Biomagnification of polybrominated diphenyl ether and hexabromocyclododecane flame retardants in the polar bear food chain in Svalbard, Norway

Concentrations of brominated flame retardants (BFRs), including polybrominated diphenylethers (PBDEs) and hexabromocyclododecane (HBCD), were investigated in an arctic marine food chain consisting of four invertebrate species: polar cod (Boreogadus saida), ringed seals (Pusa hispida), and polar bears (Ursus maritimus). The most abundant BFR, brominated diphenyl ether (BDE)-47, was found in detectable concentrations even in zooplankton, the lowest trophic level examined in this study. Most of the investigated BFRs biomagnified as function of tropic level in the food chain. A noticeable exception occurred at the highest trophic level, the polar bear, in which only BDE-153 was found to increase from its main prey, the ringed seal, indicating that polar bears appear to be able to metabolize and biodegrade most BFRs. In contrast, lower-brominated PBDEs, particularly BDE-47, showed clear signs of bioaccumulation in zooplankton, polar cod, and ringed seals. We suggest that this discrepancy in the fate of BFRs among the different species may be related to greater induction of oxidative detoxification activities in the polar bear. Absorption and debromination rates may be more important for bioaccumulation rates of BFRs in zooplankton, polar cod, and ringed seals. Lipid weight-based concentrations (LWCs) and whole body-based concentrations (WBCs) of BFRs were used to assess biomagnification factors (BMFs). Whole-body concentrations gave the most realistic BMFs, as BMFs derived from LWCs seem to be confounded by the large variability in lipid content of tissues from the investigated species. This study demonstrates that PBDEs and HBCD have reached measurable concentrations even in the lower trophic levels (invertebrates and fish) in the Arctic and biomagnifies in the polar bear food chain.

Endocrine disruption induced by organochlorines (OCs): field studies and experimental models

Long-range transport of persistent organic compounds by air and ocean currents from industrialized areas resulted in high levels of these pollutants in food webs in the Svalbard area. With the aim to test if organochlorine (OC) exposure in free-living polar bears from Svalbard affected their plasma steroid hormone concentrations, it was found that polychlorinated biphenyls (PCBs) were associated with increased progesterone levels in females. The sum of pesticides (sigma pesticides) and sigma PCBs contributed significantly negative to the variation of the plasma testosterone in males, and the overall contribution of the OCs to the plasma cortisol variation was negative. A second objective was to study the effects of selected OCs (i.e., PCB 153 and PCB 126) on animal health as a consequence of effects on endocrine-regulated functions such as reproduction and immunity in a goat model focusing on long-term and low-level exposure during the periods of fetal development and in the neonatal period. Additionally, acute exposure was studied in adult mice. The results indicated that exposure to low doses of PCB 153 in utero and in the suckling period influenced reproductive functions and both PCB 153 and PCB 126 exerted immunomodulatory effects on the offspring, whereas acute exposure of adult mice had minor effects on male reproductive function.

An assessment of the toxicological significance of anthropogenic contaminants in Canadian arctic wildlife

Anthropogenic contaminants have been a concern in the Canadian arctic for over 30 years due to relatively high concentrations of bioaccumulating and biomagnifying organochlorine contaminants (OCs) and toxic metals found in some arctic biota and humans. However, few studies have addressed the potential effects of these contaminants in Canadian arctic wildlife. Prior to 1997, biological effects data were minimal and insufficient at any level of biological organization. The present review summarizes recent studies on biological effects related to contaminant exposure, and compares new tissue concentration data to threshold effects levels. Weak relationships between cadmium, mercury and selenium burdens and health biomarkers in common eider ducks (Somateria mollissima borealis) in Nunavut were found but it was concluded that metals were not influencing the health of these birds. Black guillemots (Cepphus grylle) examined near PCB-contaminated Saglek Bay, Labrador, had enlarged livers, elevated EROD and liver lipid levels and reduced retinol (vitamin A) and retinyl palmitate levels, which correlated to PCB levels in the birds. Circulating levels of thyroid hormones in polar bears (Ursus maritimus) were correlated to PCB and HO-PCB plasma concentrations, but the impact at the population level is unknown. High PCB and organochlorine pesticide concentrations were found to be strongly associated with impaired humoral and cell-mediated immune responses in polar bears, implying an increased infection risk that could impact the population. In beluga whale (Delphinapterus leucas), cytochromes P450 (phase I) and conjugating (phase II) enzymes have been extensively profiled (immunochemically and catalytically) in liver, demonstrating the importance of contaminants in relation to enzyme induction, metabolism and potential contaminant bioactivation and fate. Concentrations of OCs and metals in arctic terrestrial wildlife, fish and seabirds are generally below effects thresholds, with the possible exception of PCBs in burbot (Lota lota) in some Yukon lakes, Greenland shark (Somniosus microcephalus), glaucous and great black-backed gulls (Larus hyperboreus and L. marinus), and TEQs of dioxin-like chemicals in seabird eggs. PCB and DDT concentrations in several arctic marine mammal species exceed effects thresholds, although evidence of stress in these populations is lacking. There is little evidence that contaminants are having widespread effects on the health of Canadian arctic organisms, with the possible exception of polar bears. However, further research and better understanding of organohalogen exposure in arctic biota is needed considering factors such as tissue levels that exceed effects thresholds, exposure to "new" organohalogen contaminants of concern, contaminated regions, and climate change.

A Norwegian DMARD register: prescriptions of DMARDs and biological agents to patients with inflammatory rheumatic diseases

Information concerning the effectiveness of drug therapy cannot be obtained only from randomized controlled clinical trials, due to limitations such as a short time frame and narrow inclusion and exclusion criteria. Therefore, complementary longitudinal observational studies performed in a real life setting are required. NOR-DMARD, a Norwegian 5-center register, was established in December 2000. All DMARD prescriptions to patients with inflammatory arthropathies are included, and patients are followed longitudinally with a variety of assessments. As of 2005, 4683 DMARD regimens have been included. Methotrexate is the most commonly used DMARD in rheumatoid arthritis and psoriatic arthritis. The proportions of patients who have received anti-TNF drugs in rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, juvenile arthritis and other diseases have been 22.5, 21.6, 53.8, 36.9 and 9.7%, respectively. The proportion of patients receiving anti-TNF drugs is considerably higher in 2004 than earlier, and criteria for prescribing anti-TNF drugs appear to be trending toward patients with less severe and active disease. Confounding by indication or channeling bias represents a challenge for the group comparisons of longitudinal effectiveness data, but can be addressed by modern statistical techniques. The NOR-DMARD register may in the future provide comparative real life effectiveness data that may also be used in cost-effectiveness analyses.

Does high organochlorine (OC) exposure impair the resistance to infection in polar bears (Ursus maritimus)? Part II: Possible effect of OCs on mitogen- and antigen-induced lymphocyte proliferation

Previous studies have reported alarmingly high levels of organochlorines (OCs), particularly polychlorinated biphenyls (PCBs), in free-ranging polar bears (Ursus maritimus). In this study plasma concentration of PCBs ranged from 14.8 to 200 ng/g wet weight. The aim of the study was to investigate associations between OCs and lymphocyte proliferation after in vitro stimulation with different mitogens and antigens. In 1998 and 1999, 26 and 30 free-ranging polar bears from Svalbard and Churchill, Canada, respectively, were recaptured 32-40 d following immunization with inactivated tetanus toxoid and hemocyanin from keyhole limpets (KLH) to sensitize lymphocytes. At recapture, blood was sampled for determination of plasma levels of PCBs and organochlorine pesticides (OCPs) and lymphocyte proliferation after in vitro stimulation with specific mitogens--phytohemagglutinin (PHA), pokeweed mitogen (PWM), concanavalin A (Con A), lipopolysaccharide (LPS), and purified protein derivative of Mycobacterium avium subsp. paratuberculosis (PPD)--and antigens: tetanus toxoid and KLH. The combinations of sum(PCBs) (sum of 12 individual PCB congeners), sum(OCPs) (sum of 6 OCPs), and their interactions contributed up to 15% of the variations in the lymphocyte responses. By using multiple regression analyses, followed by classical mathematic function analyses, thresholds for immunomodulation were estimated. Depending on the lymphocyte proliferation response studied, the estimated thresholds for significant immunomodulation were within the concentration ranges 32-89 ng/g wet weight (ww) and 7.8-14 ng/g ww for sum(PCBs) and sum(OCPs), respectively. Thus, this study demonstrated that OC exposure significantly influences specific lymphocyte proliferation responses and part of the cell-mediated immunity, which also is associated with impaired ability to produce antibodies (Lie et al., 2004).

Organochlorines affect the steroid hormone cortisol in free-ranging polar bears (Ursus maritimus) at Svalbard, Norway

Since the polar bear (Ursus maritimus) is among the most highly organochlorine-contaminated species of the Arctic mammals, there is growing concern that in addition to the natural stressors in the polar bear's environment, several organochlorines (OCs) may be able to change basic endocrine pathways. Alterations in the hypothalamic-pituitary-adrenal (HPA) axis may affect plasma cortisol concentrations and inhibit physiological processes involved in the maintenance of homeostasis in a way that may endanger the animal's health. Between 1995 and 1998, samples were collected from 121 male and 130 female free-ranging polar bears from the Svalbard area. The aim of the study was to investigate relationships between plasma cortisol concentrations, biological factors, and OCs. The variation in plasma cortisol concentrations was determined for the total sample. Axillary girth and body mass together with their interactions explained more than 50% of the variation in the plasma cortisol concentration. The sum of pesticides (Sigma pesticides) combined with the sum of polychlorinated biphenyls (Sigma PCBs) and their interactions explained over 25% of the variation in the cortisol concentration. Although Sigma pesticides contributed negatively and Sigma PCBs contributed positively to the variation in the plasma cortisol, the over-all contribution of the OCs to the plasma cortisol variation was negative. Despite the complexity on stress responses and the interactions with environmental factors, this study demonstrated that high concentrations of OCs in polar bears might alter plasma cortisol concentrations.

Relationships between PCBs and thyroid hormones and retinol in female and male polar bears

We studied the relationships between polychlorinated biphenyls (PCBs) and thyroid hormones (THs) and retinol within two groups of female polar bears (Ursus maritimus), females with cubs of the year (FWCOY) and females without cubs of the year (FWOCOY), and within a group of males. Concentrations of five of the six quantified PCB congeners, i.e., PCB-99, PCB-153, PCB-156, PCB-180, PCB-194 (sigma PCB5), correlated with each other, whereas the concentrations of PCB-118 did not correlate with the other congeners. sigma PCB5 and PCB-118 did not differ between the three different groups of polar bears, and the plasma levels ranged from 16.7 to 203.2 ng/g wet weight (ww) for sigma PCB5 and from 0.09 to 0.93 ng/g ww for PCB-118. PCBs did not affect the retinol status in any of the three groups. In FWCOY, we found negative correlations between sigma PCB5 and the three TH variables free thyroxin (FT4) (r2 = 0.35), free triiodothyronine (FT3) (r2 = 0.30), and the total T4:total T3 ratio (TT4:TT3) (r2 = 0.92). In FWOCOY, sigma PCB5 was negatively correlated to TT4 (r2 = 0.14) and positively correlated to TT3:FT3 (r2 = 0.31), whereas PCB-118 was positively correlated to FT3 (r2 = 0.21) and negatively correlated to TT3:FT3 (r2 = 0.26). In males, sigma PCB5 was negatively correlated to FT3 (r2 = 0.56) and positively correlated to FT4:FT3 (r2 = 0.78), whereas PCB-118 was negatively correlated to FT4:FT3 (r2 = 0.53). Thus, PCBs affected five TH variables in the female polar bears (TT4, FT4, FT3, TT3:FT3, TT4:TT3), but PCBs affected only two TH variables in males (FT3, FT4:FT3). Female polar bears could be more susceptible to TH-related effects of PCBs than are males. PCBs also affected T3 to a larger degree than T4.

Does high organochlorine (OC) exposure impair the resistance to infection in polar bears (Ursus maritimus)? Part I: Effect of OCs on the humoral immunity

This study was undertaken to assess if high levels of organochlorines (OCs) are associated with decreased ability to produce antibodies in free-ranging polar bears (Ursus maritimus) and thus affect the humoral immunity. In 1998 and 1999, 26 and 30 polar bears from Svalbard, Norway, and Churchill, Canada, respectively, were recaptured 32-40 d following immunization with inactivated influenza virus, reovirus, and herpes virus and tetanus toxoid. Blood was sampled at immunization and at recapture for determination of plasma levels of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs), serum immunoglobulin G (IgG) concentrations, and specific antibodies against influenza virus, reovirus, and herpes virus, tetanus toxoid, and Mannheimia haemolytica. The OCs alone contributed with up to 7% to the variations in the immunological parameters. The combination of sigma PCBs (sum of 12 individual PCB congeners), sigma OCPs (sum of 6 OCPs), and biological factors accounted for 40-60% of the variation in the immunological parameters. Negative associations were found between sigma PCBs and serum immunoglobulin G (IgG) levels and between sigma PCBs and increased antibody titers against influenza virus and reovirus following immunization. In contrast, a positive association was registered between sigma PCBs and increased antibodies against tetanus toxoid. sigma OCPs also contributed significantly to the variations in the immunological responses. OCs did not have the same impact on the antibody production against M. haemolytica. The present study demonstrated that high OC levels may impair the polar bears ability to produce antibodies and thus may produce impaired resistance to infections.

Organochlorines affect the major androgenic hormone, testosterone, in male polar bears (Ursus maritimus) at Svalbard

Normal sexual development and subsequent reproductive function are dependent on appropriate testosterone production and action. The regulation of steroid hormones, including androgens, can be influenced by both biological and environmental factors, including environmental chemicals. Concentrations of organochlorines are considerably greater in Svalbard polar bears than in polar bears from other regions. Between 1995 and 1998, samples were collected from 121 male polar bears (Ursus maritimus) from the Svalbard area. In this study, testosterone concentration variations were described for male polar bears during different seasons and for all age groups. To study possible relationships between plasma testosterone concentrations and biological factors, such as age, axial girth, and extractable plasma fat, and organochlorine contaminants including hexachlorocyclohexanes, hexachlorobenzene, chlordanes, p,p'-DDE, and 16 individual polychlorinated biphenyl (PCB) congeners, identical statistical analyses were performed on the total population and a subsample of reproductively active adults. Of the biological factors, axial girth showed a significant positive relationship and percentage extractable fat and a significant negative relationship with the testosterone concentrations. Both the epsilon pesticides and epsilon PCBs made significant negative contributions to the variation of the plasma testosterone concentration. The continuous presence of high concentrations of organochlorines in male polar bears throughout their life could possibly aggravate any reproductive toxicity that may have occurred during fetal and early postnatal development.

Geographical distribution of organochlorine pesticides (OCPs) in polar bears (Ursus maritimus) in the Norwegian and Russian Arctic

Geographical variation of organochlorine pesticides (OCPs) was studied in blood samples from 90 adult female polar bear (Ursus maritimus) from Svalbard, Franz Josef Land, Kara Sea, East-Siberian Sea and Chukchi Sea. In all regions, oxychlordane was the dominant OCP. Regional differences in mean levels of HCB, oxychlordane, trans-nonachlor, alpha-HCH, beta-HCH and p,p'-DDE were found. The highest levels of oxychlordane, trans-nonachlor and DDE were found in polar bears from Franz Josef Land and Kara Sea. HCB level was lowest in polar bears from Svalbard. Polar bears from Chukchi Sea had the highest level of alpha- and beta-HCH. The lowest alpha-HCH concentration was found in bears from Kara Sea. In all the bears, summation operator HCHs was dominated by beta-HCH. The geographical variation in OCP levels and pattern may suggest regional differences in pollution sources and different feeding habits in the different regions. Polar bears from the Western Russian Arctic were exposed to higher levels of chlordanes and p,p'-DDE than polar bears from locations westwards and eastwards from this region. This may imply the presence of a significant pollution source in the Russian Arctic area. The study suggests that the western Russian Arctic is the most contaminated region of the Arctic and warrants further research.

Polychlorinated biphenyls and reproductive hormones in female polar bears at Svalbard

High concentrations of polychlorinated biphenyls (PCBs) in polar bears from Svalbard have increased concern for that population's reproductive health. We examined whether there were associations between the plasma concentrations of PCBs and reproductive hormones [progesterone (P4)] and 17 beta-estradiol (E2)] in free-living female polar bears from Svalbard. Concentrations of P4 depended on reproductive status, and concentrations were lowest in females with offspring--females with cubs and females with yearlings. In these females, the P4 concentrations were positively correlated with plasma sigma PCBs (sum of all analyzed polychlorinated biphenyl congeners) concentrations. The sigma PCBs concentrations explained 27% of the variation in the P4 concentrations. There were no correlations between sigma PCBs and E2 and cortisol in any of the groups of polar bears, or between sigma PCBs and P4 in single polar bears. Although the sigma PCBs-P4 relationship in female polar bears with offspring is not evidence per se of a direct cause-effect association, the results indicate that PCBs may affect levels of P4 in polar bear females. There is a clear need to further assess the hormone balance and population health of polar bears at Svalbard.

Ecological risk assessment of persistent organic pollutants in the arctic

Ecological risk assessment of persistent organic chemicals in marine mammals in the Arctic would comprise assessments of both exposure and effect and risk characterization. Results from a comprehensive collaborative study between Norwegian and Canadian researchers, comprising epizoological (ecological) studies (reproductive rate, offspring survival), experimental studies on the immune system function, monitoring studies (e.g. physiological assays of thyroid hormones, retinol, IgG and testosterone) and registration of biological data (e.g. sex, age, reproductive status, nutritional status) were coupled with PCB exposure data. Assessment of the results indicates that population status and health of polar bears with very high PCB levels may be at risk.

Metal dynamics in an Antarctic food chain

The concentrations of copper, zinc, cadmium, selenium and mercury were determined in eggs, muscle, liver, kidney and stomach content of nestilings and adults of the Antarctic petrel, Thalassoica antarctica, and its predator, the south polar skua, Chataracta maccormicki, from Svarthamaren, Dronning Maud Land, Antarctica. The dominant food of the petrels is krill, Euphausia superba. The results show relatively high levels of cadmium in krill, which is assumed to be the main reason for the high levels of cadmium in petrels and skuas. Cadmium is almost absent in eggs, but accumulates very rapidly with age in nestlings. The copper concentrations in livers of nestling petrels reach very high levels during growth. This may be seen in connection with physiological development processes. Mercury seems to be accumulated with age and between trophic levels. Among the nestlings, the mercury levels decrease with increasing age, which may be accomplished by the excretion of mercury through the growth of feathers and as a dilution effect during growth. Selenium and mercury are inversely correlated in nestlings. The levels of zinc were similar for different nestling stages and between nestlings and adults in skuas and petrels.

Organochlorines in top predators at Svalbard--occurrence, levels and effects

Alarmingly high polychlorinated biphenyl (PCB) levels have been found in the top predators such as glaucous gull (Larus hyperboreus) and polar bear (Ursus maritimus) at Svalbard [Gabrielsen, G.W., Skaare, J.U., Polder, A., Bakken, V., 1995. Chlorinated hydrocarbons in glaucous gull (Larus hyperboreus). Sci. Total Environ. 160/161, 337-346; Bernhoft, A., Skaare, J.U., Wiig, O., 1997. Organochlorines in polar bears (Ursus maritimus) at Svalbard. Environ. Pollut. 95, 159-175; Henriksen, E.O., Gabrielsen, G.W., Trudeau, S., Wolkers, H., Sagerup, K., Skaare, J.U., 1999. Organochlorines and possible biochemical effects in glaucous gull (Larus hyperboreus) from Bear Island, the Barents Sea. Arch. Environ. Contam. Toxicol. (in press). ]. Studies of the possible toxic effects, particularly on the immune system and reproduction, of the very high PCB levels in these species are currently being investigated. Data obtained in the field (f.i. reproductive success in polar bears and intestinal nematodes in glaucous gulls), as well as levels of various biochemical and physiological parameters (f.i. thyroid hormones, retinol, EROD activity, CYP1A, IgG), have been coupled with the PCB levels [Skaare, J.U., Wiig, O., Bernhoft, A., 1994. Klorerte organiske miljogifter; Nivâer og effekter i isbjorn. Norwegian Polar Institute Reportseries no. 86, 1-23 (in Norwegian); Bernhoft, A., Skaare, J.U., Wiig, O., 1997. Organochlorines in polar bears (Ursus maritimus) at Svalbard. Environ. Pollut. 95, 159-175; Bernhoft, A., Skaare, J.U., Wiig, O., Derocher, A.E., Larsen, H.J., 2000. Possible immunotoxic effects of organochlorines in polar bears (Ursus maritimus) at Svalbard (in press); Henriksen, E.O., Gabrielsen, G.W., Skaare, J.U., Skjegstad, N., Jensen, B.M., 1998a. Relationship between PCB levels, hepatic EROD activity and plasma retinol in glaucous gull, Larus hyperboreus. Marine Environ. Res. 46, 45-49; Henriksen, E.O., Gabrielsen, G.W., Trudeau, S., Wolkers, H., Sagerup, K., Skaare, J.U. , 1999. Organochlorines and possible biochemical effects in glaucous gull (Larus hyperboreus) from Bear Island, the Barents Sea. Arch. Environ. Contam. Toxicol. (in press); Sagerup, K., Gabrielsen, G.W., Skorping, A., Skaare, J.U., 1998. Association between PCB concentrations and intestinal nematodes in glaucou gulls, Larus hyperboreus, from Bear Island. Organohalogen compounds 39, 449-451; Skaare, J.U., Wiig, O., Bernhoft, A., 1994. Klorerte organiske miljogifter; Nivâer og effekter i isbjorn. Norwegian Polar Institute Reportseries no. 86, 1-23. (in Norwegian)].

Elementary school children's explicit and implicit memory for faces of preschool classmates

This study examined elementary school children's memories for faces of preschool classmates after a 3-year interval. Children recognized their former classmates at an above-chance level, but their level of recognition was significantly lower than the level shown by the preschool teachers. Children showed implicit memory of classmates by making fewer errors while performing a face-matching task in classmate conditions than in control conditions. However, the classmate advantage on the face-matching task was found to decrease across the 3-year interval. Several findings in this study pointed to functional independence of implicit and explicit memory (e.g., children's explicit recognition memory, but not implicit memory, was related to amount of time children spent together at preschool).

A randomized study comparing manual lymph drainage with sequential pneumatic compression for treatment of postoperative arm lymphedema

We compared manual lymph drainage (MLD) with sequential pneumatic compression (SPC) for treatment of unilateral arm lymphedema in 28 women previously treated for breast cancer. After 2 weeks of therapy with a standard compression sleeve (Part I) with maintenance of a steady arm volume, each patient was randomly assigned to either one of two treatment regimens (Part II). MLD was performed according to the Vodder technique for 45 min/day and SPC was performed with a pressure of 40-60 mmHg for 2 hours/day. Both treatments were carried out for 2 weeks. Arm volume was measured by water displacement. Arm mobility, strength, and subjective assessments were also determined. Lymphedema was reduced by 49 ml (7% reduction) (p = 0.01) in the total group during Part I. During Part II, the MLD group decreased by 75 ml (15% reduction) (p < 0.001) and the SPC group by 28 ml (7% reduction) (p = 0.03). The total group reported a decrease of tension (p = 0.004) and heaviness (p = 0.01) during Part I. During Part II, only the MLD group reported a further decrease of tension (p = 0.01) and heaviness (p = 0.008). MLD and SPC each significantly decreased arm volume but no significant difference was detected between the two treatment methods.

Lack of prognostic significance for p53-overexpression and Ki-67-immunoreactivity in oral T1-2 squamous cell carcinomas

Previous investigations on squamous cell carcinomas (SCC) of the head and neck region have failed to reveal a significant correlation between p53-overexpression or Ki-67-immunoreactivity and survival. Contrary to these studies we restricted the evaluation to T1-2 SCC from the oral cavity. Immunohistochemically identified p53-overexpression was observed in 69% of the tumours, and Ki-67-positive cancer cells ranged from 12 to 83% in individual rumours (median 37%). No significant correlation was found between p53-overexpression or Ki-67-positivity and survival. Although the degree of tumour differentiation and the pattern of invasion correlated with prognosis (p=0.0387 and 0.0319 respectively), these associations were too weak to be used as prognostic markers.

The maximum exercise stress test: is it a behavior-modification tool?

The controlled study presented demonstrates the results obtained when using the maximum exercise stress test (MEST) as a behavior-modification tool for coronary artery disease risk factors. Changes in attitudes, behaviors, and objective measurements of health were assessed in a low-risk population. Only exercise level was significantly altered (P less than .03). Changes in the other measured parameters were insignificant. The MEST test is also expensive, and no benefit has been demonstrated in terms of its ability to decrease the morbidity and mortality seen in coronary artery disease.

Socio-economic values of wetland resources around Lake Manyara, Tanzania: assessment of environmental threats and local community awareness on environmental degradation and their effects

Understanding local people’s socio-economic values of wetlands and traditional mechanisms of managing natural resources forms the basis of conserving them. Wetlands have frequently been developed for short-term economic gains that destroy their ecological values and environmental services in the long term. A study was carried out to assess socio-economic values of the wetland resources, environmental threats around Lake Manyara and local community awareness on causes of environmental changes, degradation in the wetlands and their effects using 80 respondents. Field surveys, interviews, questionnaires and direct observation were used in data collection. It was found that local community was aware on the ecosystem services accrued from the wetlands which were unsustainably used. However, environmental degradation due to unsustainable agriculture, overgrazing, deforestation, urbanization and mining was rampant which had resulted to soil erosion, reduced water availability, wildlife mortality and frequent dry up of Lake Manyara and rivers. In order to protect the lake basin; controlled human activities, land use and water resources within the catchment are to be done in cooperation between the government departments, local authorities and the general local community around. Key words: Ecosystem services; rivers; Lake Manyara; wetland; agriculture DOI: 10.3126/jowe.v4i0.4153Journal of Wetlands Ecology, (2010) Vol. 4, pp 83-101