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Understanding the genetic makeup of key coral species is vital for effective coral reef management, as heightened genetic diversity directly influences long-term survival and resilience against environmental changes. This study focused on two widespread Indo-Pacific branching corals, Pocillopora damicornis (referred as Pocillopora cf. damicornis (as identified only morphologically) and Seriatopora hystrix, by genotyping 222 and 195 colonies, respectively, from 10 sites in the northern Gulf of Eilat, Red Sea, using six and five microsatellite markers, respectively. Both species exhibited low observed heterozygosity (0.47 for P. cf. damicornis, 0.32 for S. hystrix) and similar expected heterozygosity (0.576 for P. cf. damicornis, 0.578 for S. hystrix). Pocillopora cf. damicornis showed minimal deviations from Hardy-Weinberg equilibrium (HWE) and low but positive F values, indicating high gene flow, while S. hystrix exhibited higher diversion from HWE and positive F values, suggesting isolation by distance and possible non-random mating or genetic drift. As the Gulf of Eilat undergoes rapid urbanization, this study highlights the anthropogenic impacts on the population genetics of key ecosystem engineering species and emphasizes the importance of managing genetics of Marine Protected Areas while implementing active coral reef restoration. The differences in reproductive traits between the two species (S. hystrix being a brooder, while P. cf. damicornis a broadcast spawner), underscore the need for sustainable population genetics management of the coral reefs for the future and resilience of the coral reef ecosystem of the northern Red Sea region., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:Baruch Rinkevich reports financial support was provided by Israel Science Foundation. Baruch Rinkevich reports was provided by Ocean Citizen. Baruch Rinkevich reports financial support was provided by USAID-MERC. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Aspects of maternal-planula larval genetics in the monoecious scleractinian coral Stylophora pistillata (Red Sea, Eilat) were studied by amplified fragment length polymorphism (AFLP) methodology in two successive reproductive seasons. In total, 293 planulae and 10 adult colonies were analyzed. In June 2006, 147 planulae were collected from 10 shallow water colonies. In March, April and June 2007, 146 additional planulae were sampled from five of the ten 2006 sampled colonies. All AFLP products showed unalike band profiles indicating a fully sexual production pattern. We used 181 and 210 putative AFLP loci, of which the overall level of polymorphism in 2006 was 92 and 99  % in 2007 (respectively). Differences were also observed between 2006 and 2007 reproductive seasons in terms of total average gene diversity (0.191 vs. 0.247, respectively), suggesting fast turnover of sperm donor genotypes. In addition, increased numbers of potential sperm donor colonies in the vicinity of gravid females showed no impact on genetic differentiation levels in released larvae. UPGMA tree revealed clustering of maternal genotypes and their offspring, suggesting, as expected, high relatedness between planulae and their mothers. In addition, the average heterozygosity of each group of siblings was persistently lower than heterozygosity calculated for the respective maternal colony, suggesting the possibility of partial inbreeding. This trend of reduced genetic heterogeneity in Stylophora pistillata is an alarming sign for populations residing in the northern Red Sea coral reefs.

The soft coral Heteroxenia fuscescens is a common shallow-reef brooding species in the Red Sea. By means of amplified fragment length polymorphism markers, we studied modes of reproduction of planulae (sexual vs. vegetative) and levels of gene diversity of a population residing in the northern Gulf of Eilat, Red Sea. Eighty-nine larvae were collected from 9 mother colonies at 3 locations over a distance of 5 km. Amplifications revealed 221 putative loci, of which 81.4% were polymorphic; gene diversity was 0.29, allowing good identification of individual genotypes. No 2 identical DNA samples were present, so no asexual reproduction of planulae was indicated. The sampled planulae did not exhibit any genetic structure characteristic to a specific location, indicating one large gene pool and extensive gene flow among H. fuscescens specimens inhabiting the northern Gulf of Eilat.