Groups travel further: pelagic metamorphosis and polyp clustering allow higher dispersal potential in sun coral propagules

Abstract

We report that planulae produced by Tubastraea coccinea can metamorphose and aggregate in groups of up to eight polyps in the water column, without previous settlement on benthic substrate. We also evaluated the survival of propagules to test whether different levels of aggregation allowed for longer planktonic life and, therefore, higher dispersal potential. Our results show that pelagic polyps live longer than planulae, probably because they can feed and meet the presumably high-energy demands of swimming. Clusters of two or more individuals lived longer than solitary polyps. However, mortality did not differ between small (2-3 polyps) and large (4-8 polyps) clusters, suggesting the existence of an upper limit to cluster size. Most swimming clusters (80 %) remained alive after 6 months, suggesting that pelagic metamorphosis and cluster formation can be a key life-history feature increasing dispersal potential, population connectivity, and the colonization of new habitats in this invasive species.

Impact of diurnal temperature fluctuations on larval settlement and growth of the reef coral <i>Pocillopora damicornis</i>

“…Metamorphosed and floating larvae, previously noted in corals (Richmond, 1985;Edmunds et al, 2001;Vermeij, 2009;Mizrahi et al, 2014), were more frequent at elevated temperatures. One possible explanation is that premature metamorphosis in coral larvae is a spontaneous response to increased temperatures (Edmunds et al, 2001).…”

“…One possible explanation is that premature metamorphosis in coral larvae is a spontaneous response to increased temperatures (Edmunds et al, 2001). The floating polyps, as a result of pelagic metamorphosis, have been shown to have extended longevity, possibly because they can obtain energy from photosynthesis by maternally derived symbionts and heterotrophic feeding using tentacles (Richmond, 1985;Mizrahi et al, 2014). Thus, the plasticity of metamorphosis during the dispersive phase could be a strategy for coping with environmental stress in coral larvae, although it remains to be determined whether these floating polyps are capable of settling and contributing to recruitment in natural conditions.…”

Coral chimerism as an evolutionary rescue mechanism to mitigate global climate change impacts

“…Coral chimerism was intermittently documented during the 1970s and 1980s in studies evaluating interspecies (Rinkevich, Shashar, & Liberman, ) and allogeneic interactions in corals, including Pavona cactus (Willis & Ayre, ), Pocillopora damicornis (Hidaka, Yurugi, Sunagawa, & Kinzie, ) and Stylophora pistillata (Rinkevich & Loya, ; Figure ). The studies mentioned above, and their follow‐ups, consistently documented tissue fusions (chimerism) between young spats, or the existence of natural chimerism in adults (Amar, Chadwick, & Rinkevich, ; Amar & Rinkevich, ; Devlin‐Durante, Miller, Precht, & Baums, ; Duerden, ; Frank et al, ; Hellberg & Taylor, ; Hidaka et al, ; Jiang, Lei, Liu, & Huang, ; Linden & Rinkevich, ; Maier, Buckenmaier, Tollrian, & Nurnberger, ; Mizrahi, Navarrete, & Flores, ; Nozawa & Hirose, ; Puill‐Stephan, van Oppen, Pichavant‐Rafini, & Willis, ; Puill‐Stephan, Willis et al, ; Puill‐Stephan, Willis, Herwender, & Oppen, ; Raymundo & Maypa, ; Rinkevich, Shaish, Douek, & Ben‐Shlomo, ; Schweinsberg, Gonzalez Pech, Tollrian, & Lampert, ; Schweinsberg, Weiss, Striewski, Tollrian, & Lampert, ; Toh & Chou, ; Wijayanti & Hidaka, ). Indeed, coral chimerism usually develops between partners younger than 3 months old, in the so called “chimeric window” of ontogeny, prior to the maturation of the allorecognition system (Frank et al, ), but can also be delayed up to 1–2 years post‐settlement (Nozawa & Hirose, ).…”

“…Fusion between allogeneic corals (primarily when larvae or small spat stages are concerned) might endow the chimeric organism with an immediate survival advantage by virtue of the immediate increase in size, as chimerism is likely to be an weighty strategy for maximizing survival of vulnerable early life‐history stages of corals (Amar et al, ; Mizrahi et al, ; Puill‐Stephan, van Oppen et al, ). Yet, this is only part of the already documented benefits attributed to coral chimeras.…”

Tumbling under the surf: wave-modulated settlement of intertidal mussels and the continuous settlement-relocation model

“…Over the past few decades, much has been learned about this delicate and short-lived process we call 'settlement' (Keough & Downes 1982), including knowledge of the biological, chemical, and physical determinants of variability in time and space (see Shanks 1995, Queiroga et al 2007, Pineda et al 2010 for reviews). However, it is known that many invertebrates have a life cycle that is more complex than the 'classical' model, including optional larval stages, pelagic metamorphosis, and even reversals of metamorphosis, which can lead to a protracted and ambiguously defined settlement process (Baker & Mann 1997, Mizrahi et al 2014). Many bivalve species, including common mytilid mussels, have life cycles that include prolonged and difficult-to-define settlement periods (Baker & Mann 1997).…”