peer reviewed | female common dolphins and harbour porpoises from the Atlantic coast of Europe were frequently above the threshold at which effects on reproduction could be expected, in 40% and 47% of cases respectively. This rose to 74% for porpoises from the southern North Sea. PCB concentrations were also high in southern North Sea fish. The average pregnancy rate recorded in porpoises (42%) in the study area was lower than in the western Atlantic but that in common dolphins (25%) was similar to that of the western Atlantic population. Porpoises that died from disease or parasitic infection had higher concentrations of persistent organic pollutants (POPs) than animals dying from other causes. Few of the common dolphins sampled had died from disease or parasitic infection. POP profiles in common dolphin blubber were related to individual feeding history while those in porpoises were more strongly related to condition. High PCB levels were recorded in porpoises and common dolphins from European coasts.

peer reviewed | The effect of chronic exposure to a low concentration (0.5 microg l(-1)) of cadmium ions was investigated on escape behaviour of sea bass, Dicentrarchus labrax, using video analysis. Observations were also performed on the microanatomy of lateral system neuromasts. When fish were exposed for 4h per day over 8 days to the cadmium ions, most of both types of neuromasts observed remained intact. However, some of them presented damaged sensory maculae. Whereas before cadmium exposure, fish responded positively to nearly all the lateral system stimulations, after exposure they decreased by about 10% their positive responses to stimulations. From the 15th day after the beginning of cadmium exposure, neuromasts presented progressively less damage, cadmium accumulation in gills and scales decreased significantly and fish escape behaviour had recovered. This study presents a new concept in ecotoxicology: using behavioural change to reveal the effects of pollution levels, scarcely detectable by currently used techniques (physiological responses).

peer reviewed | 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.

peer reviewed | The objective of this paper is to evaluate using tracer tests, the role of the granular media size on the hydraulic behaviour of small -scale pilot horizontal subsurface flow (HSSF) gravel beds. The non-ideal flow was modelled by the tank-in-series model (TIS) using the moment analysis and Gamma distribution fitting using the Solver™ routine in Microsoft Excel™; the Plug Flow with Dispersion (PFD) model was also assessed. Tests were performed under a greenhouse in four identical pilot-scale gravel beds of 9:1:1 ratio, which received an equal, inflow of clear water. The influent flow rate was 40 L/day and the surface area of the pilot cells was 0.8 m². The pea gravel media used in the four beds were as follows: 3-5 mm, 6-8 mm, 8-10 mm and 10-12 mm. The tracer used was Potassium Bromide (KBr) with a concentration of 1 g Br/L, using a single-shot injection into the inlet distribution tubes. Tests were repeated three times, with identical materials and methods. Statistical differences were observed between replications. Water loss by evaporation of the unplanted gravel beds was of 11% for the smaller media size (3-5 mm) which is significantly different than the 4 to 5% obtained for the other media sizes. Tracer detention time, tracer peak time, volumetric and hydraulic efficiencies show all the same tendency which is a significant reduction with larger particles sizes. The two methods of calculation for the number NTIS by moment analysis and Gamma distribution fitting (using Solver™) are significantly different. The Gamma model increases the number of TIS with significantly higher values for smaller media sizes.