Protecting a National Treasure: The Chesapeake Bay (Part I – the Situation)

LONG AGO, it was simply the mouth of the Susquehanna River. Now the Chesapeake Bay is over 200 miles long and 35 miles wide at its widest point. Relatively shallow – only 21 feet deep, on average – the Bay is America’s largest estuary, where saltwater mixes with fresh water and nutrients from wetlands, shorelines, and over 150 rivers and streams to create one of Mother Nature’s most productive “protein factories” – producing fish at over one hundred times the rate of a comparable body of ocean.

About 2,700 species of plants and animals, including 200 species of fish, live in the Chesapeake Bay, while over 17 million people reside in, and millions more visit, its 64,000 square mile watershed, which includes six states and the District of Colombia. Comprehensive studies of the Chesapeake Bay gauge its economic worth at well over $1 trillion in terms of what it contributes to fishing, hunting, boating, tourism, recreational industries, property values, and shipping.

Since the 1980’s, however, the Bay’s productive capacity has been in tumult:

OUR TOP FIVE CONCERNS:

1) Bay Grasses

Grass beds are perhaps the Bay ecosystem’s most critical component. They pump essential oxygen into the water, trap sediment, become food for waterfowl, and provide shelter for small fish and young blue crabs (especially while they’re molting their shells).

Before 1950, the Chesapeake Bay contained about 185,000 acres of grasses. Aerial survey data from 2012 however showed only 48,191 acres of sub-aquatic vegetation (SAV). Scientists blame SAV losses on the lingering effects of 2011’s Tropical Storm Lee, which buried the Upper Bay with sediment, and the longer term, more general decline in the Bay’s water clarity. SAV can only survive in water that’s clear enough for sunlight to shine through it.

2) Oysters

Appreciated for dutifully filtering Bay water around the clock, oysters were also once the Bay's most valuable commercial fishery. Over-harvesting, outbreaks of the oyster diseases MSX and Dermo, excessive sedimentation, and periods of poor water quality however steadily decimated their numbers… Virginia’s commercial oyster industry shrunk by over $2 billion.  Bay-wide, the oyster population has fallen to less than 1% of historic levels.

3.) Shad

Since colonial times, people have valued shad for its delicious meat and eggs (called roe). Between 1831 and 1850, fishermen caught about 41,000 metric tons of shad each year. By the 1970’s, their annual catch was less than 1,000 tons. Historic overfishing and the construction of river dams that block upstream spawning runs led to shad’s demise. Maryland closed its commercial shad fishery in 1980...Virginia followed suit in 1994.

Shad spend three to five years in the ocean as adults before returning to the Bay’s rivers and streams to spawn. Spring shad spawning runs were once a major food source for many species, including bald eagles, ospreys, rockfish, bluefish, catfish, minnows and blue crabs. Without these ocean-derived shad providing food for predators, the Bay ecosystem is diminished and unbalanced.

4.) Blue Crabs

In 1993, the Chesapeake’s crab population was 852 million. It fell to just 283 million in 2008, which led to stricter controls on the harvesting of female crabs. By 2012, it had returned to 764 million.

Having enough female blue crabs is important because the average one produces over 8 million eggs over the course of her lifetime. And here’s the Wildcard in all of this:  they always lay their eggs near the mouth of the Bay, where tides and currents flush most of their larvae out into the open ocean… Later, the “chosen ones” catch prevailing winds to drift back “home” into the Bay. So part of the answer to the dramatic annual ups and downs of annual crab numbers is literally “blowin’ in the wind.”

5.) Rockfish

Rockfish — also known as striped bass or stripers — has always been one of the most sought-after commercial and recreational fish in the Chesapeake Bay. In 1973, fishermen landed 14.7 million pounds of stripers; but by 1983, their harvest had fallen to just 1.7 million pounds. Fishing moratoria ensued, and by 1995, the population increased to the point where striped bass was considered restored. Catches have been stable ever since, but scientists remain concerned about growing numbers of rockfish with mycobacterial lesions, and the localized overfishing of their meal of choice – Menhaden.

OUR TOP THREE CULPRITS:  Nitrogen, Phosphorus, and Sediment

High concentrations of Nitrogen (N) and Phosphorus (P) degrade Bay water quality by stimulating algal and plant growth beyond naturally sustainable levels. Densely woven algae and sediment (Sd) become a deadly combination for SAV by blocking its access to sunlight.

And when algal blooms die, their decomposition consumes dissolved oxygen that fish, crabs, and oysters need for breathing. “Dead zones” form characterized by large areas of fish and crab kills, surface scum, and foul odors. Adding insult to injury, resulting anoxic conditions cause phosphorus previously trapped in sediment to break free and – eventually – circulate to more oxygenated waters … which creates new algal blooms … which soon die … which expands the dead zones … which releases new phosphorus … and so on and so on.

Besides bringing in extra phosphorus, sediment inflows hamper Bay productivity more generally by making the water cloudy and burying the Bay floor in mud. Mud smothers bay grasses and makes it very difficult or impossible for oysters to filter feed. It also robs their newborn “spat” of the hard shells or shell-like surfaces they must latch onto to survive and grow....

Toxins, disease, and poor fisheries management play important roles too.  Ultimately, every contributing factor is important because the Chesapeake Bay is an advanced ecosystem: a decline (or improvement) in any one Bay component usually leads to ripple effect declines (or improvements) in its other components….

Point Source Polluters (N, P)

·  Wastewater treatment plants (WWTPs)

·  Concentrated animal feeding operations (CAFOs)

Non-Point Source Polluters (N, P, Sd)

·   Agricultural runoff, seepage, and erosion

·   Untreated stormwater runoff, non-agricultural erosion

·   Septic systems leakage and seepage

Pollution percentages (2009) by State (N, P, Sd)

·   Virginia (27%, 43%, 41%)

·   Pennsylvania (44%, 24%, 32%)

·   Maryland (20%, 20%, 17%)

·   New York (4%, 5%, 4%)

·   Delaware (2%, 2%, 1%)

·   West Virginia (2%, 5%, 5%)

·   District of Columbia (1%, 1%, <1%)