Indian River Lagoon
Species Inventory

Extreme Weather

Salt marshes, mangroves and other coastal ecosystems can usually recover quickly from natural disturbances such as fire and hurricanes. However, when disturbance events occur in close succession, they may have lasting effects on the ecosystems.

Photo credit: N. Adams

Hurricanes produce storm surges, wind and waves that can impact mangroves and marshes in several ways. Upper marshes and mangrove swamps can experience an influx of seawater at a salinity to which vegetation is not accustomed, causing dieback of several plant species. Wind can strip trees and bushes of foliage and damage the trunk. The white mangrove, Laguncularia racemosa, is the mangrove species most susceptible to wind damage (Doyle et al. 1995).

Credit: J. Whiticar

In addition, lower elevations can experience extreme rates of sedimentation or erosion. Sediment erosion can wash away much of the vegetation, reducing habitat acreage. However, sediment accretion could be more harmful, essentially covering marsh and mangrove areas (Rejmanek et al. 1998) and smothering sessile benthic invertebrates. One example of rapid sedimentation occurred in the upper Chesapeake Bay, when over a 70-year period, 50 percent of the sediment accumulation was attributed to one flood event and a single hurricane (Schubel & Hirschberg 1978). Regeneration of mangrove forests following substantial storm damage may take decades, and restored swamps may have altered biodiversity and plant zonation (Ellison & Farnsworth 1990).

Eroded shoreline at Dania Beach. Credit: D. Di Palma/Wikimedia Commons


Sources of IRL tidal flat erosion are many. Storms, wind induced waves, hurricanes, epibenthic bioturbation, prop scarring, etc., can singly and sometimes synergistically contribute to the erosion of tidal flats. Because most of IRL tidal flat areas are located in the vicinity of inlets, they are further subjected to fluctuations in tidal current velocities. As mentioned above, since most infaunal organisms burrowing on the tidal flat lack an anchoring structure, severe rapid erosion, i.e. that which outpaces the ability of these organisms to burrow more deeply, can lead to substantial changes in infaunal abundance.