The stoichiometry of carbon, nitrogen, and phosphorus in particulate matter of lakes and oceans

Abstract

The mean carbon, nitrogen, and phosphorus contents of particulate material for 51 lakes or lake basins, extending from arctic to tropical climatic regions, including small lakes as well as the largest lakes in the world, indicate that Redfield ratios are the exception rather than the rule in freshwater. The C : P and N : P ratios are more variable for lake particles but generally higher than marine particles, and the mean molar C : N, C : P, and N : P ratios are substantially higher than the Redfield ratio of 106 : 16: 1. On average, lower C : N, C : P, and N : P ratios occur in subarctic lakes while higher ratios occur in the tropics and in temperate, oligotrophic lakes on the Canadian Shield. In shield lakes with long residence times (>6 months) the high ratios of C : N, C : P, and N : P do not originate from streamborne or atmospherically deposited particles but arise from in‐lake processes. Regression analysis demonstrates that small lakes are generally more N and P deficient than large lakes. In freshwaters, particulate composition ratios imply that a wide variety of conditions exists in lakes, including N and P deficiency, as well as N and P sufficiency. In the Experimental Lakes Area of Canada, independent physiological nutrient status indicators generally agree with the status indicated by seston ratios. The relative uniformity of marine C : N : P composition (compared to lakes) at the Redfield ratio suggests that marine plankton cannot be as severely, or as frequently, limited by N and P as lake plankton. Consequently, the paradigm of N limitation in the oceans requires qualification. Based on particulate composition, it is more correct to say that ocean plankton is not as N and P deficient as lake plankton.