UFJF - Universidade Federal de Juiz de Fora

Autochthonous vs. allochthonous DOM source and bacterial metabolism: influence to the carbon balance in mesocosms experiments

Data: 10 de November de 2016

   Freshwater ecosystems processes great amounts of terrestrial carbon and is an important link to global carbon. To date it is known that most terrestrial dissolved organic matter (DOM) subsidizes aquatic mineralization processes, such as respiration. In contrast, autochtonous DOM (e.g. algal-derived) is largely used in the secondary biomass production through microbial food web. Therefore, terrestrial DOM is an important energy source while autochtonous DOM is an important organic matter source to the aquatic food web.

   Recent studies suggested that the mixture of terrestrial and autochthonous DOM may over stimulate bacterial secondary production, increasing bacterial growth efficiency (BGE), as a result of a more efficient resource use in a system with higher substrate diversity. Thus, the mixture of algal-derived and terrestrially-derived DOM might affect carbon balance in aquaticsystems, since it can affect BGE and carbon processing in lakes. 2375587

   We hypothesized that the mixture of algal and terrestrial DOM stimulates bacterial production rather than respiration, which might contributes to carbon accumulation in aquatic system due to higher BGE.

   To test this hypothesis we will set up water tank mesocosm experiments with 4 treatments:

 

  1. Lake water (control treatment)
  2. Lake water + nitrogen and phosphorous (+NP)
  3. Lake water + terrestrial litter (terrestrial organioc matter; +TOM)
  4. Lake water +NP +TOM.

 

   During 6 weeks we will measure CO2 saturation, as well as planktonic communities parameters (bacterial, phyto and zooplankton), such as biomass and biomass production, bacterial respiration and total plankton respiration. In paralel we will conduct microscale experiments to describe the leaching process of the litter. The results of this project will help to understantand whether and how DOM mixtures may affect the whole system carbon balance.

 

Members:

André Megali Amado | Coordinator

Fabio Roland

Luciana O Vidal

Natália Pessoa Noyma

Caroline Gabriela Bezerra de Moura

Tatyane Ribeiro Paitot

Bárbara de Araújo Quadros

Elinez da Silva Rocha