Ciliate communities consistently associated with coral diseasesJournal of Sea Research

About

Authors
M.J. Sweet, M.G. Séré
Year
2015
DOI
10.1016/j.seares.2015.06.008
Subject
Aquatic Science / Ecology, Evolution, Behavior and Systematics / Oceanography

Text

   

Ciliate Communities Consistently Associated with Coral Diseases

M.J. Sweet, M.G. Se´re´

PII: S1385-1101(15)30009-5

DOI: doi: 10.1016/j.seares.2015.06.008

Reference: SEARES 1373

To appear in: Journal of Sea Research

Received date: 14 November 2014

Revised date: 12 June 2015

Accepted date: 17 June 2015

Please cite this article as: Sweet, M.J., Se´re´, M.G., Ciliate Communities Consistently Associated with Coral Diseases, Journal of Sea Research (2015), doi: 10.1016/j.seares.2015.06.008

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Ciliate Communities Consistently Associated with Coral

Diseases

Sweet, M.J. 1 and Séré M.G. 2,3,4 1

Molecular Health and Disease Laboratory, College of Life and Natural Sciences, University of Derby, UK 2

ARVAM, CYROI, Technopole de La Réunion, 97490 Ste Clotilde, Reunion Island 3

Oceanographic Research Institute (ORI), PO Box 10712, Marine Parade, Durban, 4056 South Africa 4

IRD Centre Réunion, CS 41095 97495 Ste Clotilde CEDEX Reunion Island

Abstract

Incidences of coral disease are increasing. Most studies which focus on diseases in these organisms routinely assess variations in bacterial associates. However, other microorganism groups such as viruses, fungi and protozoa are only recently starting to receive attention. This study aimed at assessing the diversity of ciliates associated with coral diseases over a wide geographical range. Here we show that a w id e v a r i e t y o f c i l i a t es a r e as so c i a t ed wi t h all nine coral diseases assessed. Many of these ciliates such as Trochilia petrani and Glauconema trihymene feed on the bacteria which are likely colonizing the bare skeleton exposed by the advancing disease lesion or the necrotic tissue itself. Others such as Pseudokeronopsis and Licnophora macfarlandi are common predators of other protozoans and will be attracted by the increase in other ciliate species to the lesion interface. However, a few ciliate species (namely Varistrombidium kielum, Philaster lucinda, P. guamensis, a Euplotes sp., a Trachelotractus sp. and a

Condylostoma sp.) appear to harbor symbiotic algae, potentially from the coral themselves, a result which may indicate they play some role in the disease pathology at the very least. Although, from this study alone we are not able to discern what roles any of these ciliates play in disease causation, the consistent presence of such communities with disease lesion interfaces warrants further investigation.

Keywords: Ciliates – Disease – 18S rRNA– Philaster *E-mail: m.sweet@derby.ac.uk

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Introduction

Historically, most coral diseases (specifically those showing aspects of tissue loss) have been associated with numerous pathogenic bacteria (Richardson et al. 1998, Kushmaro et al. 2001, Ben-Haim and Rosenberg 2002, Patterson et al. 2002, Frias-Lopez et al. 2003,

Cervino et al. 2008, Sussman et al. 2008, Luna et al. 2010). However, attention is now turning to other microorganisms such as fungi, viruses and ciliates (Sweet and

Bythell 2012, Katz et al. 2014, Sweet et al. 2014). The first coral disease associated with ciliates f o r e x a m p l e was Skeleton-Eroding Band (SEB), which was initially described i n 2 0 0 1 (Antonius and Lipscomb 2001). Characterized by a speckled black band associated with the lesion interface, t h e d i s e a s e i s t h o u g h t t o b e c a u s e d b y the folliculinid ciliate, Halofolliculina corallasia (Winkler et al. 2004).

Three years later, another coral disease, Brown Band Disease (BrB), was described and associated with the ciliate Philaster guamensis, at the time described as Porpostoma guamensis (Lobban et al. 2011; Willis et al. 2004). Over in the Caribbean, two years after BrB was first described ciliates similar to those associated with SEB (Halofolliculina) were reported affecting over 26 Caribbean reef-building coral species, and the term Caribbean Ciliate Infection (CCI) was coined (Croquer et al. 2006a). Six years later still and White Syndrome (WS), the most prevalent disease sign around the world has also been shown to have a diverse ciliate community associated with the lesion interface (Sweet and Bythell 2012). More recently, White Band Disease (WBD),

White Plague, Brown Jelly Syndrome and another BrB-like syndrome in the Caribbean have all been described as having ciliates associated with the disease signs (Sweet et al. 2014;

Randall et al. 2014). Although there are an increasing number of studies linking different ciliate species to specific coral disease states, there are currently no published studies which highlight exactly how such ciliates cause disease. Furthermore, there have been no controlled inoculation experiments identifying if indeed these proposed pathogens are the primary causal agents. This has led to the general belief that many if not all these coral associated ciliates are opportunistic, eating the dead and dying tissue caused by another as yet unknown pathogenic agent. In fact, two recent studies have highlighted that this is actually likely the case, at least for WBD in the Caribbean and WS in the Indo-Pacific (Sweet et al. 2014; Sweet and Bythell 2015). However, regardless of the specific role of ciliates (which remains to be determined), a first step in understanding their importance in coral disease would be to assess the community associated with different disease states

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ACCEPTED MANUSCRIPT 3 globally. Here, we therefore aim to provide an initial baseline assessment of the ciliate communities associated with nine dominant coral diseases located in both the IndoPacific and the Caribbean. Although every care was taken to ensure a representative sample was taken, we by no means guarantee that every ciliate species has been described here in this study and it remains highly likely more species will be associated with these diseases as further studies assess for them.