Ecologically relevant dispersal of corals on isolated reefs: implications for managing resilience

“2002 ; Nuryanto and Kochzius 2009 ) and the isolation of reefs in Western Australia ( Underwood et al .”

“Review of the recent literature suggests that such small-scale population structure in reef-building corals is more common than previously thought (Severance & Karl 2006; Whitaker 2006; Underwood et al. 2007, 2009; Miller & Ayre 2008).”

“2016), determining the role of connectivity, dispersal and other movements in conferring resilience (Underwood et al. 2009), assessing the relevance of network membership for node resilience and the relevance of node participation for network resilience (Keitt, Urban & Milne 1997; Moore, Grewar & Cumming 2016), evalua…”

“Routine dispersal occurs over scales of 10–100 s of metres (Underwood et al. 2007) and is supplemented by occasional longer distance dispersal (up to 10 or 100 s of km) (van Oppen et al. 2008; Underwood et al. 2009).”

“A number of explanations have been proposed to explain this phenomenon, including: high variability in reproductive success leading to differing parents contributing to distinct sets of larvae (Hedgecock 1994; Planes & Lenfant 2002) that may be transported in groups by temporally variable currents, selection on larvae…”

“…connectivity and dispersal distances determined with genetic tools are important for choosing the most effective size of marine reserves to protect recruitment processes, which has been applied to corals (van Oppen et al. 2008, Underwood et al. 2009) and fishes (Almany et al. 2007, Buston et al .”

“hystrix has been the subject of a diverse body of biological studies from the Red Sea to subtropical eastern Australia (Hoegh-Guldberg & Smith 1989; Edmunds 2005; Maier et al. 2005; Nozawa & Loya 2005; Fan et al. 2006; Sherman 2008; Underwood et al. 2009; Putnam et al. 2010; Stella et al. 2010; Nir et al. 2011; Tchern…”

“Due to the known problem with genotyping errors especially in Acroporids (Underwood et al. 2009; Richards & van Oppen 2012), the most common genotype per colony was tested for deviations from Hardy–Weinberg equilibrium at each locus and linkage disequilibrium was tested for each pair of loci using the program ARLEQUIN…”

“Relationships between genetic diversity and the geographic position of populations have also been surveyed, and decreases in genetic diversity have been detected in peripheral populations or with increasing latitude [20–23].”

“For example, Nishikawa et al. (2003) and Underwood et al. (2009) recorded higher levels of genetic structure in brooding relative to broadcastspawning corals, and Watts and Thorpe (2006) and Sherman et al. (2008) found the same in bryozoa and cushion stars, respectively.”

“Following expectations, several coral species with brooded larvae that settle quickly exhibit higher levels of genetic structuring than spawning species whose larvae spend extended periods of time in the plankton (e.g. Hellberg 1996; Ayre and Hughes 2000; Whitaker 2004; Underwood et al. 2009).”

“Stochasticity of recruitment as well as differences in life history, larval competency periods, settlement and survival requirements (Harrison & Wallace 1990; Harrison & Booth 2007) mean that different species will have different levels of connectivity to, and genetic diversity at, isolated locations (e.g. Miller & Ay…”

“Research has demonstrated contrasting pelagic larval durations (PLD) between brooding and broadcast-spawning corals, with some studies demonstrating more pronounced genetic structure in brooders (Hellberg 1996; Ayre & Hughes 2000; Underwood et al. 2009).”

“…connectivity, given its location with respect to neighbouring reefs, assuming that more isolated coral communities may differ in structure and composition due to limited accessibility to coral larvae for recovery (Gilmour, Smith, & Brinkman, 2009; Underwood, Smith, van Oppen, & Gilmour, 2009).”

“The lack of a strong population effect in our data suggests a lack of local adaptation, which is surprising given previous evidence of population genetic structure in corals [80,81] and the benefits of being locally adapted to the parental environment [82].”

“We calculated the proportion of unique multilocus genotypes (MLGs) at each site (Ng:N) (as per Underwood et al. 2009).”

“tenuis) are differentiated across distances <10 km on reefs in Australia (Ayre & Hughes 2000; Underwood et al. 2009).”

“Genetic techniques have been widely applied to estimate patterns of genetic connectivity, and more recently demographic connectivity of tropical marine species, but the focus has primarily been on corals and fish [8–11], with little information on connectivity patterns of other reef organisms.”

“…region (Figure 1) and combined with previous data from Browse Island (n = 74), the Rowley Shoals (n = 115) and Scott Reef systems (n = 281; Underwood et al., 2009), and from the Great Barrier Reef (GBR) on the east coast of Australia (n = 876; Warner et al., 2015; data reference…”

“Broadcasters are thought to be great dispersers, whereas brooders are considered to be poor dispersers, and have the potential for self-fertilization (Carlon 1999; Ayre and Hughes 2000; Nishikawa et al. 2003; Miller and Ayre 2008; Underwood et al. 2009).”

“, brooders versus nonbrooders; reviewed in [22, 23]), there appears to be little evidence of a consistent relationship between species PLD and patterns of population connectivity [21, 24].”

“…distance based on mark – recapture (Jones, Milicich, Emslie, & Lunow, 1999), pelagic larval duration (Shanks et al., 2003), genetic divergence (Underwood, Smith, van Oppen, & Gilmour, 2009), genetic assignment (Berument et al., 2012), and through biophysical models that include critical…”

“However, while there is some evidence that a high proportion of the coral larvae produced locally might be retained close to the parental population (Sammarco and Andrews 1988; Underwood et al. 2007; Underwood et al. 2009), the relatively close proximity of the two reefs (1.”

“Microsatellite genotyping of Acropora tenuis Although species-specific microsatellites have not been developed for A. tenuis, previous research successfully used seven microsatellite loci developed for the congener A. millepora (van Oppen et al. 2007) to evaluate genetic connectivity among A. tenuis populations in Wes…”

“PLD varies across species, fertilization strategy, larval development rate, and responsiveness to settlement cues (Graham et al. 2008; Miller and Mundy 2003; Tebben et al. 2015; Underwood et al. 2009).”

“This observation is further supported by the findings of Underwood et al. (2009), which suggest that although many coral reefs are genetically differentiated, panmixia can occur at scales of tens of kilometers or less.”

“Two multiplex polymerase chain reactions (PCRs) were performed per individual using fluorescently labelled primers (details of multiplex PCR, loci characteristics and GenBank acces- sion numbers are given in Underwood et al. 2009).”

“Increasingly, individual- and parentage-based analyses are being used to provide more direct estimates of dispersal parameters in marine species (Planes et al. 2009; Underwood et al. 2009; Christie et al. 2010).”

“However, despite this notion having received substantial empirical support [2,3,4,5,6,7] a number of exceptions have also been documented.”

“Population genetic studies and oceanographic dispersal models indicate that the Rowley Shoals are ecologically independent from other reef systems and reliant on local recruitment to maintain healthy populations (Underwood 2007, 2009; Underwood et al. 2012, 2013).”

“This result is consistent with offshore studies in north-west Australia from other brooding species (Thomas et al., 2020; Underwood et al., 2009, 2018; Underwood, Smith, van Oppen, & Gilmour, 2007) but contrasts to recent evidence of panmixia over these local spatial scales (<100 km) in a different…”

“Colonies formed by clonal fragmentation comprise on average 10% of sampled colonies of A. tenuis in the GBR, where this appears to be variable per reef (Underwood, 2009).”

“The recent global bleaching events (Wilkinson 2000) have highlighted the need to consider populations as potentially isolated from colonisation processes (Underwood et al. 2009).”

“Ideally, the effective design of reserves must account for the spatial scales of larval dispersal (Underwood et al. 2009), especially when MPA networks are planned (Jones et al. 2007).”

“Brooders often display high settlement success (Szmant, 1986), and high seascape genetic structure (Underwood et al., 2009), which suggests that local retention and recruitment of larvae is a feature of their life-histories.”

“These population genetic studies suggest that some high latitude populations of common coral species are vulnerable to genetic erosion (Ayre and Hughes 2004; Underwood et al. 2009), but others are not (Noreen et al. 2009).”

“Sh2-002, Sh2-006, Sh3-004, Sh3-007 and Sh4-001 were developed by Underwood et al. (2006) and previously used in S. hystrix from Australia (Underwood et al. 2007; van Oppen et al. 2008; Noreen et al. 2009).”

“In contrast to the Great Barrier Reef and the Caribbean, where coral genetic connectivity has received considerable attention (Takabayashi et al. 2003; Magalon et al. 2005; Vollmer and Palumbi 2007; Nunes et al. 2009; Underwood et al. 2009; Van Oppen et al. 2011; Baums et al. 2012; Serrano et al. 2014; Lukoschek et al…”

“Isolated reefs are increasingly being shown to rely primarily on self-replenishment (Ayre and Hughes 2004; Underwood et al. 2009) and the extent to which the protection of these reefs from anthropogenic disturbances offsets the limitations imposed by isolation is unknown (Hughes et al.”

“2009), in isolated reefs (Ayre and Hughes 2000; Underwood et al. 2009) and in recovery of reefs (Underwood et al.”

“…within a wider network are thought to have greater genetic diversity, recover better from disturbance (Underwood, Smith, Oppen, & Gilmour, 2009), adjust better to developing threats (Belote et al., 2017), and be more resilient to change (Minor & Urban, 2008; Underwood et al., 2009).”

“based on strong genetic structure (Underwood et al. 2009; Thomas et al. 2020; Adam et al. 2022), local recruitment (Gilmour et al.”

“[31] examined coral larvae dispersal in three coral reef systems in Northwest Australia, for the brooding coral Seriatopora hystrix and the spawning coral Acropora tenuis.”

“These factors are also likely to vary among taxa, since larvae of brooding corals are thought to travel shorter distances than those of broadcasting corals (Sammarco and Andrews 1989; Underwood et al. 2009).”

“…without written consent of the publisher Mar Ecol Prog Ser 421: 131–138, 2011 Several population genetics studies (Ayre & Hughes 2000, Nishikawa et al. 2003, Baums et al. 2005, Underwood et al. 2009) have suggested that in many cases, gene flow between populations is limited in reef corals.”

“Seascape analyses have revealed the role of the environment in shaping patterns of larval dispersal and coral population connectivity (Riginos et al., 2016; Riginos & Liggins, 2013; Selkoe et al., 2016; Thomas et al., 2015; Treml et al., 2012; Underwood et al., 2020, 2009, 2013).”

“2012), although localized recruitment is more often dominant (Baums et al. 2005; Severance and Karl 2006; Underwood et al. 2009).”

“This study builds on previous work in north-west Australia on hard corals (Underwood et al. 2009) to provide a community perspective on connectivity (sensu Kinlan and Gaines 2003) for species with a wide variation of life histories that have implications for the resilience and management of these…”

“tenuis (Underwood et al. 2009; van der Ven et al. 2016) and several other acroporid species from the Pacific Ocean (Richards and van Oppen 2012).”

“…the microsatellite data from Indonesia generated in this study with the previously published data from Western Australian in Rosser (2016) and Underwood (2009), ten tissue samples that were amplified and scored in the previous studies were also amplified and scored in the present study…”

“Coral reefs’ resilience to external disturbances strongly depends on larval exchanges between them (Underwood et al., 2009).”

“For tropical reef corals, there is evidence for dispersal limitation in corals at the scale of tens of kilometers (commensurate with the scale of our analysis; Ayre and Hughes 2000; Underwood et al. 2009), so this possibility is worth investigating.”

“2005; Vollmer and Palumbi 2007), and is likely to occur at scales of tens of kilometres, rather than over hundreds of kilometres (Underwood et al. 2009).”

“An understanding of connectivity is also important for managing species resilience to local and global disturbances (Hughes et al., 2005; Underwood et al., 2009).”

“It can also have important implications for fisheries and conservation management (Palumbi, 2004; Underwood et al. 2007, 2009).”

“Genetic analysis using microsatellites suggests that offshore isolated reefs are likely to be self-seeding (Underwood, 2009; Underwood et al., 2009).”

“Larval dispersal in brooders is assumed to be limited and local, while in broadcast spawners larval dispersal is thought to be expansive [15].”

“…management of benthic ecosystems, recent genetic studies on coral reefs in north-western Australia and Indonesia are also improving our understanding of connectivity, dispersal and gene flow in coral species and isolated reef systems in the ATS region (Underwood et al. 2009; Rosser et al. 2020).”

“Although several recent meta-analytical and comparative studies lend support to these theoretical expectations [1–9], others have not been able to establish clear links between life-history traits and the strength of population structure [10–18].”

“For non-continuous reef areas (e.g. across a continental shelf), rare long-distance migration events may be significant in maintaining a metapopulation over evolutionary time scales (e.g. Underwood et al. 2009, Nakajima et al. 2012).”

“…brooding species generally display high genetic structure, while planktotrophic species with longlived planktonic embryonic and larval phases achieve genetic homogeneity over large scales (see Hunt 1993, Teske et al. 2007, Underwood et al. 2009, Haye et al. 2014, Weber et al. 2015 for comparisons).”

“Additionally, the knowledge of genetic diversity and connectivity can help determine the ideal size and location of marine protected areas (Baums 2008, Underwood et al. 2009).”