PARENT SESSION
26 - Metal Pollution: From Exposure to Ecological Effects (1)
8:30 AM to 12:20 PM, Tuesday, 14 May 2002
Session Chair: Janssen, Colin ¹, Gerhardt, Almut ¹, ¹ .
Strauss C

(26-06) Multigeneration zinc effects on Dinophilus gyrociliatus: a demographic approach.

Mauri, Marina^*,1, Simonini, Roberto¹, Baraldi, Elena¹, ¹ Università di Modena e Reggio Emilia, Modena, Italy

ABSTRACT- The effects of zinc on the life history and demography of Dinophilus gyrociliatus from a laboratory culture were studied. The life tables of three successive generations (P, F₁, F₂) were derived from a control cohort and a treated cohort kept in artificial seawater enriched with 1.0 g Zn/ml. The demographic indices of control groups were similar. Zinc affected survival and fecundity of the three successive generations with different modality and intensity, determining 1) a generalized reduction of all the demographic indices; 2) different demographic responses among generations. In respect to controls, expectation of life of treated groups was similar in P and in F₂, smaller in F₁. Net growth rate too was particularly reduced in F₁.Generation time was shorter in all treated groups. Zinc determined a significant reduction of the population growth rate () in all the treated groups; the lowest value was observed in F₁. Analysis of elasticity showed that the population growth rate was affected by variations in survival and fecundity only during the first 2-3 weeks of life. The decomposition analysis of the between control and treated group of each generation evidenced that 1) in P the greater fecundity in the early deposition partially compensated for the subsequent greater decline in reproduction; 2) in F₁ the marked reduction in both survival and fecundity determined a sharp drop of ; 3) in F₂ the was essentially due to a reduction in fecundity. Our findings underline that evaluating the complex effects of zinc at higher level than individual and during successive generations could provide more information in predicting the impact of pollutants on marine organisms.

Key words: Zinc, Dinophilus gyrociliatus, demography, multigeneration effects