Question

How do changes to a lower trophic level (ex. a decrease in producers) affect a higher trophic level? How do changes to higher trophic levels (ex. increase in secondary consumers) affect lower trophic levels?

Answer 1

Changes of numbers in lower trophic levels is likely to have the same effect on higher trophic levels, while changes of numbers in higher trophic levels will have the adverse effect on lower ones.

Explanation:

lower trophic levels:
decrease in producers -> decrease in food for primary consumers -> possible decrease in no. of primary consumers

higher trophic levels:
increase in secondary consumers -> more food needed for more consumers -> levels of lower trophic levels (primary consumers/producers) decrease