Variazione di biomassa delle larve di salamandra pezzata in ambienti epigei ed ipogei

The fire salamander, Salamandra salamandra, generally reproduces in epigean habitats, however, cases of deposition in hypogean environments can occur. Aim of this study is to understand the role that the fire salamander plays in the biomass flows that occur among the water and terrestrial environments, taking into account both epigean and hypogean habitats. To this extent we have examined the balance between the biomass of deposed fire salamander larvae and nearly metamorphosized ones: 5 epigean spring pools from an hilly area placed within the districts of Como and Lecco, were weekly monitored in the period from March to August 2014, while data on other 16 sites (12 hypogean and 4 epigean) were obtained from a previous study (2013) conducted in the same area and with the same methodology. During each monitoring we have collected weight and body size data for each larvae in every single site. The outgoing biomass balance, in terms of salamander larvae, has been obtained subtracting the sum of newborn larva weight present in each pool to the total weight of the survived larvae that reached the premetamorphic stage in the same pool. Moreover, brightness, temperature and biomass of invertebrate preys and predators present in each pool have been measured. Statistical analysis has been conducted using linear mixed models in order to determine which factors have influenced the biomass balance, distinguishing between epigean and hypogean habitats. During 2014 surveys an high initial density of newborn larvae in the monitored sites has been noticed and, although the remarkable mortality rate, on average 13.02 salamander larvae, per site have successfully reached the metamorphosis. The outgoing biomass balance has been found to be positively correlated to the brightness of the site and furthermore resulted lower in the hypogean habitats. In conclusion, these results underline how biomass balance in substantially different environments, like hypogean and epigean habitats, can be differently influenced by peculiar ecological features and how it results generally negative in scarce productive habitats such as the caves.