Open AccessPhosphorus‐limited growth dynamics in two Baltic Sea cyanobacteria, Nodularia sp. and Aphanizomenon sp.
Author(s) -
Degerholm Jenny,
Gundersen Kjell,
Bergman Birgitta,
Söderbäck Erik
Publication year - 2006
Publication title -
fems microbiology ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.377
H-Index - 155
eISSN - 1574-6941
pISSN - 0168-6496
DOI - 10.1111/j.1574-6941.2006.00180.x
Subject(s) - aphanizomenon , biology , cyanobacteria , phosphorus , nutrient , phosphorus deficiency , botany , nitrogenase , nitrogen fixation , ecology , environmental chemistry , anabaena , bacteria , chemistry , genetics , organic chemistry
Rates of carbon (C) specific growth and nitrogen (N 2 ) fixation were monitored in cultures of Baltic Sea Nodularia and Aphanizomenon exposed to gradual limitation by inorganic phosphorus (P). Both cyanobacteria responded by decreased cellular P content followed by lowered rates of growth and N 2 fixation. C‐specific growth and cellular N content changed faster in Aphanizomenon both when inorganic P was lowered as well as during reintroduction of P. Aphanizomenon also showed a more rapid increase in N‐specific N 2 fixation associated with increased C‐specific growth. When ambient concentrations of inorganic P declined, both cyanobacteria displayed higher rates of alkaline phosphatase (APase) activity. Lower substrate half‐saturation constants ( K M ) and higher V max : K M ratio of the APase enzyme associated with Nodularia suggest a higher affinity for dissolved organic P (DOP) substrate than Aphanizomenon . Aphanizomenon , which appears more sensitive to changes in ambient dissolved inorganic P, may be adapted to environments with elevated concentrations of P or repeated intrusions of nutrient‐rich water. Nodularia on the other hand, with its higher tolerance to increased P starvation may have an ecological advantage in stratified surface waters of the Baltic Sea during periods of low P availability.