  Using local nonlinear gyrokinetic simulations, we demonstrate that turbulent
eddies can extend along magnetic field lines for hundreds of poloidal turns in
tokamaks with weak or zero magnetic shear $\hat{s}$. We observe that this
parallel eddy length scales inversely with magnetic shear and at $\hat{s}=0$ is
limited by the thermal speed of electrons $v_{th,e}$. We examine the
consequences of these "ultra long" eddies on turbulent transport, in
particular, how field line topology mediates strong parallel self-interaction.
Our investigation reveals that, through this process, field line topology can
strongly affect transport. It can cause transitions between different turbulent
instabilities and in some cases triple the logarithmic gradient needed to drive
a given amount of heat flux. We also identify a novel "eddy squeezing" effect,
which reduces the perpendicular size of eddies and their ability to transport
energy, thus representing a novel approach to improve confinement. Finally, we
investigate the triggering mechanism of Internal Transport Barriers (ITBs)
using low magnetic shear simulations, shedding light on why ITBs are often
easier to trigger where the safety factor has a low-order rational value.
