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Rates of phytoplankton cell division in the field and in iron enrichment experiments
Author(s) -
Banse Karl
Publication year - 1991
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1991.36.8.1886
Subject(s) - phytoplankton , chlorophyll a , nutrient , plankton , chlorophyll , biology , algae , bloom , cell division , zoology , botany , environmental chemistry , chemistry , ecology , cell , biochemistry
Increases in chlorophyll with time for contained coastal plankton, expressed as daily division rates, are on average about as high as rates for nutrient‐replete cultures at similar temperatures, when daylength is considered. In offshore areas with persistent high nutrients but low chlorophyll, division rates from increased chlorophyll and cumulative NO 3 uptake in the controls of Fe enrichments are on average also high and do not suggest marked Fe deficiency. The normally observed phytoplankton growth in the controls is interpreted as due to release from grazing. Addition of Fe in the treatments leads to blooms and exhaustion of NO 3 . Differences between controls and treatments in rates of chlorophyll increase and NO 3 removal, however, as well as shifts in species composition toward rare species in the treatments, also indicate direct effects of Fe on phytoplankton. To clarify the issues, especially in respect to medium‐ and large‐celled phytoplankton, I recommend measurements of species‐specific division rates.