Phosphorus loadings to lakes and some of their responses. Part 2. Regression models of summer phytoplankton standing crops, winter total P, and transparency of New York lakes with known phosphorus loadings 1

Abstract

An interrelated series of regression equations is derived to define the response of lake ecosystems to mixed zone phosphorus loadings in terms of simple and readily determinable parameters. Data used were collected over 14 yr for 16 lakes in central New York State characterized by a wide variety of morphometries, hydrologies, and phosphorus loadings. The regressions describing the dependence of summer phytoplankton standing crop and winter total P concentration on loading and of standing crop on total P were linear. Those characterizing water transparency as a function of standing crop and winter total P were parabolic. All regressions showed high correlation coefficients. The overall model composed of these regressions establishes a quantitative basis for the concept that phosphorus supplied to lakes exerts a uniquely controlling role on phytoplankton standing crop. The regressions may be used for trophic state description and in the development of management strategies for lakes.

Data collection methods

“…Pond is consistent with the 0.8 m value predicted from chlorophyll measurements (Oglesby and Schaffner 1978), but the annual mean secchi disk reading was appreciably lower than the 1.6 m value predicted from the mean chlorophyll level (Vollenweider 1982) (Appendix B). This is to some degree a consequence of the shallowness of the pond (maximum depth = 1.3 m), but the pond bottom was visible at its deepest point on only three sampling dates.…”

“…Yet summer chlorophyll levels (Appendix B) in Buttonwood Pond are about 18 to 33% lower than would be predicted from phosphorus data (Jones andBachmann 1976, Oglesby andSchaffner 1978). Some of the phosphorus in the water column may be unavailable for algal uptake, but the presence of orthophosphorus at levels appreciably greater than 10 ug/l during most of the summer suggests that phosphorus availability is not a chronic limiting factor.…”

“…It is the same pigmentthat makes grass and leaves green. Chlorophyll a usually represents 0.5 to 2% of the total phytoplankton biomass and has been correlated with production and standing crop at various levels of the food web, water clarity, and phosphorus concentration (e.g., Jones and Bachmann 1976, Oglesby and Schaffner 1978, Hanson and Leggett 1982, Vollenweider 1982. Chlorophyll levels in Buttonwood Pond ranged from 3.8 to 91 ug/l, with an annual mean of 33.4 ug/l and a summer mean of 57 ug/l (Appendix B) .…”

Nutrient limitation of phytoplankton in Chesapeake Bay

“…Cultural eutrophication of lakes and estuaries results from anthropogenic inputs of nitrogen (N) and phosphorus (P) from surrounding watersheds (Edmondson 1970, Schindler 1977, Oglesby & Schaffner 1978, Smith 1982, Hecky & Kdham 1988. While there has been considerable experimental work on the causes of lake eutrophication over the last few decades (e.g.…”

Relationships between water quality and phosphorus concentrations for lakes of the Puget Sound region, Washington

“…Chapra and Tarapchak (1976) reviewed relationships between chlorophyll a_ levels and lake productivity of biomass. In general, mean summer chlorophyll a_ concentrations that average less than 3 yg/L indicate low-productivity lakes, concentrations between 3 and 9 yg/L indicate medium productivity lakes; and average concentrations greater than 9 yg/L indicate lakes with high productivity, In this study, we evaluated relationships between summer chlorophyll a (SCHLA) and both winter-spring total P and summer total P. Winter-spring Total I concentration has been used by other investigators as an index of the amount of P available for algal growth at the onset of the summer growing season and for predicting summer chlorophyll £ levels (Dillon and Rigler, 1974;Chapra and Tarapchak, 1976;and Oglesby and Schaffner, 1978). Summer epilimnion total P levels, which more directly represent the amount of P actually involved in algal growth during the summer growing season, have also been successfully used to predict summer chlorophyll £ concentration (Jones and Bachman, 1976).…”