Which of the following statements best describes the relationship between marine salinity variability and fish populations in different habitats?

• A. Marine fish are unaffected by changes in salinity because they can all tolerate a wide range of salinity levels.
• B. Variability in marine salinity leads to increased genetic uniformity among fish species.
• C. Salinity only affects plant life in marine habitats, not fish populations.
• D. Fish species are often adapted to specific salinity ranges, so variability in marine salinity can significantly impact their distribution and survival.

Answer: (D)

Verified step by step guidance

1. Step 1: Understand the concept of salinity and its role in marine environments. Salinity refers to the concentration of dissolved salts in water, typically measured in parts per thousand (ppt). Marine organisms, including fish, are adapted to specific salinity levels in their habitats.
2. Step 2: Recognize the physiological adaptations of fish to salinity. Fish species have specialized mechanisms to regulate their internal salt and water balance, a process called osmoregulation. These adaptations are often specific to the salinity range of their environment.
3. Step 3: Analyze the impact of salinity variability on fish populations. Changes in salinity can disrupt the osmoregulatory balance of fish, leading to stress, reduced survival rates, or migration to areas with more suitable salinity levels.
4. Step 4: Consider the ecological implications. Variability in salinity can affect the distribution of fish species, influence competition among species, and alter the structure of marine ecosystems.
5. Step 5: Conclude that fish species are often adapted to specific salinity ranges, and variability in marine salinity can significantly impact their distribution and survival, as stated in the correct answer.