Climatide

Heather Goldstone / WCAI

A sign marking the 2011 closure of Nauset Marsh for shellfishing. As of today, the entire system is again closed due to red tide.

Massachusetts Division of Marine Fisheries has just announced that the entire Nauset Marsh system in Eastham and Orleans, on the outer Cape, is closed for shellfish harvest effective immediately due to red tide (or, more precisely, the presence of the toxin that causes paralytic shellfish poisoning, or PSP).

Nauset Marsh is the subject of red tide studies because it tends to particularly hard hit. The sprawling system of wetlands and inlets has only escaped an outbreak once in the past twenty years. And a quick perusal of PSP notices from the Division of Marine Fisheries reveals that it’s usually the first spot in Massachusetts to be closed.

But this closure is notable for how early it is – a full month earlier than any other closure since at least 2005. State officials said it’s the earliest they’re aware of.

Why? You guessed it. It’s yet another downside to the record warm winter we’ve had.

State spokesperson Reggie Zimmerman cautions that there are lots of factors that influence red tides – temperatures, wind, rain – so it’s hard to pin this bloom on any one thing. But Don Anderson, a leading red tide researcher at Woods Hole Oceanographic Institution, says the record warmth is a likely culprit.

It is a reasonable assumption that the early bloom is because of warmer temperatures.  The bloom starts from benthic cysts that will germinate faster in warmer waters, and once the cells are in the water, they will grow faster, if indeed the water is warmer than past years.

While water temperatures around the region have been significantly warmer than usual, Anderson says they won’t have confirmation for Nauset Marsh, specifically, until Friday – when they plan to pull an instrument that’s been recording temperatures and do a full survey of Nauset Marsh. But it’s clear this bloom took the researchers by surprise. They don’t even have data from this early last year.

We did plan our first survey earlier this year, but clearly not early enough.

Whether this early start signals a bad red tide season for the rest of the region remains to be seen. Anderson’s lab started producing annual outlooks a few years ago, but this year’s is still in the works and the fact that recent weather has been so unusual may throw the computer model for a bit of a loop.

As for our Gulf of Maine forecast, the computer runs are happening now, and we will be issuing that forecast in the next several weeks.  If you are wondering if the mild winter will affect that bloom (as I certainly am), we will have to wait for some toxicity data for that.  Unfortunately, the way our forecasts work, we need to rely on past years’ data to generate a series of scenarios of possible blooms, given the weather and hydrography of those years.  So a year with unusually warm conditions will not be simulated unless that happened in the past (2004 – 2011), and it didn’t.  We are moving towards the ability to assimilate real-time data into the model, so that our weekly forecasts will someday reflect actual temperatures and water mass characteristics measured by moored instruments in the Gulf and adjacent waters, rather than long-term averages, as is the case now.   Needless to say, we are all anxious to see what happens in the Gulf, though any temperature changes due to this warm winter will be much smaller than they are in the Nauset Estuary.  The lack of snowfall, and subsequent river runoff, will be another important factor to watch, as that can have a major impact on the bloom.

So stay tuned!