Across
- 3. The Earth's system that includes all forms of water.
- 6. High in marine systems but absent in freshwater.
- 7. Major threat to aquatic ecosystems from sewage and waste.
- 9. The other primary ecosystem type besides aquatic.
- 11. Freshwater ecosystems where soil is saturated for long periods.
- 12. Small organisms that form the base of the freshwater food web.
Down
- 1. Type of discharge that releases toxic chemicals into water.
- 2. Freshwater ecosystems with fast-moving water like rivers.
- 4. Transitional areas where rivers meet the sea.
- 5. Rich variety of life supported by aquatic ecosystems.
- 8. Ecosystem type that covers 71% of the Earth's surface.
- 10. Freshwater ecosystems with still or slow-moving water like ponds.