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Mercury is a highly toxic element for consumers, but its relation to amino acids and physiology of wild fish is not well known. The main aim of this study was to evaluate how total mercury content (THg) of northern pike (Esox lucius) is related to amino acids and potentially important environmental and biological factors along a climate-productivity gradient of ten subarctic lakes. Linear regression between THg and sixteen amino acids content [nmol mg−1 dry weight] from white dorsal muscle of pike from these lakes were tested. Lastly, a general linear model (GLM) for age-corrected THg was used to test which factors are significantly related to mercury content of pike. There was a positive relationship between THg and proline. Seven out of sixteen analysed amino acids (histidine, threonine, arginine, serine, glutamic acid, glycine, and aspartic acid) were significantly negatively related to warmer and more productive lakes, while THg showed a positive relationship. GLM model indicated higher THg was found in higher trophic level pike with lower cysteine content and inhabiting warmer and more productive lakes with larger catchment containing substantial proportion of peatland area. In general, THg was not only related to the biological and environmental variables but also to amino acid content. peerReviewed

STRUCTURE-HARVESTER results for the Lake Engervann sticklebacks. (PDF 640 kb)

The invertebrate fauna sampled on four locations (with an equal sampling effort performed on each locations) in the littoral area in the brackish water Lake Engervann on two dates (data report number of individuals sampled with the percentage contribution summed over two dates and combined for stations in the lower (Lower %) and upper sections (Upper %), and for the four sites and two dates combined in last column (Total %) (all data are taken from Halvorsen et al. [1]. Sampling sites 1 and 2 are from the lower and southern section on each side of the lake while site 3 and site 4 is situated on each side in upper northern part of the lake (see Fig. 1). (PDF 199 kb)

STRUCTURE-HARVESTER results for the Lake Engervann sticklebacks. (PDF 640 kb)

DAPC analyses (Dicriminant analysis of principal components) in adegenet (Jombart 2008) performed on the three lateral plate morphs of threespine stickleback from Lake Engervann. (PDF 299 kb)

The invertebrate fauna sampled on four locations (with an equal sampling effort performed on each locations) in the littoral area in the brackish water Lake Engervann on two dates (data report number of individuals sampled with the percentage contribution summed over two dates and combined for stations in the lower (Lower %) and upper sections (Upper %), and for the four sites and two dates combined in last column (Total %) (all data are taken from Halvorsen et al. [1]. Sampling sites 1 and 2 are from the lower and southern section on each side of the lake while site 3 and site 4 is situated on each side in upper northern part of the lake (see Fig. 1). (PDF 199 kb)

DAPC analyses (Dicriminant analysis of principal components) in adegenet (Jombart 2008) performed on the three lateral plate morphs of threespine stickleback from Lake Engervann. (PDF 299 kb)

Summary statistics of stable isotopic values of putative prey items for the threespine stickleback sampled in the brackish water Lake Engervann and marine areas. (PDF 176 kb)

A table of other fish species in the sampled localities. All the Norwegian minnow (Phoxinus phoxinus) populations used in the study and the other fish species in the same locality. The species of fish are: AC = Arctic charr (Salvelinus alpinus) BL = bleak (Alburnus alburnus), BR = bream (Abramis brama), BT = brown trout (Salmo trutta), BU = burbot (Lota lota), CC = crucian carp (Carassius carassius), CH = chub (Leuciscus cephalus), EE = eel (Anguilla anguilla), GR = grayling (Thymallus thymallus), PE = perch (Perca fluviatilis), PI = pike (Esox lucius), RU = ruffe (Gymnocephalus cernuus), SS = Siberian sculpin (Cottus poecilopus), VE = vendace (Coregonus albula), WB = white bream (Blicca bjoerkna), WF = European whitefish, SM = smelt (Osmerus eperlanus), ID = ide (Leuciscus idus), DA = dace (Leuciscus leuciscus), 9-SB = nine-spined stickleback (Pungitius pungitius) and 3-SB = tree-spined stickleback (Gasterosteus aculeatus). (DOC 192 kb)

Figure of distribution of Gyrodactylus spp. individuals. Distribution of Gyrodactylus spp. individuals in the total dataset of 1278 individual minnows (Phoxinus phoxinus) hosts from 43 populations in Norway. Here the 14 native and 23 stocked populations have been pooled. On the left axis is the probability of occurrence and on right axis is given counts. (DOCX 76 kb)

A table of tests result of demographic bottleneck. All the Norwegian minnow (Phoxinus phoxinus) populations used in the study. Information from tests of demographic bottleneck using Bottleneck 1.2.0.2. (Piry et al. 1999) with the two-phase model (TPM) and the Wilcoxon sign-rank test, and demographic expansion (where the intra-locus k-test identify signals of recent population expansion, while the inter-locus g-test identify signals of more ancient population expansion) using Kg-test (Reich et al. 1999). Footnotes: *Samples used in the rarefaction analysis using EstimateS 8.2.0 (Colwell 2011) where more than 5 Gyrodactylus spp. individuals were observed in the population. This number of observed Gyrodactylus spp. individuals is needed to calculate rarefaction in EstimateS 8.2.0. # None of tests were significant. (DOC 116 kb)

Siken varierer mye i utseende innen og mellom vann. Her oppsummerer jeg egen, og til dels annen, relevant litteratur, for å reflektere rundt hvordan sikens utseende kan være påvirket av slektskap og tilpasninger til ulike forhold i innsjøen, og hvilke forvaltningsmessige konsekvenser dette kan ha. Tre genetiske hovedlinjer (basert på mitokondrie-DNA (mtDNA)), som sannsynligvis overlevde i ulike refugier gjennom siste istid, har kolonisert nordlige deler av Europa. Også innen innsjøer kan ulikt utseendemessige sikbestander være delvis genetisk adskilt. Slike bestander har en form for ufullstendig adferdsbarriere mot å parre seg med hverandre. Basert bare på utseendemessig variasjon kan nesten hver sikbestand beskrives innen binær nomenklatur til å være ulike taxonomiske arter, men dette er ikke hensiktsmessig av ulike årsaker. En viktig grunn her er at bestander som ikke er nært beslektet kan ha utviklet utseendemessige karaktertrekk gjennom parallell evolusjon. Det betyr at de uavhengig har utviklet seg mot samme form fordi de har levd under samme forhold, der karaktertrekk er strukturert av naturlig seleksjon. Like eller ulike karaktertrekk hos sik innen og mellom innsjøer kan oppstå via fenotypisk plastisitet (der den samme genotypen gir ulikt fenotypisk uttrykk i ulike miljøer) og naturlig seleksjon der morfene som er mest tilpasset et gitt miljø, får flest avkom. Mekanismene bak oppsplitting i genetikk og utseende innen- og mellom vann kan være bestemt av ulike faktorer. Den evolusjonære historien om hvor forfedrene kom fra med sine gener, er grunnleggende. Naturlig seleksjon plukker ut hvilke genkombinasjoner og karaktertrekk som går videre i neste generasjon gitt tilpasningsdyktighet utfra eksisterende variasjon. For mange arter og populasjoner kan oppvekstforholdene påvirke utseende og livshistorien ved at de er fenotypisk plastiske. Genetisk struktur og assosierte karaktertrekk kan også bli påvirket av tilfeldig genetisk drift og genflyt mellom populasjoner. Mekanismen bak sympatrisk oppdeling i ulike former av sik innen ett og samme vann kan være økologisk nisje-deling, det vil si at de forekommende formene av siken er tilpasset til å utnytte de ulike delene av innsjøen forskjellig. Gitt tid og geografisk separasjon kan slike økologiske former være på vei til å bli gode biologiske arter via økologisk artsdannelse, noe våre data støtter. Det ser også ut til at flere innvandringer av ulikt utseende sik kan forekomme i samme vann via sekundær kontakt av allopatrisk utviklede (geografisk isolerte) mtDNA-linjer. Slike forhold gir forvaltningen utfordringer med identifisering av bestander, definering av enheter for bevaring, og høsting av denne evolusjonært interessante og gode matfisken. En kombinasjon av genetikk-, utseende- og livshistorieanalyser bør ligge til grunn for å foreslå og iverksette gode forvaltningsenheter. I Norge har vi en stor sik-diversitet som vi må forvalte på en fornuftig og effektiv måte, slik at vi kan både høste av den og forske på den i framtiden.

Salinity is one of the key factors that affects metabolism, survival and distribution of fish species, as all fish osmoregulate and euryhaline fish maintain osmotic differences between their extracellular fluid and either freshwater or seawater. The threespine stickleback (Gasterosteus aculeatus) is a euryhaline species with populations in both marine and freshwater environments, where the physiological and genomic basis for salinity tolerance adaptation is not fully understood. Therefore, our main objective in this study was to investigate gene expression of three targeted osmoregulatory genes (Na+/K+-ATPase (ATPA13), cystic fibrosis transmembrane regulator (CFTR) and a voltage gated potassium channel gene (KCNH4) and one stress related heat shock protein gene (HSP70)) in gill tissue from marine and freshwater populations when exposed to non-native salinity for periods ranging from five minutes to three weeks. Overall, the targeted genes showed highly plastic expression profiles, in addition the expression of ATP1A3 was slightly higher in saltwater adapted fish and KCNH4 and HSP70 had slightly higher expression in freshwater. As no pronounced changes were observed in the expression profiles of the targeted genes, this indicates that the osmoregulatory apparatuses of both the marine and landlocked freshwater stickleback population have not been environmentally canalized, but are able to respond plastically to abrupt salinity challenges.

Background: Regressive evolution of the pelvic complex has been observed in populations of three of five stickleback genera, Gasterosteus, Pungitius, and Culaea, from young freshwater habitats (