Improvements in water chemistry have not yet reached the level necessary for acid-sensitive species to recover (biological recovery cannot start before water quality is suitable); Episodes of acid water connected with snowmelt, sea-salt deposition, etc. will prevent sustainable recovery and result in multiple recolonizations (an on/off situation of sensitive species); Bottlenecks due to dispersal of sensitive species (arrival factors); Bottlenecks due to interactions/competitions with other species (survival factors of the sensitive species); Dispersal mechanisms affected by stream/lake characteristics such as size, morphology, distance from refuge, etc.; Dispersal and recolonization dependent on life cycle and behaviour (resting eggs, flying insects, size, etc.); What is biological recovery?
a) Les améliorations de la chimie de l'eau n'ont pas encore atteint le niveau nécessaire pour que les espèces sensibles à l'acidification puissent se régénérer (la régénération biologique ne peut pas s'enclencher tant que l'eau n'a pas la qualité voulue);