Ways to know if my dependent variables are correlated?

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I have 7 dependent variables (photochemical parameters such as: Y(II), NPQ, Y(NPQ), Y(NO), qN, qP and qL) and I need to know if they are correlated in order to see the possibility of doing a multivariate analysis (all variables only take values between 0 to 1). Any idea please?

So far I have only explored graphically, but I need some test to run in r.