Cottoid Fishes Research Articles

Parasite fauna of sand and stone sculpins (scorpaeniformes, cottidae) from lake Baikal (review of research results and prospects of investigations)

A revision of the composition of parasites of two widely distributed in Baikal species of cottoid fish - the sand ( Leocottus kesslerii Dybowski, 1874) and the stone ( Paracottus knerii Dybowskii, 1874) sculpins was performed. This composition includes 60 species and subspecies of parasites belonging to 10 types, 12 classes, 14 orders, 24 families and 32 genera. It is represented by 21 endemic taxa of species and subspecies rank: these are blood parasites - trypanosomes and cryptobia (2), myxosporidia (5), infusoria (7), monogeneans (1), nematodes (2), acanthocephales (1), leeches (2) and crustaceans (1). Comparison of the parasite fauna of sand and stone sculpins with that of the families Abyssocottidae and Comephoridae showed that most of all this fauna is closely related to the parasite fauna of the family Abyssocottidae. Revision of the parasite composition of two widely distributed fish in Baikal in the light of modern data has identified a number of important problems in the study of fish parasites of this reservoir. Since there has been a transformation of views on the taxonomy of individual groups, new information has been obtained on morphology, molecular biology, biochemistry, life cycles and distribution in the plant and animal world, it is necessary to continue the study of Baikal parasites by modern methods.

Annotated catalogue of the type specimens of salmon, cod and cottoid fishes described by Dmitry Taliev

The article provides a brief biography of the ichthyologist Dmitry Nikolayevich Taliev (1908–1952), as well as information and illustrations for 24 taxa described by him from the White Sea (Gadidae – one subspecies), the coast of the Sea of Okhotsk (Salmonidae – one subspecies), Lake Baikal (Cottidae – 2 species and 4 subspecies; Abyssocottidae – 6 species and 8 subspecies), and Lake Baunt (Cottidae – 1 subspecies; Abyssocottidae – 1 species). For 19 taxa, photographs and radiographs of type specimens kept in the collection of the Zoological Institute of the Russian Academy of Sciences (Saint Petersburg, Russia) are presented for the first time. Type specimens of three species and two subspecies from the families Cottidae and Abyssocottidae found in the collection are examined and catalogued. It was revealed that Cottus kessleri bauntovi Taliev, 1946 and Limnocottus kozovi Taliev, 1946 are morphologically similar to Cottus sibiricus, a species widely distributed in Siberia, including Lake Baunt. According to modern fish taxonomy, Taliev’s 12 taxa are valid. Findings of type specimens in the historical collection are extremely important for the scientific community.

Supplementary studies on Myxobolus talievi Dogiel, 1957 (Cnidaria, Myxozoa) from the skeletal muscle of the cottoid fish Cyphocottus eurystomus in Lake Baikal: Morphological, histological and molecular characterisations.

Myxobolus talievi Dogiel, 1957 was originally described from the eyes, skeletal muscles and body cavity of endemic cottoid fish from Lake Baikal. In the present study, we supply new information on the myxospore morphology and histopathology of M. talievi; furthermore, we complete the original species description by Dogiel and Bogolepova (1957) with 18S ribosomal DNA (rDNA) sequence data. Histopathological analysis showed that the plasmodium was encapsulated by a thin layer of connective tissue and located in the intermuscular connective tissue among muscle cells. No inflammation was observed. Phylogenetic analysis revealed that M. talievi clustered with Myxobolus sp. 2 (NCBI Acc. No. U13830), an unidentified Myxobolus species from cottoid fish studied by Smothers et al. (1994), and located in the sister clade of Myxobolus spp. developing spores in the nerves of salmonids.

Differentiation of communities of macroinvertebrates and cottoid fish associated with methane seeps of different bottom landscapes of Lake Baikal

The paper presents the results of the study of communities of macroinvertebrates and cottoid fish inhabiting methane seeps of Lake Baikal. For the analysis, we used video surveillance and collection of animals carried out with the help of "Mir" deep-water submersible, as well as NIOZ-type box-corer samplers from the board of a research vessel. Posolskaya Bank and Saint Petersburg methane seeps are located in different basins (southern and middle) and at different depths (300–500 m and ~ 1400 m), characterized by the different underwater landscapes (slope of underwater upland and hills formed by gas hydrates), by the structure of gas hydrates and their depth location in sediments, as well as the composition of microbial mats and communities of microorganisms of bottom sediments. Both seeps are characterized by bubble discharge of methane gas and the formation of highly productive communities of large invertebrates and cottoid fish on seep habitats. Seep animal communities consisted of species-depleted invertebrates and fish of the surrounding deep-water benthal of the Lake. We showed the similarities and differences in the composition of the faunas of two seeps, as well as the quantitative characteristics of taxonomic groups of macroinvertebrates and cottoid fishes. Obligate species have not been revealed on the methane seep Posolskaya Bank. For the methane seep Saint Petersburg, the gastropod species Kobeltocochlea tamarae Sitnikova, Teterina et Maximova, 2021 (Caenogastropoda: Benedictiidae) was designated as an obligate species; among bottom cottoid fishes, Neocottus werestschagini (Taliev, 1953) (Cottoidei: Abyssocottidae) had possible a transitional state to obligate. We presented the data on the assimilation by seep animals of mixed photo- and chemosynthetic food with different proportions of methane-derived carbon. A hypothesis has been substantiated that deep-water seep areas could serve as refugium for the preservation of endemic fauna during the Pliocene-Pleistocene glaciations of Lake Baikal.

An annotated type catalogue of freshwater sculpins (Cottoidei) described by Lev Berg.

The catalog is represented by type specimens of species and subspecies of cottoid fishes described by Lev S. Berg which are kept in the ichthyological collection of the Zoological Institute of Russian Academy of Sciences, St. Petersburg, Russia. The collection contains type specimens representing 14 taxa (species and subspecies) of the two families Abyssocottidae and Cottidae. In total, Lev S. Berg described one family, Cottocomephoridae, five genera, Abyssocottus, Asprocottus, Baicalocottus, Batrachocottus and Cottinella, 10 species and four subspecies. Four genera and 10 species are currently considered valid.

Organization of blood oxygen transport system for cottoid fishes of Lake Baikal

The blood of cottoid fishes has the lowest parameters that characterize the ability of heamoglobin to bind oxygen. Environmental characteristics of the species determine the morphological parameters of red blood cells and the structure of haemoglobins. In red blood cells of the Baikal yellowfin sculpin under the exposure of phenol, we revealed the damage of intracellular structures and a decrease in the number of active mitochondria by 60%.

PROBLEMS OF USING MOLECULAR-GENETIC METHODS FOR THE STUDY OF FISH FEEDING

The aim of the study was an approbation of molecular-genetic methods for an analysis of contents of fish stomachs of Abyssocottus korotneffi Berg, 1906, as an example.Methods. Sampling carried out at the board of the research vessel «G.Yu. Vereshchagin» in August 2017 in the northern basin of Lake Baikal. To study a fish feeding, testing of a DNA extraction methods and PCR conditions was performed. A fragments of the CO1 gene were amplified from total DNA isolated from the contents of the fish stomachs. The composition of food was studied based on the analysis of nucleotide sequences cloned into the plasmid pJET vector.Results. One species of amphipods closest to Odontogammarus calculator Dybowsky, 1874 was detected in fish food. In addition, sequences of cottoid fish were found in the studied samples. To date, information about a presence of fish in the food spectrum of this species was absent.Conclusions. The main problem of using molecular-genetic methods in studies of fish food spectrum is not enough number of data of voucher sequences of the CO1 gene of Baikal organisms in the genetic databases. Despite on advantages of analysis of the CO1 gene in studies of fish food feeding, this approach does not allow to distinguish between organisms of the same species.

Have Niche, Will Travel. New Means of Linking Diet and Ecomorphology Reveals Niche Conservatism in Freshwater Cottoid Fishes.

SynopsisEvolutionary transitions between habitats have been catalysts for some of the most stunning examples of adaptive diversification, with novel niches and new resources providing ecological opportunity for such radiations. In aquatic animals, transitions from saltwater to freshwater habitats are rare, but occur often enough that in the Neotropics for example, marine-derived fishes contribute noticeably to regional ichthyofaunal diversity. Here, we investigate how morphology has evolved in a group of temperate fishes that contain a marine to freshwater transition: the sculpins (Percomorpha; Cottoidea). We devised a novel method for classifying dietary niche and relating functional aspects of prey to their predators. Coupled with functional measurements of the jaw apparatus in cottoids, we explored whether freshwater sculpins have fundamentally changed their niche after invading freshwater (niche lability) or if they retain a niche similar to their marine cousins (niche conservatism). Freshwater sculpins exhibit both phylogeographical and ecological signals of phylogenetic niche conservatism, meaning that regardless of habitat, sculpins fill similar niche roles in either saltwater or freshwater. Rather than competition guiding niche conservatism in freshwater cottoids, we argue that strong intrinsic constraints on morphological and ecological evolution are at play, contra to other studies of diversification in marine-derived freshwater fishes. However, several intertidal and subtidal sculpins as well as several pelagic freshwater species from Lake Baikal show remarkable departures from the typical sculpin bauplan. Our method of prey categorization provides an explicit, quantitative means of classifying dietary niche for macroevolutionary studies, rather than relying on somewhat arbitrary means used in previous literature.

Structure features and structural transformations of the maxillary bones in the Baikal cottoid fish

In this paper, we study morphogeometric parameters and histostructure of maxillary bones in three coastal Baikal Cottoidei species belonging to different trophic groups. The results of the study revealed that the main trend in the transition from benthography to ichthyography is the sequential elongation of jaws and reduction in the mouth thrust accompanied by a consistent change in the form and internal structure of bone elements. A detailed analysis of data revealed that the changes mostly concern additional morphological structures (processes) of the bones directly connected with musculoligamentous apparatus and experiencing the highest tension during the functioning of the maxillary system. The distinctive features of the structural transformations maxillary bones in different fishes is a consequence of the uneven effect of power load that changes when the body adapts to certain habitat conditions.

Trophic relationships between macroinvertebrates and fish in St. Petersburg methane seep community in abyssal zone of Lake Baikal

Trophic relationships were examined for macroinvertebrates and fish inhabiting the St. Petersburg methane seep (central part of Lake Baikal, ~1400 m depth). The analyses of the values of carbon and nitrogen stable isotopes showed that all animals associated with the seep were heterotrophs with different feeding strategies; symbiotrophes were absent. Seep animals consumed combined food with different portion of methanederived carbon ranged from 2.7 to 89%. The average δ13С values varied in the range of–26.2‰ (in benthopelagic amphipods) to–64.5‰ (in gastropods). The trophic food web in the methane seep consists of filter feeders (pelagic amphipods, trophic position (TP) is 1.9), detritophages (gastropods, TP of 2.2, and burrowing amphipods, TP of 2.1), polyphages and necrophages (nectobenthic and benthopelagic amphipods of TP 2.8–3.2), and predators (planarians of TP 3.6–4.2 and cottoid fish of TP 3.0–3.8). Animals occupying similar trophic positions significantly differed in the δ13С values and have partially overlapping components of food.

Modulation of thermal noise and spectral sensitivity in Lake Baikal cottoid fish rhodopsins.

Lake Baikal is the deepest and one of the most ancient lakes in the world. Its unique ecology has resulted in the colonization of a diversity of depth habitats by a unique fauna that includes a group of teleost fish of the sub-order Cottoidei. This relatively recent radiation of cottoid fishes shows a gradual blue-shift in the wavelength of the absorption maximum of their visual pigments with increasing habitat depth. Here we combine homology modeling and quantum chemical calculations with experimental in vitro measurements of rhodopsins to investigate dim-light adaptation. The calculations, which were able to reproduce the trend of observed absorption maxima in both A1 and A2 rhodopsins, reveal a Barlow-type relationship between the absorption maxima and the thermal isomerization rate suggesting a link between the observed blue-shift and a thermal noise decrease. A Nakanishi point-charge analysis of the electrostatic effects of non-conserved and conserved amino acid residues surrounding the rhodopsin chromophore identified both close and distant sites affecting simultaneously spectral tuning and visual sensitivity. We propose that natural variation at these sites modulate both the thermal noise and spectral shifting in Baikal cottoid visual pigments resulting in adaptations that enable vision in deep water light environments.

Communities of the cottoid fish (Cottoidei) in the areas of hydrothermal vents and cold seeps of the abyssal zone of Baikal Lake

The hydrothermal vent in Frolikha Bay and the methane cold seep “Saint Petersburg” in Baikal Lake are characterized by the highly productive communities of the aquatic invertebrates and cottoid fish (Cottoidei). The benthic and pelagic ichthyofauna of the vent comprises twelve key species belonging to eight genera, while that of the seep comprise eight species (six genera belonging to three families). The only one obligate hydrothermal species, N. thermalis, has been found; it dominated by abundance (91.6% of total abundance) in Frolikha Bay. N. werestschagini dominated in the cold seep community (39.5%). The spatial distribution of the fish around the hydrothermal vents and the cold seeps was patchy. The largest schoolings has been observed in two biotopes, in the areas of the silty bottom sediments and at the areas covered by the bacterial mats, as well as in the near-bottom water layer.

The fishes and fishery in Lake Baikal

This article reviews the fish fauna of Lake Baikal, the world's deepest and largest lake in volume. The nucleus of the fish fauna of Lake Baikal is a unique complex of endemic cottoid fishes (56% of the total number of species and 41% of the total number of genera) and endemic species and subspecies of the coregonid and thymallid families. Abundance and composition of the fish fauna have changed during the 20th Century in each of the three main parts of the lake: north, central and south. Historical and present environmental conditions, such as main habitats, water quality and anthropogenic impacts, are discussed. Key objectives of fishery management on Lake Baikal include: (i) protection of fishes, especially commercial species, during periods of preparation for spawning, on spawning runs and in spawning areas; (ii) progressive restriction of the industrial fisheries and rapid expansion of sports and recreational fisheries; (iii) reallocation of priorities in the artificial breeding of fishes to restore the natural population structure of Omul and to restore the abundance of other valuable species that are important for sport fishing; (iv) prevention of the introduction into the Baikal basin of any new non-indigenous fish species; (v) conservation of habitats used by different ecological groups of fishes.

Karyotype characterization of the endemic piscine leech from Lake Baikal with vindication of Baicalobdella cottidarum Dogiel, 1957 (Piscicolidae, Hirudinea)

In this paper, we present for the first time data on karyotype analysis of leeches of the genus Baicalobdella (Piscicolidae) parasitizing Lake Baikal endemic cottoid fishes. Both mitotic and meiotic chromosomes are described. Leech testisacs were processed by a ?shaking-blotting? technique, and chromosomal preparations were stained with water-based fuchsine. Diploid and haploid chromosome sets demonstrated 2n=34 and n=17, respectively, with maximal chromosome length of 1.5-3.0 ?m. Comparative karyotype analysis of two ecological forms of Baicalobdella leeches revealed differences in chromosome numbers and its morphology. Previously studied Baicalobdella torquata (Grube, 1871) parasitizing Baikal amphipods had smaller diploid and haploid sets (2n=32, n=16). In addition to numerical superiority, differing patterns of chromosome size gradation and presence of satellite elements were found in the karyotype of piscine Baicalobdella leeches. This confirms the systematic position of the Baikal cottoid leech parasite as a separate species, validating the original name Baicalobdella cottidarum sensu Dogiel, 1957.

Fauna of cottoid fish (Cottoidei) in the area of methane seep in the abyssal of Lake Baikal.

Fauna of cottoid fish (Cottoidei) in the area of methane seep in the abyssal of Lake Baikal.

A new greenling (Teleostei, Cottoidei) from the Miocene of Sakhalin Island, Russia

ABSTRACT The Miocene deposits of the Agnevo Formation cropping out along the western coast of Sakhalin Island, Russia, are widely known for the well-preserved fossil remains of marine organisms, including a diverse assemblage of primarily benthic and demersal teleost fishes. †Sakhalinia multispinata, gen et sp. nov., a new cottoid fish from the Miocene (Serravallian–Tortonian) finely laminated sandstone of the Agnevo Formation, is described herein based on a single, nearly complete specimen in part and counterpart. Several morphological features indicate that †Sakhalinia multispinata is a basal member of the cottoid family Hexagrammidae. Within hexagrammids, †Sakhalinia multispinata exhibits a unique combination of features and is primarily typified by slender and recurved jaw teeth, 44 (22 + 22) vertebrae, 14 (6 + 8) principal caudal fin rays, a moderate consolidation of the caudal skeleton, an entire dorsal fin with 25 thick spines and 13 soft rays, anal fin with four strong spines and 12 soft rays, and ctenoid scales. The elongated, slender, and recurved jaw teeth displayed by †Sakhalinia multispinata suggest that this hexagrammid fish was specialized to feed mainly on small crustaceans.

Assessing the distinctiveness of the Cultus pygmy sculpin, a threatened endemic, from the widespread coastrange sculpin Cottus aleuticus

The Cultus pygmy sculpin is a cottoid fish endemic to Cultus Lake, southwestern British Columbia, Canada, and is listed as 'threatened' under the federal Species at Risk Act (SARA). The Cultus pygmy sculpin was first discovered and described as a 'dwarf' coastrange sculpin Cottus aleuticus in the 1930s. It matures at a smaller size than the 'normal' C. aleuticus, has a lacustrine life history rather than a fluvial one, has different morphological features, and appears to undertake diurnal feeding migrations into the water column to feed on Daphnia, but little else of its biology is known. We used molecular genetic and behavioural assays to further assess the level of differentiation between Cultus pygmy sculpin and stream-dwelling C. aleuticus from several locations. Mitochondrial DNA haplotypes were broadly shared between Cultus pygmy sculpin and coastrange sculpin, and there was no apparent phylogeographic structure. However, analysis of 8 microsatellite analysis loci indicated significant genetic differentiation between parapatric samples of both forms. Laboratory-based experiments showed that, in gen- eral, the Cultus pygmy sculpin was found higher in the water column and was more active off the bottom than coastrange sculpin, but these behavioural differences were influenced by the pres- ence of congeneric C. asper. Molecular and behavioural results support the recognition of the Cul- tus pygmy sculpin as a conservation unit distinct from 'typical' C. aleuticus because there is some level of genetic and behavioural discreteness between the forms, and behavioural differences may represent an important aspect of the pelagic life style of the Cultus pygmy sculpin.

Egg Deposition and Development of Eggs and Larvae of Bigmouth Sculpin (Hemitripterus bolini)

The Bigmouth Sculpin, Hemitripterus bolini, is a cottoid fish in the family Hemitripteridae found throughout the Bering Sea and Gulf of Alaska to British Columbia, Canada, and northern California. Hemitripterids have internal gametic association with external fertilization as their mode of reproduction. With this strategy, spermatozoa are stored in the micropyle of eggs within the ovary after gamete transfer to the female and eggs are not fertilized until immersed in seawater. Female H. bolini deposit their eggs into at least 4 species of sponges. We collected eggs from Barrel Sponge (Halichondria lambei), Clay-Pipe Sponge (Aphrocallistes vastus), Boot Sponge (Acanthascus dawsoni), and Tree Sponge (Mycale loveni) in the Gulf of Alaska and Bering Sea. In contrast to its congeners, there has been little research on H. bolini, particularly any focusing on aspects of early life history stages. In this study, we describe the development of H. bolini eggs and larvae from newly-hatched stages to juveniles, and include general observations of osteology. The descriptions of larvae and juveniles are based on examination of 32 specimens, 5 of which were differentially cleared and stained to examine osteological development. Larvae hatch at a large size (13 to 14 mm SL) in an advanced stage of development. Postflexion occurs at approximately 20 mm SL, and transformation to the juvenile stage begins at about 31 mm SL. Larvae are heavily pigmented through late flexion, when pigmentation becomes reduced. Postflexion larvae and juveniles are also heavily pigmented. Ossification of most skeletal elements does not occur until postflexion. The description will help distinguish H. bolini from other hemitripterids and sympatric larvae of the family Agonidae that are similar in appearance but generally smaller and more slender-bodied at all developmental stages. The behavior of egg deposition in sponges, in conjunction with the use of sponges by other fishes such as juvenile rockfish and invertebrates such as Golden King Crabs (Lithodes aequispina) as refuge habitat, suggests that sponge grounds may provide essential fish habitat for H. bolini and other species.

The comparative study of endemic cottoid fishes (Cottidae, Comephoridae) and their adaptation to pelagic habitat in Lake Baikal

This article describes the adaptive processes in the evolution of bladderless fish from benthic to secondary pelagic habitation in both Lake Baikal and the Antarctic eco-systems. It demonstrates how lipids play a major role in the achievement of neutral buoyancy by the endemic Baikalian species, genus Cottocomephorus (Cottidae family), and Comephorus (Comephoridae family), similar to the Antarctic secondary pelagic species of the Notothenioidei suborder. In addition, it also describes how the skeletons of these species became lighter due to bone mass reduction and lower mineralization; and how fin surface area became larger than that of the rest of the body in order for these secondary pelagic fish to attain appropriate balance and floatation.

Molecular divergence and speciation of Baikal oilfish (Comephoridae): Facts and hypotheses

Sympatric speciation was studied in two sister species of cottoid fish from Lake Baikal (East Siberia): big golomyanka or Big Baikal oilfish (Comephorus baicalensis Pallas, 1776) and small golomyanka or Little Baikal oilfish (C. dybowski Korotneff, 1905). Analysis of nucleotide sequences of mitochondrial cytochrome b gene showed that the Little Baikal oilfish (LBO) formed a single population in the lake, whereas the Big Baikal oilfish (BBO) was divided into two genetic groups - BBOI and BBOII, which were not separated geographically. Phylogenetic analysis showed that BBO is a more ancient species than LBO and that the paraphyletic origin of LBO is from the BBO genetic lineage within the genus Comephorus. Population-genetic structure and phylogenetic relationships between the two golomyanka species are considered to be a consequence of paleoenvironmental events that took place in the Baikal region during the past hundreds of thousand years.