Metabolism and resources of spherical colonies of Nostoc zetterstedtii
Research output: Contribution to journal › Journal article › Research › peer-review
Standard
Metabolism and resources of spherical colonies of Nostoc zetterstedtii. / Jensen, Kaj Sand; Raun, Ane-Marie Løvendahl; Borum, Jens.
In: Limnology and Oceanography, Vol. 54, No. 4, 2009, p. 1282–1291.Research output: Contribution to journal › Journal article › Research › peer-review
Harvard
APA
Vancouver
Author
Bibtex
}
RIS
TY - JOUR
T1 - Metabolism and resources of spherical colonies of Nostoc zetterstedtii
AU - Jensen, Kaj Sand
AU - Raun, Ane-Marie Løvendahl
AU - Borum, Jens
PY - 2009
Y1 - 2009
N2 - Constraints imposed by the spherical form and gelatinous matrix of centimeter-thick colonies of thecyanobacterium Nostoc zetterstedtii on its functional properties were tested by examining the scaling of itscomposition, light absorption, photosynthesis, and respiration to individual size. In three summer experimentswith colonies collected from the bottom of oligotrophic lakes of low inorganic carbon concentrations (dissolvedinorganic C, DIC), metabolism and pigment density of colonies were scaled to their surface area as most algalfilaments were confined to a 2-mm-thick outer shell. Nostoc absorbed 96% of incident light from the surface to thecenter because of high areal pigment density, but absorbed photons were used with low quantum efficiency (11-38 mmol O2 mol21 photon) and photosynthesis was low relative to dark respiration (2.0-5.4). Therefore, N.zetterstedtii is threatened by reduced light availability and only extended to lake depths receiving about 12% ofsurface irradiance, whereas mosses, characeans, and angiosperms with thin photosynthetic tissues grew deeper(3.1-7.5% of surface irradiance). Nostoc ameliorated the restrictions of low lake DIC and long diffusion paths byactive transport that could extract most external DIC, accumulate DIC in the colony 150-fold above externalconcentrations, and retain respiratory CO2. The energy cost of solute transport and gel formation in Nostoccolonies and extensive self shading restrict their potential growth, whereas colony formation should preventgrazing and increase longevity and nutrient recirculation. Nostoc zetterstedtii has become one of rarest freshwatermacroalgae because of widespread lake eutrophication reducing water transparency and increasing competitionfrom taller and faster-growing stands of filamentous algae and higher plants.
AB - Constraints imposed by the spherical form and gelatinous matrix of centimeter-thick colonies of thecyanobacterium Nostoc zetterstedtii on its functional properties were tested by examining the scaling of itscomposition, light absorption, photosynthesis, and respiration to individual size. In three summer experimentswith colonies collected from the bottom of oligotrophic lakes of low inorganic carbon concentrations (dissolvedinorganic C, DIC), metabolism and pigment density of colonies were scaled to their surface area as most algalfilaments were confined to a 2-mm-thick outer shell. Nostoc absorbed 96% of incident light from the surface to thecenter because of high areal pigment density, but absorbed photons were used with low quantum efficiency (11-38 mmol O2 mol21 photon) and photosynthesis was low relative to dark respiration (2.0-5.4). Therefore, N.zetterstedtii is threatened by reduced light availability and only extended to lake depths receiving about 12% ofsurface irradiance, whereas mosses, characeans, and angiosperms with thin photosynthetic tissues grew deeper(3.1-7.5% of surface irradiance). Nostoc ameliorated the restrictions of low lake DIC and long diffusion paths byactive transport that could extract most external DIC, accumulate DIC in the colony 150-fold above externalconcentrations, and retain respiratory CO2. The energy cost of solute transport and gel formation in Nostoccolonies and extensive self shading restrict their potential growth, whereas colony formation should preventgrazing and increase longevity and nutrient recirculation. Nostoc zetterstedtii has become one of rarest freshwatermacroalgae because of widespread lake eutrophication reducing water transparency and increasing competitionfrom taller and faster-growing stands of filamentous algae and higher plants.
U2 - 10.4319/lo.2009.54.4.1282
DO - 10.4319/lo.2009.54.4.1282
M3 - Journal article
VL - 54
SP - 1282
EP - 1291
JO - Limnology and Oceanography
JF - Limnology and Oceanography
SN - 0024-3590
IS - 4
ER -
ID: 12487401