Larval Settlement: The Role of Surface Topography for Sessile Coral Reef Invertebrates

Abstract

For sessile marine invertebrates with complex life cycles, habitat choice is directed by the larval phase. Defining which habitat-linked cues are implicated in sessile invertebrate larval settlement has largely concentrated on chemical cues which are thought to signal optimal habitat. There has been less effort establishing physical settlement cues, including the role of surface microtopography. This laboratory based study tested whether surface microtopography alone (without chemical cues) plays an important contributing role in the settlement of larvae of coral reef sessile invertebrates. We measured settlement to tiles, engineered with surface microtopography (holes) that closely matched the sizes (width) of larvae of a range of corals and sponges, in addition to surfaces with holes that were markedly larger than larvae. Larvae from two species of scleractinian corals (Acropora millepora and Ctenactis crassa) and three species of coral reef sponges (Luffariella variabilis, Carteriospongia foliascens and Ircinia sp.,) were used in experiments. L. variabilis, A. millepora and C. crassa showed markedly higher settlement to surface microtopography that closely matched their larval width. C. foliascens and Ircinia sp., showed no specificity to surface microtopography, settling just as often to microtopography as to flat surfaces. The findings of this study question the sole reliance on chemical based larval settlement cues, previously established for some coral and sponge species, and demonstrate that specific physical cues (surface complexity) can also play an important role in larval settlement of coral reef sessile invertebrates.

Structuring effects of chemicals from the sea fanPhyllogorgia dilatataon benthic communities

“…The majority of marine benthic species possess a life history that includes settlement and metamorphosis, which may occur in response to specific chemical or physical cues (Tebben et al, 2015; Whalan et al, 2015). A variety of chemical signals have been shown to induce marine invertebrate settlement, thus modulating or influencing the structure of benthic marine communities (Pereira, Da Gama & Sudatti, 2017).…”

Habitat complexity effects on diversity and abundance differ with latitude: an experimental study over 20 degrees

“…, Whalan et al. ) and spatial scale (Lemire and Bourget ). The type of complexity used can dictate the body size and type of individuals recruiting (Taniguchi and Tokeshi , Lavender et al.…”

“…Additionally, taxonomic and functional group‐specific habitat associations have been identified (Lemire and Bourget , Whalan et al. , Lavender et al. ).…”

“…In addition to a latitudinal diversity gradient in these communities (Freestone and Inouye 2014), the rate of community development can also vary latitudinally Osman 2010, Bracewell et al 2017). Additionally, taxonomic and functional groupspecific habitat associations have been identified (Lemire and Bourget 1996, Whalan et al 2015, Lavender et al 2017b.…”

The cnidome and ultrastructural morphology of late planulae in Lophelia pertusa (Linnaeus, 1758)—With implications for settling competency

“…The here studied larvae had a preference for cryptic spaces, although the full settling trial failed and no larval settling could be detected on the substrates in the rotating beakers. A preference for crevices in dimensions closely matching larval widths was found for two tropical corals, A. millepora and Ctenactis crassa , in a study by Whalan, Abdul Wahab, Sprungala, Poole, and Nys (), with successful settling and metamorphosis in crevices without any chemical cues present. Other marine larvae have also been found to prefer to settle in crevices with higher survival for some of the species as a result (Walters & Wethey, ).…”