Genet-specific spawning patterns in Acropora palmata

Abstract

The broadcast spawning elkhorn coral, Acropora palmata, requires outcrossing among different genets for effective fertilization. Hence, a low density of genets in parts of its range emphasizes the need for precise synchrony among neighboring genets as sperm concentration dilutes rapidly in open-ocean conditions. We documented the genet-specific nightly occurrence of spawning of A. palmata over 8 yr in a depauperate population in the Florida Keys to better understand this potential reproductive hurdle. The observed population failed to spawn within the predicted monthly window (nights 2-6 after the full moon in August) in three of the 8 yr of observation; negligible spawning was observed in a fourth year. Moreover, genet-specific patterns are evident in that (1) certain genets have significantly greater odds of spawning overall and (2) certain genets predictably spawn on the earlier and others on the later lunar nights within the predicted window. Given the already low genet density in this population, this pattern implies a substantial degree of wasted reproductive effort and supports the hypothesis that depensatory factors are impairing recovery in this species.

Geographic distances and ocean currents influence Caribbean Acropora palmata population connectivity in the Lesser Antilles

“…In a recent study, Miller et al (2016) reported that different genotypes of a single A. palmata population did not participate synchronically to the reproduction event, or even systematically every year. Therefore, because small colonies were not targeted during our sampling in order to avoid oversampling clones, low levels of genetic diversity may result from a bias linked to our sampling strategy.…”

“…The elkhorn coral A. palmata, as many other coral species, is known to reproduce both sexually and asexually, through fragmentation (Highsmith 1982). Because (1) sexual reproduction occurs only once a year, through the synchronized release of gametes in the water column (generally after the August full moon, Szmant 1986;Miller et al 2016) and (2) pelagic larvae can settle from 5 days up to a maximum of 20 days after fertilization in conditions not propitious to earlier larval recruitment (Baums et al 2005b), larval dispersal, in terms of distance and frequency, and genetic connectivity of this species are expected to be limited. Previous genetic studies on A. palmata Caribbean populations, both in terms of geographical variation of its clonal structure and spatial genetic structuring, have mainly been conducted along the reefs of the Gulf of Mexico (Florida, Baums et al 2005a, b, 2006a, the Bahamas (Baums et al 2005b(Baums et al , 2006aGarcia Reyes and Schizas 2010;Mège et al 2015) the Greater Antilles (Puerto Rico and US Virgin Islands, Baums et al 2005bBaums et al , 2006aGarcia Reyes and Schizas 2010;Mège et al 2015), the Mesoamerican Reef System (MRS, Baums et al 2005bBaums et al , 2006aPorto-Hannes et al 2015) and the islands off the Venezuelan coast (Los Roques National Park and the Netherlands islands of Curaçao and Bonaire, Baums et al 2005bBaums et al , 2006aZubillaga et al 2008;Porto-Hannes et al 2015;Mège et al 2015).…”

The Effects of Anthropogenic Stressors on Reproduction and Recruitment of Corals and Reef Organisms

“…Intraspecific variation, or inter-individual differences, in traits arise from genetic predispositions, past experiences and physiological states (Guest et al, 2012;Nanninga and Berumen, 2014), and is increasingly recognized as an important ecological factor that affects population dynamics and evolution of species, including reproductive success (Benton et al, 2006;Bolnick et al, 2011). In reef-building corals, significant differences in larval success has been observed among different genotypes (Meyer et al, 2009;Baums et al, 2013;Miller, 2014;Miller et al, 2016), as well as due to the parental experiences of exposure to stressful conditions (Putnam and Gates, 2015). This tells us that the larval stages are subject to strong selective pressures from their environmental conditions.…”

First Records for Spawning of Caribbean Acropora Species in Colombian MPAs

“…Global stressors, such as climate change, have been shown to cause spawning asynchrony in the Red Sea (Fogarty and Marhaver 2019, Schlesinger and Loya 2019), which could serve to reduce the overall fitness of populations, especially for species similar to A. palmata, which has a highly variable window for gamete release (Jordan 2018). Miller et al (2016) documented spawning variations in a population of A. palmata and noted that spawning asynchrony is particularly detrimental to populations with fewer individual genets, such as the depauperate Colombian reefs observed in this study. Spawning asynchrony, coupled with the loss of valuable genetic diversity and the stress of disease (Sokolow 2009), may reduce chances of recovery.…”