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  • 1
    Publication Date: 2022-05-26
    Description: © The Author(s), 2016. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Marine Ecology Progress Series 550 (2016): 65-81, doi:10.3354/meps11687.
    Description: Protozoa play important roles in grazing and nutrient recycling, but quantifying these roles has been hindered by difficulties in collecting, culturing, and observing these often-delicate cells. During long-term deployments at the Martha’s Vineyard Coastal Observatory (Massachusetts, USA), Imaging FlowCytobot (IFCB) has been shown to be useful for studying live cells in situ without the need to culture or preserve. IFCB records images of cells with chlorophyll fluorescence above a trigger threshold, so to date taxonomically resolved analysis of protozoa has presumably been limited to mixotrophs and herbivores which have eaten recently. To overcome this limitation, we have coupled a broad-application ‘live cell’ fluorescent stain with a modified IFCB so that protozoa which do not contain chlorophyll (such as consumers of unpigmented bacteria and other heterotrophs) can also be recorded. Staining IFCB (IFCB-S) revealed higher abundances of grazers than the original IFCB, as well as some cell types not previously detected. Feeding habits of certain morphotypes could be inferred from their fluorescence properties: grazers with stain fluorescence but without chlorophyll cannot be mixotrophs, but could be either starving or feeding on heterotrophs. Comparisons between cell counts for IFCB-S and manual light microscopy of Lugol’s stained samples showed consistently similar or higher counts from IFCB-S. We show how automated classification through the extraction of image features and application of a machine-learning algorithm can be used to evaluate the large high-resolution data sets collected by IFCBs; the results reveal varying seasonal patterns in abundance among groups of protists.
    Description: This research was supported in part by NSF (grants OCE-1130140, OCE-1434440), NASA (grants NNX11AF07G and NNX13AC98G), the Gordon and Betty Moore Foundation (grants 934 and 2649), and the Woods Hole Oceanographic Institution’s Innovative Technology Program.
    Keywords: Protozoa ; Microzooplankton ; Automated imaging ; Fluorescent staining ; Flow cytometry
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 2
    Publication Date: 2022-05-26
    Description: Author Posting. © Inter-Research, 2014. This article is posted here by permission of Inter-Research for personal use, not for redistribution. The definitive version was published in Marine Ecology Progress Series 503 (2014): 1-10, doi:10.3354/meps10784.
    Description: Plankton images collected by Imaging FlowCytobot from 2006 to 2013 at the Martha’s Vineyard Coastal Observatory (Massachusetts, USA) were used to identify and quantify the occurrence of the diatom Guinardia delicatula and of a parasite that seems specific to this host. We observed infection with morphological stages that appear similar to the parasite Cryothecomonas aestivalis. Our results show that events during which infection rates exceed 10% are recurrent on the New England Shelf and suggest that the parasites are an important source of host mortality. We document a significant negative relationship between bloom magnitude and parasite infection rate, supporting the hypothesis that the parasites play a major role in controlling blooms. While G. delicatula is observed during all seasons, the infecting stages of the parasite are abundant only when water temperature is above 4°C. The anomalously warm water and small G. delicatula bloom during the winter of 2012 provided evidence that parasites can be active through winter if temperatures remain relatively high. As climate change continues, winter periods of water below 4°C may shorten or disappear in this region, suggesting that parasite effects on species such as G. delicatula may increase, with immediate impacts on their population dynamics.
    Description: This work was supported by grants from NSF’s Ocean Technology and Interdisciplinary Coordination program, NASA’s Ocean Biology and Biogeochemistry program and Biodiversity and Ecological Forecasting program, the Gordon and Betty Moore Foundation, and the National Ocean Partnership Program.
    Keywords: Phytoplankton ; Diatom ; Parasite ; Imaging flow cytometry ; MVCO ; Guinardia delicatula ; Cryothecomonas aestivalis
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
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  • 3
    Publication Date: 2022-05-26
    Description: © The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Earth System Science Data 11(3), (2019): 1037-1068, doi: 10.5194/essd-11-1037-2019.
    Description: A global compilation of in situ data is useful to evaluate the quality of ocean-colour satellite data records. Here we describe the data compiled for the validation of the ocean-colour products from the ESA Ocean Colour Climate Change Initiative (OC-CCI). The data were acquired from several sources (including, inter alia, MOBY, BOUSSOLE, AERONET-OC, SeaBASS, NOMAD, MERMAID, AMT, ICES, HOT and GeP&CO) and span the period from 1997 to 2018. Observations of the following variables were compiled: spectral remote-sensing reflectances, concentrations of chlorophyll a, spectral inherent optical properties, spectral diffuse attenuation coefficients and total suspended matter. The data were from multi-project archives acquired via open internet services or from individual projects, acquired directly from data providers. Methodologies were implemented for homogenization, quality control and merging of all data. No changes were made to the original data, other than averaging of observations that were close in time and space, elimination of some points after quality control and conversion to a standard format. The final result is a merged table designed for validation of satellite-derived ocean-colour products and available in text format. Metadata of each in situ measurement (original source, cruise or experiment, principal investigator) was propagated throughout the work and made available in the final table. By making the metadata available, provenance is better documented, and it is also possible to analyse each set of data separately. This paper also describes the changes that were made to the compilation in relation to the previous version (Valente et al., 2016). The compiled data are available at https://doi.org/10.1594/PANGAEA.898188 (Valente et al., 2019).
    Description: This research has been supported by the ESA Climate Change Initiative – Ocean Colour project (ref: AO-1/6207/09/I-LG).
    Repository Name: Woods Hole Open Access Server
    Type: Article
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