Corals hosting symbiotic hydrozoans are less susceptible to predation and disease

Abstract

CitationMontano S, Fattorini S, Parravicini V, Berumen ML, Galli P, et al. (2017) No changes can be made after publication. Q1A funding statement has been added to your paper; please check that this is correct. SQ1Your supplementary material will be published online alongside your article and on rs.figshare.com exactly as the file(s) are provided. Therefore, please could you either confirm that your supplementary material is correct, or -if you have any changes to make to these files -email these along with your proof corrections to the journal inbox. Your ESM files are listed here for your convenience: SM1.csv SQ2Your paper has exceeded the free page extent and will attract page charges. Here we show how a largely overseen association such as that between hydrozoans and scleractinian corals could be possibly associated with a reduction in coral susceptibility to ever-increasing predator and disease outbreaks. We examined 2450 scleractinian colonies (from both Maldivian and the Saudi Arabian coral reefs) searching for non-random patterns in the occurrence of hydrozoans on corals showing signs of different health conditions (i.e. bleaching, algal overgrowth, corallivory and different coral diseases). We show that, after accounting for geographical, ecological and co-evolutionary factors, signs of disease and corallivory are significantly lower in coral colonies hosting hydrozoans than in hydrozoan-free ones. This finding has important implications for our understanding of the ecology of coral reefs, and for their conservation in the current scenario of global change, because it suggests that symbiotic hydrozoans may play an active role in protecting their scleractinian hosts from stresses induced by warming water temperatures.

Green Fluorescence Patterns in Closely Related Symbiotic Species of Zanclea (Hydrozoa, Capitata)

“…Additionally, scleractinians hosting Zanclea showed micro-alterations related to the presence of symbionts, as already observed in Goniastrea, Pavona, and Porites corals [21]. The presence of these modifications may support the hypothesis that at least some Zanclea species are mutualistically associated with their hosts, since they may provide additional protection and competitive advantages to their hosts and in turn benefit from being partially enclosed in hard carbonatic structures [36,37].…”

Polyphyly of the genus Zanclea and family Zancleidae (Hydrozoa, Capitata) revealed by the integrative analysis of two bryozoan-associated species

“…The majority of zancleid species live in strict association with other organisms, and the relationships with their hosts span from a presumable mutualism (Osman and Haugsness, 1981;Ristedt and Schuhmacher, 1985;Montano et al, 2017a) to parasitism (Piraino et al, 1992). Among the 30 species with a described benthic polyp stage, 16 are specifically associated with bryozoans Pica et al, 2017), four with scleractinians Pantos and Bythell, 2010;Hirose and Hirose, 2011;Montano et al, 2015a), two with octocorals (Puce et al, 2008;Varela, 2012), two with bivalves , two with algae Galea, 2008), while four other show no substrate specificity (Agassiz, 1862;Schuchert, 2010;Peña Cantero et al, 2013).…”

A mesophotic hotel: the octocoral Bebryce cf. grandicalyx as a host

“…Mutualistic overgrowth has been proposed for many benthic organisms, but the cost-benefit of these associations is still poorly known and often challenging to define, especially in organisms with complex life cycles. According to our observations and the literature, the possible advantages can be related to escape from reduced space on the substratum (McKinney et al 1990), increased ability to overgrow competitors (Osman and Haugsness 1981), expanded chemical or physical defense from predators (Osman and Haugsness 1981, Wulff 1997, Montano et al 2017b, increased ability to hold to the substratum (Wulff 1997), and enhanced food supply (Buhl-Mortensen and Mortensen 2004). Interestingly, in our case one of the octocoral's epibionts (the hydroid) was in turn partially overgrown by another epibiont (the sponge).…”

“…Instead, both the sponge and hydroids may provide their host with additional defense from predators. For instance, sponges associated with the octocoral Carijoa riisei in Hawai’i suppress nudibranch predation, probably because of the production of toxic compounds (Wagner et al ), and Zanclea polyps associated with scleractinian corals likely protect their hosts from gastropod and fish predation, thanks to their additional nematocyst complement (Montano et al ). In the association reported here, these two acquired defensive mechanisms may act in synergy to protect the octocoral and each of its associates from multiple sources of predation and overgrowth by other organisms.…”

“…The Scientific Naturalist Ecology, 101(4), 2020, e02950 © 2019 by the Ecological Society of America additional nematocyst complement (Montano et al 2017b). In the association reported here, these two acquired defensive mechanisms may act in synergy to protect the octocoral and each of its associates from multiple sources of predation and overgrowth by other organisms.…”