SS3.10 Ecological Implications of Terrestrial Inputs into Lakes and Ponds
Date: Tuesday, June 11, 2002
Location: Poster Session - VCC
 
Di LonardoSS, Louis Calder Center – Biological Station, Fordham University, Armonk, NY 10504, USA, dilonardo@fordham.edu
Wehr, J, D, Louis Calder Center – Biological Station, Fordham University, Armonk, NY 10504, USA, wehr@fordham.edu
Perrone, A, A, Louis Calder Center – Biological Station, Fordham University, Armonk, NY 10504, USA, aperrone@fordham.edu
 
EFFECTS OF TERRESTRIAL VERSUS AQUATIC SOURCES OF DOC ON A PLANKTON COMMUNITY UNDER DIFFERING UV RADIATION REGIMES.
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A study using 5400L lakewater mesocosms examined chemical, optical and biological responses of a summertime planktonic community to experimental manipulations of DOC using terrestrial (oak + maple) and aquatic (Vallisneria) detritus to roughly double DOC levels (Calder Lake ambient 5.1 mg DOC/L). Nested microcosms (1200 mL) compared effects of ambient and reduced UV radiation (>90% UVA+B removed). Amended DOC concentrations were initially similar across POC and UVR treatments (9.1 - 9.7 mg/L), and declined more rapidly in systems with aquatic detritus (-3.6 mg/L in 48h) than terrestrial (-1.7 mg/L), but rates did not differ among UVR treatments. UV absorbances (OD 310, 250 nm) were initially 50% greater with aquatic and 2.5X greater with terrestrial DOC than controls. ODs declined over time (aquatic DOM > terrestrial), with slightly greater rates in +UV microcosms (no apparent UV effect in terrestrial DOM microcosms). Other water chemistry variables (P, N, O2, pH) were also affected by treatments, but over different time courses. Phytoplankton, bacterioplankton and heterotrophic protist densities varied across treatments and time, but did not appear to be dependent on UVR treatments.