Detection and quantification of a keystone pathogen in a coastal marine ecosystem

Abstract

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 606:79-90 (2018) - DOI: https://doi.org/10.3354/meps12776 Detection and quantification of a keystone pathogen in a coastal marine ecosystem Robyn Buchwald, Robert E. Scheibling*, Alastair G. B. Simpson Department of Biology, Dalhousie University, Halifax, NS, B3H 4R2, Canada *Corresponding author: rescheib@dal.ca ABSTRACT: The pathogenic amoeba Paramoeba invadens causes recurrent mass mortalities of green sea urchins Strongylocentrotus droebachiensis in coastal Nova Scotia, Canada, driving regime shifts from urchin barrens to kelp beds. Outbreaks of the disease (paramoebiasis) are sporadic, and the source population(s) and epizootiology of the amoeba are poorly understood. We developed PCR-based detection of P. invadens in urchin tissue, sediment, and seawater. Primers specific to the P. invadens nuclear SSU rRNA gene were designed and used in PCR and qPCR analyses to better detect and quantify P. invadens during, following, and in the absence of a natural disease outbreak. A comparison of pathogen load in asymptomatic and symptomatic sea urchins indicated a lower threshold of ~1 cell mg-1 tissue for observing overt signs of paramoebiasis in urchins. P. invadens was detected for the first time in sediment during and following an outbreak of disease in 2014. It also was detected in low abundance (<10 cells l-1) in seawater in fall 2015 in the absence of sea urchin mass mortality or a strong storm event, but not under similar conditions in summer/fall 2016 and 2017. The ability to detect and quantify this pathogen in sea urchins and environmental samples sheds new light on mechanisms of introduction, spread, and persistence of P. invadens along the Nova Scotian coast and the role of large-scale meteorological events and ocean warming in these processes. KEY WORDS: Epizootic · Ecosystem dynamics · Paramoeba invadens · Strongylocentrotus droebachiensis · Quantitative real-time PCR · Pathogenic amoebae · Sea urchins Full text in pdf format Supplementary material PreviousNextCite this article as: Buchwald R, Scheibling RE, Simpson AGB (2018) Detection and quantification of a keystone pathogen in a coastal marine ecosystem. Mar Ecol Prog Ser 606:79-90. https://doi.org/10.3354/meps12776 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 606. Online publication date: November 15, 2018 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2018 Inter-Research.