Effects of olive mill wastewater discharge on benthic biota in Mediterranean streams.

Olive mill wastewaters (OMW) discharging in river ecosystems cause significant adverse effects on their water chemistry and biological communities. We here examined the effects of OMW loads in four streams of a Mediterranean basin characterized by changing flow. The diatom and macroinvertebrate community structures were compared between upstream (control) and downstream (impacted) sites receiving OMW discharge. We also tested if effects occurred at the organism level, i.e. the occurrence of deformities in diatom valves, and the sediment toxicity on the midge Chironomus riparius. We evaluated these effects through a two-year analysis, at various levels of chemical pollution and dilution capacity. The impacted sites had high phenol concentrations and organic carbon loads during and after olive mill (OM) operation, and were characterized by higher abundances of pollution-tolerant diatom and macroinvertebrate taxa. Diatom valve deformities occurred more frequently at the impacted sites. The development of C. riparius was affected by phenolic compounds and organic carbon concentrations in the sediments. The similarity in the diatom and macroinvertebrate assemblages between control and impacted sites decreased at lower flows. Diatoms were more sensitive in detecting deterioration in the biological status of OMW receiving waterways than macroinvertebrates. Our results indicate that the negative effects of OMW extended to the whole benthic community, at both assemblage and organism level.

Pharmacokinetics of flumequine and in vitro activity against bacterial pathogens of gilthead sea bream Sparus aurata.

The present study investigated the kinetic profile of flumequine (FLU) in gilthead sea bream Sparus aurata (170 g) held at 19 degrees C and evaluated its in vitro efficacy against important bacterial diseases in Mediterranean mariculture. Following a single intravascular injection (10 mg kg(-1) fish), the distribution half-life (t1/2alpha) and the half-life of the terminal phase of elimination (t1/2gamma) of the drug were 0.2 and 30 h respectively. Tissue penetration of FLU was low, since both the apparent distribution volume of the drug at steady-state (Vd(SS)) and the apparent volume of the central compartment (Vc) were small (0.57 and 0.15 l kg(-1)). The mean residence time (MRT) was short (11 h) and the total clearance (CL(T)) of the drug was slow (0.05 l kg(-1) h(-1)). Following oral administration (20 mg kg(-1)), the bioavailability (F %) of FLU was 29% and the maximum plasma concentration was 1.7 microg ml(-1). The minimum inhibitory concentration (MIC) of the drug in distilled water supplemented with 2% NaCl against Vibrio anguillarum Serotype 1b, Photobacterium damsela ssp. piscicida, V. alginolyticus, V. damsela and V. fluvialis was 0.15, 0.3, 1.2, 0.019 and 0.15 microg ml(-1) respectively. The addition however of 10 mM Ca2+ and 55 mM Mg2+ to the medium resulted in an 8- to >120-fold reduction in FLU activity. The results indicate that FLU has an adequate kinetic profile in gilthead sea bream and that marine cations induce a significant impact on the activity of FLU, rendering its use against bacterial pathogens questionable.