PhD Advisor: Professor Carlos M. Duarte

Abstract:
Macroalgae structure coastal habitats, shape community dynamics, and anchor blue-bioeconomy potential. The Red Sea’s narrow, environmentally extreme basin and strong latitudinal gradients provide a natural testbed to assess how macroalgal abundance can be constructive, competitive, or convertible to societal value under climate change. This dissertation: (i) synthesizes Red Sea macroalgal research, showing spatial/thematic biases, unresolved taxonomy, understudied calcifiers, and gaps in ecophysiology; (ii) establishes coast-wide baselines across reefs and seagrass meadows, revealing strong latitudinal structuring and a nonlinear coral decline with combined algal cover, including empirical reef-collapse thresholds; (iii) tests an invasive peyssonnelid (Ramicrusta sp.) under nighttime deoxygenation, showing suppressed respiration with coordinated metabolic, metabolomic and microbial tolerance; (iv) screens multi-species nutrient/element portfolios and targeted fatty acids, identifying phylogenetically structured, application-specific trade-offs for arid-coast cultivation; and (v) applies untargeted metabolomics to resolve chemotaxonomic structure enabling species-level bioprospecting. Collectively, the work defines decision-relevant thresholds, reveals mechanisms of a rising cryptic competitor, and delivers data-driven shortlists aligning blue-bioeconomy potential with ecological baselines.