Mountain river ecosystems naturally receive particulate organic materials such as leaf litter, wood and branches from the riparian vegetation, which are substrata and organic matter source for microbial communities. Human activity may drive a further input of particulate organic materials such as plastic in these ecosystems, as well as bioplastics which have emerged as an alternative to plastics. We aimed to analyze the differences in biomass and function of microorganisms colonizing plastics and natural materials in a mountain river ecosystem. Samples of 2 natural materials (leaves and wood), 2 bioplastics (PHA, PLA), and 2 plastics (PE, PP) were immersed in the Torrent de Concròs (1400 m.a.s.l., eastern Pyrenees), and collected after 120, 202, 316 and 383 days. Microbial biomass and autotrophic and heterotrophic functions (net primary production, respiration, extracellular enzyme activities, and nutrient uptake) were analyzed together with weight loss (i.e.  decomposition rate). We found higher values of microbial biomass, β-glucosidase, phosphatase and lipase activities, and weight loss in natural materials. Phenol-oxidase activity did not present clear differences between natural and non-natural materials, which could mean that this activity plays a role in the degradation of non-natural materials. Results suggest that higher heterotrophic activity and biomass enhances the decomposition of natural materials while autotrophic colonization of plastics and bioplastics suggest these materials are behaving more as an inert substrata than as an organic matter source.

Primary Presenter: Mar Oliva-Albert, University of Girona (u1952356@campus.udg.edu)

Authors:

Mar Oliva-Albert, University of Girona  (u1952356@campus.udg.edu)

Alba Bellostas-Carreras,   (albabellostas@gmail.com)

José Luís Guijosa-Ortega,   (u1959420@campus.udg.edu)

Anna Doménech-Pascual, University of Girona  (a.domenech@udg.edu)

Judit Boadella, University of Girona  (judit.boadella@udg.edu)

Laura Ayuso,   ()

David Pineda, CEAB  ()

Joan Pere Casas-Ruiz, University of Girona  (jpcasasruiz@gmail.com)

Eugènia Martí, CEAB  (eugenia@ceab.csic.es)

Helena Guasch, CEAB  (helena.guasch@ceab.csic.es)

Joan Artigas, Université Clermont Auvergne  (joan.artigas_alejo@uca.fr)

Anna Lupón, CEAB  (alupon@ceab.csic.es)

Anna M. Romaní, University of Girona  (anna.romani@udg.edu)