IV is independent variable, DV stands for dependent variable (output). So in this case you indeed have one independent (input/cause) variable: the amount of bullying and 3 outcome variables which are studies (i.e. Productivity, Self-Confidence and Self-Esteem). A regression analysis should be applied to test for effects.
MANOVA would be used to test multiple groups and although your question does not clearly state this, I am going to assume you have one group of persons on which measured the amount of IV and tested all 3 DVs, so MANOVA is not the thing you need.
In this case you could also choose to test for correlations between variables instead of using a regression technique, i.e. to correlate the IV with the 3 DVs, although now you use these variables as random variables.