Döda laxyngel leder till att tiaminbrist upptäcks i miljön
I slutet på 1980-talet observerades en omfattande dödlighet hos laxyngel i flera svenska älvar. Undersökningar inleddes för att ta reda på orsaken och 1994 upptäckte man att laxynglen led av brist på vitamin B1, eller tiamin som det också kallas.
Thiamine deficiency impairs common eider (Somateria mollissima) reproduction in the field
The Baltic Sea population of the common eider (Somateria mollissima) has declined dramatically during the last two decades. Recently, widespread episodic thiamine (vitamin B1) deficiency has been demonstrated in feral birds and suggested to contribute significantly to declining populations. Here we show that the decline of the common eider population in the Baltic Sea is paralleled by high mortality of the pulli a few days after hatch, owing to thiamine deficiency and probably also thereby associated abnormal behaviour resulting in high gull predation. An experiment with artificially incubated common eider eggs collected in the field revealed that thiamine treatment of pulli had a therapeutic effect on the thiamine status of the brain and prevented death. The mortality was 53% in untreated specimens, whereas it was only 7% in thiamine treated specimens. Inability to dive was also linked to brain damage typical for thiamine deficiency. Our results demonstrate how thiamine deficiency causes a range of symptoms in the common eider pulli, as well as massive die-offs a few days after hatch, which probably are the major explanation of the recent dramatic population declines.
Supporting variables for biological effects measurements in fish and blue mussel
Biological effects measurements in fish and blue mussel are fundamental in marine environmental monitoring. Nevertheless, currently used biomarkers may be confounded by basic physiological phenomena, such as growth, reproduction, and feeding, as well as thereby associated physiological variation. Here, we present a number of supporting variables, which are essential to measure in order to obtain reliable biological effects data, facilitate their interpretation, and make valid comparisons. For fish, these variables include: body weight, body length, condition, gonad maturation status, various somatic indices, age, and growth. For blue mussels, these variables include: volume, flesh weight, shell weight, and condition. Also, grossly visible anomalies, lesions, and parasites should be recorded for both fish and blue mussels. General confounding factors and their effects are described, as well as recommendations for how to handle them.
Vitaminbrist som dödar
Brist på vitaminet tiamin har orsakat massdöd bland sjöfåglarna. Svensk forskning visar att problemet är mer utbrett än så. Nu gäller det att förstå orsaken.
Vitaminbrist i havet
På 1970-talet dog periodvis stora mängder laxyngel utan att man förstod varför. Syndromet fick namnet M74. Kring millennieskiftet började man hitta allt fler döende sjöfåglar i våra skärgårdar, och ”fågeldöden” blev ett nytt begrepp. Nu finns övertygande bevis för att allvarlig brist på ett vitamin ligger bakom båda dessa fenomen, och att betydligt fler arter är drabbade. Den stora frågan är dock fortfarande hur detta går till.
Utbredd tiaminbrist på norra halvklotet
Bristen på vitamin B1 (tiamin) hos vilda djur är tidigare känd som ett problem inom vissa arter i relativt begränsade geografiska områden. Nu visar forskare vid Stockholms universitet och flera andra forskningsinstitutioner i Europa och Nordamerika att bristen på tiamin är betydligt mer utbredd än vad man tidigare känt till.
Widespread episodic thiamine deficiency in Northern Hemisphere wildlife
Many wildlife populations are declining at rates higher than can be explained by known threats to biodiversity. Recently, thiamine (vitamin B1) deficiency has emerged as a possible contributing cause. Here, thiamine status was systematically investigated in three animal classes: bivalves, ray-finned fishes, and birds. Thiamine diphosphate is required as a cofactor in at least five life-sustaining enzymes that are required for basic cellular metabolism. Analysis of different phosphorylated forms of thiamine, as well as of activities and amount of holoenzyme and apoenzyme forms of thiamine-dependent enzymes, revealed episodically occurring thiamine deficiency in all three animal classes. These biochemical effects were also linked to secondary effects on growth, condition, liver size, blood chemistry and composition, histopathology, swimming behaviour and endurance, parasite infestation, and reproduction. It is unlikely that the thiamine deficiency is caused by impaired phosphorylation within the cells. Rather, the results point towards insufficient amounts of thiamine in the food. By investigating a large geographic area, by extending the focus from lethal to sublethal thiamine deficiency, and by linking biochemical alterations to secondary effects, we demonstrate that the problem of thiamine deficiency is considerably more widespread and severe than previously reported.
Pollutant concentrations and toxic effects on the red alga Ceramium tenuicorne of sediments from natural harbors and small vessel harbors on the west coast of Sweden
This investigation set out to analyze the toxicity of surface sediments in a number of natural harbors and small boat harbors on the west coast of Sweden. This was done with the growth inhibition method with Ceramium tenuicorne. Also, concentrations of copper (Cu), lead (Pb), zinc (Zn), irgarol, organotin compounds, and polycyclic aromatic hydrocarbons (PAHs) in the sediments were analyzed. The small boat harbors were heavily polluted by Cu, Zn, butyltins, and PAHs, and to a lesser extent by Pb. The Cu, Pb, Zn, and butyltins probably originated from their past and/or present use in antifouling paints, whereas the PAHs probably had multiple sources, including boat motor exhausts. The measured toxicity of the sediment was generally related to their Cu, Zn, and butyltin content, although other toxic substances than those analyzed here probably contributed to the toxicity in some of the harbors. The natural harbor sediments contained less pollutants and were less toxic than the small boat harbor sediments. Nevertheless, our data indicate that the boating pressure today may be high enough to produce toxic effects even in natural harbors in pristine areas. The strongest relationship between toxicity and the major pollutants was obtained when the sediment toxicity was expressed as gram wet weight per liter compared with gram dry weight per liter and gram total organic carbon per liter. Hence, for pollutants that can be elutriated with natural sea water, sediment toxicity expressed as gram wet weight per liter appears preferable.
Biomarker investigations in adult female perch (Perca fluviatilis) from industrialised areas in northern Sweden in 2003
Since the new millennium, a notion has developed in certain parts of society that environmental pollutants and their associated effects are under control. The primary objective of this investigation, performed in 2003, was to test whether this was actually the case in an industrialised region in the County of Västernorrland in northern Sweden with well-documented environmental pollution from past and present activities. This was performed by measuring a moderate battery of simple biomarkers in adult female perch at several stations. The point sources included sewage-treatment plants, pulp and paper mills, as well as other industries. The biomarkers included growth, somatic indices, gonad maturation status, gonad pigmentation, fin erosion, skin ulcers, and ethoxyresorufin-O-deethylase (EROD) activity in the liver. The results showed that the environmental pollutants and their associated effects were not under control. In fact, the health of the perch was impaired at all of the polluted stations. Many responses were unspecific with respect to underlying cause, whereas some effects on EROD activity and gonad maturation status were attributed to historical creosote pollution and current kraft pulp mill effluents, respectively. The data presented may also be used as reference values for future investigations of health effects in perch.
Cytological and biochemical biomarkers in adult female perch (Perca fluviatilis) in a chronically polluted gradient in the Stockholm recipient (Sweden)
By measuring a battery of cytological and biochemical biomarkers in adult female perch (Perca fluviatilis), the city of Stockholm (Sweden) was investigated as a point source of anthropogenic aquatic pollution. The investigation included both an upstream gradient, 46 km westwards through Lake Mälaren, and a downstream gradient, 84 km eastwards through the Stockholm archipelago. Indeed, there was a graded response for most of the biomarkers and for the muscle concentrations of Sum-PBDE, four organotin compounds and PFOS in the perch. The results indicated severe pollution in central Stockholm, with poor health of the perch, characterised by increased frequency of micronucleated erythrocytes, altered liver apoptosis, increased liver catalase activity, decreased brain aromatase activity, and decreased liver lysosomal membrane stability. Some biomarker responses were lowest in the middle archipelago and increased again eastwards, indicating a second, partly overlapping, gradient of toxic effects from the Baltic Sea.
Thiamine deficiency affecting wildlife health in the Baltic Sea area
Thiamine (vitamin B1) is synthesized in plants, fungi, and bacteria and is essential for all fish and bird species. Thiamine deficiency causes metabolic disorders in several subcellular compartments, such as the cytosol, mitochondria, and peroxisomes. Clinical symptoms include ataxia, convulsions, paralysis, immune suppression, behavioral and memory disorders, reduced feeding, and anorexia. In the Baltic Sea salmon (Salmo salar), thiamine deficiency has been observed since 1974. This disorder has been named the M74 syndrome. It occurs in episodes affecting the reproduction in 10–90% of the females, depending on year and river. The disorder causes neurological disturbances and histopathological changes in the brain, muscles and kidneys, both in the yolk-sac fry and in the adults.
Recently, thiamine deficiency has also been demonstrated in adults, newly hatched young, and eggs of herring gulls (Larus argentatus), and common eider (Somateria mollissima) in connection with extensive paralysis and mortality in bird colonies in the Baltic Sea area. We have observed in these colonies reproductive disorders, with a reduced number of laid eggs, and high mortality (> 90 percent) in eider ducklings during their first week of life. The many observations of advanced thiamine deficiency in adult birds imply that a varying degree of moderate thiamine deficiency occurs among the affected species. This might be an explanation for the observed increased occurrence of incomplete nest building and misplaced eggs in nests of other bird species. The thiamine deficiency may be induced either by a causative agent(s) acting directly on the affected individual, by reduced uptake of thiamine, and/or by insufficient transfer of thiamine between the trophic levels in the food web. Further studies will focus on thiamine levels in the food for these birds, as well as factors involved in the high mortality of juvenile eider ducklings.