Variation in growth rate, carbon assimilation, and photosynthetic efficiency in response to nitrogen source and concentration in phytoplankton isolated from upper San Francisco Bay.
J Phycol
; 53(3): 664-679, 2017 06.
Article
em En
| MEDLINE
| ID: mdl-28328165
ABSTRACT
Six species of phytoplankton recently isolated from upper San Francisco Bay were tested for their sensitivity to growth inhibition by ammonium (NH4+ ), and for differences in growth rates according to inorganic nitrogen (N) growth source. The quantum yield of photosystem II (Fv /Fm ) was a sensitive indicator of NH4+ toxicity, manifested by a suppression of Fv /Fm in a dose-dependent manner. Two chlorophytes were the least sensitive to NH4+ inhibition, at concentrations of >3,000 µmoles NH4+ · L-1 , followed by two estuarine diatoms that were sensitive at concentrations >1,000 µmoles NH4+ · L-1 , followed lastly by two freshwater diatoms that were sensitive at concentrations between 200 and 500 µmoles NH4+ · L-1 . At non-inhibiting concentrations of NH4+ , the freshwater diatom species grew fastest, followed by the estuarine diatoms, while the chlorophytes grew slowest. Variations in growth rates with N source did not follow taxonomic divisions. Of the two chlorophytes, one grew significantly faster on nitrate (NO3- ), whereas the other grew significantly faster on NH4+ . All four diatoms tested grew faster on NH4+ compared with NO3- . We showed that in cases where growth rates were faster on NH4+ than they were on NO3- , the difference was not larger for chlorophytes compared with diatoms. This holds true for comparisons across a number of culture investigations suggesting that diatoms as a group will not be at a competitive disadvantage under natural conditions when NH4+ dominates the total N pool and they will also not have a growth advantage when NO3- is dominant, as long as N concentrations are sufficient.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Fotossíntese
/
Fitoplâncton
/
Carbono
País/Região como assunto:
America do norte
Idioma:
En
Revista:
J Phycol
Ano de publicação:
2017
Tipo de documento:
Article
País de afiliação:
Estados Unidos