Shell color change

[jensbe]

Hopefully someone experienced the same color change.
I added a male to my group of 3 female Marginated in spring this year.
The two oldest were mounted frequently and one just started to lay eggs.
Both are over 12 years old and their shells were almost all black with some amber color on each scute. Since summer both got much lighter and added a brownish red on the carapace as well. There is absolutely no change in behavior or appetite and the only information I found was from someone who reported a red color change of the plastron due to a blood poisoning after brumation.
Any ideas of what is happening here?
Cheers,
Jens

 

[ascott]

Are the spots in the areas where "manhandling" so to speak..from the male mounting her??

 

[jensbe]

Are the spots in the areas where "manhandling" so to speak..from the male mounting her??

Thank you for your response. The change of color is in almost every scute.
The brownish/red is new and the whole shell is getting lighter again.
Very strange after they were both almost totally black and the change took place in less than 6 months.
Any clue here?
Cheers,
Jens

 

[Moozillion]

I am a newbie and have no clue about your question/problem, but I wanted to say that's a beautiful tort!

 

[jensbe]

I am a newbie and have no clue about your question/problem, but I wanted to say that's a beautiful tort!

Thank you she has a lot of personality as well.