Gravatar images in WordPress sites don`t have alt and title tags, with this plugin you can resolve this problem on your site.

Gravatar SEO

A light and simple plugin to insert automatically ALT & TITLE tags into Gravatar images in your site.

SEO_tools

Image ALT attribute is certainly significant for SEO and usability.
Increase the Google Search Visibility of your articles with BULK SEO Image
Without BULK SEO Image, you need to write manually the ALT attribute of each image, or you can use a plugin that does it for you, but it may slow down the loading speed of your page
Now, with BULK SEO Image, this light and simpe plugin, you can update all the ALT attributes at once.
Save one at a time, or save all changes with one click

Bulk SEO Image

Easily update all the ALT attribute of your images. Can add the Article Name automatically to all your images improving traffic from search engines.

Gravatar SEO vs Bulk SEO Image