Rising sea level puts salt marsh habitat in danger

Members of the Hernando Audubon Society trek across the Weekiwachee Preserve on Saturday, passing a mangrove plant, a saltwater plant usually found closer to the coast. Group leader Clay Black said seeing the plant this far inland is one example that demonstrates the rise of the saltwater in the area.

CHRIS PRICE | Special to the Times

Members of the Hernando Audubon Society trek across the Weekiwachee Preserve on Saturday, passing a mangrove plant, a saltwater plant usually found closer to the coast. Group leader Clay Black said seeing the plant this far inland is one example that demonstrates the rise of the saltwater in the area.

If the vast expanse of black needlerush made the coastal marsh feel a little like the high plains, then the twisted, sun-bleached roots — relics of a long-gone stand of pines — was the ghost town.

And just when I thought all we needed to complete the picture was a skull, Clay Black pointed to a skeleton on a patch of bare sand.

"Do we have a mammalogist in the crowd?" asked Mike Wollam, a retired Pasco-Hernando Community College biology professor, who picked up the white head bone of what appeared to be a raccoon or opossum.

"That was the good thing about Kristin Wood," said Black, referring to the former director of the Chinsegut Nature Center and probably the best all-around naturalist in Hernando County. "She could tell you what everything was."

So here you have the three main themes of the Salt Marsh Safari, a Hernando Audubon Society coastal hike led Saturday morning by Black: continued lamentation about the state Fish and Wildlife Conservation Commission's recent, inexplicable decision to force the resignation of Wood, a longtime Audubon member; wonder at this closeup look at marshes that most us just drive by; and lots of sobering signs that this varied, fertile habitat is endangered by rising sea levels.

Until I wrote last month about the signs of this rise on the Chassahowitzka River, I wasn't aware of all the documentation supporting it. You can find it on the National Oceanic and Atmospheric Administration website — noaa.gov — which displays historic records of sea levels at sites all over the United States.

The monitoring station in Cedar Key, in operation since 1914, shows sea levels rising at a rate of about 7 inches per century. Readings on Clearwater Beach, which date to 1973, put the increase at about 9.6 inches per 100 years.

The NOAA website lists several possible reasons for long-term fluctuations, including rising temperatures and melting ice packs. But whatever the main cause — and whether or not you choose to believe in global warming — there's no indication this rise is going to stop or even slow down.

That, however, wasn't the first thing on our minds as we set out for the salt marsh, especially because most of our party of 15 or so hikers had never been there before.

We followed Black into a section of the Weekiwachee Preserve west of Shoal Line Boulevard and south of Hernando Beach. We emerged from a short stretch through pine flatwoods to a view of the previously mentioned needlerush savannah and, beyond it, the Gulf of Mexico. To the south, we could see the coastal development in New Port Richey, looking much grander and whiter from a distance than it does up close. To the north, we saw an eagle perched in a tree that Black estimated was more than a mile away.

The closeup views were at least as compelling, especially because Wollam was on hand to tell us what we were looking at.

All those holes in the sand? The hiding places of fiddler crabs, Wollam said — lots of different varieties, which is why some of the holes were barely big enough to fit a pinky and others were as big around as a quarter.

And the neat little sand balls around these openings? Those are the work of crabs, too. They swallow the soil, extract the organic matter and spit out BBs of pure sand.

Females "are two-fisted eaters," Wollam said. Males are the ones with the fiddler's famous, disproportionately large claw, with which they fight off competition and impress potential mates. "When they show that to the female, they're saying, 'Come over here and check out my etchings,' " Wollam said.

Farther out toward the gulf, the sand was wetter and the holes smaller. These are made by polychete worms, which come in even greater variety than fiddlers — dozens of species — and feed with even more simplicity, sucking sand into one end and emitting it from the other.

Hundreds of worms live in each square meter, Wollam said, and with their constant digestion they keep the top layer of sand bright white — and keep the fish fed. At high tide, Wollam said, these waters teem with redfish scooping up worms and fiddlers with their low-slung jaws.

It's crucial habitat that — surprise, surprise — might not be around long.

Even far out into the marsh, we saw patches of forested high ground, or what was once high ground. On all of them, trees are dying as the soil grows wetter and saltier. Fronds of some cabbage palms are brown and sickly. Three of them far out in the marsh are nothing but bare trunks, an indication of things to come.

"I call those the three sentinels," said Black, who during the week works as a stormwater engineer for the Southwest Florida Water Management District.

The old, weathered roots of the former pine forest where we found the skeleton (with Wood gone, it never was identified) make it clear the decline has been going on for decades. Black has seen these pine forests in old aerial photographs, but they were gone by the time he made his first trips out here 10 years ago.

"One thing I have noticed," he said, "is mangroves."

Adapted to saltwater, they usually hug the coast. He pointed to one specimen — waist high and as vigorous as suburban ligustrum — a mile inland. It was one more indication of the advancing sea. In a few decades, it could consume most of the land we walked over, most of what we saw.

Heading back into the flatwoods, one of the hikers, Michelle Dachsteiner, said she was glad to be done with the soggy trail and calf-deep mud holes of the swamp.

"This is a nice, hard-packed trail,'' she said.

"Enjoy it while you can,'' Wollam said.

Rising sea level puts salt marsh habitat in danger 01/11/11 [Last modified: Tuesday, January 11, 2011 7:57pm]

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