Interpretation of fast repetition rate (FRR) fluorescence: signatures of phytoplankton community structure versus physiological state

Suggett, David J., Moore, C. Mark, Hickman, A and Geider, Richard J. (2009) Interpretation of fast repetition rate (FRR) fluorescence: signatures of phytoplankton community structure versus physiological state. Marine Ecology Progress Series, 376, 1-19. (doi:10.3354/meps07830).

Abstract

Introduction of active chlorophyll a fluorescence
protocols, in particular fast repetition rate
(FRR) fluorometry, to oceanography and limnology
15 yr ago has enabled rapid assessment of photosynthetic
physiology in situ. The FRR protocol generates
simultaneous measurements of Photosystem II (PSII)
effective absorption cross sections (termed ?PSII) and
photochemical efficiency (termed Fv/Fm). Both Fv/Fm
and ?PSII measurements have been utilised to examine
the effects of physiological stress on the photosynthetic
apparatus of phytoplankton in an ever growing number
of fluorescence-based studies. However, it is now
becoming clearer that in situ values of Fv/Fm and ?PSII
also contain taxonomic information. Here, we present
a synthesis of previously unpublished and published
data, which show that Fv/Fm and ?PSII vary principally
with broad-scale changes in community structure.
These patterns observed in situ conform to trends
observed in laboratory-grown cultures of a range of
phytoplankton taxa. The magnitudes of variability in
Fv/Fm and ?PSII driven by changes in phytoplankton
community structure often exceed that induced by
nutrient limitation (as determined from controlled
nutrient addition experiments). An exception to this
general trend occurs in high-nutrient, low-chlorophyll
a (HNLC) regions, where strong phenotypic changes
in Fv/Fm and ?PSII have been repeatedly demonstrated
on relief of iron limitation. Overall, FRR fluorescence
measurements of both Fv/Fm and ?PSII in natural populations
represent a combination of the taxonomic ‘signature’
(values of Fv/Fm and ?PSII determined by the
taxa present) within the phytoplankton community
that is further modified according to the (photo-) physiological
status. As such, fluorescence-based investigations
of mixed populations must account for potential
variations in phytoplankton community structure before
interpretations of physiological status are made.

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Contributors

Author: C. Mark Moore

Author: A Hickman

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