Structuring effects of chemicals from the sea fanPhyllogorgia dilatataon benthic communities

Abstract

Despite advances in understanding the ecological functions of secondary metabolites from marine organisms, there has been little focus on the influence of chemically-defended species at the community level. Several compounds have been isolated from the gorgonian octocoral Phyllogorgia dilatata, a conspicuous species that forms dense canopies on rocky reefs of northern Rio de Janeiro State, Brazil. Manipulative experiments were performed to study: (1) the effects of live colonies of P. dilatata (physical presence and chemistry) on recruitment of sympatric benthic organisms; (2) the allelopathic effects of its chemicals on competitors; and (3) chemotactic responses of the non-indigenous brittle star, Ophiothela mirabilis. Early establishment of benthic species was influenced on substrates around live P. dilatata colonies and some effects could be attributed to the gorgonian’s secondary metabolites.In addition, the gorgonian chemicals also exerted an allelopathic effect on the sympatric zoanthid Palythoa caribaeorum, and positive chemotaxis upon O. mirabilis. These results indicate multiple ecological roles of a chemically-defended gorgonian on settlement, sympatric competitors, and non-indigenous species.

Gorgonians Are Foundation Species on Sponge-Dominated Mesophotic Coral Reefs in the Caribbean

“…It is possible that the gorgonian allelochemicals we isolated were selected for their allelopathic effects on a particular spacedominant sponge species (e.g., A. clathrodes), and a result of that competitive success was the recruitment of less competitive species into the benthos. These results are consistent with associational defense systems (e.g., algae : Hay, 1986; soft corals: Kerr and Paul, 1995;Ribeiro et al, 2017;sponges: Farren and Donovan, 2007) often attributable to FS (Stachowicz, 2001). Alternatively, these gorgonians may make the substrate more suitable for recruits (sponges, hard and soft corals, and/or tunicates), akin to the role of the Mesquite in semi-arid savannas of the southwest United States (Archer et al, 1988).…”

“…Although ecological processes such as overgrowth and/or shading are common amongst these taxa, contact-mediated or water-borne delivery of allelopathic compounds is another competitive option for some species of algae, sponges, and gorgonians (Granéli and Pavia, 2006;Slattery and Gochfeld, 2012). For example, allelochemicals from the Brazilian gorgonian, Phyllogorgia dilatata, reduced growth rates in the zoanthid, Palythoa caribaeorum (Ribeiro et al, 2017). Likewise, 29 gorgonian species exhibited competitive interactions that effected spatial distributions of this taxa in St. John USVI (Gambrel and Lasker, 2016).…”

Rhodoliths: Can Its Importance on a Large Scale Be Promoted by a Microscale and Invisible Phenomenon?

“…In addition to rhodolith-forming algae, bacteria (Dobretsov et al, 2009) and several other coralline (Kim et al, 2004), and fleshy macroalgae (Longo and Hay, 2017) as soon as marine invertebrates, such as sponges (e.g., Pawlik, 2011), gorgonians (e.g., Ribeiro et al, 2017), corals (Changyun et al, 2008), bryozoans (Sharp et al, 2007), and other benthic organisms that live in rhodolith beds, can also produce diverse substances capable of generating structuring-effects in these environments.…”