Articles
Phylogenetic analysis of coccidia (Apicomplexa: Eimeriorina) in the belica Leucaspius delineatus (Heckel, 1843)
Abstract
This study was aimed to carry out a comparative analysis and reconstruction of the phylogenetic position of coccidia from the intestine of the belica Leucaspius delineatus (Heckel, 1843) from the Irkutsk Reservoir. Determination and comparative analysis of the nucleotide sequences of the cox1 gene fragment, obtained and available in genetic databases, demonstrated paraphilia of the genera Eimeria and Goussia. The sequences in the phylogenetic tree formed a distinct cluster at the base of the tree. Thus, the hypothesis that fish coccidia were ancestors of coccidia of other vertebrates was indirectly confirmed. The need for additional research and revision of coccidia in fishes from the Angara River and Lake Baikal is discussed.
Limnology and Freshwater Biology. 2023;(4):104-118
104-118
Annual temperature regime of the shallow zone of Lake Baikal inferred from high-resolution data from temperature loggers
Abstract
Annual changes in temperature characteristic of the shallow zone during 2017-2022 have been studied in this work. Dataset was contrasted based on 8 transects located in South, Central and Northern Baikal at depths of 3, 4, 6, 12, 15 and 26 m. Temperatures were measured every 1.5-3 hour. It was determined that modal values of maximal heating of the shallow zone at all stations and depths were 15-16°C, however, distribution of maximal temperatures of South Baikal shifted toward the low temperatures, and these maximums could be only 9-10°C. Temperature regime of the shallow zone during warm seasons is characterized by sharp changes due to wind mixing and upwelling, when temperature drops dramatically from 16-18°C to 4°C for the 1-1.5 day. In most cases, the duration of stabile temperature condition without wind mixing was 4 days. On average, upwelling events occurred 5 times (maximum - 13 events) from July to November. As a result of wind mixing, the shallow zone is characterized as moderately warm with average temperatures of 6-7°C from June to November. A temperature effect on the shallow zone of Lake Baikal due to the Global warming is smoothed by cooling of the zone by deep waters during upwellings.
Limnology and Freshwater Biology. 2023;(4):119-125
119-125
Acoustic-trawl studies of the Coregonus migratorius (Georgi,1775) in the Selenga shallow water zone of Lake Baikal, 2023
Abstract
Study of peculiarities of distribution of aggregations and size-age structure of the Baikal omul feeding stock in the Selenga shallow water zone of Lake Baikal were studied using the hydroacoustic method in combination with control trawls. Comparative analysis of the results of 2023 with the data of 2015-2022 showed significant changes in the general character of distribution of the Baikal omul aggregations in the water area and depth. Standard length of fish from different shallow water zones ranged from 10 to 39 cm with a sample median of 17 cm. In terms of weight, individuals of 18-26 cm in length were dominant. A “length-age” equation allows making an operational assessment of age class abundance correlation based on the probability of assigning individuals of a certain length to them. It is shown that 3-5 years old fish form the basis of the biomass of feeding stock in the Selenga fishing zone. A significant proportion of young fish indicates that there is sufficient recruitment to increase the biomass of the Baikal omul stock in 5 years perspective.
Limnology and Freshwater Biology. 2023;(4):126-136
126-136