Can New Jersey Marshes just “Fuhgettabout” Superstorm Sandy?

A Hurricane in New Jersey?

The infamous extratropical Hurricane Sandy made landfall on southern New Jersey in October of 2012. With wind gusts up to 80 mph and over 5 feet of storm surge, it was one of the largest Atlantic Hurricanes ever recorded. And to add insult to injury, 10 days after Sandy made landfall, a northeaster weather event brought unseasonal rain and snow to the area.

Satellite image of Hurricane Sandy making landfall. Source: NOAA/NASA GOES Project

Record breaking storm surge from the hurricane rose 4-75 times higher than average high tide, and wave activity from winds pounded the coastline for over 30 hours. Famed boardwalks along the state were ripped apart and countless homes were destroyed from flooding.

Coastal wetlands, especially salt marshes, are a part of the first line of defense for our coastal communities during these dangerous storms. One model from Siddharth Narayan from UC Santa Cruz estimated that wetlands saved NJ $625 Million in property damages by mitigating flooding during Hurricane Sandy.

But in many cases protection comes at a cost. Reports from other regions cite uprooting of vegetation, erosion, deposition of large amounts of sediment and physical changes that compress or tear up the marsh surface as a result of intense storms.

Homes and bridge destroyed from ocean water breaking through barrier island. Mantoloking, New Jersey October 31, 2012.  Source: Mario Tama / Getty Images

Aerial photographs comparing NJ coastal marshes before and after Sandy suggested that this was the case. Many people worried that wetlands, and the services they provide like water quality treatment, animal habitat and protection from future storms were jeopardized for years to come.

Luckily for coastal NJ, plant ecologist Dr. Tracy Quirk had been studying the very marshes that experienced stress from the storm for years before Hurricane Sandy hit. Equipped with past marsh elevation and plant data, she surveyed the wetlands following the hurricane and subsequent northeaster to confirm if the images were telling the whole story.

Dr. Quirk studied 6 marsh sites throughout the state with varying elevations and distances from the storm track. 3 were in Barnegat Bay protected by a barrier island and the rest in tributaries of the large Delaware Bay at the south end of New Jersey.

Map of marsh study sites in Barnegat Bay (circles) and Delaware Estuary (triangles). Green areas are wetlands.
Source: Quirk, 2016

After observing changes in elevation of the marsh, soil characteristics and plant density, Dr. Quirk reported mostly temporary, localized impacts from the storm at her sites. She determined that the low-lying wetlands in the area returned to pre-storm elevations within 5 months and plant biomass could recover after just a few growing seasons.

But after a hurricane that left 149 people dead, how could the wetlands escape the same fate?

In other parts of the country, regional factors like wind intensity, relative location of the marsh to the storm or existence of natural protective barrier islands are thought to determine how a salt marsh will respond to stress from a storm. It turns out, however, that small scale features such as elevation, soil type, soil microbes and connectivity to water sources play a larger role in local NJ marshes.

For example, Dr Quirk observed a change in elevation at some sites. Normally elevation change after a storm is attributed to new sediments that the storm deposited on top of the marsh. At the studied sites, however, the cause of change was more related to temporary compaction processes occurring below the marsh surface from the weight of flood water.

The Future of NJ Wetlands

Marsh ecosystems will respond to intense weather events differently depending on small- or large-scale factors that can be external or internal. It is essential for coastal managers to understand how NJ marshes differ in their reactions to extreme weather so they can appropriately protect salt marshes from damage and accelerate recovery in the future.

If you’re from a coastal community and are concerned about the ever-increasing frequency of large tropical storms, you’re probably right to worry! But have hope that as researchers continue to look at the impact of tropical storms on east coast wetlands they will gain more understanding of the many interactions that can make or break these ecosystems.

Salt marshes are our best hope in protecting future coastlines, especially with eminent climate change, sea level rise and increasing numbers of severe weather events. Wetlands can survive these storms and continue to protect our coastlines if we work to secure their future.

 

Source: https://doi.org/10.1016/j.ecss.2016.09.006

 

For more information on the Quirk Lab click here!

 

Find Alina Spera on twitter @empressalina !

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