Loop Current influence on the connectivity of the West Florida Shelf and impacts on red tide events

TL;DR

This study examines how the Loop Current affects Gulf of Mexico connectivity and red tide events, using Markov Chain models based on buoy data to predict harmful algae blooms and identify high-risk regions.

Contribution

It introduces a Markov Chain approach to model Gulf connectivity during different Loop Current phases and links invariant regions to red tide hotspots.

Findings

Loop Current phases significantly alter Gulf connectivity.

Invariant regions correlate with red tide hotspots.

Markov Chain models can forecast red tide events.

Abstract

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.