Lack of population genetic structuring in the marine planktonic diatom Pseudo-nitzschia pungens (Bacillariophyceae) in a heterogeneous area in the Southern Bight of the North Sea

Several marine holoplanktonic organisms show a high degree of geographically structured diversity for which it often remains unclear to what extent this differentiation is due to the presence of cryptic taxa. For the genetically distinct diatom Pseudo-nitzschia pungens var. pungens, we used six microsatellite markers to investigate the spatial and temporal genetic composition in the heterogeneous Southern Bight of the North Sea. Although our sampling area (ca. 100 km) comprised water bodies with different environmental conditions (marine, estuary, saline lake) and different degrees of connectivity (from complete isolation to supposedly free exchange between environments), no evidence of genetic differentiation was found. Expanding our sampling area (ca. 650 km), suggested a homogenous population structure over even larger areas in the North Sea. Our results suggest that the population structure of this diatom is mainly shaped by strong homogenizing effects of gene flow preventing genetic drift, even in water bodies with limited connectivity. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

A screening of liver,kidney, and thyroid gland morphology in organochlorine-contaminated glaucous gulls (Larus hyperboreus) from Svalbard

Concentrations of organochlorine (OC) contaminants and histomorphology of liver, kidney, and thyroid tissues were studied in nine adult and one subadult glaucous gulls (Larus hyperboreus) collected at Svalbard on 2 August 2011. Concentrations of liver polychlorinated biphenyls (PCB; range: 150–2820?ng?g^?1 ww), dichlorodiphenyltrichloroethane (DDT; range: 58–724?ng?g^?1 ww), and chlordanes (CHL; range: 11–126?ng?g^?1 ww) dominated the OC profile followed by hexachlorobenzene (HCB; range: 11–42?ng?g^?1 ww), mirex (range: 2–52?ng?g^?1 ww), and β-hexachlorocyclohexane (β-HCH; range: 1–7?ng?g^?1 ww). Histological examination of the liver showed mononuclear cell infiltrations and granulomas in 10 and 6 gulls, respectively, while intense intrahepatic lipid accumulation (steatosis) was found in two and focal necrosis in one gull. In kidney, glomerular sclerosis and adhesions was found in five and one gull, respectively. Thickening of the glomerular basement membranes and tubular necrosis was found in four and seven gulls, respectively, while mononuclear cell infiltrations were found in two individuals. In the thyroid gland, a high density of small follicles accompanied by follicular epithelial cell proliferation was observed in five glaucous gulls. Gulls with hepatic steatosis had significantly higher ΣDDT levels than the gulls without hepatic steatosis and a similar trend was found for ΣPCB. When normalizing OC concentrations for lipid content in liver, gulls with lipid granulomas had significantly lower β-HCH and significantly higher mirex levels, respectively, than gulls without lipid granulomas. Also; gulls with thickening of the glomerular basement membranes had non-significantly higher ΣPCB levels than gulls without. The histological findings were similar to those of controlled laboratory studies and OC-contaminated wildlife (e.g., polar bears; Ursus maritimus) and the data of this study therefore suggest that OC exposure may be a co-factor in the development of organ alterations in glaucous gulls. However, other environmental factors such as age, element exposure, and infectious micropathogens cannot be ruled out as co-factors, and it is uncertain if the tissue changes found exert adverse health effects on the population of Svalbard glaucous gulls.