status quo before the start of the work (i.e. the identification of the living spe cies and the existing habitat), the ante operam monitoring must: document the dynamic evolution of each individual environmental variable subjected to “stress” during the work site phases, making an as sessment of its response; report the occurrence of any envi ronmental emergencies, so that ac tion may be taken in the most suitable times, methods and forms; guarantee the control of specific situations.