Modelling the physical connectivity and marine ecosystem of the Red Sea with application to seascape genetics

Embargo End Date
2024-12-15

Type
Dissertation

Authors
Wang, Yixin

Advisors
Hoteit, Ibrahim
Raitsos, Dionysios E.

Committee Members
Berumen, Michael
Moraga, Paula
Miller, Arthur J.

Program
Marine Science

KAUST Department
Biological and Environmental Science and Engineering (BESE) Division

Date
2023-12-14

Access Restrictions
At the time of archiving, the student author of this dissertation opted to temporarily restrict access to it. The full text of this dissertation will become available to the public after the expiration of the embargo on 2024-12-15.

Abstract
Connectivity, the exchange of individuals and genes among geographically separated marine populations, plays a key role in coral reef biodiversity and resilience. The Red Sea is a semi-enclosed basin with dynamic circulation and abundant coral reefs, making it a natural laboratory for connectivity studies; yet, a full understanding of the Red Sea connectivity is still lacking. Using hydrodynamic and Lagrangian particle tracking models, a high-resolution circulation-driven physical connectivity atlas covering every Red Sea coral reef — including seasonality — is simulated, revealing important roles for northern reefs as sources/sinks and weak east-west connections between southern reefs. Additional backward simulations conducted in the southern Red Sea reveal dynamic linkages between the southern reefs and the Indian Ocean, explaining the genetic separation previously reported in the basin. Understanding the Red Sea ecosystem variability at various spatiotemporal scales is crucial for the Red Sea ecology. Previous studies mostly utilized remote sensing or in situ data which are limited to the ocean surface or sparse locations in the basin. Biogeochemical modeling presents a powerful tool for simulating the three-dimensional evolution of marine ecosystems. Here, a coupled physical-biogeochemical model is developed, enabling the investigation of Red Sea biogeochemistry at diel, seasonal, and interannual timescales. We reveal a chlorophyll diel cycle with near-sunset maxima in the Red Sea, demonstrate the importance of incorporating a spatially varying diffuse attenuation coefficient to reproduce the summer bloom in the southern basin, and explain impact of climate drivers (e.g., ENSO) on nutrient supply through the Bab-Al-Mandeb strait. Seascape genetics investigate how seascape features (e.g., circulation, temperature, productivity) shape the spatial genetic structures of marine species. Three theories — Isolation-By-Distance, Isolation-By-Circulation, and Isolation-By-Environment — were previously developed, but not fully examined in the Red Sea. Using previously published genetic datasets for multiple coral reef species and outputs from the physical connectivity and physical-biogeochemical models, we develop the first seascape genetic model that provides a full description of all three theories in the Red Sea, revealing the important roles of circulation and environment in shaping genetic structures. The developed models provide a unique tool for predicting the genetic structures of multiple Red Sea reef species.

DOI
10.25781/KAUST-P9I7I