Question

part 3:short - answer questions answer the following questions in 2 - 3 complete sentences. 15. explain the difference between freshwater, brackish water, and saltwater in levels. 16. how do organisms like salmon survive in both freshwater and saltwater? 17. what might happen to an estuary ecosystem if freshwater input is reduced due to human activity or climate change? part 4: critical thinking answer in 4 - 5 complete sentences, using evidence from the passage or your own knowledge. 18. if a river’s salinity suddenly increases due to a prolonged drought, how might it affect the plants and animals that live there? 19. human activities, such as excessive water use and pollution, impact ecosystems. what are some possible solutions to reduce these effects on life?

Explanation:

1. Freshwater has low salt - content. Brackish water has a moderate salt - content, a mix of fresh and saltwater. Saltwater has high salt - content, like in oceans.
2. Salmon are osmoregulators. They can adjust their physiological processes to maintain proper salt - water balance in both freshwater and saltwater environments.
3. Reduced freshwater input could increase salinity in the estuary. This may harm freshwater - adapted organisms and disrupt the estuary's food web.
4. Higher salinity can be stressful to most river organisms. Freshwater plants may wilt and die. Animals may experience osmotic stress, leading to reduced populations.
5. Solutions include water conservation measures like drip irrigation and rainwater harvesting. Pollution control through better waste - water treatment can also help protect aquatic ecosystems.

Answer:

1. Freshwater has low salt content; brackish water is a mix with moderate salt; saltwater has high salt content.
2. Salmon are osmoregulators and can adjust to maintain salt - water balance in different environments.
3. Increased salinity may harm freshwater - adapted organisms and disrupt the estuary food web.
4. Higher salinity can stress organisms; plants may die and animals may face osmotic stress and reduced populations.
5. Water conservation (e.g., drip irrigation, rainwater harvesting) and pollution control (better waste - water treatment) can help.