What is the adaptive significance of the pneumatocysts of seaweeds?

Pneumatocysts are gas-filled bladders found in certain seaweeds, primarily used to keep the plant buoyant and ensure it remains close to the water's surface, where light is abundant for photosynthesis. This adaptation allows seaweeds to maximize their exposure to sunlight and efficiently capture nutrients from the surrounding water. Additionally, being buoyant helps these organisms resist damage from wave action and increases their access to carbon dioxide, enhancing their overall growth and reproductive success.