Aquatic Sciences Meeting, Albuquerque 2001

SS01 Submerged Aquatic Vegetation and the Water Column (Environmental Connections)

Date: Tuesday, February 13, 2001, Time: 4:15:00 PM

Location: Galisteo

Colman, J, A, U.S. Geological Survey, Northborough, USA, jacolman@usgs.gov

Portnoy, J, W, National Park Service, Wellfleet, USA, John_Portnoy@nps.gov

METALIMNETIC PRODUCTION IN 3 KETTLE-HOLE LAKES: REGULATION BY NITELLA AND NUTRIENT SUPPLY

Changes in metalimnetic [O2] during 2-week intervals over the stratified periods of 3 years (1997-1999) were used to calculate metalimnetic net production (P-R) in 3 kettle-hole lakes in eastern Massachusetts, two with the benthic metalimnetic macroalga Nitella (Walden Pond in Concord; Gull Pond in Wellfleet) and one without (Duck Pond in Wellfleet). High net production (0.3-0.5 g O2 /m2/d) in April in Walden Pond, supported in part by dense stands of Nitella, decreased to zero from May through September. Metalimnetic [O2] increased, 11.3 to 13.5 mg/L, and remained at 13.5 mg/L for 5 months, until destratification. In Gull Pond, metalimnetic net production was zero from April through July and increased in August (0.1 g O2 /m2/d). Although metalimnetic net production in April in Duck Pond was similar to that in Walden Pond, net production in summer was negative (R>P). Evidence indicates that Nitella is nutrient limited after April and that R-P stoichiometry keeps metalimnetic [O2] constant in Walden Pond, and to an extent in Gull Pond, since respiratory degradation of particulate organic matter would be the principal source of nutrients for any Nitella growth.

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Aquatic Sciences Meeting, Albuquerque 2001

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