Warming Winters and Storm-Driven Dispersal Facilitate Northward Mangrove Expansion Along the US Atlantic Coast

9 January 2026

Mangrove forest range expansion at the expense of salt marshes in north Florida (near Cedar Key). Highly productive grass- and succulent plant-dominated marshes and comparatively tall (>6 m height) mangrove trees. (Image credit: Michael Osland)

A new study by an international team of scientists, led by Lucia Enes Gramoso at the Vrije Universiteit Brussel, was recently published in the leading climate-change ecology journal Global Change Biology. The study, in collaboration with Moss Landing Marine Laboratories, UCLA, and USGS, examined how mangroves at this specific northern range limit may shift over the 21st century under climate change by combining climate projections with ocean circulation, biological observations, and historical hurricane data. The results show that warmer winters and storm-driven dispersal are key drivers of this expansion, potentially allowing mangroves to reach South Carolina by 2100.

Using species distribution models under four widely used climate scenarios, the researchers project a substantial increase in climatically suitable habitat beyond the current mangrove range by the end of the century. The strongest increases occur under scenarios associated with greater warming, indicating that rising winter temperatures are an important driver of poleward mangrove range expansion.

However, suitable climate conditions alone are not sufficient for mangrove expansion into salt marsh area. Mangroves rely on floating propagules (seedlings) that are dispersed by ocean currents. To assess whether propagules can reach newly suitable areas, the team used high-resolution ocean current simulations together with observations of propagule production and release.

The results indicate that ocean currents can transport propagules from both existing northern-edge and more southern mangrove populations to areas beyond the current range limit, suggesting that dispersal is unlikely to strongly limit expansion. “Our results indicate that winter warming is expanding the climatic envelope for mangroves, while ocean currents provide connectivity between current and potential future habitats,” said Lucia Enes Gramoso, lead author of the study. “Even low propagule densities reaching suitable sites may be sufficient for population establishment.”

The study also used historical storm track data to explore how hurricanes may contribute to mangrove dispersal at this northern range limit. “Because mangrove propagule production coincides with the hurricane season, storms can act as episodic, high-energy vectors that align with biological timing, increasing the potential for propagule transport along the coast,” said Tom Van der Stocken, principal investigator of the project.

By identifying regions that are both climatically suitable and accessible to dispersing propagules, the study provides a framework for anticipating climate-driven mangrove expansion and supporting site-specific coastal conservation and management strategies.

Reference:

Enes Gramoso, L. I. A., D. Carroll, K. C. Cavanaugh, R. Bardou, M. J. Osland, and T. Van der Stocken. 2026. “ 21st-Century Mangrove Expansion Along the Southeastern United States.” Global Change Biology 32, no. 1: e70676. https://doi.org/10.1111/gcb.70676.

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