title: Forests fuel fish growth in freshwater deltas.
abstract: Aquatic ecosystems are fuelled by biogeochemical inputs from surrounding lands and within-lake primary production. Disturbances that change these inputs may affect how aquatic ecosystems function and deliver services vital to humans. Here we test, using a forest cover gradient across eight separate catchments, whether disturbances that remove terrestrial biomass lower organic matter inputs into freshwater lakes, thereby reducing food web productivity. We focus on deltas formed at the stream-lake interface where terrestrial-derived particulate material is deposited. We find that organic matter export increases from more forested catchments, enhancing bacterial biomass. This transfers energy upwards through communities of heavier zooplankton, leading to a fourfold increase in weights of planktivorous young-of-the-year fish. At least 34% of fish biomass is supported by terrestrial primary production, increasing to 66% with greater forest cover. Habitat tracers confirm fish were closely associated with individual catchments, demonstrating that watershed protection and restoration increase biomass in critical life-stages of fish.
authors.affiliation: 1] Vale Living with Lakes Centre, Laurentian University, 935 Ramsey Lake Road, Sudbury, Ontario, Canada P3E 2C6 [2].
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Tanentzap
authors.affiliation: Vale Living with Lakes Centre, Laurentian University, 935 Ramsey Lake Road, Sudbury, Ontario, Canada P3E 2C6.
authors.forename: Erik J
authors.initials: EJ
authors.lastname: Szkokan-Emilson
authors.affiliation: Biology Department, Queen's University, 116 Barrie Street, Kingston, Ontario, Canada K7L 3J9.
authors.forename: Brian W
authors.initials: BW
authors.lastname: Kielstra
authors.affiliation: 1] Environment Canada, 867 Lakeshore Road, PO Box 5050, Burlington, Ontario, Canada L7R 4A6 [2].
authors.forename: Michael T
authors.initials: MT
authors.lastname: Arts
authors.affiliation: 1] Dorset Environmental Science Centre, 1026 Bellwood Acres Road, Dorset, Ontario, Canada P0A 1E0 [2] York University, 4700 Keele Street, Toronto, Ontario, Canada M3J 1P3.
authors.forename: Norman D
authors.initials: ND
authors.lastname: Yan
authors.affiliation: Vale Living with Lakes Centre, Laurentian University, 935 Ramsey Lake Road, Sudbury, Ontario, Canada P3E 2C6.
authors.forename: John M
authors.initials: JM
authors.lastname: Gunn
mesh_terms: D000818:Animals; D018533:Biomass; D017753:Ecosystem; D005399:Fishes; D020387:Food Chain; D065928:Forests; D005618:Fresh Water; D060106:Lakes; D045483:Rivers; D015048:Zooplankton