Why are shellfish populations often a good indicator of water quality? a. many shellfish are filter feeders that absorb toxins from the water b. many shellfish are herbivors, and reduce vegetation overgrowth c. many shellfish are photosynthesizers, and add oxygen to the water d. many shellfish are predators, and reduce the number of waste-creating fish

What is one affect on the australian environment due to the introduction of non-native european rabbits? (a) more grass grew in response to the need of the growing population of rabbits. (b) the rabbits balance out the food chain as they became a natural prey to many predators. (c) the rabbits the land by digging, which caused the soil to spread much needed nutrients. (d) the rabbits out-competed other small animals species and caused them to go extinct.