Topic 3.3 - Nutrient Cycles

Marine ecosystems depend not only on energy flow, but also on the continuous movement and recycling of nutrients. While energy flows in one direction through ecosystems and is eventually lost as heat, nutrients are recycled again and again. Understanding nutrient cycles helps explain: Why some areas of the ocean are highly productive Why others are nutrient-poor How human activities can disrupt marine ecosystems Disruptions to nutrient cycles—such as pollution, overfishing, or climate change—can have significant impacts on marine ecosystems.