Catalan Water Research Institute research and innovation for the sustainable use of water

Defense of the doctoral thesis, Ferran Romero. Multiple stressor effects on river biofilm communities: from community composition to ecosystem processes using experimental mesocosms

11 a.m. ICRA meeting room

Defense Thesis: Multiple stressor effects on river biofilm communities: from community composition to ecosystem processes using experimental mesocosms

By: Ferran Romero

Thesis directors: Sergi Sabater (ICRA and UdG) and Vicenç Acuña (ICRA)

abstract:

Human activity worldwide exposes aquatic ecosystems to multiple anthropogenic stressors. Freshwater ecosystems are of special concern because of their remarkable sensitivity to stressors and relevance for global biodiversity and human well-being. Among the many stressors that threaten freshwater ecosystems, those derived from land-use change include the release of many pollutants into rivers and streams flowing through urban and agricultural areas. Also, climatic stressors such as warming, and others related to human action such as hydrological stress, affect river ecosystems on a global scale by modifying biodiversity patterns and ecosystem functioning. Among the many organisms exposed to multiple stressors in freshwater ecosystems, those attached to river and stream sediments play a crucial role in virtually all major ecosystem processes and are frequently used as sentinels when assessing stressor impacts on freshwater ecosystems. This thesis aims to identify the single and multiple-stressor effects of warming, hydrological stress and pollutant exposure on river biofilms. To that purpose, I used several experimental approaches, consisting of glass crystallizers and artificial streams to expose river biofilms to single and multiple-stressor scenarios under controlled conditions. I tested the river biofilm response both at the structural and the functional scale, employing response variables that ranged from photosynthetic and enzymatic activity to gene expression and bacterial community composition. I detected that hydrological stress was the most influential stressor, especially impairing the biofilm community growing on cobbles. Water warming had lesser effects, mostly affecting bacterial activity due to the dependence of metabolic activity on temperature, but showed limited effects on bacterial community composition. Pollutant exposure had contrasting results depending on the nature of the pollutant used. The results presented in this thesis show that single and multiple stressors affect both biofilm community structure and function, and emphasize that river biofilms show an adaptive nature when facing multiple-stressor scenarios.

  • Data

    Friday, 20 December 2019

  • Share