title: The effects of wastewater effluent and river discharge on benthic heterotrophic production, organic biomass and respiration in marine coastal sediments.
abstract: We examine effects of high river particulate flux and municipal wastewater effluent on heterotrophic organic carbon cycling in coastal subtidal sediments. Heterotrophic production was a predictable (r(2)=0.95) proportion (56%) of oxidized OC flux and strongly correlated with organic/inorganic flux. Consistent growth efficiencies (36%) occurred at all stations. Organic biomass was correlated with total, OC and buried OC fluxes, but not oxidized OC flux. Near the river, production was modest and biomass high, resulting in low P/B. Outfall deposition resulted in depleted biomass and high bacterial production, resulting in the highest P/B. These patterns explain why this region is production "saturated". The δ(15)N in outfall effluent, sediments and dominant taxa provided insight into where, and which types of organisms feed directly on fresh outfall particulates, on older, refractory material buried in sediments, or utilize chemosynthetic symbiotic bacteria. Results are discussed in the context of declining bottom oxygen conditions along the coast.
authors.affiliation: Institute of Ocean Sciences, Box 6000, Sidney, BC V8L4B2, Canada. Electronic address: burdb@dfo-mpo.gc.ca.
authors.forename: B
authors.initials: B
authors.lastname: Burd
authors.forename: T
authors.initials: T
authors.lastname: Macdonald
authors.forename: S
authors.initials: S
authors.lastname: Bertold
mesh_terms: D000818:Animals; D059001:Aquatic Organisms / Q000145:classification* / Q000254:growth & development; D017753:Ecosystem; D004784:Environmental Monitoring; D019015:Geologic Sediments / Q000737:chemistry*; D052836:Heterotrophic Processes; D045483:Rivers / Q000737:chemistry; D062065:Wastewater / Q000032:analysis* / Q000706:statistics & numerical data; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D062065:Wastewater; D014874:Water Pollutants, Chemical
keywords: Organic biomass; Outfall exposure; River sedimentation; Sediment fluxes; Sediment heterotrophic production; Strait of Georgia