Hi Jeanne, The basic answer to your "Specific" question is "No" you wont damage it at
low levels. Only if you push it can that happen...Traditionally, Bass Amps have 15-18" speakers as opposed to the smaller ones used in guitar amps 8,10,12. Guitar amps say 100w are powerful for guitar but for bass 300w is norm.this tells you that much more power is needed to transfer bass notes into "Clean" sound.
In years gone by however many noteable bass players used normal guitar amps for their basses playing some fairly heavy stuff jack Bruce and Noel Redding to mention just two
So "Steady past your grannies" and all will be well
Fenderphil