Hi Mary Jane,
The AHRENS surname is somewhat common in Mecklenburg, so to do any good you
will have know the town they came from of the old Grand Duchies of Mecklenburg-Schwerin
or Mecklenburg-Strelitz.
Once the town is known you could order the parish records on microfilm through
your local Family History Center.
I have many ways to locate the town, and I also have AHRENS on my tree from
Mecklenburg. Please write me with more info, like immigration year, family names
and ages who came over, any ship info, have you found them in the census, and
do you know any local U.S. church where any German born immigrants married?
Thanks,
Fritz