Kilometer-Scale Larval Dispersal Processes Predict Metapopulation Connectivity Pathways for Paramuricea biscaya in the Northern Gulf of Mexico

Santiago Herrera,Guangpeng Liu,Annalisa Bracco,Andrea M. Quattrini

doi:10.3389/fmars.2021.790927

Abstract

Fine-scale larval dispersal and connectivity processes are key to species survival, growth, recovery and adaptation under rapidly changing disturbances. Quantifying both are required to develop any effective management strategy. In the present work, we examine the dispersal pattern and potential connectivity of a common deep-water coral, Paramuricea biscaya, found in the northern Gulf of Mexico by evaluating predictions of physical models with estimates of genetic connectivity. While genetic approaches provide estimates of realized connectivity, they do not provide information on the dispersal process. Physical circulation models can now achieve kilometer-scale resolution sufficient to provide detailed insight into the pathways and scales of larval dispersal. A high-resolution regional ocean circulation model is integrated for 2015 and its advective pathways are compared with the outcome of the genetic connectivity estimates of corals collected at six locations over the continental slope at depths comprised between 1,000 and 3,000 m. Furthermore, the likely interannual variability is extrapolated using ocean hindcasts available for this basin. The general connectivity pattern exhibits a dispersal trend from east to west following 1,000 to 2,000-m isobaths, corresponding to the overall westward near-bottom circulation. The connectivity networks predicted by our model were mostly congruent with the estimated genetic connectivity patterns. Our results show that although dispersal distances of 100 km or less are common, depth differences between tens to a few hundred meters can effectively limit larval dispersal. A probabilistic graphic model suggests that stepping-stone dispersal mediated by intermediate sites provides a likely mechanism for long-distance connectivity between the populations separated by distances of 300 km or greater, such as those found in the DeSoto and Keathley canyons.

Highlights

Deep-water or cold-water corals are long-lived and slow-growing organisms commonly found at depths greater than 50 m (Cairns, 2007; Roark et al, 2009; Sherwood and Edinger, 2009)
In this work we focused on dispersal processes, but larval traits, e.g., swimming, settlement, and mortality, should be further investigated to improve the realism of modeling studies of coral connectivity
Such variability can result at times in eastward transport, as verified in CROCO in February and August 2015 (Figures 5, 6) and in HYCOM in April 2011, with high variance in the modeled displacement of larval particles in both models, and contributes to the diversity of connectivity patterns found in this region

Summary

Introduction

Deep-water or cold-water corals are long-lived and slow-growing organisms commonly found at depths greater than 50 m (Cairns, 2007; Roark et al, 2009; Sherwood and Edinger, 2009). They play an essential role in providing habitats for a diversity of vertebrate and invertebrate species and are highly susceptible to natural and anthropogenic disturbances (Guinotte et al, 2006; Turley et al, 2007; White et al, 2012; Hoegh-Guldberg et al, 2017). Recent studies suggest that this biophysical framework offers meaningful predictions of connectivity (Gary et al, 2020; Ross et al, 2020), despite the uncertainties related to the sparsity of in situ measurements and model biases in the representation of bottom boundary layer dynamics (see Bracco et al, 2020 for a recent review pertinent to the Gulf of Mexico)

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Results

Conclusion