Friday, May 23, 2008

The Perfect Storm: September 11th 2007

Last fall during a heaving storm we lost much of what was one of the most incredible meadows in the Peconic Estuary. We are used to seeing meadows in the PE slowly wither over time as multiple stressors take their toll and they get smaller and smaller and smaller until they reach a point of no return and don’t come back the next year. In the last 15 years this has happened in Southold Bay, Northwest Harbor, Orient Harbor and many other sites I would rather not mention...

The Orient Point meadow was different though. This large meadow located in the cool clear waters near Plum Gut was one of our favorites and it showed no signs of stress or the slightest inkling of a problem, because up until September 2007, there was no problem.

For almost 10 years we have marveled at this site. From a practical point of view it was easily accessible by boat or truck and provided us with an endless supply of naturally uprooted shoots for transplant stock or seeds for our seeding efforts. In both cases we couldn’t collect 1% of what was available so we were confident that we were not having an impact. Our monthly dives here confirmed this.

Then came September 11th 2007… From my office window at Cedar beach in Southold, 12 miles west, which just happens to share the same exposure as Orient Point, I could see that it was bad, but I didn’t know how bad. I did take note of the fact that the wind never seemed to stop and the waves were crashing on our beach for almost two whole days.

But eventually as it always does, the storm stopped and we got back to the routine field work or early fall, collecting shoots and stockpiling them in our greenhouse for the upcoming restoration season. Everything was good, or so we thought…

It wasn’t until October 16th, when we happened to visit Orient on one of our regular shoot collection missions that we realized something was wrong, very wrong. Steve and Kim had gone out as they often do, but this time the report back was that not only were there no shoots to collect, but even worse, the meadow had vanished! The bottom was naked and only a few plants remained where previously there were more than 500 in a square meter.

When I got the news I was in disbelief. How could this be? What happened? Eventually, I thought about the storm we had in September and pieced together the timeline based on our dive logs. We had been to the site on September 1st and there was NO sign of anything wrong.

A search through the NOAA weather buoy archives provided the proof that I needed. A perfect storm of wind direction, intensity and duration had started on September 11th and ran into the 13th. Average seas in the area were 3-4’ over an 18hr period! Somehow the wind had passes south of Plum Island and north of the Gardiners Island ruins hitting Orient at an oblique angle that proved devastating.

My first dive on the site was on October 18th. When I dropped in I was shocked at what I saw. It looked like someone had come along and cut off all of the shoots, especially in the middle to deeper areas. Despite this devastation I was able to pick out some clues that told the story. One interesting observation was the fact that the rhizome mat was still intact throughout the meadow so the storm was not violent enough to rip the plants out entirely. What appears to have happen was even more bizarre. As I looked closely at what remained I found that the terminal ends of the rhizomes (where the shoot had once been attached) were frayed and rotting. This led me to the conclusion that the waves had actually taken the leaves and either rocked them back and forth and/or twisted them to the point where they simply broke off.

On a more positive note, there were still small clumps of plants next to larger rocks that apparently afforded some protection. Even more surprising was the fact that the inner, shallowest edge appeared to weather the storm better than the deeper areas. I must admit that this part did not make sense. The fact that the rhizome mat and most of the sediments were still there also means that there was the potential for seedling recruitment.

What is the fate of the Orient Point meadow? Is it lost forever? Will it recover?

In a future post I will describe subsequent observations at this site and a project we have recently initiated to track what we hope will be natural recovery over the coming years. As the old saying in ecology goes: “Mother Nature abhors a vacuum”; I just hope she fills it with eelgrass and not algae in this case!



Anonymous said...

Have other seagrass researchers seen a similar level of intense storm damage to non-stressed, dense, healthy beds? And have they rebounded? How common is this level of destruction?

Anonymous said...

I am not aware of any published studies or reports that describe a similar event for Zostera. Studies relating to storm damage in tropical species are more common. However, I am sure that this has happened elsewhere with eelgrass. With regard to recovery it will be a function of seedling recruitment and rhizome branching. In a future blog I plan to describe how we will be monitoring this process. I do not know how common this level of destruction is, but I believe it may have also happened a number a of years ago in a meadow a mile or so west along Orient Beach State Park...


Chris said...

I guess I should have used my registered my identity