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Presented at the NABS Annual meeting, Anchorage, Alaska, 2006
in Watershed Science in Surface Drinking Water Supplies 2
Algal biomass and metabolic rates in New York City drinking water reservoirs and tributary streams
T.L. Bott, D. Montgomery, J.D. Newbold, D.B. Arscott, and C.L. Dow.Stroud Water Research Center, 970 Spencer Rd., Avondale PA, U.S.A. 19311
Measures of algal biomass and metabolism were conducted in 12 reservoirs and 17 tributaries annually for 3 – 6 y as indicators of nutrient status and ecosystem integrity. Chlorophyll was greater in 6 reservoirs located east of the Hudson R. (EOH) than in 6 of 7 west of the Hudson (WOH) reservoirs, with gradients in some. Reservoir Gross Primary Productivity (GPP; from light bottle – dark bottle measurements) normalized for photosynthetically active radiation ranged from 0.025 to 0.18 g O2/mol quanta, and was greater in EOH than in most WOH reservoirs. Chlorophyll was greater in WOH streams, but not invariably. Stream GPP (from open system diel O2 change measurements with reaeration from propane evasion) ranged from 0.22 to 4.2 g O2⋅m-2⋅d-1, with higher rates in the larger WOH streams. EOH streams were both smaller and more densely shaded. All streams were heterotrophic, with greater respiration (1.6 to 12.5 g O2⋅m-2⋅d-1) than GPP. P/R ratios ranged from 0.43 to 0.58 in most WOH streams, and from 0.17 to 0.38 in EOH streams. Results from functional measures will be related to other indices of aquatic ecosystem condition and land uses, which were primarily forest and suburban EOH and forest and agriculture WOH.
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