2023 Early Hearing Detection & Intervention Conference

March 5-7, 2023 • Cincinnati, OH

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5/23/2019 | 11:45 AM - 12:00 PM | DIVING INTO MURKY WATERS - EFFECTS OF BROWNIFICATION ON STREAM BIOFILM QUALITY, FUNCTIONING AND STRUCTURE | 254 B

DIVING INTO MURKY WATERS - EFFECTS OF BROWNIFICATION ON STREAM BIOFILM QUALITY, FUNCTIONING AND STRUCTURE

Colour of surface waters has darkened throughout the northern hemisphere due to alteration of the quantity and quality of terrestrially-produced dissolved organic carbon (DOC). Forestry actions intensify ‘brownification’ by soil modification and enhance light availability via removal of riparian canopy. We used near-natural stream mesocosms to test experimentally, whether brownification and canopy removal affect the nutritional quality, functioning and structure of stream biofilm communities. Elevated DOC resulted in significantly higher bacterial production, likely fuelled by excess C, as we detected a simultaneous increase in biofilm respiration. Algal productivity and amount of essential fatty acids (EPA and DHA) decreased drastically and terrestrially-produced low-quality fatty acids (LSAFA) increased with brownification. Canopy removal mainly attenuated the effects of elevated DOC as algae benefitted from less limited light conditions. Overall, our results indicate that brownification cause a strong shift towards heterotrophy in system metabolism. Changes that occur in stream biofilm are likely to cascade higher up in stream food webs and downstream in a stream network. Thus, understanding the consequences of brownification is crucial for more effective water quality and carbon cycling management.

Carbon
Mesocosm
Aquatic-terrestrial Linkage

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Presenters/Authors

Maria Rajakallio (), University of Oulu, maria.rajakallio@oulu.fi;