4. Scientists are studying photosynthesis in a forest ecosystem that has plants, animals, and
decomposers (which consume dead things). Which group or groups of organisms in the forest
carry out photosynthesis?

It must be measured in k.hope my answer is to you : )

Answerchemical energy;

The population of unionid mussels decreased after zebra mussels were introduced. zebra mussels competed with the unionid mussels for food. the zebra mussels were able to displace the unionid mussels, allowing the zebra mussel population to increase  over the years. the unionid mussel population decreased because  of lack of food.