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Particle tracking in a salinity gradient: A method for measuring sinking rate of individual phytoplankton in the laboratory
Author(s) -
O'Brien Katherine R.,
Waite Anya M.,
Alexander Bridget L.,
Perry Karen A.,
Neumann Luis E.
Publication year - 2006
Publication title -
limnology and oceanography: methods
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.898
H-Index - 72
ISSN - 1541-5856
DOI - 10.4319/lom.2006.4.329
Subject(s) - settling , phytoplankton , oceanography , particle (ecology) , population , salinity , environmental science , particle size , tracking (education) , atmospheric sciences , ecology , biology , physics , geology , environmental engineering , paleontology , psychology , pedagogy , demography , sociology , nutrient
This paper presents a new method to measure the sinking rates of individual phytoplankton “particles” (cells, chains, colonies, and aggregates) in the laboratory. Conventional particle tracking and high resolution video imaging were used to measure particle sinking rates and particle size. The stabilizing force of a very mild linear salinity gradient (1 ppt over 15 cm) prevented the formation of convection currents in the laboratory settling chamber. Whereas bulk settling methods such as SETCOL provide a single value of sinking rate for a population, this method allows the measurement of sinking rate and particle size for a large number of individual particles or phytoplankton within a population. The method has applications where sinking rates vary within a population, or where sinking rate‐size relationships are important. Preliminary data from experiments with both laboratory and field samples of marine phytoplankton are presented here to illustrate the use of the technique, its applications, and limitations. Whereas this paper deals only with sinking phytoplankton, the method is equally valid for positively buoyant species, as well as nonbiological particles.