Publication Date:
2020-03-05
Description:
Aim: Most protist plankton are mixotrophic, with potential to engage in photoautotrophy
and phagotrophy; however, the ecology of these organisms has been misdiagnosed
for over a century. A large proportion of these organisms are constitutive
mixotrophs (CMs), with an innate ability to photosynthesize. Here, for the first time,
an analysis is presented of the biogeography of CMs across the oceans.
Location: Global marine ecosystems.
Time period: 1970–2018.
Major taxa studied: Marine planktonic protists.
Methods: Records for CM species, primarily from the Ocean Biogeographic
Information System (OBIS), were grouped by taxonomy and size to evaluate sampling
efforts across Longhurst's oceanic provinces. Biases were evaluated through nonparametric
tests and multivariate analysis. Biogeographies of CMs from OBIS data
were compared with data from studies that specifically targeted these organisms.
Results: Constitutive mixotrophs of different taxonomic groups, across all size
ranges, are ubiquitous. However, strong database biases were detected with respect
to organism size, taxonomic groups and region. A strong bias was seen towards dinophytes.
Species 〈 20 μm, especially non‐dinophytes, were least represented, with
their recorded distribution limited to coastal regions and to temperate and polar seas.
Studies specifically targeting these organisms revealed their distribution to be much
wider. Such biases are likely to have occurred owing to a failure to capture and correctly
identify these organisms in routine sampling protocols.
Main conclusions: Constitutive mixotrophs are dominant members of organisms traditionally
termed “phytoplankton”. However, lack of routine protocols for measuring
phagotrophy in “phytoplankton” protists has led to widespread misrepresentation of
the fundamental nature of marine planktonic primary producers; most express both
“animal‐like” and “plant‐like” nutrition. Our results have implications for studies of the
global biogeography of plankton, of food web dynamics (including models) and of
biogeochemical cycling in the oceans.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
isiRev
Format:
application/pdf
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