Effects of persistent organic pollutants on the thyroid function of the European sea bass (Dicentrarchus labrax) from the Aegean sea, is it an endocrine disruption?

We evaluated the alterations of organochlorinated compounds such as polychlorobiphenyls (PCB), dichloro-diphenyl-dichloroethylene (DDE) and dichloro-diphenyl-trichloroethane (DDT) on the thyroid in wild and cultured sea bass (Dicentrarchus labrax) at environmental concentrations. These compounds influence the endocrine system of many fish species and are qualified as endocrine disruptors. The thyroid seems to be a target organ. Two alteration endpoints: the thyroid histology and the muscular thyroid hormone concentrations, were used simultaneously.High concentrations in PCBs and DDT were detected in muscles, supporting the idea that the Mediterranean fauna could be more polluted than the Atlantic fauna. The high abundance of DDE indicates a progressive degradation of remnant DDT load and the absence of new inputs in this area. Aquaculture sea bass shows a significant higher amount of pollutants on fresh weight basis (especially PCBs) in their muscles compared to the wild sea bass. Those differences may be related mainly to the contaminations of diet.Thyroid parameters vary between wild and aquaculture sea bass, wild sea bass were characterized by higher follicle diameters, epithelial cell heights and muscular T₄ concentrations. A significant relationship between persistent organic pollutants (muscular PCBs and DDT concentration) and the different thyroid parameters (diameters of follicles, epithelial cell heights and muscular T₄ levels) could be observed, which support the hypothesis that these compounds have an adverse impact on thyroid morphometry and function.     

Environmentally relevant exposure of 17α-ethinylestradiol impairs spawning and reproductive behavior in the brackish medaka Oryzias melastigma

We assessed the effects of 17α-ethinylestradiol (EE2) on spawning and reproductive behavior of the brackish medaka Oryzias melastigma at environmental concentrations. Breeding pairs were exposed to EE2 at either lower concentrations (0, 1, and 10 ng/L) or higher concentrations (0, 50, and 100 ng/L) for 14 days. Swimming performance and reproductive behavior (following, dancing, and copulation) of the males were analyzed at the end of exposure. Additionally, gonad histology was conducted in the males in the higher EE2 experiment. We found that spawning was significantly inhibited in the 50–100 ng/L EE2 groups. Swimming performance was not affected in all groups. Dancing and copulation were significantly suppressed in the 50–100 ng/L groups. No effect was observed in testis histology in the 50–100 ng/L groups. Our data suggests that reproductive behavior of O. melastigma can be utilized as a behavioral endpoint for ecotoxicology studies of endocrine disruptors in estuarine/marine environments.     

A numerical study on the effects of wave–current–surge interactions on the height and propagation of sea surface waves in Charleston Harbor during Hurricane Hugo 1989

The effects of wave–current interactions on ocean surface waves induced by Hurricane Hugo in and around the Charleston Harbor and its adjacent coastal waters are examined by using a three-dimensional (3D) wave–current coupled modeling system. The 3D storm surge modeling component of the coupled system is based on the Princeton Ocean Model (POM), the wave modeling component is based on the third generation wave model, Simulating WAves Nearshore (SWAN), and the inundation model is adopted from [Xie, L., Pietrafesa, L. J., Peng, M., 2004. Incorporation of a mass-conserving inundation scheme into a three-dimensional storm surge model. J. Coastal Res., 20, 1209–1223]. The results indicate that the change of water level associated with the storm surge is the primary cause for wave height changes due to wave–surge interaction. Meanwhile, waves propagating on top of surge cause a feedback effect on the surge height by modulating the surface wind stress and bottom stress. This effect is significant in shallow coastal waters, but relatively small in offshore deep waters. The influence of wave–current interaction on wave propagation is relatively insignificant, since waves generally propagate in the direction of the surface currents driven by winds. Wave–current interactions also affect the surface waves as a result of inundation and drying induced by the storm. Waves break as waters retreat in regions of drying, whereas waves are generated in flooded regions where no waves would have occurred without the flood water.     

A numerical study on the mixed layer depth variability and its influence on the sea surface temperature during 2013–2014 in the Bay of Bengal and Equatorial Indian Ocean

Ocean Dynamics - This study addresses the air–sea interaction processes and mixed layer variability, which cause the intraseasonal oscillations in the sea surface temperature (SST) during...     

Annual variation of sea surface height, dynamic topography and circulation in the South China Sea —— A TOPEX/Poseidon satellite altimetry study

The South China Sea (SCS) is a semi-enclosed deep basin with complex topography includ-ing broad continental shelves, steep slopes, and a large deep basin. It is dominated by prevailing southwest monsoon in summer and by much stronger northeast monsoon in…