title: Chemical mediation of coral larval settlement by crustose coralline algae.
abstract: The majority of marine invertebrates produce dispersive larvae which, in order to complete their life cycles, must attach and metamorphose into benthic forms. This process, collectively referred to as settlement, is often guided by habitat-specific cues. While the sources of such cues are well known, the links between their biological activity, chemical identity, presence and quantification in situ are largely missing. Previous work on coral larval settlement in vitro has shown widespread induction by crustose coralline algae (CCA) and in particular their associated bacteria. However, we found that bacterial biofilms on CCA did not initiate ecologically realistic settlement responses in larvae of 11 hard coral species from Australia, Guam, Singapore and Japan. We instead found that algal chemical cues induce identical behavioral responses of larvae as per live CCA. We identified two classes of CCA cell wall-associated compounds--glycoglycerolipids and polysaccharides--as the main constituents of settlement inducing fractions. These algae-derived fractions induce settlement and metamorphosis at equivalent concentrations as present in CCA, both in small scale laboratory assays and under flow-through conditions, suggesting their ability to act in an ecologically relevant fashion to steer larval settlement of corals. Both compound classes were readily detected in natural samples.
authors.affiliation: School of Biological Earth and Environmental Sciences, Centre for Marine Bio-Innovation, The University of New South Wales, Sydney, 2052 NSW, Australia.
authors.forename: J
authors.initials: J
authors.lastname: Tebben
authors.affiliation: Australian Institute of Marine Science, Townsville, 4810 QLD, Australia.
authors.forename: C A
authors.initials: CA
authors.lastname: Motti
authors.affiliation: 1] Australian Institute of Marine Science, Townsville, 4810 QLD, Australia [2] Plant Functional Biology and Climate Change, University of Technology Sydney, Ultimo, 2007 NSW, Australia.
authors.forename: Nahshon
authors.initials: N
authors.lastname: Siboni
authors.affiliation: Australian Institute of Marine Science, Townsville, 4810 QLD, Australia.
authors.forename: D M
authors.initials: DM
authors.lastname: Tapiolas
authors.affiliation: Australian Institute of Marine Science, Townsville, 4810 QLD, Australia.
authors.forename: A P
authors.initials: AP
authors.lastname: Negri
authors.affiliation: Institute for Chemistry and Biology of the Marine Environment Terramare, University of Oldenburg, 26382 Wilhelmshaven, Germany.
authors.forename: P J
authors.initials: PJ
authors.lastname: Schupp
authors.affiliation: Okinawa Environment Science Center, Urasoe, Okinawa 901-2111, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Kitamura
authors.affiliation: Graduate School of Humanities and Sciences, Ochanomizu University, Tokyo 112-8610, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Hatta
authors.affiliation: 1] School of Biological Earth and Environmental Sciences, Centre for Marine Bio-Innovation, The University of New South Wales, Sydney, 2052 NSW, Australia [2] Sydney Institute of Marine Science, Mosman, 2088 NSW, Australia [3] Advanced Environmental Biotechnology Centre, Nanyang Technological University, Singapore 639798, Singapore.
authors.forename: P D
authors.initials: PD
authors.lastname: Steinberg
authors.affiliation: 1] School of Biological Earth and Environmental Sciences, Centre for Marine Bio-Innovation, The University of New South Wales, Sydney, 2052 NSW, Australia [2] Australian Institute of Marine Science, Townsville, 4810 QLD, Australia.
authors.forename: T
authors.initials: T
authors.lastname: Harder
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000502:physiology*; D001419:Bacteria; D003463:Cues; D007814:Larva