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 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.
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.
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.
Effects of an oil spill in a harbor assessed using biomarkers of exposure in eelpout
Oil spills occur commonly, and chemical compounds originating from oil spills are widespread in the aquatic environment. In order to monitor effects of a bunker oil spill on the aquatic environment, biomarker responses were measured in eelpout (Zoarces viviparus) sampled along a gradient in Göteborg harbor where the oil spill occurred and at a reference site, 2 weeks after the oil spill. Eelpout were also exposed to the bunker oil in a laboratory study to validate field data. The results show that eelpout from the Göteborg harbor are influenced by contaminants, especially polycyclic aromatic hydrocarbons (PAHs), also during “normal” conditions. The bunker oil spill strongly enhanced the biomarker responses. Results show elevated ethoxyresorufin-O-deethylase (EROD) activities in all exposed sites, but, closest to the oil spill, the EROD activity was partly inhibited, possibly by PAHs. Elevated DNA adduct levels were also observed after the bunker oil spill. Chemical analyses of bile revealed high concentrations of PAH metabolites in the eelpout exposed to the oil, and the same PAH metabolite profile was evident both in eelpout sampled in the harbor and in the eelpout exposed to the bunker oil in the laboratory study.
Nutrient deficit among Swedish wildlife
Thiamine (vitamin B1) is a water-soluble vitamin essential for all living cells. In the cell, thiamine is phosphorylated to thiamine diphosphate, which functions as a cofactor for at least five life sustaining enzymes in the cellular metabolism. Previous studies have shown that sub-lethal thiamine deficiency in vertebrates gives rise to a large number of health effects, such as reduced feeding, memory and learning disturbances, immune suppression, and damage to the blood-brain barrier, as well as altered carbohydrate, protein, and lipid metabolism.
During the last decades, thiamine deficiency has been observed in various animal classes such as fish, birds, and reptiles. Methods to discover and characterize thiamine deficiency among wildlife include analysis of thiamine concentrations and thiamine ratios between various tissues, measurement of thiamine dependent enzyme activities and percentage of apoenzyme, as well as thiamine treatment of thiamine deficient animals (i.e. response to treatment).
Hanöbukten, a bay in southern Sweden, where thiamine (vitamin B1) deficiency cannot be excluded as the primary cause of the ecosystem disturbance
Hanöbukten is a large bay at the east coast of the County of Skåne in southern Sweden. It faces the Baltic Sea just south of the waters and archipelago of the County of Blekinge.
During a period of approximately 6–10 years, residents fishing in Hanöbukten have observed an alarming decline in the fish abundance. In fact, the decline is so severe that many local fishermen have given up their profession and sold their boats and equipment, even in cases where their families have been fishing in Hanöbukten for many generations.
These observations have resulted in a public enquiry about the situation in Hanöbukten (Anonymous 2013), executed by the staff at the Swedish Agency for Marine and Water Management (HaV) as a commission from the Swedish government.
The public enquiry of Hanöbukten (Anonymous 2013) indicates that the problems have appeared in recent years, and according to local fishermen, the problems occur in episodes. Hence, it is very interesting that the thiamine deficiency, documented in fish and birds close to Hanöbukten, also occur in episodes and is the only known disorder today with dire consequences for individual specimens as well as entire populations.
The thiamine deficiency may be caused by one, today unknown, substance by a certain biochemical mechanism. Thiamine has a central role in the cellular metabolism of e.g. sugar, lipids, and protein, and thiamine deficiency may compromise several physiological functions, such as the immune defence, vision and hearing, long and short time memory functions, the blood brain barrier, reproduction, temperature regulation, nerve function, reproduction, and survival. Our knowledge so far makes thiamine deficiency a plausible cause for the ongoing disturbance of the ecosystem in Hanöbukten.
On this foundation, we suggest an investigation of thiamine status in some well-characterised vertebrate model-species to elucidate whether biota in Hanöbukten suffer from thiamine deficiency or not.
Reference: Anonymous (2013) Hanöbukten. Regeringsuppdrag. Havs- och vattenmyndighetens rapport 2013-10-31. Havs- och vattenmyndigheten, Göteborg, Sweden, 107 pp.
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.