Weather-driven ecology of planktonic diatoms in Lake Tovel (Trentino, Italy)

摘要

The seasonal development of planktonic diatoms in Lake Tovel has been studied from 2002 to 2004 within the SALTO research project. The objective was to investigate the role of weather conditions and lake hydrology in regulating the development of iCyclotella and iFragilaria functional species groups. The different responses of the two species to the environmental variability and their reciprocal relationships were considered. iCyclotella showed a weak relationship with the selected environmental variables and its seasonal development was difficult to interpret, also in relation to its opportunistic behaviour. On the contrary, iFragilaria complex showed a prompt response to environmental variability and its seasonal development appeared to be mainly regulated by hydrological conditions, through nitrate nitrogen and, secondarily, by silica concentrations. Water temperature and thermal stability affected only iFragilaria species, while different nutrient requirements allowed iCyclotella species to grow under conditions of limited resources for iFragilaria. Since Lake Tovel has scarce internal nutrient reserves and its hydrology is strongly affected by precipitation both in winter and summer, diatom phenology seems to be indirectly regulated by weather conditions.