  We investigate the influence of the Loop Current (LC) on the connectivity of
the Gulf of Mexico, with a focus on the West Florida Shelf (WFS), using in situ
trajectories from satellite-tracked drifting buoys in the Gulf of Mexico (GoM).
We subset the dataset into two groups, Loop Current extended and retracted
phases, that are used to construct two Markov Chains representing the distinct
underlying dynamics during those two periods. The LC phases were found to
impact and modify substantively the general connectivity of the GoM.
Additionally, we highlight the presence of almost-invariant regions, where
particles tend to remain for an extended period, on the WFS when the LC is
extended. Those regions are bounded by a previously identified Cross-Shelf
Transport Barrier and correspond to records of high-density areas of Karenia
Brevis, a dinoflagellate responsible for red tides. Finally, we show that
Markov Chain modeling could help forecast harmful algae blooms by using the
devastating 2017 red tide event as a test case. The development phase on the
WFS and its further propagation to Florida's east coast ecosystems is
presented.
