Croissance et structure de l'opercule calcifié du gastéropode polynésien Turbo setosus (Prosobranchia: Turbinidae): détermination de l'âge individuel

Turbo setosus Gmelin were collected in 1979 and 1982 in French Polynesia (Tuamotu). Ground cross-sections of calcified opercula revealed 3 distinct types of growth lines (A, B and C), the appearance and periodicity of which are described. Two months after fluorescent labelling with alizarin and fluorescein, permanent marks were easily visible in the operculum, enabling the 3 types of growth lines to be interpreted and a growth pattern distinguished: Type A growth lines, which are very translucent under transmitted light, are irregularly deposited after individual traumatisms and are termed stress lines; Type B lines exhibit a regular periodicity and correspond to a daily growth rhythm; Type C lines reflect a subdaily growth pattern. Vital staining enabled calcification of the operculum to be followed, and the speed of deposition has been estimated. The textural organization of the organic and mineral phases varies according to operculum area and depends on local speed of growth. In those areas of rapid growth (more than 20 m d^-1), deposits are cone-shaped and interlocked, and in those areas where growth is slower (less than 20 m d^-1), this type of organization disappears and is replaced by a regular organization without cone-shaped deposits. The number of daily growth lines, counted on 66 opercula, allowed us to accurately assess individual age and longevity in this species, which did not exceed 3 yr in our sample.     

Dynamic extreme values modeling and monitoring by means of sea shores water quality biomarkers and valvometry

Water quality can be evaluated using biomarkers such as tissular enzymatic activities of endemic species. Measurement of molluscs bivalves activity at high frequency (e.g., valvometry) during a long time period is another way to record the animal behavior and to evaluate perturbations of the water quality in real time. As the pollution affects the activity of oysters, we consider the valves opening and closing velocities to monitor the water quality assessment. We propose to model the huge volume of velocity data collected in the framework of valvometry using a new nonparametric extreme values statistical model. The objective is to estimate the tail probabilities and the extreme quantiles of the distribution of valve closing velocity. The tail of the distribution function of valve closing velocity is modeled by a Pareto distribution with parameter ??_t,τ, beyond a threshold τ according to the time t of the experiment. Our modeling approach reveals the dependence between the specific activity of two enzymatic biomarkers (Glutathione-S-transferase and acetylcholinesterase) and the continuous recording of oyster valve velocity, proving the suitability of this tool for water quality assessment. Thus, valvometry allows in real-time in situ analysis of the bivalves behavior and appears as an effective early warning tool in ecological risk assessment and marine environment monitoring.     

Cytotoxic effects of seven Tunisian hospital wastewaters on the proliferation of human breast cancer cell line MDA-231: correlation with their chemical characterization

Environmental Science and Pollution Research - Hospital wastewaters contain large amounts of pharmaceutical residues, which may eventually be discharged into the aquatic environment through...