GLOBAL PRESSURES, SPECIFIC RESPONSES. THE EFFECT OF NUTRIENT ENRICHMENT IN CONTRASTING STREAMS

ARTIGAS, J.; GÓMEZ N.; DONATTO, J; GIORGI, A; ELOSEGUÍ. A; FEIJOO, C.; MUÑOZ, I.; RODRIGUES CAPITULO A.; ROMANÍ, A; SABATER, S.

Nueva Mexico

Congreso; Aquatic Sciences: global changes from the center to the edge Aslo & Nabs; 2010

Aslo & Nabs

  We analyzed  how much different will be the response of streams in different bioclimatic regions ( Mediterranean, Andean and Pampean  lotic ecosystem ) when are exposed to enrichment with nutrients.Two   hypothesis  were made a)nutrients intensify biological activities and drive changes in aquatic food webs, but b) The amplitude  of the response depends on site-specific environmental conditions (light, temperature, hydrology, nutrient condition). The main conclusions were :The peak biomass response to the enrichment was the highest in the most nutrient-limited stream. • The duration of the response was related to the existence of windows of opportunity (when accompanying limiting factors are not relevant) • The effects on consumers depend on the magnitude and duration of the enrichment effect in primary producers, but also on the food web complexity • The lowest response to nutrient enrichment would be expected in streams with environmental constraints (forested, high hydrological variability) • When climate change opens new windows of opportunity, effects may be multiplicative- and extended to apparently  wellprotected systems.