Final answer:
Coral bleaching is caused by the stress of increased ocean temperatures, leading corals to expel their algae and lose color. Rising CO2 and ocean acidification worsen the situation by interfering with corals' calcification, affecting reef biodiversity and dependent marine life.
Step-by-step explanation:
The light bleached color of dying coral in marine ecosystems is most likely the result of coral bleaching. This process occurs when coral reefs, stressed by higher ocean water temperatures due to climate change and human activities, expel their symbiotic, food-producing algae called zooxanthellae. Without these algae, corals lose their vivid colors and, if the condition persists, the corals can eventually die.
Additionally, rising levels of atmospheric CO2 are causing ocean acidification, which interferes with the corals' ability to calcify and maintain their hard calcium carbonate skeletons, exacerbating the bleaching effect. This loss not only affects the corals themselves but also the entire marine ecosystem, including the biodiversity and the various animals that rely on coral reefs for food and shelter.