If you're running wordpress, consider turning off Gravatar until this is fixed. See this Wordfence article for full details.

To disable gravatars in Wordpress go to Settings > Discussion. Scroll down to the Avatars section and uncheck the box next to ‘Show Avatars’ option. Remember to save! 

I tried a plug-in that claims to do locally stored avatars, BP Local Avatars but it doens't seem to have done anying, i.e. the existing users without avatars didn't get them when I told it to generate them. We'll see if it does anythign with new members.