Sensing coral reef connectivity pathways from space

Abstract

Coral reefs rely on inter-habitat connectivity to maintain gene flow, biodiversity and ecosystem resilience. Coral reef communities of the Red Sea exhibit remarkable genetic homogeneity across most of the Arabian Peninsula coastline, with a genetic break towards the southern part of the basin. While previous studies have attributed these patterns to environmental heterogeneity, we hypothesize that they may also emerge as a result of dynamic circulation flow; yet, such linkages remain undemonstrated. Here, we integrate satellite-derived biophysical observations, particle dispersion model simulations, genetic population data and ship-borne in situ profiles to assess reef connectivity in the Red Sea. We simulated long-term (>20 yrs.) connectivity patterns driven by remotely-sensed sea surface height and evaluated results against estimates of genetic distance among populations of anemonefish, Amphiprion bicinctus, along the eastern Red Sea coastline. Predicted connectivity was remarkably consistent with genetic population data, demonstrating that circulation features (eddies, surface currents) formulate physical pathways for gene flow. The southern basin has lower physical connectivity than elsewhere, agreeing with known genetic structure of coral reef organisms. The central Red Sea provides key source regions, meriting conservation priority. Our analysis demonstrates a cost-effective tool to estimate biophysical connectivity remotely, supporting coastal management in data-limited regions.

Sensitivity Studies of the Red Sea Eddies Using Adjoint Method

“…Eddies in the Red Sea have been reported to be playing a crucial role in transporting energy, heat, and biogeochemical particles across the basin. The eddies make a remarkable contribution to the overturning circulation (Yao, Hoteit, Pratt, Bower, Köhl, et al, ; Yao, Hoteit, Pratt, Bower, Zhai, et al, ; Zhan et al, ), plankton blooms (Raitsos et al, ; Triantafyllou et al, ), species connectivity (Nanninga et al, ; Raitsos et al, ), brine, and discharge diffusion processes (Zhan et al, ), as well as other effects. In particular, a semipersistent cyclonic eddy (CE) in the northern Red Sea was reported to have uplifted colder water to the surface and created a substantial negative SST anomaly that was considered to favor the preconditioning of intermediate water formation (Papadopoulos et al, ).…”

“…Circulation in the Red Sea is highly variable and characterized by large surface temperature gradients (Bower & Farrar, 2015;Sofianos & Johns, 2007;Yao, Hoteit, Pratt, Bower, Zhai, et al, 2014), boundary currents (Bower & Farrar, 2015;Zhai et al, 2015;Zhan et al, 2015), and multiple recurrent and transient mesoscale and submesoscale eddies filling the basin (Chen et al, 2014;Papadopoulos et al, 2015;Zhai & Bower, 2013;Zhan et al, 2014Zhan et al, , 2016. Eddy activities have been captured by different types of observations, namely, remote sensing data from projects measuring Sea Level Anomalies (SLA; Bower & Farrar, 2015;Raitsos et al, 2017;Zhai & Bower, 2013;Zhan et al, 2014), Sea Surface Temperature (SST; Papadopoulos et al, 2015), chlorophyll-a (Raitsos et al, 2013), Synthetic Aperture Radar imagery (Karimova & Gade, 2014), and in situ observations (Sofianos & Johns, 2007). Unfortunately, most of the available observations are spatially or temporally sporadic and sparse, making any attempt to construct a full picture of the circulation structure very difficult.…”

Baroclinic Tides Simulation in the Red Sea: Comparison to Observations and Basic Characteristics

“…Seasonal variations in the general circulation also greatly modulates the water stratification, especially in the southern Red Sea and at the entrance to the BAM Strait (Yao, Hoteit, Pratt, Bower, Zhai, et al, ; Yao, Hoteit, Pratt, Bower, et al, ), which may have an important impact on the generation of baroclinic tides. The Red Sea contains a unique large marine ecosystem and most of its coastline is bordered by a coral reef system (Madah et al, ; Raitsos et al, , ). Therefore, studying the properties of baroclinic tides and the associated breaking and mixing processes is crucial to understand not only the physical processes but also the ecological and environmental system.…”

Three‐Dimensional Signature of the Red Sea Eddies and Eddy‐Induced Transport

“…In the Red Sea, however, the movement of individual eddies is impeded due to the limited width of the basin (Zhan et al, 2014). Meanwhile, the eddy-induced zonal transport is reported to promote active material and genes exchange among coral reefs between the two coasts of the Red Sea, supporting survival connectivity for the biologically diverse ecosystems in the basin (Raitsos et al, 2017). Meanwhile, the eddy-induced zonal transport is reported to promote active material and genes exchange among coral reefs between the two coasts of the Red Sea, supporting survival connectivity for the biologically diverse ecosystems in the basin (Raitsos et al, 2017).…”

“…These have been captured in various independent observations, including remotely sensed sea surface height (SSH) data (Bower & Farrar, 2015;Raitsos et al, 2017;Zhan et al, 2014), sea surface temperature (SST) data (Papadopoulos et al, 2015), chlorophyll-a data (Raitsos et al, 2013), synthetic aperture radar imagery (Karimova & Gade, 2014), and in situ observations (Sofianos & Johns, 2007;Zarokanellos et al, 2017;Zhai & Bower, 2013). These have been captured in various independent observations, including remotely sensed sea surface height (SSH) data (Bower & Farrar, 2015;Raitsos et al, 2017;Zhan et al, 2014), sea surface temperature (SST) data (Papadopoulos et al, 2015), chlorophyll-a data (Raitsos et al, 2013), synthetic aperture radar imagery (Karimova & Gade, 2014), and in situ observations (Sofianos & Johns, 2007;Zarokanellos et al, 2017;Zhai & Bower, 2013).…”