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Variation in growth rate, carbon assimilation, and photosynthetic efficiency in response to nitrogen source and concentration in phytoplankton isolated from upper San Francisco Bay
Author(s) -
Berg Gry Mine,
Driscoll Sara,
Hayashi Kendra,
Ross Melissa,
Kudela Raphael
Publication year - 2017
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1111/jpy.12535
Subject(s) - biology , phytoplankton , bay , diatom , algae , ammonium , photosynthesis , estuary , total inorganic carbon , nitrogen , nitrate , botany , growth rate , chlorophyll a , photosystem ii , zoology , environmental chemistry , nutrient , oceanography , ecology , carbon dioxide , chemistry , geometry , mathematics , organic chemistry , geology
Six species of phytoplankton recently isolated from upper San Francisco Bay were tested for their sensitivity to growth inhibition by ammonium ( NH 4 + ), and for differences in growth rates according to inorganic nitrogen (N) growth source. The quantum yield of photosystem II (F v /F m ) was a sensitive indicator of NH 4 + toxicity, manifested by a suppression of F v /F m in a dose‐dependent manner. Two chlorophytes were the least sensitive to NH 4 + inhibition, at concentrations of >3,000 μmoles NH 4 + · L −1 , followed by two estuarine diatoms that were sensitive at concentrations >1,000 μmoles NH 4 + · L −1 , followed lastly by two freshwater diatoms that were sensitive at concentrations between 200 and 500 μmoles NH 4 + · L −1 . At non‐inhibiting concentrations of NH 4 + , 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 ( NO 3 − ), whereas the other grew significantly faster on NH 4 + . All four diatoms tested grew faster on NH 4 + compared with NO 3 − . We showed that in cases where growth rates were faster on NH 4 + than they were on NO 3 − , 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 NH 4 + dominates the total N pool and they will also not have a growth advantage when NO 3 − is dominant, as long as N concentrations are sufficient.