Original paper

Tripton, trophic state metrics, and near-shore versus pelagic zone responses to external loads in Cayuga Lake, New York, U.S.A.

Effler, Steven W.; Prestigiacomo, Anthony R.; Matthews, David A.; Gelda, Rakesh K.; Peng, Feng; Cowen, Edwin A.; Schweitzer, Seth A.


An analysis of limnological and input monitoring data for Cayuga Lake, New York, U.S.A., is presented that addresses differences in trophic state metrics and turbidity between pelagic waters and a shallow (<6 m) near-shore area (shelf) that receives multiple inputs. the effects of tripton (inanimate particles) on the observed patterns, and the contrasting responses of the shelf to local inputs of tripton versus phosphorus (p), are demonstrated. the analysis is based on a combination of long-term monitoring and shorter-term studies, including: (1) 10 to 20 years of concentrations of chlorophyll-a (Chl), total P (TP), and other forms of P; (2) 10 years of Secchi disc (SD) and surrogates of the light scattering coefficient, including turbidity (Tn) and the beam attenuation coefficient at 660 nm [c(660)]; (3) loading estimates of Tn and forms of P in point sources and tributaries to the shelf (4 to 10 y) and; (4) longitudinal patterns of thermal stratification, fluorometric Chl, and c(660) from a lake-wide 40 site transect; and (5) 10 years of hourly measurements of near-surface temperature on the shelf. The generally higher TP, particulate P, c(660), and Tn, and lower SD on the shelf compared to pelagic waters, particularly after runoff events, is shown to reflect higher tripton levels in the near-shore area. Tripton was also an important regulator of these attributes in pelagic waters. The effects of tripton compromise TP and SD as trophic state metrics in this lake. The light scattering and clarity impacts of tripton are demonstrated to be primarily attributable to clay mineral particles in the 1-10 μm size range. Despite the P loads received from local sources, summer average Chl levels on the shelf were not significantly higher than in bounding pelagic waters because the flushing rate associated with mixing processes, particularly from seiche activity, was high compared to phytoplankton growth rates.


pelagic zonenear-shore zonetrophic statetriptonlight scatteringclay mineral particlesseiche