Trait‐based analysis of subpolar North Atlantic phytoplankton and plastidic ciliate communities using automated flow cytometer

Abstract

Plankton are an extremely diverse and polyphyletic group, exhibiting a large range in morphological and physiological traits. Here, we apply automated optical techniques, provided by the pulse-shape recording automated flow cytometer-CytoSense-to investigate trait variability of phytoplankton and plastidic ciliates in Arctic and Atlantic waters of the subpolar North Atlantic. We used the bio-optical descriptors derived from the CytoSense (light scattering [forward and sideward] and fluorescence [red, yellow/green and orange from chlorophyll a, degraded pigments, and phycobiliproteins, respectively]) and translated them into functional traits to demonstrate ecological trait variability along an environmental gradient. Cell size was the master trait varying in this study, with large photosynthetic microplankton (> 20 μm in cell diameter), including diatoms as single cells and chains, as well as plastidic ciliates found in Arctic waters, while small-sized phytoplankton groups, such as the picoeukaryotes (< 4 μm) and the cyanobacteria Synechococcus were dominant in Atlantic waters. Morphological traits, such as chain/colony formation and structural complexity (i.e., cellular processes, setae, and internal vacuoles), appear to favor buoyancy in highly illuminated and stratified Arctic waters. In Atlantic waters, small cell size and spherical cell shape, in addition to photo-physiological traits, such as high internal pigmentation, offer chromatic adaptation for survival in the low nutrient and dynamic mixing waters of the Atlantic Ocean. The use of automated techniques that quantify ecological traits holds exciting new opportunities to unravel linkages between the structure and function of plankton communities and marine ecosystems.

Small phytoplankton dominate western North Atlantic biomass

“…Whether NAAMES observations of small phytoplankton in the western North Atlantic, including multiple taxa never before documented in this environment, are due to physical differences between the western and eastern North Atlantic [68], ocean warming and higher atmospheric CO 2 concentrations [69,70], constraints of previously applied methodologies, or are a coincidental annual anomaly, is still to be determined. Of these explanations, which are not mutually exclusive, differences between the west and east Atlantic in eddy kinetic energy, mixed layer depth, photosynthetic active radiation and the influence of arctic water masses, have been proven by previous studies to affect composition and biomass of the phytoplankton blooms [67,71]. If our results are representative of the broader western North Atlantic, then they have major implications on current understanding of phytoplankton bloom impacts on regional carbon biogeochemistry.…”

Evaluating the Cytometric Detection and Enumeration of the Wine Bacterium, Oenococcus oeni

“…For example, the Amnis ImageStream (Luminex, Japan) is a flow cytometer that can take an image of every particle that passes through the machine's laser, which could aid in tackling problems such as bacterial chaining. Alternatively, there are cytometers that can provide data on the shape of the pulse generated from scanning a particle, such as the CytoSense (CytoBuoy, the Netherlands; 43,44). A pulse scan may provide more detail on particle morphology compared to recording a single value for each particle.…”

Computational Analysis of Microbial Flow Cytometry Data

“…However, the data can contain distinct cell populations caused by differences in cell size, morphology, and autofluorescent properties (e.g., phytoplankton [ 45 ]) or due to the use of specific stains (e.g., a nucleic acid stain to detect nucleic acid populations in aquatic environments [ 46 ]). While these are routinely gated manually, cell population identification algorithms detect these automatically and therefore reduce the bias and analysis time inherent in manual gating procedures by experts ( 20 ).…”