Several experiments were performed to evaluate the fertilization capability of Paracentrotus lividus sea urchin gametes, which are usually used in fertilization tests, but which, until now, were employed only for few hours after spawning. The aim of this work is to evaluate the possibility of performing the bioassay for longer periods, employing 'conserved' gametes. As far as the method, the sperm was stored 'dry' at 4 degrees C; eggs were conserved in an antibiotic solution at 4 degrees C, and they were exposed both to copper solutions as reference toxicant and to aqueous matrices. The use of conserved gametes in the fertilization bioassay lead to EC50 values which were acceptable for about 3 days. Moreover, these experiments permitted to identify the limiting factor: the male gamete.

The sperm cell toxicity test with Paracentrotus lividus is widely used in Italy to assess the quality of complex aqueous matrices, but at present there is a shortage of standardized methodologies for the bioassay performance. In this work several critical points were considered, in order to verify the reliability of this bioassay and to improve its standardization. In particular, we have studied the differences in EC50 values at different sperm: egg ratios and with different quantities of gametes; the influence of sperm and eggs on fertilization rate and the influence of different recipients materials (plastic or glass). At the same time, it was evaluated if the obtained EC50 values were in accordance with those reported in literature. Experiments performed yielded EC50 values for copper ranging from 16.54 microg/l to 69.59 microg/l, with a total mean value +/- SD of 39.79 microg/l +/- 11.17. These data fit with those found in literature for other echinoid species. According to the same authors, poor fertilization was probably due to the effects on sperm and not on eggs, and moreover the linear regression analysis performed on each experiment suggested that the best amount of eggs to use in the test was 1000. Results from the comparison between the performance of the test in plastic or glass tubes showed an higher success in fertilization rate using borosilicate glass tubes.

The aim of this work was to monitor the sensitivity of two populations of Corophium orientale (Crustacea: Amphipoda) living at the outfall of two rivers (Magra and Serchio), comparing their responses towards two different toxicant solutions. Sensitivity was monthly checked performing the 96h-LC50 static water only test with Cd(NO3)2 and SDS. If no significant differences were found between the two populations, they could have been employed without distinction to perform sediment toxicity bioassays. As regard to Cd, an increasing in LC50 values from summer to winter was evident in each population (Serchio River: August 2003 = 1,36 mg/l, February 2004 = 7,23 mg/l; Magra River: August = 1,21 mg/l, April = 5,01 mg/l). This pattern was correlated to the droop of temperatures in winter period. The responses of the two populations towards the cadmium were compared using the ANOVA. The analysis showed any significant differences between the populations (p = 0.12). The pattern of sensitivity towards SDS for the population living on Magra River was similar to the same pattern found for Cd; as regard to the population living on Serchio River, data were not enough to describe the annual pattern. Anyway, statistical analysis was performed and no significant differences were found between the two populations (p = 0.34).