Is it permissible for me to keep the phone numbers of my female university colleagues on my phone, which allows me to see their statuses that may include their pictures, knowing that I try to lower my gaze, and this is for the necessity of communication related to university work? Is that considered forbidden? And is there any advice for girls who publish their pictures?

There is no harm in adding female students on social media if there is a need and benefit, provided that there is no fitnah (temptation/strife) and no suspicion, and while observing the Shariah controls by not exceeding the extent of the need and avoiding causes of fitnah. If there is no need or if fitnah is feared, then caution is obligatory, because Islam has placed strong boundaries for interaction between a man and a non-mahram woman, lest they follow the footsteps of Satan.

Viewing their statuses may be an entry point for Satan, especially for those who post their pictures. If a picture is seen unintentionally, there is no harm, according to the verse: "And there is no blame upon you for that in which you have erred." The girls who post their pictures in violation of Shariah must fear Allah, for this action contradicts modesty, causes fitnah for young men, opens doors to evil, and their pictures may be manipulated by criminals, which could lead to scandal and the attribution of crimes they did not commit.