Microsatellites from the burbot (Lota lota), a freshwater gadoid fish (Teleostei)

We developed 21 polymorphic dinucleotide microsatellite loci, (CA)_n and (CT)_n, for the Holarctic freshwater fish, Lota lota, using an enriched genomic library protocol. The species has an interesting life history because winter‐spawning adults migrate over long distances to form spawning aggregations, a behaviour which should maintain genetic homogeneity across large spatial scales. Availability of the reported microsatellites will facilitate the investigation of population genetic structure with regard to postglacial colonization history and conservation strategies. The primers were screened on 30 individuals from a natural population (Lake Constance, southern Germany), revealing three to 24 alleles per locus with expected heterozygosities ranging from 0.48 to 0.93.     

The status of the burbot Lota lota (L.) (Gadidae) in Britain

Records of burbot Lota lota (L.) captures from the early nineteenth century to the present have been gathered and arranged watershed by watershed in chronological order. Most are from eastward-flowing river systems from Durham southwards to the Great Ouse, but a few records from westward-flowing systems are considered. In many areas the records imply a decline of burbot numbers and distribution during the present century, though burbot may never have been more than locally abundant. Local over-fishing, pollution and habitat changes are considered the most likely causes of decline. Conservation measures seem desirable.     

Population genetic structure and geographical differentiation of burbot (Lota lota) in China

The burbot (Lota lota Linnaeus, 1758) is the only freshwater species of the family Gadidae. There is a longstanding controversy about taxonomic status of the burbot from the Amur River basin. It is necessary to investigate population genetic structure and geographical differentiation among burbot populations from the Irtysh River basin and Amur River basin by mitochondrial DNA nucleotide sequence analysis. A 572 bp segment of cytochrome b and 425 bp segment of control region gene were sequenced from 4 populations. The results showed that there was lower genetic diversity of burbot in China and highly significant genetic difference between populations in the Amur River basin (P < 0.01). Demographic analysis indicated that the burbot from the Amur River basin experienced population expansion (Cytb: F _S = ? 0.912 (P = 0.287), D = ? 0.399 (P = 0.375); CR: F _S = ?4.771 (P = 0.015), D = ?1.523 (P = 0.03)). The data of 4 populations in China combining with the published data representing the Eurasian and North American burbot, revealed three distinct phylogenetic lineages (labelled EB, NA, Amur).     

A checklist of protozoan and metazoan parasites of the burbot (Lota lota)

The parasite fauna of the burbot (Lota lota) within its natural range is reviewed. The sent paper summarizes the data on parasites of the burbot from water bodies of Eurasia and North America, based on published monographs, reviewed journals, scientific reports, conference contributions, and PhD theses. The checklist includes all protozoan and metazoan parasites of the burbot. A total of 242 parasite species/taxa were recorded in the burbot (Ki-netoplastomonada--4, Parasitomonada--3, Coccidiomorpha--1. Microsporidea--3, Myxosporidia--35, Pleurostomata--1. Cyrtostomata--3, Peritricha--20. Protozoa incertae sedis--1. Monogenea--8, Cestoda--23, Digenea--50. Nematoda--36, Acanthocephala--28, Hirudinea--11. Bivalvia--5, Crustacea--10). Most parasites belong to digenean trematodes. Most of these species (183 species/taxa) were recorded on Eurasian and only 92--in North America fishes. Several parasite species recorded from the burbot are discussed in relation to host specificity and their geographical distribution.     

Indications of polymorphism in the behaviour and morphology of burbot (Lota lota) in a European lake

Hydrobiologia - In this study, polymorphism in behaviour, morphology, and stable isotope signatures of burbot from Lake Southern Konnevesi, Finland, Europe, was examined. First, local knowledge was...     

Phylogenetic relationships among Palearctic and Nearctic burbot (Lota lota): Pleistocene extinctions and recolonization

The burbot (Lota lota Linnaeus, 1758) is the only freshwater species from the cod family. Various taxonomic hypotheses were tested against molecular data by sequencing the mitochondrial cytochrome b locus of 120 burbot from 41 populations together with the related species Molva molva (ling) and Brosme brosme (tusk), which represented the other Lotinae genera. Within the genus Lota two distinct phylogroups were observed: one in North America south of the Great Slave Lakes (Lota lota maculosa) and one in Eurasia and the remainder of the Nearctic region (Lota lota lota). The burbot lineage separated 10 Myr BP from the other Lotinae, while the genetic variation within burbot appeared to be approximately 1 Myr old. However, fossil evidence suggested that burbot already existed in the Early Pliocene in Europe, from were it probably colonized North America in the Early Pleistocene. While Nearctic burbot survived climatic oscillations and diverged in several refugia, the Eurasian form became extinct or was reduced to a very small population. In the Late Pleistocene the species recolonized the Palearctic region to establish its present distribution range.     

Discriminating glacial races of burbot (Lota lota) by means of PCR‐RF‐SSCP (PRS) analysis of the mitochondrial control region

We used closely related haplotypes of the mitochondrial control region of burbot (Lota lota) (Teleostei; Gadidae) with known sequences to assess the sensitivity of a standardized PRS (PCR‐RF‐SSCP) approach. In total, 537 pairwise comparisons between PRS patterns were evaluated. Only seven mutations did not result in a detectable change that resulted in 11 pairwise comparisons (2%) with indistinguishable haplotypes. The haplotypes that could not be discriminated were always characteristic for a certain assemblage (glacial race). As such, this method provides a reliable alternative to direct sequencing for phylogeographic studies in case intrapopulation diversity is limited.     

The cryopreservation of spermatozoa of the burbot,Lota lota (Gadidae,Teleostei)

The cryopreservation of spermatozoa of a teleost fish, the burbot, Lota lota (Gadidae) was investigated. Cryopreserved semen had the highest motility rate (46.6+/-8.0%, fresh semen control 86.5+/-8.2%) and fertility (78.1+/-2.7% embryo survival in hatching stage, fresh semen control 82.2+/-2.9%) when 10% methanol, 1.5% glucose and 7% hen egg yolk were used as cryoprotectants. Freezing was performed in 0.5-ml straws in the vapour of liquid nitrogen at 1cm above the level of liquid nitrogen and thawing in water at 25 degrees C for 20s. For optimal fertilization cryopreserved semen was first mixed with the eggs and then 25 or 50 mmol/L NaCl solution (pH 8.5) was added at a ratio of 1:24 (semen:saline solution). Under these conditions fertilization ratios in the range of fresh semen control were obtained at minimal sperm to egg ratios of 1.7 x 10(6):1. Fertilization with cryopreserved semen had no influence on the embryonic development, as the ratio of embryos which stopped development and the ratio of embryonic malformations were similar to fresh semen.     

Larval morphology of North American burbot (Lota lota maculosa) from two spatially separated populations

Hydrobiologia - Burbot (Lota lota) are a freshwater fish that exhibits a circumpolar distribution and is considered an indicator species for climate change. Adult burbot were artificially...     

Oxygen consumption of burbot, Lota lota(L.), fed different rations of vendace, Coregonus albula L.

The oxygen consumption of adult burbot, Lota lota (L.), was examined to determine the effects of fasting and meal ration on oxygen consumption rates. The temperature (2.1 °C) was selected to represent ambient conditions for burbot in winter. The average pre‐feeding oxygen consumption rate was 29.5 mg kg^?1 h^?1. Feeding affected the oxygen consumption rates since the apparent heat increment correlated significantly with the meal ration. However, the meal ration (i.e. vendace, Coregonus albula L.) did not affect the proportion of the ingested meal energy used in the apparent heat increment. When the meal ration was increased, peak oxygen consumption ranged from 1.2 to 2.2 times higher than the fasting level. Observed low oxygen consumption values suggest that the metabolic processes of burbot are strongly reduced in low temperatures.     

Genetic admixture of burbot (Teleostei: Lota lota) in Lake Constance from two European glacial refugia

The burbot, Lota lota, is the only freshwater species of the codfish family and has a Holarctic distribution. Pleistocene glaciations caused significant geographical differentiation in the past, but its life history characterized by winter spawning migrations over large distances is likely to homogenize populations by contemporary gene flow. We investigated the population genetic structure of 541 burbots from Lake Constance and adjacent Rhine and Danube tributaries in Europe using the entire mitochondrial DNA (mtDNA) control region and 11 microsatellites. Microsatellites revealed considerable population divergence (F(ST) = 0.26) and evidenced recent bottlenecks in two Central European rivers. In accordance to previous evidence two main phylogeographic lineages (Atlantic and Danubian) were found co-occurring at similar frequencies in Lake Constance, where they currently undergo random mating as indicated by microsatellites. The Danubian lineage contributed only a small proportion to the lake's mtDNA diversity, and probably expanded within the lake shortly after its formation approximately 10,000-15,000 BP. The larger Atlantic haplotype diversity suggested a population expansion older than the lake itself. Levels of admixture at microsatellite loci were less obvious due to their high variability, and coalescence methods were used to estimate past admixture proportions. Our results reinforce a model of a two-step colonization of Europe by burbot from an ancestral Danubian refuge, and confirm the persistence of a secondary Atlantic refuge, as proposed to exist for other freshwater fish. We conclude that the present-day burbot population in Lake Constance bears the genetic signature of both contemporary gene flow and historical separation events.     

Leptin,ghrelin, and energy metabolism of the spawning burbot (Lota lota,L.)

The aim of this study was to investigate the energy metabolism of the burbot (Lota lota, n=38) before, during, and after spawning, which represents the greatest annual metabolic demand for the species. A decrease in body mass, relative weight of the livers, and glycogen concentration of the livers was observed toward the end of spawning. The prespawning period was characterized by high rates of liver glycogenolysis and lipid mobilization. Also, plasma triiodothyronine and sex steroid levels were high before reproduction. During spawning, liver lipolysis was reduced and muscle glycogenolysis stimulated. The levels of triiodothyronine and sex steroids decreased. After reproduction, liver glycogenolysis was suppressed and the rate of gluconeogenesis increased. Thyroid hormone levels were elevated after spawning. Leptin protein and a ghrelin-immunoreactive peptide were detected in burbot plasma. Their concentrations were relatively low before and during reproduction but increased after spawning. The functions of leptin and the ghrelin-immunoreactive peptide in the physiology of the burbot are not consistent with the models of their function in mammals.     

Diet, prey selection, and growth of larval and juvenile burbot Lota lota (L.)

The diet, prey selection, and growth of larval and juvenile Oneida Lake burbot, Lota lota (L.), was investigated from the time of first hatch in mid-April until their disappearance from the pelagic zone at the beginning of June. Mean length increased exponentially from 3–20 mm on 18 April to 15–00 mm on 29 May. The number and size of prey in burbot stomachs, and the prey size most selected by burbot increased as they grew. Prey width, not prey length, limited the size of prey ingested. The smallest burbot ate and selected highly for the largest prey they could ingest, but older burbot did not. As burbot grew, prey selection was highest first for the rotifer Asplanchna , followed by copepod nauplii, then cyclopoid copepods. Daphnia and calanoid copepods and cyclopoid copepods were selected to similar degrees by 29 May. For a given size, however, cyciopoid copepods were selected more strongly than any other prey type from 18 to 29 May. There were no significant differences in prey selection among offshore, nearshore, and onshore habitats, nor among depths in the offshore habitat.     

The response of burbot (Lota lota) to change in lake trout (Salvelinus namaycush) abundance in Lake Opeongo,Ontario

The purpose of this study was to test the hypothesis that the burbot and lake trout compete with or prey on each other, and that a change in the abundance of lake trout has triggered a response in the burbot population. Burbot growth, length-weight relationship and population size did not change, and it appears that at these population levels, the changes in lake trout abundance had no detectable effect on burbot. It is suggested that the burbot population in Lake Opeongo is limited at the larval stage by competition with, or predation by, a planktivore, the lake herring.     

Seasonal changes in morphometric and biochemical endpoints in northern pike (Esox lucius), burbot (Lota lota) and slimy sculpin (Cottus cognatus)

1. Morphometric and biochemical endpoints were used to assess growth and energetics in young‐of‐the‐year (YOY) northern pike (Esox lucius), YOY burbot (Lota lota) and slimy sculpin (Cottus cognatus) collected upstream and downstream of a uranium mining operation in northern Saskatchewan, Canada. 2. Water sampled at sites downstream of uranium mining and milling effluent discharge was higher in certain trace metals (arsenic, molybdenum), ions (conductivity, hardness, ammonia and sulphate) and total dissolved solids compared with ecologically similar reference sites. 3. Overwinter survival potential was estimated by determining total body lipids and total body triglycerides in fishes collected in late autumn and early spring. Two‐factor anova indicated no site or season differences in total body lipids or triglycerides in YOY northern pike. In spring, burbot collected from the exposure site were higher in total body lipids and triglycerides compared with the previous autumn and compared with fish collected from the reference site. Slimy sculpin from both exposure and reference sites had lower total body lipid and triglyceride content in spring compared with the previous autumn. In addition, sculpin from the exposure site had lower total body lipids and triglycerides in spring compared with fish collected from the reference site. 4. Biochemical estimates of fish growth (muscle RNA/DNA ratio and muscle protein concentration) exhibited clear seasonal differences, with consistent decreases in this endpoint for all fish species in spring relative to the previous autumn at both exposure and reference sites. 5. Results for total body lipids and triglycerides were inconclusive and inconsistent between species and exposure scenarios. However, all species exhibited a similar seasonal decrease in muscle protein and to a lesser extent, muscle RNA/DNA ratio.     

Isolation and characterization of new microsatellite markers from the burbot (Lota Lota)

Ten polymorphic microsatellite markers were developed to examine the population structure of the burbot (Lota Lota). The number of alleles ranging from 2 to 14 and the expected heterozygosity ranging from 0.306 to 0.926 were screened in the wild samples from Wusuli River in Heilongjiang Province, China. Eight loci significantly deviated from Hardy–Weinberg equilibrium. No evidence showed significant linkage disequilibrium between pairs of loci. These newly isolated markers would also enrich the available molecular resources of the burbot.