In aquatic ecosystems, the limiting factor for the productivity is _________.

Explanation

**Step-by-Step Solution:**

1. **Understanding Aquatic Ecosystems**: Recognize that aquatic ecosystems include various bodies of water like oceans, rivers, lakes, and ponds, where different organisms interact with each other and their environment.

2. **Identifying Factors Affecting Productivity**: In ecosystems, productivity refers to the rate at which plants and algae (the primary producers) convert sunlight into energy through photosynthesis. Several factors can limit this productivity.

3. **Recognizing the Role of Light**: Among the various factors that influence productivity in aquatic ecosystems, light is a crucial component. Light is essential for photosynthesis, which is the process by which plants and algae produce energy.

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