The Impact of Oil and Hydrocarbons on Macroalgae: Physiological, Biochemical, and Ecological Consequences
Macroalgae are essential primary producers in coastal ecosystems, yet their vulnerability to petroleum-derived contaminants is often underestimated, especially when compared to the attention typically given to fauna or plankton during oil spill events. This review synthesizes current knowledge on the physiological, biochemical, and ecological impacts of crude oil, aliphatic hydrocarbons, and polycyclic aromatic hydrocarbons on marine macroalgae. We examine the properties of these contaminants and the environmental pathways that determine their bioavailability, emphasizing how their hydrophobic and persistent nature promotes strong interactions with macroalgal surfaces. At the organismal level, hydrocarbon exposure reduces photosynthetic efficiency, accelerates pigment degradation, and induces oxidative stress through the excessive production of reactive oxygen species. These processes impair growth, reproductive success, and overall metabolic stability. At the community level, contamination leads to declines in canopy-forming species, shifts toward opportunistic taxa, and a loss of structural complexity that affects associated fauna and food-web dynamics. The resulting degradation of ecosystem services, including carbon sequestration, nutrient cycling, habitat provision, and coastal protection, contributes to reduced ecosystem resilience. The review also discusses mitigation measures, the potential of macroalgae and associated microbes in bioremediation, natural recovery dynamics, and the main knowledge gaps that still need to be addressed.