Assessing the aquatic metabolic-balance response to future condition in a Mediterranean site: from an experimental-design perspective

Abstract

Context

Metabolic balance determines whether an ecosystem acts as a source or sink of carbon dioxide (CO₂) and considering that a substantial portion of inland aquatic ecosystems act as a source of CO₂ to the atmosphere, it is important to highlight that there is still no agreement on how global change will affect the ecosystem metabolic-balance response. It then becomes more important to study the interactions between global-change drivers and aquatic metabolism.

Aims

Assess possible shifts in ecosystem metabolic balance owing to global-change factors.

Methods

Collapsed factorial designs and novel experimental units have been used to study responses to future conditions.

Key results

In the study site, bacterial production was not affected by an increased temperature alone; however, increased nutrient availability may unmask UV or CO₂ as a source of stress to bacteria. A synergistic effect between temperature and the combined effect of nutrients and CO₂ on primary producers was also found.

Conclusions

In future scenarios, some heterotrophic inland water ecosystems may shift from heterotrophic to autotrophic states and therefore act as CO₂ sinks.

Implications

This study provides a framework to support a deepening of knowledge on this topic.