Year: 2009
Type: article
Abstract: This study evaluated the wide-scale applicability of the Redfield ratio, which is a measure of the molar relationship of the macronutrients carbon, nitrogen, and phosphorus (C:N:P) in plankton.By measuring the elemental stoichiometry of phytoplankton, we can gain insights into the availability of nutrients in the water column.Several lines of evidence reported in recent years have given cause to reexamine the ubiquity of the Redfield ratio.Among these is the observation that a pool of cellular phosphorus is adsorbed to the cell exterior and may not be readily available for assimilation by the cells.With this study, we aimed to assess the cellular allocation of phosphorus along a trophic continuum of lakes in Ohio and Indiana including two inland lakes as well as coastal and pelagic locations in Lake Erie ranging from eutrophic to oligotrophic in status.Biomass as gauged by extractive chlorophyll was consistent with our designation of lake trophic status established prior to the survey with Nettle Lake and a nearshore station in Maumee Bay (MB20) supporting the highest chlorophyll levels whereas Crooked Lake and the eastern basin of Lake Erie were characterized as low chlorophyll sites.Despite the identifiable gradient in trophic status, total dissolved phosphate was relatively low at all locations yet not all indicators of cellular phosphorus status were indicative of P deficiency.For example, only at the two oligotrophic sites (Lake Erie station 452 and Crooked Lake, IN) were cellular N:P and C:P ratios suggestive of P deficiency using Redfield stoichiometry as a guide.Further, alkaline phosphatase activity was negligible at the Lake Erie stations sampled during February, 2007.In our limited survey, partitioning of cellular P correlated to lake trophic status with intracellular P representing a lower percentage of total P (14, 57%) at the two iii oligotrophic sites (Crooked Lake and Erie station 452, respectively) compared to mesotrophic and eutrophic sites where intracellular P ranged from 70-95% (median: 82%) of the total cellular allocation.Our confirmation that substantial amounts of P are allocated to the cell surface and that the P allocation may vary with lake trophic status lends further evidence in support of a broader reexamination of the Redfield ratio in its broad scale application to assess nutrient status of phytoplankton.iv
Author: Robyn M. Duckworth
Institution: Bowling Green State University
Language: English
Subfield: Environmental Chemistry
Field: Environmental Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2596024915