Effects of forestry on the thermal habitat of Dolly Varden (<Emphasis Type="Italic">Salvelinus malma</Emphasis>)

Forestry activities in riparian areas are known to affect stream communities considerably. Not only do riparian deforestation resulting from agriculture or urbanization developments affect stream communities but extensive commercial plantation and forestry practices can alter stream environments adjacent to remaining, intact or secondary forests. Because forestry often includes the construction of logging roads through the riparian zone, this can directly degrade stream environments. Twelve streams in the Shiretoko Peninsula, Hokkaido were investigated so as to determine the effects of forestry practices on stream temperature, periphyton biomass, grazer (benthic invertebrates) biomass and Dolly Varden (Salvelinus malma Walbaum) biomass. The greater the proportion of planted area in the catchment, the higher the stream temperature. Stream temperature directly affects periphyton biomass and Dolly Varden biomass negatively. Neither stream temperature nor periphyton biomass predicted grazer biomass, whereas a positive correlation was found between grazer biomass and Dolly Varden biomass that forage on invertebrates. The overall results indicated that Dolly Varden in the Shiretoko streams were negatively affected by forestry practices and the resultant stream temperature increases. Without effective future riparian forest management, the complex effects of both riparian disturbance and ongoing global warming could further reduce Dolly Varden populations in the region.     

Population genetic structure of northern Dolly Varden char <Emphasis Type="Italic">Salvelinus malma malma</Emphasis> in Asia and North America

The level of genetic differentiation of northern Dolly Varden char Salvelinus malma malma from Asia and North America was evaluated using the data on mtDNA variation (regions ND1/ND2, ND5/ND6, and Cytb/D-loop) obtained by means of PCR-RFLP analysis. For S. m. malma, the mean values of haplo-type and nucleotide diversity were 0.5261 ± 0.00388 and 0.001558, respectively. The mean estimate of the population nucleotide divergence constituted 0.055%. It was demonstrated that S. m. malma on the most part of the species range examined (drainages of the Beaufort Sea, Chukotka Sea, Bering Sea, and the Sea of Okhotsk) was characterized by the population genetic structure with the low level of genetic differentiation and divergence. At the same time, populations from the Pacific Ocean Gulf of Alaska demonstrated marked genetic differentiation, supported by the high pairwise G4ST values (from 0.4198 to 0.5211) and nucleotide divergence estimates (mean divergence, 0.129%), from Asian and North American populations. Analysis of molecular variance (AMOVA) showed that most of the mtDNA variation in S. m. malma fell in the intrapopulation component (72.5%). At the same time, the differences between the populations (21.1%) and between the regions (6.4%) made lower contribution to the total variation.     

Genetic divergence of mitochondrial DNA in white char <Emphasis Type="Italic">Salvelinus albus</Emphasis> and northern Dolly Varden char <Emphasis Type="Italic">Salvelinus malma malma</Emphasis>

Comparative analysis of mitochondrial DNA variation was performed in white char Salvelinus albus Glubokovsky and in its putative ancestor species, northern Dolly Varden char Salvelinus malma malma Walbaum. Highly statistically significant differentiation of S. albus and S. m. malma in the areas of sympatric (Kamchatka River basin) and allopatric (Kronotskoe Lake and Kronotskaya River) residence was demonstrated. The mtDNA divergence between S. albus and S. m. malma did not exceed the range of intraspecific variation in the populations of northern Dolly Varden char. At the same time, clusterization pattern of the Salvelinus chars provides hypothesis on the common origin of two allopatric populations of white char. Genealogical analysis of haplotypes indicates that S. albus and S. m. malma currently demonstrate incomplete divergence of mitochondrial lineages. The low nucleotide divergence estimates between S. albus and S. m. malma reflect the short time period since the beginning of the divergence of ancestral lineages. These estimates are determined by ancestral polymorphism and haplotype exchange between the diverged phylogenetic groups as a result of introgressive hybridization.     

Genetic connectivity between sympatric populations of closely related char species,Dolly Varden <Emphasis Type="Italic">Salvelinus malma</Emphasis> and white char <Emphasis Type="Italic">Salvelinus albus</Emphasis>

The closely related chars Salvelinus malma and Salvelinus albus, which sympatrically inhabit the Kamchatka River basin and Kronotsky Lake (Kamchatka), attract the attention of the researchers because of their debated origin and taxonomic status. Previous studies of sympatric populations of these chars revealed small but statistically significant genetic differences between these species at a number of molecular markers, suggesting the presence of the genetic exchange and hybridization. In this study, based on genotypic characterization of nine microsatellite loci, a considerable level of historical and contemporary genetic migration between sympatric populations of these chars was demonstrated. At the individual level, a high degree of hybridization was observed, mainly among the Dolly Varden individuals from the studied populations. The obtained evidences on the genetic connectivity between sympatric S. malma and S. albus do not support the separate species status of S. albus.     

Flexible seaward migration of Dolly Varden <Emphasis Type="Italic">Salvelinus malma</Emphasis> in the Shiretoko Peninsula,Hokkaido, Japan

The migratory history of Dolly Varden Salvelinus malma was investigated in 30 streams in the Shiretoko Peninsula, Hokkaido, Japan, which is in the southern part of their distribution. Captured Dolly Varden were classified into two categories by their body coloration: silvery fish were thought to be an anadromous form, and non-silvery fish a fluvial form that remains in freshwater throughout its life. Forty-seven of 1,739 Dolly Varden collected in the spring and ten of 2,126 Dolly Varden collected in the autumn were silvery fish. Twenty silvery fish and 120 non-silvery fish were examined by analysis of otolith Sr:Ca ratio. Three silvery fish from autumn and 15 non-silvery fish had migrated to salt water or brackish water. The other specimens of silvery fish were regarded as smolt or pre-smolt before seaward migration. The present study suggests that Dolly Varden in the Shiretoko Peninsula have a flexible migratory history, where some of the non-silvery fish utilize marine environments while some individuals follow an anadromous life history.     

Differentiation of Dolly Varden Char <Emphasis Type="Italic">Salvelinus malma</Emphasis> from Asia and North America Inferred from PCR-RFLP Analysis of Mitochondrial DNA

Genetic differentiation of Dolly Varden char Salvelinus malma Walbaum from the Asian and North American Pacific coasts was studied. We examined restriction fragment length polymorphism of three mitochondrial DNA (mtDNA) fragments amplified in polymerase chain reaction, which encoded four NADH dehydrogenase subunits, the cytochrome b gene, and a D-loop segment. The mtDNA haplotypes were shown to form three phylogenetic groups, whose geographic distribution corresponded to three Dolly Varden subspecies: S. malma malma, S. malma krascheninnikovi, and S. malma lordi. The nucleotide sequence divergence between S. malma malma and S. malma krascheninnikovi was 3.8%; between S. malma malma and S. malma lordi, 3.1%; and between S. malma krascheninnikovi and S. malma lordi, 2.5%. The northern Dolly Varden S. malma malma from Asia was shown to be genetically identical to that from North America.__________Translated from Genetika, Vol. 41, No. 5, 2005, pp. 626–634.Original Russian Text Copyright © 2005 by Oleinik, Skurikhina, Brykov, Crane, Wenburg.     

Genetic relationships of Chukchi charr <Emphasis Type="Italic">Salvelinus andriashevi</Emphasis> and Taranetz charr <Emphasis Type="Italic">Salvelinus taranetzi</Emphasis>

On the basis of sequence analysis of the mitochondrial DNA (mtDNA) control region (CR), cytochrome b (Cytb), and cytochrome oxidase-1 (CoI) genes, the relationships of endemic species Salvelinus andriashevi Berg, 1948, represented by the only population from Lake Estikhed (Chukotka), were estimated. The data on the genealogical analysis of mtDNA haplotypes supported phylogenetic closeness of S. andriashevi and S. taranetzi. It was also demonstrated that the specimens of Chukchi charr, along with Salvelinus sp. 4 (Lake Nachikinskoe), S. krogiusae (Lake Dal’nee), S. boganidae and S. elgyticus (Lake El’gygytgyn), and S. a. erythrinus from Canada’s Northwest Territories (NWT) belonged to the Arctic group of Taranetz charr. The problem of coincidence of taxonomic differentiation of charrs of the genus Salvelinus based on morphological and genetic analyses is discussed.     

The trace element contents in tissues of Dolly Varden <Emphasis Type="Italic">Salvelinus malma</Emphasis> Walbaum, 1792 sympatric morphs from Lake Kronotskoe (Kamchatka)

The liver, gonads, gills, and muscles of five trophically distant charr morphs from Lake Kronotskoe, as well as silty sediments of the lake, were tested for trace-element contents. Concentrations of Mn, Fe, Ni, Cu, Zn, Rb, Sr, As, and Se were detectable in the fish tissues, while the xenobiotics Hg, Cd, and Pb were not determined. The current data indicate a strong correlation between trace-element content and the ecology of each morph and no relationship to the fish length. In the majority, the Ni, Cu, and Zn levels were strongly dependent on trophic biology. The contents of Rb, Mn, and Se were dependent on the distribution of the charr morphs along the depth gradient and correlated with the accumulation of these elements in the bottom sediments.     

A comparison of different structures and methods for estimating age of northern-form Dolly Varden <Emphasis Type="Italic">Salvelinus malma malma</Emphasis> from the Canadian Arctic

Assessment of anadromous northern-form Dolly Varden Salvelinus malma malma in the Western Canadian Arctic requires reliable methods for estimating ages. Additionally, conservation efforts warrant determining whether fin rays provide a non-lethal alternative to otoliths. Precision and bias of whole and sectioned otoliths, and sectioned pectoral and pelvic fin rays were examined. Two age readers with different levels of experience ageing this species read each structure three times. Coefficient of variation (CV) was calculated to measure precision, and age bias plots were created for each method of preparation/structure within and between readers. The experienced reader demonstrated the highest precision with sectioned otoliths (CV = 1.6 %) followed by whole otoliths (CV = 4.2 %) while pectoral and pelvic fins were the lowest, CV = 7.7 % and 7.5 %, respectively. The age bias plot showed little difference between whole and sectioned otoliths, although greater imprecision/bias was evident for whole otoliths at age ≥9. Compared to otoliths, fin rays produced younger age estimates starting at 5 years; however, pelvic fins were more biased towards younger estimates than pectoral fins. The less experienced reader had greater inconsistencies, tending to overage younger and underage older samples for all methods compared to the more experienced reader, underscoring the importance of experience when estimating age for this species. We conclude that both types of fin rays are a poor non-lethal alternative to otoliths for fish ≥5 years and recommend an experienced ager could use whole otoliths up to age 8 and sectioned otoliths for fish ≥9 years (>500 mm fork length).     

Differentiation of deep-water lake charr <Emphasis Type="Italic">Salvelinus namaycush</Emphasis> in North American lakes

Deep-water morphs of lake charr, Salvelinus namaycush, are found, with one exception, in four of the largest lakes in the world: lakes Superior and Mistassini (QC) and Great Bear and Slave lakes. This paper advances a hypothesis for resource polymorphisms involving two types of deep-water morph, one of which is characteristic of the humper and the other of the siscowet charrs of Lake Superior. My hypothesis states that, first, the humper, or a humper-like morph, diverged postglacially in sympatry from the ancestral common (shallow-water) lake charr and became a feeding specialist on Mysis relicta. Second, in at least two of the four lakes the siscowet, or a siscowet-like charr, diverged as a feeding specialist on postglacially derived forms of deep-water ciscoes. In Lake Superior a successional process may have resulted in dominance of the siscowet at the expense of the humper charr. I concur with a previous inference that the one occurrence of a deep-water charr in a small lake (the above exception) represents emigration from Lake Superior. I further infer that this event involved an early humper charr, which implies that this morphotype had differentiated in Lake Superior in less than 1,900 year. I suggest that innate differences in plasticity, breeding behavior and assortive mating, and philopatry account for why Arctic charr isolate readily in small lakes whereas lake charr do not. My hypothesis assumes divergence of deep-water morphs occurred postglacially, an idea consistent with genetic and biogeographical evidence.     

<Emphasis Type="Italic">Gyrodactylus salaris</Emphasis> (Monogenea,Gyrodactylidae) infections on resident Arctic charr (<Emphasis Type="Italic">Salvelinus alpinus</Emphasis>) in southern Norway

This study surveys the distribution of Gyrodactylus salaris on resident Arctic charr, Salvelinus alpinus, in lakes connected to three south-Norwegian watercourses: Numedalsvassdraget, Skiensvassdraget and Hallingdalsvassdraget. Gyrodactylus salaris infected charr was only recorded in Numedalsvassdraget. The parasites had the same mitochondrial haplotype as those previously reported on charr in Lake Pålsbufjorden, which is part of Numedalsvassdraget. Since the G. salaris-charr association is persistent in Pålsbufjorden and has a wide distribution above the stretches of the watercourse inhabited by anadromous salmonids, this is considered a stable, although perhaps relatively young, host-parasite system. More detailed analyses of these interactions revealed seasonal variations in the parasite population dynamics between late summer and late autumn, with heavier infections occurring in males and older fish in October. This is explained by the combined action of seasonal differences in temperature and physiology and ecology of host cohorts. It is assumed that the occurrence of G. salaris on charr in Pålsbufjorden resulted from a host switch to charr from rainbow trout, Onchorynchus mykiss. Host switches may cause significant expansions of the geographical range of pathogenic variants of G. salaris. Therefore, observations of frequently occurring G. salaris on charr have implications for the diagnosis, management and control of salmonid gyrodactylosis.     

Stream-dwelling Dolly Varden (<Emphasis Type="Italic">Salvelinus malma</Emphasis>) density and habitat characteristics in stream sections installed with low-head dams in the Shiretoko Peninsula,Hokkaido, Japan

Numerous low-head dams have been constructed for erosion control and installed in almost all mountainous streams in Japan. Shiretoko Peninsula, Hokkaido, is considered as one of the most intact areas in Japan, however, more than 331 low-head dams have been installed in 39 streams of the peninsula since the 1960s. In this study, the density of stream-dwelling Dolly Varden (Salvelinus malma) and the habitat characteristics in dam-installed sections were investigated in Shiretoko streams and compared with unaltered sections in which no dams have been installed as a reference. Fish density in dam-installed sections was significantly lower than reference sections. Canopy cover, maximum temperature, wetted width, frequencies of pebble, bedrock and boulder, and areas of rapid, glide and riffle was significantly differed between dam-installed and reference sections. High stream temperature, occurrence of glides, and loss of boulder in dam-installed sections may reduce the suitability of habitats for fish and minimize the population size. We suggest that negative effects of dam installations on Dolly Varden populations have occurred in Shiretoko streams.     

Observations of a wild polar bear (<Emphasis Type="Italic">Ursus maritimus</Emphasis>) successfully fishing Arctic charr (<Emphasis Type="Italic">Salvelinus alpinus</Emphasis>) and Fourhorn sculpin (<Emphasis Type="Italic">Myoxocephalus quadricornis</Emphasis>)

Polar bears, Ursus maritimus, throughout their range, are nutritionally dependent on ringed (Phoca hispida) and bearded seals (Erignathus barbatus), which are predominantly caught on the sea ice. Other marine prey species are caught and consumed, but less frequently. As the annual sea ice retreats, polar bears throughout their range are forced ashore, where they mostly live off their stored adipose tissue. However, while land-bound they have been observed catching birds and terrestrial mammals. Although polar bears evolved from brown bears (U. arctos), direct observations of polar bears diving for and catching fish have not been reported. Here, we document observations of a young male polar bear catching Arctic charr (Salvelinus alpinus) and Fourhorn sculpin (Myoxocephalus quadricornis) by diving in Creswell Bay, Nunavut. We recorded six search bouts, where six fish were caught during dives, which were preceded by a snorkel. The average dive and snorkel length was (mean ± SD) 13 ± 5 and 6 ± 2 s, respectively.     

Morphophysiological patterns of life history strategy adoption in Dolly Varden <Emphasis Type=Italic>Salvelinus malma</Emphasis> in Kamchatka

Growth, age composition, gonad maturity and patterns of life history strategy adoption in the population of Dolly Varden from the Kol River (West Kamchatka) are studied. Major factors controlling differentiation of juveniles and trajectories of ontogenetic developments, growth rate and gametogenesis in generations in particular years. The differentiation in a generation into anadromous and resident groupings is completed mainly at the age of 4 years. The process of formation of resident and migratory life history strategy in Dolly Varden is epigenetic. Bifurcation in the life of one specimen is observed once in life, and that in a generation is observed four times: at the first, the second, the third, or the fourth year. The life cycle of females from the Kol River is invariant until they reach the age of 1 year, and that in males is during the 4 years of the freshwater phase. In Kamchatka, all spawners, including precocious males, may reproduce several times during life.     

Diversity of nosed charrs <Emphasis Type="Italic">Salvelinus malma</Emphasis> (Salmonidae) of Lake Kronotskoe (Kamchatka)

The littoral benthivorous charrs Salvelinus malma with subterminal mouth distributed in Lake Kronotskoe basin are separated into three distinct morphs. These morphs significantly differ in head proportions, jaws' length, skull structure, and degree of gill rakers' reduction. The morphs spawn in distant lake tributaries at the spawning grounds of various types. Joint spawning has never been observed for these morphs in any type of spawning grounds. The differences in the external morphology and growth rate of the morphs become evident during the riverine life stage. The adult charrs inhabit the same sites of the littoral zone. No reliable difference is found in the diet among morphs, since all nosed charrs dominantly feed on amphipods with the exception of a few individuals that fed on chironomid larvae.     

Phylogeography of southern Asian Dolly Varden char <Emphasis Type="Italic">Salvelinus malma krascheninnikovi</Emphasis>: Genealogical analysis of mitochondrial DNA

Phylogeography of southern Asian Dolly Varden char was studied using the data on mtDNA variation (regions ND1/ND2, ND5/ND6, and Cytb/D loop) obtained using PCR-RFLP analysis. Analysis of contemporary population genetic structure showed that Salvelinus malma krascheninnikovi throughout the whole species range was characterized by high population differentiation in combination with rather small differences between the populations from remote regions. The genealogy of mtDNA haplotypes was reconstructed and nested clade analysis of geographical distances was performed. Geographical distribution of mtDNA haplotypes of S. m. krascheninnikovi was explained by population genetic processes (restricted gene flow), as well as by historical demographic events (range expansion and fragmentation). It was demonstrated that the main demographic events were associated with cyclic processes of the geological formation of the Sea of Japan and adjacent territories. Furthermore, genealogical tree of S. m. krascheninnikovi contained the traces of secondary contact between isolated phylogeographical lineages.     

<Emphasis Type="Italic">Ty</Emphasis>1<Emphasis Type="Italic">/copia</Emphasis>- and <Emphasis Type="Italic">Ty</Emphasis>3<Emphasis Type="Italic">/gypsy</Emphasis>-like DNA sequences in <Emphasis Type="Italic">Helianthus </Emphasis>species

Two repeated DNA sequences isolated from a partial genomic DNA library of Helianthus annuus, p HaS13 and p HaS211, were shown to represent portions of the int gene of a Ty3 /gypsy retroelement and of the RNase-Hgene of a Ty1 /copia retroelement, respectively. Southern blotting patterns obtained by hybridizing the two probes to BglII- or DraI-digested genomic DNA from different Helianthus species showed p HaS13 and p HaS211 were parts of dispersed repeats at least 8 and 7 kb in length, respectively, that were conserved in all species studied. Comparable hybridization patterns were obtained in all species with p HaS13. By contrast, the patterns obtained by hybridizing p HaS211 clearly differentiated annual species from perennials. The frequencies of p HaS13- and p HaS211-related sequences in different species were 4.3x10(4)-1.3x10(5) copies and 9.9x10(2)-8.1x10(3) copies per picogram of DNA, respectively. The frequency of p HaS13-related sequences varied widely within annual species, while no significant difference was observed among perennial species. Conversely, the frequency variation of p HaS211-related sequences was as large within annual species as within perennials. Sequences of both families were found to be dispersed along the length of all chromosomes in all species studied. However, Ty3 /gypsy-like sequences were localized preferentially at the centromeric regions, whereas Ty1/ copia-like sequences were less represented or absent around the centromeres and plentiful at the chromosome ends. These findings suggest that the two sequence families played a role in Helianthusgenome evolution and species divergence, evolved independently in the same genomic backgrounds and in annual or perennial species, and acquired different possible functions in the host genomes.     

New combinations and typifications in <Emphasis Type="Italic">Bistorta</Emphasis>, <Emphasis Type="Italic">Persicaria</Emphasis>, <Emphasis Type="Italic">Polygonum,</Emphasis> and <Emphasis Type="Italic">Rumex</Emphasis> (Polygonaceae)

New combinations are proposed in anticipation of the Polygonaceae treatment in the forthcoming volume of Intermountain Flora: Polygonum kelloggii var. esotericum, P. kelloggii var. watsonii , Rumex densiflorus var. pycnanthus , R. salicifolius var. utahensis, and R. occidentalis var. tomentellus. Typifications are proposed to facilitate ongoing studies in Polygonaceae and to maintain current usage.     

<Emphasis Type="Italic">In silico</Emphasis> and <Emphasis Type="Italic">in situ</Emphasis> characterization of the zebrafish (<Emphasis Type="Italic">Danio rerio</Emphasis>) <Emphasis Type="Italic">gnrh3</Emphasis> (sGnRH) gene

Background

Gonadotropin releasing hormone (GnRH) is responsible for stimulation of gonadotropic hormone (GtH) in the hypothalamus-pituitary-gonadal axis (HPG). The regulatory mechanisms responsible for brain specificity make the promoter attractive for in silico analysis and reporter gene studies in zebrafish (Danio rerio).

Results

We have characterized a zebrafish [Trp⁷, Leu⁸] or salmon (s) GnRH variant, gnrh 3. The gene includes a 1.6 Kb upstream regulatory region and displays the conserved structure of 4 exons and 3 introns, as seen in other species. An in silico defined enhancer at -976 in the zebrafish promoter, containing adjacent binding sites for Oct-1, CREB and Sp1, was predicted in 2 mammalian and 5 teleost GnRH promoters. Reporter gene studies confirmed the importance of this enhancer for cell specific expression in zebrafish. Interestingly the promoter of human GnRH-I, known as mammalian GnRH (mGnRH), was shown capable of driving cell specific reporter gene expression in transgenic zebrafish.

Conclusions

The characterized zebrafish Gnrh3 decapeptide exhibits complete homology to the Atlantic salmon (Salmo salar) GnRH-III variant. In silico analysis of mammalian and teleost GnRH promoters revealed a conserved enhancer possessing binding sites for Oct-1, CREB and Sp1. Transgenic and transient reporter gene expression in zebrafish larvae, confirmed the importance of the in silico defined zebrafish enhancer at -976. The capability of the human GnRH-I promoter of directing cell specific reporter gene expression in zebrafish supports orthology between GnRH-I and GnRH-III.

     

Winter ecology of Arctic charr (<Emphasis Type="Italic">Salvelinus alpinus</Emphasis>) and brown trout (<Emphasis Type="Italic">Salmo trutta</Emphasis>) in a subarctic lake,Norway

We studied habitat choice, diet, food consumption and somatic growth of Arctic charr (Salvelinus alpinus) and brown trout (Salmo trutta) during the ice-covered winter period of a subarctic lake in northern Norway. Both Arctic charr and brown trout predominantly used the littoral zone during winter time. Despite very cold winter conditions (water temperature <1°C) and poor light conditions, both fish species fed continuously during the ice-covered period, although at a much lower rate than during the summer season. No somatic growth could be detected during the ice-covered winter period and the condition factor of both species significantly declined, suggesting that the winter feeding rates were similar to or below the maintenance requirements. Also, the species richness and diversity of ingested prey largely decreased from summer to winter for both fish species. The winter diet of Arctic charr <20 cm was dominated by benthic insect larvae, chironomids in particular, and Gammarus lacustris, but zooplankton was also important in December. G. lacustris was the dominant prey of charr >20 cm. The winter diet of brown trout <20 cm was dominated by insect larvae, whereas large-sized trout mainly was piscivorous, feeding on juvenile Arctic charr. Piscivorous feeding behaviour of trout was in contrast rarely seen during the summer months when their encounter with potential fish prey was rare as the small-sized charr mainly inhabited the profundal. The study demonstrated large differences in the ecology and interactions of Arctic charr and brown trout between the winter and summer seasons.