EMERGENT LINKAGES AMONG DISSOLVED ORGANIC MATTER COMPOSITION, MICROBIAL ASSEMBLAGES AND RESPIRATION

Dissolved organic matter (DOM) fuels microbial activity in aquatic ecosystems, and linking the supply and characteristics of DOM with dynamics of microbial assemblages is necessary to mechanistically explain variation in ecosystem respiration. Yet, the DOM pools and the microbial communities that process DOM are each complex, and understanding of their interactions is elusive. We conducted an experiment where microbial assemblages acclimated to 3 sources of DOM (fulvic acid standard, soil leachate, algal leachate) were grown on all three DOM sources in a factorial design for 14 days. We hypothesized that DOC removal and respiration would be highest when microbial assemblages were acclimated to the DOM source. Maximum CO₂ accumulation rates were highest in the treatments with algal-derived DOM and algal-acclimated microbiota, and were significantly affected by DOM source, microbial enrichment and incubation time, but not the interaction among the 3. By day 10, total CO₂ accumulation was 2x greater in the algal DOM than the soil DOM treatments, which in turn were an order of magnitude greater than the fulvic acid DOM treatments. Total CO₂ accumulation was also affected by the interaction between DOM source and microbial enrichment, while change in DOC concentration was only affected by DOM source. We are using machine learning to determine which characteristics of DOM and microbial assemblages can accurately predict respiration rates, and whether experimentally-derived models can be applied to understanding ecosystem respiration in natural aquatic environments.

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Primary Presenter: Amy Marcarelli, Michigan Technological University (ammarcar@mtu.edu)

Authors:

Amy Marcarelli, Michigan Technological University  (ammarcar@mtu.edu)

Michelle Kelly, Michigan Technological University  (mckelly1@mtu.edu)

Isaac Bigcraft, Michigan Technological University  (isbigcra@mtu.edu)

Prajakta Kokate, Michigan Technological University  (pkokate@mtu.edu)

Evan Kane, Michigan Technological University  (eskane@mtu.edu)

Laura Brown, Michigan Technological University  (lebrown@mtu.edu)

Stephen Techtmann, Michigan Technological University  (smtechtm@mtu.edu)