Philadelphia’s Diatom Archive Is a Way, Way, Wayback Machine

In recent decades, however, the sea has dominated the once dynamic coastal zone, pushing further inland as sea levels rise. Over the past century, sea levels along New Jersey have risen by 0.45 meters, more than double the global average of 0.18 meters. By 2100, sea levels could rise by more than one meter.

The dramatic rise in sea levels has proven catastrophic for the patchwork of marshes along the coast of New Jersey, some of which have succumbed to the sea. However, the full extent of the loss of these wetlands is difficult to analyze because environmental monitoring is only a few decades old.

Without awareness of the natural condition of the wetlands, ecological restoration is difficult. Having that information is crucial, Enache said. “Not available [it], you are in the dark. “Thankfully, some of this missing data is captured in the academy’s diatom cache.

Like most coastal regions aside, New Jersey is used to sea level rise. During the Pleistocene, when New Jersey was covered in ice and inhabited by mastodons, sea ice formed reservoirs of seawater. About 18,000 years ago, sea levels sank more than 130 meters below current levels – extending the New Jersey coastline more than 110 kilometers into the Atlantic Ocean.

The end of the last ice age caused a steady rise in sea levels. The receding ice sheets caused parts of New Jersey to sink. According to Jennifer Walker, a sea level researcher at Rutgers University, this subsidence, combined with the melting of the ice, has demonstrated a powerful combination of rapidly rising sea levels.

In a published study Last year, Walker went back in time to contextualize New Jersey’s current sea level rise. “If we can understand how changes in temperature, atmosphere, and sea level are related in the past, that’s what we can use to predict future changes. change in the future.”

To measure sea level fluctuations over the past 2,000 years, her team examined the shells of a single-celled organism known as foraminifera, finely calibrated for specific environmental conditions. This makes them a valuable proxy for reproducing sea level change. By determining the presence of certain species of foraminifera in sediment cores collected from various points along the Jersey coast, her team concluded that New Jersey’s coast was experiencing an increase in fastest sea level in 2,000 years.

NJDEP hopes diatoms can serve as a similar tool to understand how coastal marshes respond to sea level rise. Like foraminifera, each species of diatoms is extremely sensitive to environmental conditions. For example, species like the rolling head Nitzschia microcephala thrive in nitrogen-rich environments, making their shells a common sign of nutrient contamination. Other species, such as Diploneis smithii, whose segmented crust resembles a slender trilobite, prefers saltwater. Their presence inland is a good indication of past sea level intrusion and helps researchers infer which marshes have flooded in the past.

To pinpoint exactly where these microindices once existed, NJDEP deployed a team of researchers into several marshes along the coastline, from the heavily polluted marsh in the north to almost pristine tidal marsh in the south. At each site, they entered the swamp, taking samples up to 2 meters deep at certain points. Enache compares this method to slicing into a stack of pancakes — as you cut deeper, you’re essentially stepping back in time from a steaming pancake that just came out of the grill to a soggy pancake. at the bottom of the cake stack. When they dug deeper, the researchers went back decades. In total, they collected nine cores from five wetlands.

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