Respiration is increased by macrophyte structural complexity and epiphytic interactions in stream benthic communities

Complexity of macrophyte architecture could influence metabolic reactivity in streams due to an effective streambed occupation of the macrophyte-epiphyton ensembles, which promotes a more efficient use of solute resources. Here, we assessed the influence of the macrophyte complexity and macrophyte-epiphytic interaction on the community-level respiration in a microcosm experiment. We compared the respiration of two macrophyte species with higher (Elodea ernstae) and lower (Stuckenia striata) architectural complexity. The experiment had four treatments (with five replicates): E. ernstae with (E+) and without (E-) epiphyton, and S. striata with (S+) and without (S-) epiphyton. Respiration was determined using the smart trace Rezasurin (Raz). We did not observe significant differences in epiphytic chlorophyll-a and particulate organic contents among treatments. However, respiratory activity was consistently higher in the species with more complex structure (E. ernstae) than in those with less complex structure (S. striata). In addition, the presence of epiphyton on macrophytes significantly increased the respiratory activity of E. ernstae, but not of S. striata. Our results show that higher macrophyte complexity can increase epiphytic development; and thus, its contribution to the benthic respiration. This suggests that in-stream presence of more complex macrophytic species may reduce dissolved oxygen availability and promote CO₂ emissions to the atmosphere.

Presentation Preference: Standard Oral (12 Minutes)

Primary Presenter: Claudia Feijoó, Instituto de Ecología y Desarrollo Sustentable (INEDES; CONICET-UNLu) (clasife@yahoo.com.ar)

Authors:

Claudia Feijoó, Instituto de Ecología y Desarrollo Sustentable (CONICET-UNLu); CONICET  (clasife@yahoo.com.ar)

Liria Campos, Instituto de Ecología y Desarrollo Sustentable (CONICET-UNLu); CONICET  (liriabelencampos@gmail.com)

Rolando Caraballo, Instituto de Ecología y Desarrollo Sustentable (CONICET-UNLu); CONICET  (rolot4@gmail.com)

Miquel Ribot, Centre d’Estudis Avançats de Blanes  (mribot@ceab.csic.es)

Adonis Giorgi, Instituto de Ecología y Desarrollo Sustentable (CONICET-UNLu); CONICET  (adonisgiorgi16@gmail.com)

Eugenia Martí, Centre d’Estudis Avançats de Blanes  (eugenia@ceab.csic.es)