rutilus L), bleak (Alburnus alburnus L), and blue bream (Abramis ballerus L.) were investigated weekly to define the ontogenetic development of prey detection capacities. Visual acuity was determined by measuring reactive distances for zooplankton prey for fish from 8 to 50 mm standard length using video recordings. Data of reactive distances, swimming speeds, and the characteristics of the visual field were combined to calculate prey location volumes. Prey location capacity increased exponentially with fish size which implies enormous differences in prey encounter rates among size classes of cyprinids. Distinct differences of prey location capacities occurred between species in the juvenile, planktivorous stages of the three cyprinids coinciding with the trophic differentiation of the adults.


1969 ◽  
Vol 26 (11) ◽  
pp. 2795-2805 ◽  
Author(s):  
I. Mackay ◽  
K. H. Mann

Egg production by two cyprinids in the River Thames at Reading, England, was studied quantitatively from January to June 1966. Roach (Rutilus rutilus) had a short spawning period, shedding all their eggs in one batch, whereas bleak (Alburnus alburnus) had a protracted spawning period and produced two or three batches of eggs. The relationship between egg numbers (Y) and age (X) for roach was given by log Y = 0.0840X + 3.2085; the estimated fecundity of a 6-year-old fish was 5157 with 95% confidence limits at 4725 and 5631. For bleak the relationship was log Y = 0.0564X + 3.5221, and the estimated fecundity of a 5-year-old fish was 6356 with 95% confidence limits at 5987 and 6776. Combining previously obtained data on population density with new data on sex ratio and percentage breeding in each age class, the population fecundity for roach was about 600 eggs/m2 and for bleak about 3000 eggs/m2.The roach population had lower fecundity than roach populations in other studies and there was some evidence that a proportion of females ceased egg production during the period of the study. The possibility that low fecundity was a response to food shortage is discussed.


Zoodiversity ◽  
2021 ◽  
Vol 55 (4) ◽  
pp. 295-306
Author(s):  
A. A. Tsyba ◽  
M. Ghazali ◽  
S. V. Kokodiy ◽  
S. V. Mezhzherin

The large-scale hybridization of fishes of the subfamily Leuciscinae in the subordinate systems of the Dnipro River basin is presented by the data on two pairs of species, roach Rutilus rutilus × bream Abramis brama, and bleak Alburnus alburnus × rudd Scardinius erythrophthalmus. The hybridization and occurrence of F1 hybrids are confirmed with allozyme spectra and morphological characters on series of samples. A complete morphometric analysis of the characteristics of bleak and rudd hybrids was performed. The paper discusses the intergeneric hybridization in nature, which is a unique phenomenon characteristic only of some groups of cyprinids. The most likely reason is the overestimation of the taxonomic status of European cyprinids, which is confirmed by the insignificant level of intergeneric genetic divergence.


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