Commentary: Chesapeake film ‘Twilight Estuary’ unravels a mystery

The Chesapeake’s seagrasses were dying, from Havre de Grace, Maryland, to Norfolk, Virginia, up rivers and down. Meadows of underwater vegetation, which nurture crabs and fish, provide oxygen and sequester carbon, had decreased from an estimated half-million acres to around 40,000 by the mid-1980s. No one knew why. But losing an immensely productive ecosystem that had persisted throughout the Chesapeake for thousands of years signaled something ominous.”

The Chesapeake Bay has long inspired notable films, dating at least to 1965, when avid sailor and CBS news icon Walter Cronkite produced “The Sailing Oystermen” aboard the skipjack Ruby Ford with legendary Smith Island Capt. Daniel Harrison and his brother, Edward.

David Harp, Sandy Cannon-Brown and I have made a few films ourselves for the Chesapeake Bay Journal, dealing with more current topics like sea level rise and beavers’ potential to restore water quality.

But if I had to suggest only one film to watch, it might be Michael Fincham’s gem, “Chesapeake: The Twilight Estuary,” which debuted in 1985. It’s an environmental mystery tale, a scientific detective saga, a gripping story finely told, which stands the test of time.

I showed the 40-minute film to seventh graders in the 1980s when I taught at Smith Island for the Chesapeake Bay Foundation. I show it now to most of my college classes at Salisbury University.

Fincham, a prolific science writer, documentary producer and Emmy-winning videographer, scavenged funds from sports videos he did for teams at the University of Maryland and produced it for the university’s Sea Grant College.

The Chesapeake’s seagrasses were dying, from Havre de Grace, Maryland, to Norfolk, Virginia, up rivers and down. Meadows of underwater vegetation, which nurture crabs and fish, provide oxygen and sequester carbon, had decreased from an estimated half-million acres to around 40,000 by the mid-1980s.

No one knew why. But losing an immensely productive ecosystem that had persisted throughout the Chesapeake for thousands of years signaled something ominous.

The film begins in beauty: deep summer, Smith Island, sun rising on graceful crabbing boats that underpin a whole culture, harvesting soft crabs in the grassy shallows where they go to shed their shells.

“We got a gold mine down here,” waterman Denny Bradshaw says to the camera, adding, “long as everybody takes care of everything” — which clearly was not the case.

Was the culprit the thousands of factories and power plants that discharged their wastes into the bay? The scientists quickly rule out these obvious suspects; they have their issues but aren’t causing such widespread decline.

Next up is the “killer” that the scientists are betting on: farm chemicals. Indeed, Fincham said he spent so much of his time and budget on that topic that he had to scramble to film what turned out to be the real answer.

But at the moment, many were convinced it was herbicides, which farmers across the region had been doubling and tripling their use of during the 1970s and ’80s. More weedkillers on the land, running off into the water, coincided seamlessly with the “weeds” (aquatic grasses) dying in the bay.

I wrote an article that led the Baltimore Sun’s front page Aug. 8, 1977, about research indicating herbicides were possibly the problem.

The agriculture industry and its supporters in the University of Maryland’s farm research college were so rattled that they worked to obstruct and deny the research. The interference got bad enough that some of the seagrass scientists said privately that they “really hoped” the gathering evidence would indict big agriculture.

But it didn’t — not the way everyone expected.

Painstaking measurements that looked for farm chemicals running off in high-enough concentrations to kill seagrasses found that, yes, locally, like in a farm drainage ditch after a rainstorm, the stuff was killing off some underwater grasses. But in creeks, seldom. In larger rivers, never. In the bay’s mainstem, not even close. It added stress maybe but no smoking gun.

What remained was sunlight, which all green plants need to grow. In Virginia, a young Bob Orth and Dick Wetzel and, in Maryland, a young Walter Boynton, Michael Kemp and Court Stevenson began developing a new storyline — that the once-clear Chesapeake had become murkier, a twilight estuary.

All those researchers would make distinguished careers on the Chesapeake and beyond. Their new culprit for what was killing the grasses turned out to be all of us, or at least most everything humans did across a huge watershed some 16 times as large as the bay itself.

The problem, they learned, is nutrients: nitrogen and phosphorus from sewage, from farm fertilizers and manure, from developments and from air pollution (though the air’s importance was not understood until later). Also sediment, running from fields and housing developments and clear-cut forests, measurable in tons per acre.

It was all clouding the water, cutting the light that the grasses needed for growth. The coup de grace came from something that cut light even further. And though it was right in front of their eyes, for a while, the scientists didn’t see it.

It was “epiphytic growth,” essentially slime, fueled by excess nutrients, that was coating the leaves of the seagrasses. Fincham recalled: “We were all sitting in a room screening footage that showed extreme epiphytic fouling, (and) not one of us remarked on it or wondered what effect that might have on the grass demise.”

The young scientists, smart as they were, had little experience with the healthy, clean-leaved grasses that had existed decades and centuries before. The fouling looked normal. A lowly grad student, Ken Staver, finally drew attention to it.

The scientists featured in “The Twilight Estuary” did their jobs well. Society has done its job of controlling nutrients and sediment less well. The bay grasses have rebounded to about 70,000 to 108,000 acres, varying year to year, but further progress seems stalled.

Other factors like climate change, scarcely an issue in the 1980s, are complicating the situation now. I’m talking with Fincham and others about an update film on the grasses.

But “Chesapeake: The Twilight Estuary” remains a classic primer on how the Chesapeake ecosystem works and on the importance of science — science pursued baywide — for restoring this estuary.

Tom Horton, a Chesapeake Bay Journal columnist, has written many articles and books about the Chesapeake Bay. He currently teaches writing and environmental topics at Salisbury University. This was first published by Bay Journal.

Editor’s note: Maryland Sea Grant has made “Chesapeake: The Twilight Estuary” available free via YouTube through the end of 2021. Watch it here.