When cold weather arrives, blue crabs up and down the Chesapeake Bay stop their scurrying. The summertime rush of food-hunting and mate-finding is over, and the crustaceans will spend the winter months buried in sand and sediment. It is at this moment that researchers in Maryland and Virginia must strike: to count the crabs while they are still.
Known as the winter dredge survey, this annual count of the Bay’s blue crab population is a critical part of blue crab management. Without an accurate estimate of blue crab abundance, fisheries managers cannot set harvest limits for the season ahead.
“The winter dredge survey is the most vital tool that we have in crab management,” said Chris Walstrum, a natural resources biologist with the Maryland Department of Natural Resources (DNR). “This is the best chance we have to assess the [blue crab] population, because the crabs are stationary.”
Walstrum and his team are responsible for counting crabs in Maryland waters; the Virginia Institute of Marine Science (VIMS) conducts the winter dredge survey in the Virginia portion of the Bay. Between the two agencies, a total of 1,500 Bay sites are visited over the course of three and a half months before the numbers are crunched and fisheries managers can make recommendations on how blue crab harvests should or shouldn’t change.
On a warmer-than-normal January morning, Walstrum is aboard a boat in Broad Creek, a tributary of the Choptank River on Maryland’s Eastern Shore. The DNR vessel has been captained for more than a decade by Roger Morris, a fifth-generation waterman who used to dredge for crabs commercially and whose skills are invaluable to the success of the survey.
“Whether people like it or not, the winter dredge survey is the whole basis for our [blue crab harvest] limits,” Morris said. “That’s why I try to do the best I can do at it. It takes experience. You just can’t walk on a crab dredge boat and expect to catch crabs.”
At each survey site—six of them in this particular waterway—Morris will line up his boat and drop its so-called Virginia crab dredge into the water. The metal dredge is towed along the bottom for one minute before it is hoisted back on board, where the newly caught contents of its mesh liner are dumped out and sorted through. In each catch, there are brown leaves, oyster shells, little fish and, more often than not, a collection of blue crabs.
Each crab is weighed, measured and sexed before it is tossed back into the water. This provides an accurate picture of the blue crab population, as researchers track the number of young crabs that will form the backbone of the fishery next fall and the number of females that will produce the next generation of blue crab stock.
“The winter dredge survey provides us with a cornerstone piece of data from which to operate our [blue crab] management,” said Brenda Davis, chief of the DNR Blue Crab Program.
“It’s a long-running survey, and it’s been consistently accurate,” Davis said. “It gives us a good, static picture of the number of crabs in the Bay.”
Video produced by Steve Droter.
Close to 15,000 acres of underwater grasses have disappeared from the Chesapeake Bay.
While robust grass beds on the Susquehanna Flats and expanding beds in the James River offer two examples of the Bay’s resilience, an aerial survey conducted by the Virginia Institute of Marine Science (VIMS) showed a 21 percent decline in the Bay’s grasses in 2012. This so-called “alarming” loss—from just over 63,000 acres in 2011 to just over 48,000 in 2012—approaches lows last reported in 1986.
In a report released this week, Chesapeake Bay Program scientists attributed last year's decline in grass beds to warmer-than-normal water temperatures seen in 2010 and strong storms seen in the fall of 2011. The former "cooked" grasses in the Lower Bay, while the latter pushed excess sediment into rivers and streams, clouding the water and creating unfavorable growing conditions for aquatic plants in the Upper and Middle Bay.
These strong storms and episodes of heat stress have occurred alongside a widespread decline in water clarity, said Bob Orth, coordinator of the VIMS Submerged Aquatic Vegetation Survey. While Orth remains "concerned" over the decline in bay grasses, he noted that favorable growing conditions in the future could lead to quick signs of recovery in a species that is fast to respond to water quality changes—both good and bad.
"The best thing we can do [for bay grasses] is to improve water quality," said Lee Karrh, a biologist with the Maryland Department of Natural Resources (DNR) and chair of the Bay Program's Submerged Aquatic Vegetation Workgroup. "If you improve water quality and reduce chronic problems, then the Bay should be able to deal with episodic events easier than it has been able to in the past."
Underwater grasses—also known as submerged aquatic vegetation or SAV—are critical to the Bay ecosystem, offering food and habitat to countless critters while absorbing nutrients, trapping sediment and reducing shoreline erosion. The Bay Program uses underwater grass abundance as an indicator of Bay health, and has this week released a data visualization tool that allows users to track changes in grass abundance over time, as dominant species ebb and flow and grass beds shrink and expand.
Read more about the 2012 Distribution of Submerged Aquatic Vegetation in the Chesapeake Bay.
Owning and maintaining waterfront property can be an expensive commitment. Residents across the Chesapeake Bay watershed must contend with shoreline erosion and rising sea level, while adapting to environmental regulations that protect water quality. One strategy for tackling all of these issues has gained increasing popularity: living shorelines that not only protect human property, but also utilize and even enhance the Bay’s unique natural habitat.
Scott Hardaway and Karen Duhring are marine scientists and living shoreline experts at the Virginia Institute of Marine Science (VIMS), which sits at the mouth of the York River in Gloucester Point, Va.
Scott Hardaway began working for VIMS in 1979, and is now the director of the Shoreline Studies Program. He is a leading authority on the design and implementation of “headland breakwaters,” a living shoreline technique that creates protected “pocket beaches” like those constructed at VIMS in 2010.
Headland breakwater systems are built using large stone structures called “headlands,” which sit offshore and disrupt the incoming waves that can cause shoreline erosion. Mathematical formulas determine the necessary angle, shape and placement of each headland. Wider gaps between breakwaters create long, narrow pocket beaches, while narrow gaps create wide, circular beaches.
Their wave-blocking action creates a calm, shallow lagoon between the breakwaters, which are connected to shore by a sandbar called a “tombolo.”
Additional sand must be brought in to form the tombolo and stabilize the beach. This raises the cost of these projects, but is critical to the final phase of construction: planting native beach and dune vegetation.
Karen Duhring is an educator and researcher at the VIMS Center for Coastal Resources Management (CCRM), where she helps manage and monitor living shoreline projects.
According to Duhring, on-shore plantings serve key ecological functions that enhance the effectiveness of living shorelines. On sandy beaches, plant roots stabilize loose material and improve water quality, as they filter pollutants from upland runoff.
Living shorelines use native plants—smooth and saltmeadow cordgrass here in the Bay—that have adapted to thrive and reproduce in a specific environment. Once established, cordgrass recruits naturally along the beach, dispersing seeds and rhizomes that spread horizontally beneath the sand to establish new plants in empty areas.
Beach plantings are susceptible to damage from foot traffic, so precautions should be taken to prevent the trampling of plants. Access restrictions allowed for more expensive plantings on the VIMS western shore, while heavy use from research activities limited plantings on the other.
During high tides, organic material washes onto the beach and provides nutrients for the growing plants, which in turn provide habitat and food for native wildlife.
Headland breakwaters themselves also provide habitat for crabs, mollusks and other aquatic species that thrive on underwater reefs. Along the VIMS shoreline, oysters have settled on the granite rocks to form the beginnings of a complex reef community.
According to Hardaway, headland breakwaters are not always the perfect solution for every sandy shoreline. Whenever possible, existing habitat for submerged aquatic vegetation and shellfish should remain undisturbed. While the costly structures do come with some tradeoffs, they also offer invaluable protection for human infrastructure. The once-vulnerable VIMS shoreline, for instance, has withstood Hurricanes Irene and Sandy—thanks to its headland breakwaters.
As the living shorelines at VIMS demonstrate, projects such as these—which successfully address the needs of both humans and nature—are critical to Bay restoration. Through the work of experts like Hardaway and Duhring, these living shorelines continue to serve both practical and educational purposes, teaching the public how we can responsibly manage our natural resources today in order to preserve them long into the future.
View full-resolution photos on the Chesapeake Bay Program Flickr page.
A recent assessment of Superstorm Sandy shows the hurricane did less damage to the Chesapeake Bay than some feared, thanks in large part to its timing and track.
According to a University of Maryland report, the late-October hurricane whose path traveled north of the Bay had “ephemeral” impacts on Bay water quality—especially when compared to past storms.
The summertime arrival of Tropical Storm Agnes in 1972, for instance, coincided with a critical growing period for oysters, crabs and underwater grasses, and had a damaging effect on all three. But because Sandy arrived in the fall, the nutrients and sediment that it sent into the Bay were unable to fuel harmful algae blooms or damage the underwater grasses that had already begun to die back for the season. And while Tropical Storm Lee in 2011 brought heavy rainfall and a large plume of sediment to the Susquehanna River, the bulk of Sandy’s rainfall was concentrated elsewhere, meaning minimal scouring of sediment from behind the Conowingo Dam and “virtually no sediment plume” in the Upper Bay.
These findings echo those released in November by the National Oceanic and Atmospheric Administration (NOAA) and the U.S. Geological Survey (USGS).
Read more about the ecological impacts of Sandy on the Chesapeake Bay.
An unusual sequence of weather events, including a wet spring, a hot, dry summer, and two tropical storms, caused the Chesapeake Bay’s health to decline in 2011, according to the University of Maryland Center for Environmental Science (UMCES) and the National Oceanic and Atmospheric Administration (NOAA).
(Image courtesy Chesapeake EcoCheck)
Scientists gave the Bay a D+ on the latest Chesapeake Bay Report Card, an annual assessment of the health of the Bay and its tidal rivers. The score of 38 percent was the second lowest since assessments began in 1986 and down from a C- in 2010.
Only two areas – the lower western shore and the Patapsco and Back rivers – improved last year. The rest of the Bay’s segments remained the same or got worse. Scientists recorded lower scores in the Patuxent River, Rappahannock River, James River, Tangier Sound, and the upper and middle Bay.
"The spring rains and hot, dry summer followed by Tropical Storm Lee and Hurricane Lee led to poor health throughout Chesapeake Bay and its tributaries," said Dr. Bill Dennison of the University of Maryland Center for Environmental Science. "While we have been making considerable progress in various restoration activities, these results indicate we still need to do much more to reduce the input of nutrients and sediments from stormwater runoff into the Bay."
The Bay’s health is largely affected by weather conditions. Rainfall carries pollution from farms, cities and suburbs to storm drains, streams and eventually the Bay. Even as the government, communities and citizens work to reduce pollution, an increase in stormwater runoff can mask the effects of these improvements.
Wet weather last spring washed more nutrient pollution into the water, fueling the growth of algae blooms that blocked sunlight from reaching bay grasses. Hot, dry weather allowed these algae blooms to persist through summer, leading to low-oxygen “dead zones” in the Bay’s bottom waters. In late summer, the Bay was slammed by the effects of Hurricane Irene and Tropical Storm Lee, both of which worsened water clarity.
"The report card clearly indicates that the Chesapeake Bay watershed is a dynamic ecosystem subject to severe weather events," said Bay Program Director Nick DiPasquale. “The silver lining is that the Hopkins-UMCES study of 60 years of water quality data concluded that a decrease in the frequency and severity of dead zones in the Bay is the direct result of implementing measures to reduce nitrogen and phosphorus pollution. We know what works; we just need to do more of it."
The Chesapeake Bay Report Card, produced by the EcoCheck partnership, offers a timely and geographically detailed assessment of the health of the Bay’s water quality and aquatic life. Visit EcoCheck’s website for more information about the report card, including region-specific data and downloadable graphics.
Fewer acres of bay grasses grew in the shallows of the Chesapeake Bay and its tidal rivers in 2011, according to scientists with the Chesapeake Bay Program. Bay grass acreage fell to an estimated 63,074 acres in 2011, down from 79,664 acres in 2010. This is the lowest Bay-wide acreage measured since 2006.
Because of heavy rainstorms that led to cloudy, muddy conditions that blocked monitoring efforts, only 57,956 acres of bay grasses were actually mapped in 2011. However, scientists believe about 5,119 acres of bay grasses may have been present during the height of the growing season, leading to the final estimated Bay-wide figure of 63,074 acres.
Bay grasses – also known as submerged aquatic vegetation or SAV – are a critical part of the Bay ecosystem. These underwater meadows provide fish, crabs and other aquatic life with food and habitat, absorb nutrients, trap sediment, reduce erosion, and add oxygen to the water. Bay grasses are also an excellent measure of the Bay's overall condition because their health is closely linked with the Bay’s health.
“2011 was the year that bucked two trends we’ve seen over the last decade,” said Lee Karrh, chair of the Bay Program’s Submerged Aquatic Vegetation (SAV) Workgroup. “The Upper Bay had major decreases after years of increasing or sustained high acreages. On the other hand, the brackish parts of the Middle Bay witnessed dramatic increases in 2011, after prolonged decreases since the turn of the century.”
Experts agree that extreme weather conditions in 2010 and 2011 led to the substantial decrease in bay grasses. According to Bob Orth, scientist with the Virginia Institute of Marine Science (VIMS) and coordinator of the annual bay grass survey:
In the upper Bay (from the mouth of the Susquehanna River to the Chesapeake Bay Bridge), bay grasses covered approximately 13,287 acres, down from 21,353 acres in 2010. This is most likely an underestimate because scientists did not monitor the area until November, once muddy conditions improved but well past the end of the growing season. One bright spot in the upper Bay was the more than doubling of bay grass acreage in the Chester River and near Eastern Neck.
In the middle Bay (from the Bay Bridge to Pocomoke Sound and the Potomac River), bay grasses decreased 4 percent to an estimated 34,142 acres, down from 35,446 acres in 2010. (Only 29,023 acres were mapped, but scientists estimate that an additional 5,119 acres may have been present.) Large eelgrass losses were observed in Tangier Sound. These were offset by widgeon grass gains in many areas, including Eastern Bay and the Choptank River.
In the lower Bay (south of Pocomoke Sound and the Potomac River), bay grasses covered 15,645 acres, down 32 percent from 22,685 acres in 2010. Hot summer temperatures in 2010 led to this significant drop in acreage, which offset any gains that followed in 2011. Eelgrass in many parts of the lower Bay had been recovering from similar heat-related losses that took place in 2005.
Despite Bay-wide losses, there were a few bits of good news for bay grasses last year. The huge, dense bed on the Susquehanna Flats – which has increased threefold in size over the past 20 years – survived the late summer tropical storms, showing how resilient healthy bay grass beds can be to natural disturbances. Also, scientists recorded the first-ever bay grass bed in the mainstem James River since the area was first surveyed in 1998.
Annual bay grass acreage is estimated through an aerial survey, which is conducted from late spring to early autumn. Residents can do their part to help restore bay grasses by not fertilizing in the spring and planting more plants to reduce polluted runoff from backyards.
For detailed information about 2011 bay grasses acreage, including aerial photos and year-to-year comparisons, visit VIMS' SAV blog. For more information about the aerial survey and bay grass monitoring efforts, visit VIMS’ SAV website.
The return of ospreys whistling through the air is a surefire sign of spring in the Chesapeake Bay region. But even those who can’t make it to the Bay’s shores can enjoy a glimpse of this remarkable raptor through online osprey cams at Blackwater National Wildlife Refuge and the Virginia Institute of Marine Science (VIMS).
The Blackwater osprey cam is located on an osprey platform in a marsh on the wildlife refuge’s grounds in Dorchester County, Maryland. The VIMS osprey cam is trained on a nest at the top of a water tower on the school’s campus in Gloucester Point, Virginia.
The two osprey cams provide real-time views of osprey pairs during their annual nesting and breeding season in the Chesapeake region. Both osprey cams include a blog, where you can view photos and journal entries chronicling the lives and milestones of each osprey family.
Want to learn more about ospreys? Visit our osprey page in our Chesapeake Bay Field Guide.
Though the final figures on the overall health of the Bay’s underwater grasses won’t be available for a few months, in late November, scientists with the Chesapeake Bay Program’s (CBP’s) team that monitors the abundance of the Bay’s grasses had a pleasant surprise. Aerial survey images of the vast grass-filled Susquehanna Flats, the circular area where the Susquehanna River meets the Bay, were not pictures of devastation as was feared, but pictures of health, showing that these valuable Bay habitats survived the fall’s deluge of runoff and sediment better than expected.
During Hurricane Irene and Tropical Storm Lee, experts out monitoring the effects of these storms noted large tangles of all varieties of uprooted Bay grasses floating downstream. Based on these visual accounts and their knowledge of the devastation that events such as Tropical Storm Agnes wrought on the Bay’s grass beds almost forty years ago, hopes among scientists were not high for these habitats, which are a critical food source for over-wintering waterfowl at this time of year and that are vital as shelter for juvenile Bay creatures in the spring.
“We were incredibly surprised at how much of the grass bed remained on the Flats,” says Robert Orth of Virginia Institute of Marine Sciences (VIMS) and leader of the team that conducts the annual survey of Bay grasses. “While we did see some declines along the flanks and edges of that big bed, my gut feeling says next year should be ok for grass beds up there. And the fact that we are now seeing overwintering waterfowl in our photographs is a good sign that lots of food is available.”
CBP’s Associate Director for Science Rich Batiuk commented, “Back on those days of Tropical Storm Lee, looking at the deluge of water over the Conowingo Dam, I would’ve bet that we had lost the Flats grasses entirely. Their survival is a good example of how large, dense beds can survive extreme conditions and another indicator of the Bay’s resilience.”
Compare the underwater grass beds on the Susquehanna Flats in VIMS aerial photographs in 2010 and 2011 at http://thumper-web.vims.edu/bio/sav/wordpress/archives/1458
A new study analyzing 60 years of water quality data shows that efforts to reduce pollution from fertilizer, animal waste and other sources appear to be helping the Chesapeake Bay’s health improve.
The study, published in the Nov. 2011 issue of Estuaries and Coasts, was conducted by researchers from The Johns Hopkins University and the University of Maryland Center for Environmental Science (UMCES).
The research team found that the size of mid- to late-summer low oxygen areas, called “dead zones,” leveled off in the Bay’s deep channels during the 1980s and has been declining ever since. This is the same time that the Bay Program formed and federal and state agencies set the Bay’s first numeric pollution reduction goals.
“This study shows that our regional efforts to limit nutrient pollution may be producing results,” said Don Boesch, president of the University of Maryland Center for Environmental Science. “Continuing nutrient reduction remains critically important for achieving bay restoration goals.”
The study also found that the duration of the dead zone – how long it persists each summer – is closely linked to the amount of nutrient pollution entering the Bay each year.
For more information about the dead zone study, visit UMCES’s website.
A new study by researchers with the University of Maryland Center for Environmental Science recommends that Maryland place a moratorium on commercial oyster harvest from the Chesapeake Bay.
According to the study, Maryland’s oyster population is only 0.3 percent of what it was at its peak in the late 1800s. The population decline is due to a number of factors, including disease, pollution and overfishing.
Scientists with the U.S. Geological Survey (USGS) measured a near-record flow of 775,000 cubic feet per second (CFS) at Conowingo Dam on the Susquehanna River on the morning of Friday, Sept. 9. The river is expected to reach the third-highest flow in history this weekend, ranking behind the June 1972 flow of 1,130,000 cfs and the January 1996 flow of 909,000 cfs.
2011 will most likely be one of the highest annual flow years on record for the Susquehanna River due to wet spring weather and the September tropical storms Irene and Lee. High river flows are also being measured throughout other parts of the Bay watershed. (Visit the USGS’s real-time streamflow website for more information about the region’s river flows.)
Scientists expect that the sheer magnitude of the flood waters – which carry nutrient and sediment pollution from the land to the water – will have a negative effect on the Bay’s health. Some concerns and potential effects of the flooding include:
Timing makes a big difference in whether flood events have a short-term or long-term effect on the Bay’s health. Because these storms occurred in late summer, the Bay Program expects that there will be fewer long term impacts to the Bay ecosystem. September is the end of the peak growing season for bay grasses and is not a major spawning period for aquatic life. Additionally, cooler temperatures should prevent large algae blooms from growing in response to excess nutrient pollution.
It will take time for Bay Program partners to monitor and assess conditions before the true impact of the rain events is known. Maryland and Virginia are working closely with scientists from universities, the U.S. EPA and NOAA to expand monitoring of the Bay and its tidal rivers in the coming days and weeks. The USGS is working with the six Bay states, the District of Columbia and the Susquehanna River Basin Commission to measure nutrient and sediment pollution at key monitoring sites as part of the Bay Program’s non-tidal water quality monitoring network.
Scientists with the Virginia Institute of Marine Science and other Bay Program partners have released a mid-year update on bay grass monitoring in the Chesapeake Bay.
Some highlights of the mid-year monitoring update include:
The full results of the Bay Program’s annual bay grass monitoring will be released next spring.
Visit VIMS’s website to learn more about bay grass monitoring.
The early summer dissolved oxygen forecast (called an “anoxia forecast”) is based on nitrogen loads to the Bay during winter and spring, as well as high river flow in May due to heavy rainfall. According to scientists, the Bay’s 2011 low-oxygen area – commonly called the “dead zone” – could be the fourth-largest since 1985.
The annual summer ecological forecast uses data such as nitrogen loads, wind direction and sea level to predict dissolved oxygen levels in the Bay’s mainstem. The forecast is split into early summer (June to mid-July) and late summer (mid-July to September) because scientists have observed a significant change in oxygen levels following early summer wind events.
The forecast is supported through research at the Chesapeake Bay Program, Johns Hopkins University, Old Dominion University, and the University of Maryland Center for Environmental Science Horn Point Lab.
For more information about the dissolved oxygen forecast, visit Chesapeake Eco-Check’s website.
The Chesapeake Bay has received a C-minus on the University of Maryland Center for Environmental Science’s (UMCES) 2010 Bay Health Report Card. The 2010 grade is a 4 percent decrease from 2009, when the Bay’s health received a C.
Higher rainfall – which led to increased stormwater runoff from the land – drove down scores for water quality and biological heath indicators. Researchers believe that two closely timed, large-scale weather events in winter 2010 played a role in the decrease.
The Bay’s health is affected by many factors, including human activities and natural variations in rainfall, which is the major driver of runoff from farms, cities and suburbs. Even as pollution is reduced, higher rainfall and associated runoff can mask the effects of these improvements.
“One of the main drivers of annual conditions in Chesapeake Bay is river flow related to weather patterns,” said UMCES-EcoCheck scientist Dr. Heath Kelsey. “While efforts to reduce pollution have been stepped up in recent years, nature overwhelmed those measures in 2010 and temporarily set the Bay back a bit.”
The declines are the first observed since 2003 and are on par with conditions observed in 2007. Annual weather-related variability in scores, even as more pollution-reduction measures are put into place, is to be expected in a highly complex ecosystem like the Bay, according to Dr. Kelsey.
Overall, the Lower Bay’s health score stayed relatively steady from 2009, while the Mid- and Upper Bay regions declined slightly. Results were fairly consistent in that declines were seen in most indicators.
The report card, based on data collected by state and federal agencies through the Chesapeake Bay Program, provides an independent analysis of Chesapeake Bay ecosystem health. It is expected that Bay Health Index scores will increase over time, as restoration and pollutant reduction activities are increased.
The report card analysis is conducted through the EcoCheck partnership between UMCES and the NOAA Chesapeake Bay Office. In addition to the Bay-wide reportcard, UMCES works with local watershed organizations to develop river-specific report cards to give residents a creek-by-creek look at their local waters.
For more information about the 2010 Chesapeake Bay Health Report Card, including region-specific data, visit the Chesapeake EcoCheck website.
Underwater bay grasses covered 79,675 acres of the Chesapeake Bay and its tidal rivers in 2010, according to data from scientists with the Chesapeake Bay Program. This is a 7 percent decrease from 2009, when bay grasses covered 85,914 acres of the Bay’s shallows.
Despite the drop, the 2010 bay grass acreage estimate ranks as the third-highest Bay-wide acreage since 1984, when the annual survey began.
"Even with the decreases in the 2010 bay grass coverage, the patterns are similar to previous years,” said Lee Karrh, living resources assessment chief with the Maryland Department of Natural Resources and chair of the Bay Program's SAV Workgroup. “Many of the fresh and low salinity areas have very high abundances, including 16 that have reached their restoration targets. However, the saltier parts of the Bay continue to struggle, with most areas well below the restoration goals, with only the mouth of the James River exceeding the goal.”
Bay grass abundance is currently at 43 percent of the Bay Program’s 185,000-acre goal. This goal is based on approximate historic bay grass abundance from the 1930s to present.
“We were pleased that grasses remain healthy and abundant in two areas where nutrient pollution was reduced: the upper Potomac River and Susquehanna Flats,” said Bob Orth, scientist with the Virginia Institute of Marine Science and leader of the baywide annual survey. “However, the overall condition for bay grasses remains one of concern with many areas still having few, if any, grass beds.”
In the upper Bay (from the Susquehanna Flats to the Chesapeake Bay Bridge), bay grasses covered about 21,353 acres. This is a 10 percent decrease from 2009. Large increases were observed in the Chesapeake and Delaware Canal and part of the Sassafras River. However, these were offset by large decreases in local rivers, including the Bush, Bohemia and Magothy. The massive grass bed in the Susquehanna Flats continues to dominate this area.
In the middle Bay (from the Chesapeake Bay Bridge to the Potomac River and Pocomoke Sound), bay grass acreage decreased 11 percent to 35,446 acres. Most segments in this part of the Bay lost grasses. The largest percentage decreases occurred in the middle and lower central Bay, as well as the Choptank, Honga, Patuxent and Potomac rivers. Increases were seen in Tangier and Pocomoke sounds and the Manokin and Big Annemessex rivers, where eelgrass continued to come back following a 2005 die-off.
In the lower Bay (south of the Potomac River), scientists mapped 22,876 acres, a 1 percent increase from 2009. This is the fourth year that bay grasses in this part of the Bay have increased since 2005, when hot summer temperatures caused a dramatic large-scale eelgrass die-off. Most of the gains were in the upper Rappahannock, lower Piankatank, and the upper section and mouth of the James River. These gains offset losses in other areas.
“In 2010, our big concern arose in the lower Bay where eelgrass appeared to suffer another setback from the incredibly hot summertime temperatures,” said Orth. “Since we had mapped those beds prior to the heat wave, losses there are not reflected in our final figures. We believe the really hot summer temperatures in the early part of the growing season may have just cooked the grasses before we were able to map them, e.g. parts of the Honga River. The changes also occurred in areas dominated by just one species, widgeongrass, which has been shown to be a boom or bust species. 2010 may have been the hottest on record but it was those summer time temperatures in June that may have tipped the scale for SAV in some areas.”
Bay grasses – also known as submerged aquatic vegetation or SAV – are a critical part of the Bay ecosystem. They provide underwater life with food and habitat, absorb nutrients, trap sediments, reduce erosion, and add oxygen to the water.
Bay grasses are also an excellent measure of the Bay’s overall condition. The health of bay grasses is closely linked with Bay health. Annual bay grass acreage estimates are an indication of the Bay’s response to pollution control efforts.
Annual bay grass acreage is estimated through an aerial survey, which is conducted from late spring to early autumn. For more information about the aerial survey, and to view an interactive map of bay grass acreage throughout the Bay and its tidal rivers, visit VIMS’ website.
The Chesapeake Bay’s blue crab population is at its second-highest level since 1997, according to results from the 2011 Blue Crab Winter Dredge Survey. At 460 million crabs, the blue crab population is nearly double the record low of 249 million in 2007.
Additionally, the survey shows that there are 254 million adult crabs in the Bay, a figure that is above the 200 million population target for the third year in a row. This marks the first time since the early 1990s that there have been three consecutive years where the adult population was above the target.
These figures indicate that emergency crab management measures put into place in 2008 are helping the Bay’s blue crabs recover, according to the Maryland Department of Natural Resources (DNR) and the Virginia Marine Resources Commission (VMRC).
“We continue to realize the benefits of the very tough decisions we made three years ago – decisions that are bringing us closer to our ultimate goal: a self-sustaining fishery that will support our industry and recreational fisheries over the long term,” said Maryland Gov. Martin O’Malley.
“The stock’s improved status from just a few short years ago is neither a random event nor a reflection of improved environmental conditions,” said Dr. Rom Lipcius, who directs the Virginia component of the dredge survey for the Virginia Institute of Marine Science (VIMS).
The unusually high crab abundance allowed watermen to harvest more than 89 million pounds of crabs, the largest amount since 1993. In addition, recreational crabbing license sales increased by 8 percent in 2010. However, the combined commercial and recreational blue crab harvest did not exceed the target of 46 percent. This shows that a healthy crab industry can coexist with stronger regulations, according to VMRC.
Despite these positive figures, overall crab abundance declined due to this past winter’s deep freeze that killed as many as 31 percent of Maryland’s adult crabs, compared to about 11 percent in 2010. Crab reproduction – which is heavily influenced by environmental conditions – was also lower in 2011.
“It was a harsh winter and crab mortality was higher than normal. In fact, it was the worst we’ve seen since 1996,” said VMRC Commissioner Steven G. Bowman. “Thankfully, we acted when we did in 2008 to begin rebuilding the crab population, or the crab census results we see today would be grim indeed.”
“The evidence indicates we’ve succeeded in rebuilding the stock to a degree that it can withstand a perfect storm of rapid temperature drop as crabs move into their overwintering grounds in the lower end of the Chesapeake Bay, followed by a prolonged bout of cold weather,” said VMRC Fisheries Chief Jack Travelstead.
Abundance estimates for young of the year, mature female and adult male crabs are developed separately. Together, these groups of crabs will support the 2011 fishery and produce the next generation of crabs.
The annual Blue Crab Winter Dredge Survey is the primary assessment of the Bay’s blue crab population. Since 1990, Maryland DNR and VIMS have sampled for blue crabs at 1,500 sites throughout the Chesapeake from December to March. By sampling during winter – when blue crabs “hibernate” by burying themselves in the mud – scientists can develop the most accurate estimate of the Bay’s blu crab population.
For more information about the blue crab survey results, view this presentation from Maryland DNR.
You may think being a Chesapeake Bay scientist is a fun, easy job, but have you ever wondered what it's like to work on the water in the middle of winter? U.S. Fish & Wildlife Service biologists Pete McGowan and Chris Guy give you a first-hand account of their experiences on the Bay in the frigid cold. It may be freezing, but as you'll read, they wouldn't want to be anywhere else.
The weatherman is calling for another frigid day with high temperatures just above freezing. Most people have long since winterized their boats and would not dream of boating 20 miles down the South River and across the Chesapeake Bay, putting on waders and plodding through thigh-deep (often ice-topped) water, to see if muskrats are active. But then again most people are not U.S. Fish and Wildlife Service biologists working at the Paul S. Sarbanes Ecosystem Restoration Project at Poplar Island, better known (and easier to say) as Poplar Island. We remain very active outdoors even in the coldest of weather.
Before you pity us, let us tell you that winter is often our favorite time to be out working in the marshes and Chesapeake Bay. In fact, while working in the hot and humid days of July and August, we often talk about those cold winter days without mosquitoes and biting flies, when the vegetation has died back and the marsh has frozen, making it easier to walk and do our work.
Often in the warmer months we are dodging thunderstorms and are rushed in our work because eggs are hatching, the chicks are fledging and everything seems to be coming at once. In the winter things slow down a bit and we can take the opportunity to regroup and prepare for the upcoming nesting season. This is the time of year when we build, repair, and install osprey platforms and bird boxes, and use old Christmas trees to develop snags for egrets to roost and nest upon. The Christmas trees also provide cover and nesting cavities for black ducks.
Boating is a little more relaxed, as you rarely see another boat on the water, and we can move freely without getting in anyone’s way or having them in our way. In this sense, winter is a time to pause and think about what we have accomplished and what we want to accomplish. It is a time of hope and optimism in our efforts to restore the Chesapeake Bay.
This is not to say that winter is an easy time to be a wildlife biologist. During the winter we have the real and ever-present threat of cold, icy water. Although we do not often speak of it, it is always on our minds. Unlike cars, most boats (including ours) do not have heating; the only heat we have available is that generated by the crew in our 25’ Boston Whaler. Did we mention there is only room for one or two people in the cabin? This means that on most days the crew rides outside and often has to deal with a formidable wind chill. Even on the calmest of days when the boat is operating at speeds of 25-30 knots, an air temperature of 32 degrees Fahrenheit equates to a wind chill of 17 degrees. Then there are the days where icing on the gunnels and deck (and at times the crew) from boat spray adds an extra layer of slipperiness to our day. And of course, there is always the task of shoveling fresh snow from the boat’s deck. Last year’s record snowfall made for lots of shoveling.
During extreme cold periods when ice forms on the rivers and Bay, trying to get our boat out of the marina can be frustrating. On many occasions while departing the South River this winter, we have had to break skim ice for miles. We are always checking to make sure it is not so thick that we will get stuck, or worse, put a hole through the boat’s fiberglass hull. Our boat is supposed to be one that can be cut in half and won’t sink, but who really wants to put that theory to the test in the middle of winter?
We prepare for the cold mostly by layering on the clothes, with as many as four layers to separate our flesh from the cold elements. Then there is the bulky survival suit with built-in flotation, plus hats, scarves, gloves and heavy boots. All these layers reduce our flexibility, not to mention causing us a bit of discomfort (try carrying around an extra 50 pounds of clothes when you work). Believe us, you need a lot of extra time if you need to use the bathroom! We often joke that the hardest part of our day is getting dressed and undressed.
Winter weather conditions wreak havoc on field gear. Batteries in electronics such as cameras, GPS units and field computers drain faster in cold temperatures. And trying to write field notes can be a bear when your fingers are numb.
Not to be forgotten is that pinhole leak in waders or gauntlet gloves that you can never seem to find and repair, and always seems to get bigger when standing or working in cold water. This makes for extended uncomfortable conditions, particularly when temperatures are near or below freezing. Drying these and other wet field items always takes longer in winter, too.
On a crisp winter day when the air is still, sometimes we just stop and wait to see the world around us. We see the marsh hawks that have come to the Chesapeake Bay for the winter zigzagging around the marsh looking for field mice and voles; what a thrill when they find one! There are always a few bald eagles around, either perching on an osprey nest or majestically soaring through the air. The great blue herons are always present and never seem to mind the cold. Short-eared owls and the occasional snowy owl will show up in the winter, and it is alwaysa real treat to get a glimpse. Then there are the wintering waterfowl – puddle ducks, diving ducks, bay ducks and sea ducks – as they fly into the Bay and marshes in the thousands.
Winter is an active and lively time on the Chesapeake Bay. It is amazing to think that we have an opportunity to experience something that few others get to, especially considering we are doing it within 40 miles of the Washington/Baltimore metropolitan area. We wouldn’t trade our jobs in any season.
All images courtesy Pete McGowan and Chris Guy, U.S. Fish & Wildlife Service
Underwater bay grasses covered 85,899 acres of the Chesapeake Bay and its tidal rivers in 2009, about 46 percent of the 185,000-acre baywide abundance goal, according to data from scientists with the Chesapeake Bay Program. This was a 12 percent increase from 76,860 acres in 2008 and the highest baywide acreage since 2002.
Bay grasses -- also called submerged aquatic vegetation or SAV -- are critical to the Bay ecosystem because they provide habitat and nursery grounds for fish and blue crabs, serve as food for animals such as turtles and waterfowl, clear the water, absorb excess nutrients and reduce shoreline erosion. Bay grasses are also an excellent measure of the Bay's overall condition because they are not under harvest pressure and their health is closely linked to water quality.
“The overall increase in SAV acreage in 2009 was strongly driven by changes in the middle and lower Bay zones, including Tangier Sound, the lower central and eastern lower Chesapeake Bay, Mobjack Bay, and the Honga, Rappahannock and lower Pocomoke rivers,” said Bob Orth, scientist with the Virginia Institute of Marine Science (VIMS) and leader of the SAV baywide annual survey.
Bay grass acreage increased in all three of the Bay’s geographic zones – upper, middle and lower – for just the second time since 2001.
Upper Bay Zone (from the Chesapeake Bay Bridge north)
In the upper Bay zone, bay grasses covered about 23,598 acres, just shy of the 23,630-acre goal for this area and a 3 percent increase from 2008.
Large percentage increases were observed in the Northeast River, part of the Sassafras River and the upper central Chesapeake Bay, an area just north of the Bay Bridge. However, bay grass acreage in a few local rivers, such as the Bush and Magothy, decreased significantly and offset increases elsewhere.
Overall, the massive grass bed on the Susquehanna Flats continues to dominate this zone.
“The growth and persistence of the SAV bed in the Susquehanna Flats – including the largest bed in the Bay – continues to be a major success story for bay grass recovery today,” said Lee Karrh, living resources assessment chief with the Maryland Department of Natural Resources and chair of the Bay Program's SAV Workgroup. “Many of the Bay’s lower salinity areas are doing well and seem to be driven by reductions in nutrient pollution entering the Bay. Seventeen segments in this zone have met or exceeded their restoration targets.”
Middle Bay Zone (from the Chesapeake Bay Bridge to the Potomac River and Pocomoke Sound)
In the middle Bay zone, bay grass acreage increased 15 percent to 39,604 acres, 34 percent of the 115,229-acre goal.
Eighty-four percent of the acreage increase in the middle Bay zone occurred in five segments: Eastern Bay, the Honga River, Pocomoke and Tangier sounds, and the lower central Chesapeake Bay. These changes reflect a large expansion of widgeon grass – the dominant SAV species in the middle Bay zone – as well as the continued recovery of eelgrass in Tangier Sound.
Elsewhere in the middle Bay zone, large percentage declines in bay grass acreage were observed in the Severn River and Piscataway Creek, a tributary of the Potomac River.
Lower Bay Zone (south of the Potomac River)
In the lower Bay zone, researchers mapped 22,697 acres of bay grasses – a 17 percent increase from 2008 and 49 percent of the 46,030-acre restoration goal. This is the third year that bay grasses in the lower Bay zone have increased since 2005, when hot summer temperatures caused a dramatic large-scale dieback of eelgrass.
Eighty-two percent of the acreage increase in the lower Bay zone occurred in Mobjack Bay, the lower Rappahannock River and the eastern lower Chesapeake Bay.
None of the 28 segments in the lower Bay zone saw large declines in bay grasses in 2009.
“We are cautiously optimistic about eelgrass recovery now that it is into its third year following the 2005 dieback,” said Orth. “But we are concerned about the long-term absence of eelgrass from areas that traditionally supported large dense beds, such as much of the York and Rappahannock rivers, many of the mid-Bay areas just north of Smith Island, and in the deeper areas of Pocomoke Sound. Declining water clarity noted in much of the lower Bay may be a major impediment to eelgrass recovery.”
Annual bay grass acreage estimates are an indication of the Bay's response to pollution control efforts, such as implementation of agricultural best management practices (BMPs) and upgrades to wastewater treatment plants.
Bay watershed residents can do their part to help bay grasses by reducing their use of lawn fertilizers, which contribute excess nutrients to local waterways and the Bay, and participating with their local tributary teams or watershed organizations.
Bay grass acreage is estimated through an aerial survey, which is flown from late spring to early fall. Visit VIMS’s website for additional information about the aerial survey and an interactive map of bay grass acreage throughout the Bay.