On Oct. 29, 2012, Hurricane Sandy sent a tidal surge roaring through Lower Manhattan, pouring millions of gallons of seawater into South Ferry Station. Metro transit authorities who inspected the subway station encountered what they called âa large fish tank.â The spillover from New York Bay had filled the tunnels with water 80 ft. (24 m) deep.
Nearly two and a half years later, South Ferry Station has long since been drained. But Hurricane Sandyâs imprint remainsâon a microscopic level. Thatâs according to a study just published in Cell Systems, which its authors have used to create PathoMap, a cartographic sketch of the New York subway systemâs microorganism populations.

While the unseen world that teems around New York commuters vary slightly from neighborhood to neighborhoodâsee this Wall Street Journal map for specific stationsâtheyâre all roughly similar. Not the still-shuttered tunnels of South Ferry Station, though.
âIf you saw [the stationâs bacterial colony] youâd think, âOh, this looks like a fishâit looks like something youâd find in a fish,'â says the studyâs lead researcher, Christopher Mason, an assistant professor at Weill Cornell Medical College. âAnd some are just associated with cold marine environments.â
Several of South Ferry Stationâs unique bacteria hail from polar waters or the North Seaâlike Pseudoalteromonas haloplanktis, for instance. This map compares the concentrations of three bacteria. The first two maps show the prevalence of the human gut bacteria Enterococcus faecium and Staphylococcus aureus, which colonizes peopleâs skin. P. haloplanktis, however, tends to thrive in chilly Antarctic waters.

In fact, the bacteria in South Ferry Station arenât common to New York coastal water at all. After comparing the stationâs microbiome with that of Brooklynâs Gowanus Canal, the researchers found that the majority of samples from each site differed starkly. (Gowanus was also packed with industrial bacteria that likely relate to its severe pollution problems in the past).
The difference almost certainly came down to what Mason calls the âmolecular echoâ of Hurricane Sandy, whose tidal storm surge transplanted a colony of fishy, polar sea bugs.
This is a phenomenon scientists have never before demonstratedâproof that, as Mason puts it, âan environmental disaster can be rendered onto the surfaces of a given area.â
âThat alone has never been shown beforeâbut especially in an urban environment,â he says. âThe key question is how long it will last.â
Probably not much longer. The now-closed parts of South Ferry Station are slated to open up again in 2016. Then the rigorous off-hours scrubdown will zap the microscopic post-Sandy squatters, clearing the way for new colonies to form each morning, as commuters smear surfaces with their own bacteria. In time, South Ferry Stationâs microbiome will probably look once again like it did on Oct. 28, 2012, teeming with bugs that prefer human hosts to fish.