Jim Ledford said:

however, unless they are [FIRE] ants, most people would
consider ants in a garden a plus.

Or, rather, an indication that there possibly will-be/is an aphid problem.
Certain aphids are a food source for certain ants. Depends on what kind of
ants. If they're there because of the sugars that the aphids secrete,
they'll stay until the aphids are gone, moving from plant to plant with
them. It's definately worth checking out.

The OP didn't state what kind of ants, but judging from their location, I'm
guessing they're not fire ants.

soil aeration is an ant's specialty.

In topsoil, but garden soil should get turned plenty to keep it aerated.
The ants will have little, if any effect, on the aeration of the garden
bed, IMO.

--
Eggs

-How to become immortal: Read this signature tomorrow and follow its
advice.