Advocacy Blog: Rust Tide in the Bay

By Tom Kutcher, Narragansett BayKeeper

Anyone who has spent much time on the Bay in the last few weeks has probably noticed some patchy but abundant tea-colored water in the Bay. The culprit? “Rust tides,” according to scientists with the R.I. Department of Environmental Management (DEM). Rust tide is an algae bloom of microscopic dinoflagellates that use a red pigment to photosynthesize. The bloom is happening pretty much throughout the Bay and has been documented in nearby waters such as the Narrow River, our coastal ponds and estuaries in New York and Massachusetts.

DEM reports that the bloom is not toxic to humans, but may have negative effects on sensitive fish species. However, although I have been seeing numerous large, dark streaks and patches of rust tide throughout the Bay, I’ve also been witnessing many schools of pogies being chased by bluefish in the upper and mid Bay, which seems to be a good sign that they are not being incapacitated by this event.

Rust tide is naturally occurring, but some scientists are suggesting that this may be the largest rust-tide event we’ve seen in decades. DEM expects the bloom to dissipate as waters approach 60 degrees, which doesn’t usually happen until sometime in October. Until then, please report any signs of fish stress to me directly at 401-272-3540 ext 116, or to Dr. Chris Deacutis (christopher.deacutis@dem.ri.gov) at RI DEM Fisheries.