RECOGNITION AND SELECTION OF SETTLEMENT SUBSTRATA DETERMINE POST-SETTLEMENT SURVIVAL IN CORALS

Habitat recognition and selective settlement by dispersive propagules greatly increases the post-settlement survival chances of sessile organisms. To better understand the key role some species can play in the structure of highly complex coral reef ecosystems, we compare the role of two independent, but sequential, processes: settlement choice and post-settlement survival. This study describes the chemical and physical recognition and ranking of specific settlement substrata by coral larvae. Several species of crustose coralline algae (CCA) are known to induce coral settlement; however they also employ physical and biological anti-settlement defense strategies that vary greatly in effectiveness. We examine the interactions between settling larvae of two common reef building coral species (Acropora tenuis and A. millepora) and five species of CCA (Neogoniolithon fosliei, Porolithon onkodes, Hydrolithon reinboldii, Titanoderma prototypum, and Lithoporella melobesioides) that co-occur on reef crests and slopes of the Great Barrier Reef, Australia. Distinct settlement patterns were observed when coral larvae were provided with a choice of settlement substrata. Settlement on the most preferred substratum, the CCA species T. prototypum, was 15 times higher than on N. fosliei, the least preferred substratum. The rates of post-settlement survival of the corals also varied between CCA species in response to their anti-settlement strategies (shedding of surface cell layers, overgrowth, and potential chemical deterrents). Rates of larval settlement, post-settlement survival, and the sensitivity of larvae to chemical extracts of CCA were all positively correlated across the five species of CCA. Nonliving settlement substrata on coral reefs is sparse; consequently the fact that only a few CCA species (notably T. prototypum) facilitate coral recruitment, has important implications for structuring the reef ecosystem.

[1]  D. Keats,et al.  Antifouling effects of epithallial shedding in three crustose coralline algae (Rhodophyta, Coralinales) on a coral reef , 1997 .

[2]  T. Kawaguchi,et al.  Isolation of an allelopathic substance from the crustose coralline algae, Lithophyllum spp., and its effect on the brown alga, Laminaria religiosa Miyabe (Phaeophyta) , 1998 .

[3]  R. Steneck,et al.  Settlement-driven, multiscale demographic patterns of large benthic decapods in the Gulf of Maine , 1999 .

[4]  A. Morse,et al.  THE CONSEQUENCES OF COMPLEX LARVAL BEHAVIOR IN A CORAL , 2000 .

[5]  Degnan,et al.  Inhibition of settlement and metamorphosis of the ascidian Herdmania curvata by non-geniculate coralline algae , 1999, The Biological bulletin.

[6]  A. Heyward,et al.  Natural inducers for coral larval metamorphosis , 1999, Coral Reefs.

[7]  P. Sammarco,et al.  Shedding new light on scleractinian coral recruitment , 1994 .

[8]  B. Degnan,et al.  Bacterial induction of settlement and metamorphosis in marine invertebrates , 1997 .

[9]  A. Baird,et al.  Induction of metamorphosis in larvae of the brooding corals Acropora palifera and Stylophora pistillata , 2004 .

[10]  R. Tibshirani,et al.  Generalized Additive Models , 1991 .

[11]  D. Morse,et al.  Recruitment and metamorphosis of Haliotis larvae induced by molecules uniquely available at the surfaces of crustose red algae , 1984 .

[12]  L. Blackall,et al.  Metamorphosis of a Scleractinian Coral in Response to Microbial Biofilms , 2004, Applied and Environmental Microbiology.

[13]  A. Antonius.  Pneophyllum conicum, a coralline red alga causing coral reef-death in Mauritius , 2001, Coral Reefs.

[14]  M. Littler,et al.  BLADE ABANDONMENT/PROLIFERATION: A NOVEL MECHANISM FOR RAPID EPIPHYTE CONTROL IN MARINE MACROPHYTES , 1999 .

[15]  R. Grosberg.  Competitive ability influences habitat choice in marine invertebrates , 1981, Nature.

[16]  D. Morse,et al.  Control of larval metamorphosis and recruitment in sympatric agariciid corals , 1988 .

[17]  P. Raimondi.  Patterns, Mechanisms, Consequences of Variability in Settlement and Recruitment of an Intertidal Barnacle , 1990 .

[18]  T. Hughes,et al.  Competitive dominance by tabular corals: an experimental analysis of recruitment and survival of understorey assemblages. , 2000, Journal of experimental marine biology and ecology.

[19]  R. Babcock,et al.  Habitat selection by larvae influences the depth distribution of six common coral species , 2003 .

[20]  L. Airoldi.  EFFECTS OF DISTURBANCE, LIFE HISTORIES, AND OVERGROWTH ON COEXISTENCE OF ALGAL CRUSTS AND TURFS , 2000 .

[21]  M. Keough,et al.  Recruitment of marine invertebrates: the role of active larval choices and early mortality , 1982, Oecologia.

[22]  D. Morse,et al.  Enzymatic Characterization of the Morphogen Recognized by Agaricia humilis (Scleractinian Coral) Larvae. , 1991, The Biological bulletin.

[23]  J. Marsh,et al.  Primary productivity of reef-building calcareous red algae , 1970 .

[24]  C. Mundy,et al.  Coral recruitment: Consequences of settlement choice for early growth and survivorship in two scleractinians , 1996 .

[25]  T. Hayashibara,et al.  An Ancient Chemosensory Mechanism Brings New Life to Coral Reefs. , 1996, The Biological bulletin.

[26]  K. Sebens.  Spatial Relationships among Encrusting Marine Organisms in the New England Subtidal Zone , 1986 .

[27]  C. Johnson,et al.  The crustose coralline alga, Phymatolithon Foslie, inhibits the overgrowth of seaweeds without relying on herbivores , 1986 .

[28]  P. McCullagh,et al.  Generalized Linear Models , 1984 .

[29]  P. Dunstan,et al.  Spatio-temporal variation in coral recruitment at different scales on Heron Reef, southern Great Barrier Reef , 1998, Coral Reefs.

[30]  M. Ruiz-Zárate,et al.  Relationships between Manicina areolata (Cnidaria : Scleractinia), Thalassia testudinum (Anthophyta) and Neogoniolithon sp (Rhodophyta) , 2000 .

[31]  P. Sammarco,et al.  Effects of soft corals on scleractinian coral recruitment. I:Directional allelopathy and inhibition of settlement , 1995 .

[32]  K. Sand‐Jensen,et al.  Interactions among phytoplankton, periphyton, and macrophytes in temperate freshwaters and estuaries , 1991 .

[33]  Anthony C. Davison,et al.  Bootstrap Methods and Their Application , 1998 .

[34]  T. Masaki.  Observation on the spore germination of Laminaria japonica on Lithophyllum yessoense (Rhodophyta, Corallinaceae) in culture. , 1981 .

[35]  W. Adey,et al.  The crustose coralline algae (Rhodophyta, Corallinaceae) of the Hawaiian Islands , 1982 .

[36]  C. Mundy,et al.  Role of light intensity and spectral quality in coral settlement: implications for depth-dependent settlement? , 1998 .