In many ways, 2002 was a year that offered a glimpse of what a restored Chesapeake Bay might look like.
Algae blooms were scarce. Its oxygen- depleted “dead zone” shrunk in size. And grass beds appear to have continued the expansion begun last year.
“In a way,” Maryland Department of Natural Resources Secretary Chuck Fox said recently, “this is what we are trying to achieve.”
But he and many others acknowledge that this year’s Bay was more the result of intervention by Mother Nature than by human actions.
Without heavy rains to flush nutrients off the land and into the Bay where they cause water quality problems, fertilizers stayed in the soil throughout the watershed.
Last year was the driest year on record since 1941, and — through September — this year’s river flows in the Chesapeake were even lower, according to figures from the U.S. Geological Survey.
Average freshwater flow into the Bay during the first nine months of 2001 was 58,400 cubic feet per second; this year it was 51,300 cfs. River flows into the Chesapeake were below average every month except May, according to the USGS. Average streamflow this year for the Potomac, the Bay’s second largest tributary, was the lowest since record-keeping began in 1930.
Throughout the region, streams and groundwater levels were at or near all-time lows, according to the USGS.
The result was not only reduced runoff, but increased salinities in the Chesapeake — including record high salinities in many areas of the Bay and its tidal tributaries.
That was a mixed bag for the Bay: Underwater grasses have been rebounding, but oysters are more hard hit by disease. Saltwater fish moved up the Bay, adding excitement for anglers, but low flows contributed to poor reproduction for striped bass and a number of other freshwater spawning species.
And one concern looms for future years: This year’s drought could contribute to increased nutrients entering the Bay in coming years.
The drought held back the growth of corn and other major crops, causing economic disasters in some places. U.S. Department of Agriculture figures from September predicted that corn production in the region was expected to be down 41 percent from last year and down 47 percent from 2000. Soybean production was forecast to be down 47 percent from last year and 52 percent from the year before.
That’s bad news for the Bay. Because the crops were not growing, they were not using fertilizer that had been applied in the spring, said Tom Simpson, of the University of Maryland’s College of Agriculture and Natural Resources.
“One of our problems is that we apply fertilizer as if we are going to get a good yield every year,” he said. “So when we only get a portion of a typical yield, we have all that extra fertilizer out there.”
That unused fertilizer either runs off, or enters the groundwater. Either way, it will increase nutrients going into the Bay in coming years. “The drought makes everything look pretty in the Bay,” Simpson said, “but it stores up a slug of stuff to come down later.”
Peter Bergstrom, a biologist with the U.S. Fish and Wildlife Service, began noticing the effects this spring when he began taking water quality samples in Maryland’s Magothy River.
“The nitrate in the Magothy was so low in April that I actually contacted the lab,” he said. “They reran the samples for me, but they were still low. And apparently they were low all over the Bay.”
Normally, April nitrate levels are high because terrestrial plants have not yet begun to grow and draw the nutrients out of the ground. This year, there just wasn’t much flow to wash them into the Bay.
In the mainstem of the Bay, fewer nutrients translated into fewer blooms of water-clouding algae.
“Definitely, we’ve see less overall algal blooms and specifically fewer dinoflagellate [a free-swimming type of phytoplankton] blooms this year,” said Harold Marshall, a phytoplankton expert at Old Dominion University who has monitored swings in the Bay’s algae population for years.
“This might well be related to the reduced entry of nutrients coming into the system because of the reduced rainfall and surface drainage,” he said.
Less algae, coupled with reduced river flows, also helped to reduce the oxygen-depleted dead zone in the Bay.
In typical years, strong river flows create a barrier between the upper, fresher layer of the Bay and the lower, saltier layer. That barrier helps to keep top and bottom layers from mixing.
When that happens, and algae blooms are plentiful, dead and dying algae sink to the bottom and are consumed by bacteria in a process that consumes oxygen in the water. When the Bay is strongly stratified, the lower layer cannot be replenished with oxygen from the water directly above. The result is a zone with little or no oxygen where fish and many other species cannot survive, or are greatly stressed.
In most years, that results in about 40 percent of the Bay’s water having reduced levels of oxygen — and the deepest areas having none at all. But preliminary information suggests that the Chesapeake will have one of its better years for dissolved oxygen in recent decades. That’s good news not only for fish, but also for the benthic organisms that live on the bottom — and are an important food source for other species — which cannot move.
Less algae also meant more sunlight for underwater grass beds. Biologists believe the surge of underwater grasses that began last year has continued this year. “I think we will set another record for 2002,” said Mike Naylor, a biologist with the Maryland Department of Natural Resources and chair of the Bay Program’s Submerged Aquatic Vegetation Workgroup.
One drawback, though, is that reduced freshwater river flows have sent salinities to record highs in many parts of the Bay. In some places, such as parts of the Potomac, that has caused a die-back of freshwater underwater grass species, said Bob Orth, of the Virginia Institute of Marine Science, who oversees the Bay Program’s annual underwater grass survey. In other areas, such as the Chester River, he said high salinities may be hindering the rebound of grass beds.
The high salinities brought mixed news for the Bay’s oysters. Anecdotal reports in both Virginia and Maryland suggest spat counts — measures of oyster larvae that successfully attach to solid substrates — may have been better than normal this year.
The bad news is that the diseases MSX and Dermo, which have devastated the Bay’s oyster population, thrive in high salinities. Although fall surveys are not complete, “disease is very bad this year,” said Steve Jordan, director of the Oxford Cooperative Laboratory in Maryland. “I don’t have any numbers, but I think it is pretty clear it is not going to be a good year.”
Not only are disease levels high, but Maryland has had poor oyster reproduction since 1997, Jordan said. In the past, when severe disease outbreaks caused big increases in adult mortality, there were plenty of small oysters from previous years left to grow and take their place.
“In earlier years, when we had these terrible disease outbreaks, we had a lot of small oysters, so there was something coming behind,” Jordan said. “When conditions faded a little bit, you could see some growth in the population.”
Low flows and higher salinities also resulted in poor reproduction for striped bass and most other anadromous species — those that spend most of their lives in the oceans but return to freshwater to spawn.
Virginia’s striped bass index was 4, its third lowest since the Virginia Institute of Marine Science started keeping track in 1965. The long-term average is 6.8. Maryland’s striped bass index was 4.7, below the long-term average of 11.6.
The indices are the average number of juvenile fish caught in 100-foot seine nets during standard surveys.
Herb Austin, a fisheries scientist with VIMS, said the higher salinities resulting from low flows compresses the available freshwater spawning habitat for striped bass and other anadromous spawners.
The low flows also tend to affect the timing and abundance of zooplankton that striped bass larvae eat, he said.
“In a dry year, there is a lot of starvation.” In addition, Austin said, the fact that the larvae and young fish are constricted in a small area is likely to increase their vulnerability to predators.
Besides striped bass, poor survival was reported for shad and river herring in many, but not all, areas. The Potomac, by contrast, reported near-record juvenile shad production.
But yellow perch, which have been the target of restoration efforts in Maryland, were squeezed into small spawning areas in many tributaries this year. “We found them spawning in relatively high salinities of eight or nine parts per thousand,” said Harley Speir, a DNR fisheries biologist. “That just is not going to work. They probably are not going to survive.”
Both Austin and Speir said blue crabs were reported much farther up tributaries than typically seen.
Austin said the low flows may be good news for blue crab reproduction. Females spawn near the mouth of the Bay, after which larvae float out onto the coastal ocean before returning to the Chesapeake. The low flows could result in more larvae staying close to the Bay’s mouth, allowing more post-larvae to return to the Bay later on, Austin said.
On the other hand, he said adult females with egg masses were observed much farther up the Bay than usual — some as far north as the Bay Bridge in Maryland. He said it’s unlikely such far-flung crabs will successfully make it back to the mouth of the Bay to spawn.
High salinities also meant a greater number of unusual fish, especially saltwater species, showing up in Maryland’s portion of the Bay. Speir said he got many reports of seahorses in crab pots, especially in the Eastern Bay and South River.
With reports of the nonnative snakehead in the news, people began mistaking some of saltwater species rarely seen in upper parts of the Bay for exotic species.
Seaweed blennies and striped blennies, were seen “way up the Bay” with sightings reported in the Magothy and Patapsco rivers, Speir said. Likewise, the inshore lizard fish — a long-finned, toothy saltwater species — turned up in many places. So many people thought the fish were snakeheads, the DNR began posting pictures on its web site so people could tell the difference.
The saltwater red drum was found in good numbers as far up the Bay as Pooles Island. Maryland even reported a “fair flounder fishery this year,” Speir said.
The drought also impacted aquatic life in streams throughout the watershed. Biologists never stocked trout in a number of streams throughout the region because of low flows.
In Maryland, a survey of 26 “sentinel site” streams — places with minimal human impacts — showed that three went “bone dry” during the summer, and another five had no flows and were only standing pools, said Paul Kazyak, who oversees stream monitoring for the DNR.
Normally, Kazyak said, it is difficult to find dead fish in streams because they are quickly eaten by crayfish or raccoons. But in surveys this year, he said many dead fish were seen. “There were so many fish, apparently the raccoons couldn't eat them all,” he said.
Two Maryland streams got so dry they wiped out native brook trout populations.
Low flows caused streams to pull away from the vegetated riparian zones that normally serve as a buffer between streams and upland areas. “This is the first time I saw mature hardwood trees with droopy leaves in riparian areas,” Kazyak said.
It’s too early to tell how quickly the streams will recover from the drought impact, he added. Already, Kazyak said, he was surprised at how hard it has been to find the blacknose dace — the state’s most common fish — returning to hard-hit streams.
Exactly how long it takes for the region to return to “normal” is unclear. The National Weather Service was predicting below normal precipitation through the fall, and normal precipitation for the winter. But with groundwater running far below normal, streamflows are likely to remain depressed for a while, according to the USGS.
But then, what’s normal is really a matter of perspective.
Over the long term, such ebbs and flows — and their impacts on species in the Bay — are the norm, rather than the exception, Speir noted.
“Most of us who have been around Chesapeake Bay fisheries for a while just accept this,” he said. “The average is really a huge range of population distributions. There is some predictability to it, so it’s not startling. It is just part of the pattern.”