Small but significant

The fate of creatures we barely notice can tell the most about our fragile environment

March 22, 2010|By Tom Horton

"Bald Eagle To Be Removed From Maryland's Threatened List"

Headline from Associated Press article, Jan. 21


It was the news, but not the real story. We'll always be eagle-centric, attentive to the "charismatic megafauna" like eagles and elephants, whales and sad-eyed seal pups.

But read beyond the tidings of our national symbol's comeback from endangerment. Maryland also took action on dozens of other species scarcely mentioned in the AP story. And their fates tell us more about the Mid-Atlantic's environment than the eagle, whose rebound is predominantly due to a nationwide ban on DDT decades ago.

The time had come, scientists decided, to throw in the towel on the bridle shiner, a tiny fish last seen 26 years ago around Havre de Grace at the head of the Chesapeake Bay.

It required clear water to hunt its food and underwater grasses for habitat - the grasses themselves also dependent on clear water. By the 1970s, much of the Chesapeake had turned cloudy and barren of sea grasses.

Lately, the upper bay has seen grasses come back, but too late for the bridle shiner, which was reclassified in January as "extirpated - just gone," explained Gwen Brewer of the Maryland Natural Heritage Program.

To which some might reply, "So what?"

"Well, it's one of the parts of the ecosystem," Ms. Brewer said. "It eats things and other things eat it, and when you lose it there are consequences, though they may be small, and we may not even know what they are for many years."

For example: A once-common mussel that filtered and cleansed water in the Susquehanna River has been heading toward extinction there for no apparent reason. New research indicates it needed migrating eels to transport its larvae. Dams erected decades ago blocked eels - and mussel reproduction.

Also officially biting the dust: the dusky azure butterfly, obligated to a few small patches of a single plant to host its larvae. It succumbed, probably, to widening and paving a road. The hoary elfin, another butterfly tied to a single plant for habitat, was listed as endangered.

The people in charge of looking after our endangered species don't publish the exact locations of rare and endangered species because of fear that collectors may push them over the edge. In fact, overzealous scientists from Cornell University may have inadvertently contributed to extinction of the Maryland darter, which existed only in one riffle on Deer Creek in Harford County. The state years ago let the scientists collect some of the little fish for research, and they allegedly took dozens. It was the last anyone saw of the darter.

Sometimes a species becomes less endangered simply because scientists start looking harder for it. The sable clubtail dragonfly got an upgrade that way from endangered to "in need of conservation."

Generally, though, dragonflies and damselflies, species that need excellent water quality, didn't fare well in January's new listings: two are now considered threatened, four more endangered, and two extirpated.

The common theme is almost always habitat loss, Ms. Brewer said. Once, that came mainly from clearing for agriculture, but now it's often from development.

Development, along with farm irrigation, can affect habitat indirectly for some of "the rarest of the rare," isolated species of isopods and amphipods, aquatic invertebrates that dwell in tiny spring-fed seeps that may cover only a few square meters of boggy ground.

Storm water runoff and groundwater withdrawals can disrupt the seeps. Three species of isopod and amphipod were added to Maryland's endangered list in January, about the same time the eagle came off the threatened list.

It's not all bad news even for the spring-seep-dependent species. A plant, the long-stalked crowfoot (Ranunculus hederaceus), was discovered again after it was thought to have vanished. It was re-listed as endangered.

Sometimes we act in time to afford protection for the fragiler parts of our ecosystems. Soldiers Delight Natural Environment Area in Baltimore County, an unusual occurrence of serpentine rock barrens, was preserved years ago. It holds the entire world population of the Eastern sedge barren leafhopper, just added to the state endangered list.

Endangered species focus us on the intricate workings of nature. Some need the ultimate stability of old-growth forests, like the red cockaded woodpecker, which only nested in pines so old they had heart rot. It vanished from Maryland when the last old pines were cut 50 years ago. Other species, such as the endangered piping plover, need the opposite, the chaotic and ephemeral Atlantic beach sands, where predators on their eggs are few.

Many endangered species that depend on disrupted habitat are now found mostly along power line rights of way, Ms. Brewer said.

Although the Rock Creek groundwater amphipod and its like will never achieve bald eagle status, protecting them all implies the same things: protecting natural landscapes, clean water, and an environment safe for health.

Tom Horton covered the Chesapeake Bay for 33 years for The Sun and is author of six books about the bay. This article is distributed by Bay Journal News Service.

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