Population structure of the corals Orbicella faveolata and Acropora palmata in the Mesoamerican Barrier Reef System with comparisons over Caribbean basin-wide spatial scale

Threatened Caribbean coral communities can benefit from high‐resolution genetic data used to inform management and conservation action. We use Genotyping by Sequencing (GBS) to investigate genetic patterns in the threatened coral, Acropora cervicornis, across the Florida Reef Tract (FRT) and the western Caribbean. Results show extensive population structure at regional scales and resolve previously unknown structure within the FRT. Different regions also exhibit up to threefold differences in genetic diversity (He), suggesting targeted management based on the goals and resources of each population is needed. Patterns of genetic diversity have a strong spatial component, and our results show Broward and the Lower Keys are among the most diverse populations in Florida. The genetic diversity of Caribbean staghorn coral is concentrated within populations and within individual reefs (AMOVA), highlighting the complex mosaic of population structure. This variance structure is similar over regional and local scales, which suggests that in situ nurseries are adequately capturing natural patterns of diversity, representing a resource that can replicate the average diversity of wild assemblages, serving to increase intraspecific diversity and potentially leading to improved biodiversity and ecosystem function. Results presented here can be translated into specific goals for the recovery of A. cervicornis, including active focus on low diversity areas, protection of high diversity and connectivity, and practical thresholds for responsible restoration.

supporting

confidence: 83%

Genomic patterns in Acropora cervicornis show extensive population structure and variable genetic diversity

Drury

Schopmeyer

Goergen

et al. 2017

“…With the use of five microsatellites, Porto‐Hannes et al. () did not detect significant differentiation between O. faveolata populations near these two sites. However, we were able to distinguish significant structure at this small spatial scale, likely due to the additional four microsatellite markers utilized.…”

Section: Discussionmentioning

confidence: 93%

“…More recently, however, Porto‐Hannes et al. () observed significant genetic structure within the Mesoamerican Barrier Reef System. These divergent findings illustrate that larval dispersal across the Caribbean may be influenced by multiple complex processes, which leads to uncertainty about the degree of population connectivity unless the entire basin is considered.…”

Section: Introductionmentioning

confidence: 99%

Population structure and connectivity of the mountainous star coral, Orbicella faveolata, throughout the wider Caribbean region

Rippe

Matz

Green

et al. 2017

As coral reefs continue to decline worldwide, it becomes ever more necessary to understand the connectivity between coral populations to develop efficient management strategies facilitating survival and adaptation of coral reefs in the future. Orbicella faveolata is one of the most important reef‐building corals in the Caribbean and has recently experienced severe population reductions. Here, we utilize a panel of nine microsatellite loci to evaluate the genetic structure of O. faveolata and to infer connectivity across ten sites spanning the wider Caribbean region. Populations are generally well‐mixed throughout the basin (FST = 0.038), although notable patterns of substructure arise at local and regional scales. Eastern and western populations appear segregated with a genetic break around the Mona Passage in the north, as has been shown previously in other species; however, we find evidence for significant connectivity between Curaçao and Mexico, suggesting that the southern margin of this barrier is permeable to dispersal. Our results also identify a strong genetic break within the Mesoamerican Barrier Reef System associated with complex oceanographic patterns that promote larval retention in southern Belize. Additionally, the diverse genetic signature at Flower Garden Banks suggests its possible function as a downstream genetic sink. The findings reported here are relevant to the ongoing conservation efforts for this important and threatened species, and contribute to the growing understanding of large‐scale coral reef connectivity throughout the wider Caribbean.

“…were major reef framework builders historically, but subsequent to a wide-spread epizootic event in the 1970/80s populations remain severely diminished (Alvarez-Filip, Dulvy, Côte, Watkinson, & Gill, 2011;Aronson & Precht, 2001;Gladfelter, 1982). Following the loss of Acropora, species of the genus Orbicella are the major framework builders on many of today's Caribbean reefs (McClanahan & Muthiga, 1998;Perry et al, 2012;Porto-Hannes et al, 2015). Although the effect of herbivory on Orbicella spp.…”

mentioning

confidence: 99%

Herbivory facilitates growth of a key reef‐building Caribbean coral

Suchley

Álvarez‐Filip

2017

The decline of reef‐building corals in conjunction with shifts to short‐lived opportunistic species has prompted concerns that Caribbean reef framework‐building capacity has substantially diminished. Restoring herbivore populations may be a potential driver of coral recovery; however, the impact of herbivores on coral calcification has been little studied. We performed an exclusion experiment to evaluate the impact of herbivory on Orbicella faveolata coral growth over 14 months. The experiment consisted of three treatments: full exclusion cages; half cage procedural controls; and uncaged control plates, each with small O. faveolata colonies. We found that herbivorous fish exclusion had a substantial impact on both macroalgal cover and coral growth. Fleshy macroalgae reached 50% cover within some exclusion cages, but were almost absent from uncaged control plates. Critically, O. faveolata calcification rates were suppressed by almost half within exclusion cages, with monthly coral growth negatively related to overgrowth by fleshy macroalgae. These findings highlight the importance of herbivorous fishes for coral growth and the detrimental impact of macroalgal proliferation in the Caribbean. Policy makers and local managers should consider measures to protect herbivorous fishes and reduce macroalgal proliferation to enable coral communities to continue to grow and function.