title: Toward an ecologically meaningful view of resource stoichiometry in DOM-dominated aquatic systems.
abstract: Research on nutrient controls of planktonic productivity tends to focus on a few standard fractions of inorganic or total nitrogen (N) and phosphorus (P). However, there is a wide range in the degree to which land-derived dissolved organic nutrients can be assimilated by biota. Thus, in systems where such fractions form a majority of the macronutrient resource pool, including many boreal inland waters and estuaries, our understanding of bacterio- and phytoplankton production dynamics remains limited. To adequately predict aquatic productivity in a changing environment, improved standard methods are needed for determining the sizes of active (bioavailable) pools of N, P and organic carbon (C). A synthesis of current knowledge suggests that variation in the C:N:P stoichiometry of bioavailable resources is associated with diverse processes that differentially influence the individual elements across space and time. Due to a generally increasing organic nutrient bioavailability from C to N to P, we hypothesize that the C:N and N:P of bulk resources often vastly overestimates the corresponding ratios of bioavailable resources. It is further proposed that basal planktonic production is regulated by variation in the source, magnitude and timing of terrestrial runoff, through processes that have so far been poorly described.
authors.affiliation: Department of Physical Geography and Ecosystem Science , Lund University , SE-223 62 Lund , Sweden.
authors.forename: Martin
authors.initials: M
authors.lastname: Berggren
authors.affiliation: Department of Ecology and Environmental Science , Umeå University , SE-901 87 Umeå , Sweden.
authors.forename: Ryan A
authors.initials: RA
authors.lastname: Sponseller
authors.affiliation: Department of Physical Geography and Ecosystem Science , Lund University , SE-223 62 Lund , Sweden.
authors.forename: Ana R
authors.initials: AR
authors.lastname: Alves Soares
authors.affiliation: Department of Ecology and Environmental Science , Umeå University , SE-901 87 Umeå , Sweden.
authors.forename: Ann-Kristin
authors.initials: AK
authors.lastname: Bergström
keywords: bacterioplankton production; basal resource stoichiometry; bioavailability; dissolved organic matter; nutrient limitation; phytoplankton primary production