Well That Clears Things Up

At the Bay Journal, Understanding Chesapeake Bay water clarity isn’t clear cut

One of the murkiest questions surrounding the Chesapeake Bay cleanup effort seems like it should be the easiest to answer: Is the water getting clearer? For decades, widely used data indicate that, overall, water clarity is getting worse. Earlier this year, for instance, the Chesapeake Bay Report Card released by the University of Maryland Center for Environmental Science reported that 2024 water clarity was “very poor” and that “water clarity scores continue to show a significant decline over time.”

One of the major goals of the state-federal Bay Program partnership is to reduce the amount of sediment and nutrients entering the Bay to improve clarity so that underwater grass beds can get enough light to survive.  The region has spent billions of dollars to control sediment and nutrient-fueled algae blooms that cloud the water — seemingly without significant results. Yet underwater grass beds in the Bay have expanded even as data seem to show that the water is murkier. The amount of submerged aquatic vegetation, or SAV, increased from 38,227 acres in 1984 to 78,451 acres last year.

If the water is cloudy, how are grasses getting enough light to expand? A recent analysis published in the Annual Review of Marine Science came up with an answer, though it is murky too: The amount of light available for plants is improving, even if it doesn’t always look that way.  “For a long time, the story was that we’ve been cleaning up the watershed, but clarity is not improving,” said Jessie Turner, an assistant professor in the Department of Ocean and Earth Sciences at Old Dominion University, who was the lead author of the journal article. “That has switched, but it was hard to untangle things.”

Turner has been trying to sort out the story for nearly a decade, first as a student at the Virginia Institute of Marine Science and then in her current position. Former colleagues from VIMS and the University of Delaware are co-authors of the article. It turns out that how far we see into the water — how visibly “clear” it is — is not the same thing as how much light is passing through that water.

The Bay goal is to get more light to underwater plants, but the main tool for measuring clarity has been the Secchi disk — a black and white disk that is lowered into the water until it disappears. The Secchi disk is cheap and easy to use and has been relied upon for decades by researchers and citizen scientists. But it measures visual clarity, not the amount or quality of light that might be reaching plants on the bottom.

Bay water is filled with tiny particles. Some are bits of sediment, but many are tiny algae cells and microscopic bits of detritus from organic material that is breaking down in the water. Those organic particles limit visibility, but they don’t block light waves. Instead, they scatter them, reflecting light through the water column. Turner likens it to headlights in a fog bank. The headlights brighten the fog, which is made up of tiny water particles, but a driver can’t see very far into it.

 

“You can have a lot of light getting to your eyeball in the fog, but the visibility is very poor,” Turner said. “In the water, that would look like a very shallow Secchi depth reading. But you still have enough light for something like seagrass.” “What ultimately matters to something like SAV is how much light is getting to the bottom.”

When Turner and her colleagues examined historical data gathered with specialized light sensors, they found a different trend than those seen with Secchi disks. Data from those sensors, which assess the amount of sunlight that is penetrating the water, including the specific wavelengths that are important for plant photosynthesis, show improvements since around 1990.

So they've been measuring the wrong thing for the last 35 years? Actual light, including spectrums, aren't that tough to measure. 

The Wombat has Rule 5 Sunday: In Honor Of Alice Cooper available for browsing at the usual place and time.

Scallops Returning to Chesapeake Bay

Good News Network, Locally Extinct for a Century, Bay Scallops Thriving Again on Virginia Shore of Chesapeake Bay

Bay scallops are making an incredible resurgence in coastal bays along Virginia’s Eastern Shore, according to a new survey.

The exponential population growth is the result of decades of dedicated seagrass restoration efforts that allowed scientists to reintroduce the species to its former home.

Locally extinct since the 1930s due to habitat loss, bay scallops are thriving again, with help from the College of William & Mary’s and VIMS Eastern Shore Laboratory (ESL) in Wachapreague, Virginia.

The comeback could possibly set the stage for a future recreational fishery.

 

During the Bay Scallop Survey for 2025, the group routinely documented finding multiple scallops within a single square meter—something unimaginable just a few years ago.

Additionally, the researchers estimate the population will double in less than 18 months.

Virginians may one day be able to harvest local bay scallops for themselves, if the current moratorium on harvesting them along Virginia shores were lifted with the approval of the Virginia Marine Resources Commission.

“The restoration of bay scallops to their former range along the Virginian Eastern Shore represents a significant societal and ecological achievement,” said VIMS ESL Director Richard Snyder in a media release. 

Bay scallops (Argopecten irradians) once thrived in Virginia waters until an eelgrass wasting disease in the 1930s decimated their natural habitat. For approximately 90 years, the species was absent from the commonwealth’s coastal bays.

However, in 1997, William & Mary’s Batten School & VIMS researchers launched a seed-based submerged aquatic vegetation restoration project, now considered the largest and most successful seagrass restoration in the world.

Early years showed relatively low, fluctuating numbers, but recently the population has grown exponentially and researchers say its upper limit remains unknown. “It’s incredibly fulfilling to see this progress,” said Darian Kelley, a nursery manager at VIMS ESL who works closely with regional shellfish farmers.

But, but,  Seagrass swap could reshape Chesapeake Bay food web

Beneath the surface of the Chesapeake Bay, a subtle but dramatic shift is taking place as eelgrass gives way to its warmer-water relative, widgeon grass. A new study from researchers at William & Mary's Batten School & VIMS shows that this seagrass swap could have ecological impacts across the Bay’s food webs, fisheries and ecosystem functions.

Published in Marine Ecology Progress Series, the study reveals that while both seagrass species offer valuable habitat, they support marine life in very different ways. The researchers estimate that the continued shift from eelgrass to widgeon grass could lead to a 63% reduction in the total quantity of invertebrate biomass living in seagrass meadows in the Bay by 2060.

“Several factors including water quality, rising temperatures and human development are threatening eelgrass in the Chesapeake Bay. In its place, particularly in the middle Bay, widgeon grass has expanded due to its ability to tolerate warmer, more variable conditions,” said Associate Professor Chris Patrick, who is also director of the Submerged Aquatic Vegetation (SAV) Monitoring & Restoration Program at the Batten School of Coastal & Marine Sciences & VIMS. “However, the two grasses provide structurally distinct habitats that shape the animals living within.”

So, it's the most successful seagrass restoration ever, but now it's being threatened by Widgeongrass? 

The Wombat has Rule 5 Sunday: Terrain Features Part II at the usual time and place.

Bay Grasses a Mixed Bag in 2024

At the Bay Journal, Underwater grass skyrockets in parts of the Chesapeake Bay, decreases in others "One percent overall drop in underwater grass acreage Bay-wide."

In 2024, it is estimated that the abundance of underwater grasses fell by 1% in the Chesapeake Bay, despite observed gains in three out of four salinity zones. In 2024, 82,778 acres of underwater grasses were mapped in the Chesapeake Bay and its tributaries, compared to 83,419 acres in 2023. The Chesapeake Bay Program’s Bay-wide Submerged Aquatic Vegetation (SAV) Outcome remains “off-course” even as progress is made in some regions.

Scientists categorize the Bay into four salinity zones to track changes in underwater grass abundance over time, accounting for how the grass beds respond to storms, drought and other growing conditions. In 2024, researchers observed in the “very salty” Polyhaline Zone, which extends from the mouth of the Bay near Virginia Beach, Virginia up to lower Bay near the Maryland-Virginia border, a historic increase of 21,803 acres in 2023 to 24,800 acres in 2024. This is the highest coverage since annual mapping began in 1984 and is a 74% achievement of the acreage target for that region. The largest gains occurred in Mobjack Bay, Poquoson Flats and nearby Western Shore areas.

 

Eelgrass, a species of underwater grass that grows in the Polyhaline Zone, did particularly well. This species hit a low in 2019, when the Bay saw historic levels of rainfall. In recent years, eelgrass has recovered and then surpassed all previous monitoring records. Researchers say that eelgrass has moved into deeper parts of the Bay, expanding the available habitat for underwater grasses and indicating that water quality improvements are likely responsible.

“It’s just been amazing to watch the expansion of the meadows! We now have eelgrass happily growing at 8-9 feet at low tide in some places, which was unthinkable just a few years ago,” said Christopher J. Patrick, associate professor and director of the SAV Monitoring and Restoration Program at the Virginia Institute of Marine Science (VIMS). “But beyond the polyhaline, it’s another example of how incredibly fast SAV can expand and recover when conditions are right. We saw the same story in the Susquehanna Flats 15 years ago. It shows that recovery isn’t incremental, it's rapid when it happens, and that gives me hope for us achieving the Chesapeake Bay wide goals in the future even if they seem far off now.”

The 2024 mapping also revealed a modest increase in the Bay’s Tidal Fresh Zone and a significant increase in the slightly salty Oligohaline Zone. In the Tidal Fresh Zone, underwater grass beds increased from an estimated 19,823 acres to 20,218 acres, a 98% achievement of the SAV target of 20,602 acres for that region. In the Oligohaline Zone, underwater grass beds increased from an estimated 3,422 acres to 4,730 acres, a 46% achievement of the 10,334-acre target.

However, underwater grass decreased by 14% in the moderately salty Mesohaline Zone, from 38,371 acres to 33,031 acres, a 27% achievement of the 120,306-acre target for that zone. Losses in the Mesohaline Zone, which is the largest zone in the Bay, mainly occurred along the Eastern Shore of Maryland in the Choptank and Little Choptank rivers, as well as in Tangier Sound.

These decreases were enough to offset gains, resulting in a 1% drop in underwater grass abundance Bay-wide. This marks a 64% achievement of the SAV Outcome’s 2025 restoration target of 130,000 acres in the 2014 Chesapeake Bay Watershed Agreement and 45% of the long-term target of 185,000 acres that is needed for a fully restored estuary.

My guess is that they were quite generous when they set the restoration targets, since there was probably no bay wide grass census prior to the great catastrophe of Hurricane Agnes back in 1972 which flooded the bay with freshwater and sediment and all but eliminated SAV for years. After all, more is better, right? I further posit that currently SAV are close to their current carrying capacity in the Bay, with coverage varying year to year due to weather events, and how they effect different areas. Short of a major change in the Bay, and I'm not sure what that would be, that's likely to be the story for the foreseeable future.

The Wombat has Rule Five Sunday: The End of Summer up and garnering clicks at The Other McCain.

Where Did the Swans Go?

From the Bay Journal, Where did the Chesapeake’s elegant tundra swans go?

Tundra swans breed in the Arctic during warmer months. In North America, they are grouped into Eastern and Western populations. The Eastern band travels more than 4,000 miles to winter in coastal areas from Maryland to North Carolina — mostly the latter nowadays.

Annual surveys conducted by the U.S. Fish and Wildlife Service typically count 90,000-100,000 birds in the Eastern population, but their numbers unexpectedly dropped from a record high of 137,000 in 2023 to a 45-year low of 64,000 in 2024. Wildlife officials chalk up that decline to normal annual variation and not to any specific factors or threats.

As recently as the 1960s, the tundra swan population in North Carolina only numbered in the low thousands. In recent decades, the state has averaged approximately 65,000-75,000 wintering tundra swans, mostly in and immediately around the neck of land between the Albemarle and Pamlico sounds, Morris said. He suspects that the birds found the region more hospitable after many of its forests were plowed under for cropland, offering them a ready food source. “We had swans, but nothing anywhere near like it is now,” he said.

But that influx might not have happened if not for concurrent changes in the Chesapeake Bay’s fragile ecosystem, according to Morris and other experts.

 

The Bay’s water quality had been on the decline for many years largely because of increasing nutrient and sediment pollution flowing off city streets, suburban yards and farm fields during heavy rain. The biggest turning point came in 1972, when the remnants of Hurricane Agnes triggered widespread flooding and a multi-decade downturn in the Bay’s health.

The cloudy water in the Bay and its tributaries smothered much of the underwater grasses that had fed and nourished generations of tundra swans, said Kayla Harvey, waterfowl program manager for the Maryland Department of Natural Resources. As their preferred food dwindled, tundra swans began feeding in farm fields on waste grains, such as corn and soybeans.

By the 1980s and ’90s, North Carolina surpassed the Chesapeake as the population’s most important wintering ground.

Hunting pressure doesn’t appear to have impeded that trend. While Maryland legislators tried to legalize hunting the birds, arguing that it would bring in permit revenue, the bill died in committee. North Carolina, though, is among 10 states (including Delaware and Virginia in the Bay watershed) where tundra swan hunting is allowed. Because North Carolina has the largest population, the state receives the lion’s share of the federally allocated permits for the Eastern region — usually around 4,800 of the 5,600 total.

Bringing more tundra swans back to the Chesapeake will require continued efforts to revive its ecosystem, Harvey said. The biggest determinant will be increasing underwater grasses through actions such as direct seeding and improving water quality to support more growth, she added.

There used to be a pretty reliable small flock of Tundra Swans that occupied the shallow bar area between Matoaka Cottages and Western Shores to the north of us for the winter season. In the the last few years, I would say 5 or so, there have been only the occasional swan up there. I think I only saw a couple of them up there once this winter.

It's curious that they seem to be blaming a recent decline in the swans in the Bay region to water quality, which the Bay program would insist has seen a measurable, if small improvement due to the $25 billion or so spent to clean up the bay. 

The emphasis on SAV seems misplaced too. In North Carolina, their increase is credited to more farming, Could it be the decline here could due to a decrease in farming, and an increase in suburbs

Speaking of SAV, also at the Bay Journal, Goal for restoring Chesapeake’s underwater grasses might be increased

Meeting the Chesapeake Bay’s underwater grass restoration goal could soon get more difficult.

The state-federal Bay Program partnership may increase its goal for underwater grasses, an important habitat for blue crabs and many other species, from 185,000 to 196,000 acres.

Even the smaller of those numbers is more than double what’s been observed in the Bay in recent years, and the region has never come close to the 185,000-acre figure since Baywide measurements of the grass beds — officially called submerged aquatic vegetation, or SAV — began in the early 1980s.

Nonetheless, scientists and state officials say the goal should be updated to better reflect the amount of potential SAV habitat if the region meets its pollution reduction goals in the future.

The Bay Program established the 185,000 figure in 2003 using photographs from aerial surveys conducted during the 1900s — mostly old agricultural surveys — to map the location of all grass beds that could be seen in different parts of the Bay at some point in time.

Brooke Landry, a biologist with the Maryland Department of Natural Resources and chair of the Bay Program’s Submerged Aquatic Vegetation Workgroup, said that when the original maps were drawn, portions of some shoreline grass beds were inadvertently cut off in the mapping process, resulting in an underestimation of the observed amount.

Also, grass beds have been observed in recent years in some locations where they had not been previously mapped.

When those areas are included, the extent of Bay bottom that supports SAV, or is known to have done so at some point in the last century, increased to about 196,000 acres.

That updated figure is being proposed as a goal for the revised Chesapeake Bay Watershed Agreement, the policy document that guides Bay restoration efforts, which is being updated this year.

Landry acknowledged that meeting the goal will be difficult. While 196,000 acres of the Bay may have supported SAV at some point in time, it’s unclear whether that much ever existed in any single year during the past century.

The greatest extent of grass beds observed in recent decades was about 108,000 acres in 2018. Since then, the amount observed in annual aerial surveys has ranged from roughly 63,000 to 83,000 acres.

 So we're nowhere near the current goal, and they're proposing to increase the goals for the next go around. Seems like a pretty sure way to achieve failure the next time around. And do we really have any specific mechanism proposed to increase SAV, beyond further restricting nutrients?

The Wombat has Rule 5 Sunday: The Last Champion of Cracker Barrel up at the Other McCain.

Anacostia Improves Grade to D+

WTOP, The results are in: Anacostia River gets a D-plus, but that’s an improvement

The annual report card is in for the Anacostia River, and while the overall grade is a D-plus, there are some positives in terms of the future of the river’s heath.

In its 2024 State of the River Report, The Anacostia Watershed Society said the water quality of the Anacostia is the best it’s been in 10 years. Several points of measurement are showing improvement, including the amount of submerged aquatic vegetation. This year, the river received an A — a perfect score of 100 in that category. That means, according to the report, the Anacostia has at least 20 acres of submerged vegetation. Over the past decade, that acreage has fluctuated between 5% and 100% and likely experienced a rejuvenation because of improved land management and green infrastructure in the city.

Another positive is the amount of measured chlorophyll in the river. The report gives the river a score of 81, a B-minus, which means the Anacostia is doing better when it comes to having the appropriate amount of nutrients that should be in the water.

However, the river failed in 3 areas — the amount of dissolved oxygen in the water, the amount of stormwater runoff and water clarity. In addition, the report said fecal bacteria in the river is still a big problem. Although the score for fecal bacteria improved over the last year from 53% to 60%, levels remain high in parts of the river despite the dramatic reduction in sewer overflows as a result of the completion of D.C. Water’s Anacostia River Tunnel, the report said.

But, Mom  a D is passing! 

WUSA9, DC pays more than $1 billion to construction company allegedly polluting Anacostia River, other District waterways. There's plenty good money to be made in pollution.

Bay Grasses Doing OK

 MDDNR, Maryland Reports Steady Underwater Grass Abundance in Chesapeake Bay for 2023

Underwater grass abundance–a key indicator of water quality and habitat–remained steady in 2023 in the state’s portion of Chesapeake Bay, reaching 37,770 acres, according to data released this week by the Chesapeake Bay Program and Maryland’s Department of Natural Resources (DNR).

Overall, an estimated 82,937 acres of underwater grasses, also called submerged aquatic vegetation (SAV), were distributed throughout Chesapeake Bay and its tidal tributaries in 2023, a 7% increase over 2022 acreage.

In Maryland, all or part of four rivers surpassed their restoration goals. These include the Northeast River at 109%, the Upper Chester River at 432%, the Honga River at 138%, and the Wicomico River at 270%. An additional three segments reached 75 percent or more of their restoration goals, including the Northern Chesapeake Bay that encompasses the Susquehanna Flats at 86%, the Bush River at 83%, and Mattawoman Creek at 98% of their goals.

“I’m glad to see the Bay’s underwater grasses continue to recover following losses in 2019, and despite some declines in the upper Bay, the Susquehanna Flats are holding strong and the news is positive,” said Brooke Landry, Maryland DNR’s Program Chief of Living Resource Assessment and Chair of Chesapeake Bay Program SAV Workgroup. “ I am confident that we will continue to make progress on restoration, especially with species like Horned pondweed and Sago pondweed becoming so abundant in the mid-Bay. Their skyrocketing expansion in recent years, according to observations that my colleagues and I are making along with data collected by Chesapeake Bay SAV Watchers program volunteers, is exciting to see since both plants offer such beneficial ecosystem services.”

Submerged aquatic vegetation (SAV), also known as underwater grasses, play a critical role in maintaining the health of the Chesapeake Bay ecosystem. These grasses absorb and filter out nutrients and sediment, reduce shoreline erosion, provide habitat and protection for important species such as blue crabs and largemouth bass, support and sustain migrating waterfowl, and mitigate climate impacts.

The annual underwater grass survey was conducted by the Virginia Institute of Marine Science between May and November 2023. While the acreage falls short of Maryland’s 2025 restoration goal of 79,800 acres, airspace restrictions prevented complete surveys of the Upper and Middle Potomac River, including Piscataway Creek. If these areas had been fully mapped, observations suggest that Maryland’s SAV acreage would have been higher in 2023.

A significant loss of freshwater grasses in the upper Bay in 2023 offset an equally significant expansion of brackish water grasses in the mid- and lower portions of Maryland’s Chesapeake Bay. The loss of freshwater grasses did not extend to the iconic Susquehanna Flats grass beds, which continued to expand and now cover over 11,000 acres. Grass beds in the mid-Bay were bolstered by the continued expansion of Sago pondweed (Stuckenia pectinata), a species that doesn’t get much attention in the grand scheme of Chesapeake Bay SAV dynamics. According to observations made by Bay scientists and data collected by Chesapeake SAV Watchers volunteers, Sago pondweed is possibly the most abundant species in several Maryland rivers on both the eastern and western shores, including the Severn and Choptank Rivers, and Eastern Bay.

Further south and into slightly saltier water, widgeon grass (Ruppia maritima) continued to recover from major losses in 2019. Both widgeon grass and eelgrass (Zostera marina) are common in Tangier Sound, where grass beds gained 1,285 acres of SAV between 2022 and 2023.

From what I've seen in Tangier Sound this year, those numbers should hold up.  

Wednesday Wetness

With Gádor Muntaner@gadormunta Marine Scientist 🐚 Shark Conservationist & Researcher🦈 @natgeoesp Ambassador 🌊 📩 collab:gador@swaymgmt.es @aqualungdivers & @onlyone Ambassador🤍

The Wombat has Rule 5 Sunday: 2B or not 2B up on time and under budget at The Other McCain.

Chesapeake Bay Continues to get Bad Grades

 Couldn't even must the gentleman's C: “Tough News”: CBF’s Bay Health Grade Remains At D+

The Chesapeake Bay Foundation (CBF) just released its State of the Bay report, which comes out every two years. The overall score for 2022 remained unchanged from 2020’s grade at a D-plus—not the result the foundation was hoping for.

The State of the Bay report looks at 13 indicators within the categories of pollution, habitat and fisheries. Each indicator gets a score, and together they provide an overall score out of 100. A score of 70 would mean a fully-restored Bay has been achieved; a 100 is the Bay’s condition before European settlers arrived in the 1600s.

This year, the score remained a 32/100. Three indicators improved, three worsened, and the remaining seven were unchanged.

Phosphorus levels came down, but overall water clarity worsened. Nitrogen, toxics, and dissolved oxygen indicators were unchanged from 2020.

CBF says one of the biggest places where Bay restoration efforts are struggling is agriculture pollution. Urban and suburban runoff are also increasing due to land development, increased stormwater from climate change, and “inconsistent enforcement by government agencies,” CBF says.

In one sign of hope, the Bay’s dead zone in the 2022 season was the 10th-smallest since the states began tracking it 38 years ago. And the Bay region has seen more farm conservation funding from the federal government and the states that should reduce nitrogen and phosphorous.

The Environmental Protection Agency’s (EPA) Chesapeake Bay Program recently acknowledged that the Bay states aren’t going to reach the 2025 “pollution diet” goals set back in 2010.

The Total Maximum Daily Load (TMDL) was meant to task each state and Washington with reducing a set quantity of pollution, with specific deadlines to reach benchmarks. CBF praises this federal/state pollution plan as the most promising for restoring rivers, streams, and the Bay. However, CBF says implementation has been lacking.

When asked whether the TMDL should be abandoned now that its 2025 goal is out of reach, CBF President Hilary Harp Falk said, “2025 was always the milestone and not necessarily the end. Those efforts the states and the EPA will continue and we’re excited to create more momentum towards these goals.”

Looking at the State of the Bay data on fisheries, we find good news for oysters, reason for optimism on rockfish and worsening blue crab population health. CBF says oysters are seeing a “renaissance” after years of overharvesting and declining natural reproduction. According to CBF Senior Regional Ecosystem Scientist Chris Moore, watermen are expecting a good harvest in the next few years, but regulators need to ensure reproductive sustainability.

“That’s something we haven’t always been good at in the Bay—when abundance is high, making sure we don’t take too much of a good thing.”

In the striped bass fishery, Atlantic coast managers have been fighting a declining population with strong catch limits and measures to prevent catch-and-release deaths in rockfish. CBF says these regulations should allow the striped bass population to rebuild by 2029.

In the fisheries category, the rockfish (striped bass) and oyster indicators rose, while the blue crab indicator declined.

The worst news among the three major Bay fisheries is a large drop in the blue crab population. CBF’s overall score for blue crabs fell five points. The 2022 dredge survey found the lowest abundance of crabs in the survey’s history. Storms, predators like blue catfish and a lack of underwater grasses (key habitat for crabs) have all contributed, Moore says. When it comes to the crab harvest, Moore wants to get better information about just how many crab pots are out there and what impact the shift from a female- to a male-focused fishery is having.

The State of the Bay’s habitat report finds that underwater grasses are sitting at 70,000 acres, down from a high of 105,000 in 2019. Eelgrass, in particular, is in danger. CBF Director of Science and Agricultural Policy Beth McGee says some models show eelgrass disappearing entirely from the Bay in the next decades. Forest buffers and wetlands scores also remain unchanged, but there was a drop in “resource lands” like forests and open areas, thanks to development.

When it comes to funding and projects, CBF says it’s prioritizing those with multiple benefits. For example, cover crops and tree plantings reduce runoff and also help reduce greenhouse gases to help fight climate change.

And funding is coming: the federal Inflation Reduction Act includes $20 billion for the U.S. Department of Agriculture to support farm pollution reduction practices nationwide, and Pennsylvania and Virginia have both built agricultural conservation funding into their budgets. The key is to direct these funds to the places where they can have the biggest impact.

About right. Crabs and Striped Bass not doing especially good, oysters improving, but nowhere near historical abundances. After most of the $25 billion dollars that were expected (but not really) to "restore" the Bay by 2025 have been expended, it's really hard to point to much that's actually been changed. Nutrients might be down a hair, and hypoxia slightly less as a result, but the trends are not outside the envelope for the last 30 years, with weather being an important driver.

Remember, "restoring" the Bay is a major industry in our region, and actually fixing it would put a lot of people out of a job in a hurry. Lucky for them, that doesn't seem likely.

Bay Grasses Up a Little for 2021

Chesapeake Bay Program, Chesapeake Bay Program notes slight increase in underwater grass abundance

In 2021, an estimated 67,470 acres of underwater grasses were mapped in the Chesapeake Bay and its tidal tributaries, achieving 37% of the ultimate restoration goal of 185,000 acres. However, it is likely that more underwater grasses grew in the Bay in 2021 than the mapped acreage suggests. Adverse weather conditions, such as frequent rain and cloudy water, prevented researchers from successfully collecting imagery over the Mattaponi and Pamunkey rivers.

While underwater grass abundance did increase by almost 9% from 2020 to 2021, the preliminary acreage observed in 2021 is still a slight decrease from the long-term average of 69,623 acres, and approximately a 38% decline from 2018, when it was estimated that the Bay might have supported up to 108,078 acres.

Underwater grass abundance can vary from species to species and river to river. In 2021, local highlights included:

Northern Maryland: Underwater grass abundance in and around the Susquehanna Flats region increased from 9,200 acres in 2020 to 10,331 acres in 2021. However, the Elk River decreased from 613 acres in 2020 to 190 acres in 2021.

Middle and Eastern Chesapeake Bay: Underwater grass acreage in the Little Choptank River continued to decline, dropping from 551 acres in 2020 to 175 acres in 2021. Likewise, the Choptank River to its north decreased its acreage from 4,562 acres in 2020 to 4,132 acres in 2021. The Eastern Bay did not fare much better, declining from 840 acres in 2020 to 507 acres in 2021. On the middle Western shore of the Bay, the Severn and Magothy rivers both saw significant decreases in underwater grass acreage. The Severn declined from 294 acres in 2020 to 227 acres in 2021, while the Magothy decreased from 124 acres in 2020 to 59 acres in 2021.

Mid-to-Lower Chesapeake Bay: In the Virginia portion of the mid-to-lower Bay, underwater grasses did particularly well in the Corrotoman and Rappahannock rivers, as well as in Mobjack Bay. The Rappahannock, which includes the Corrotoman, increased from 2,204 acres in 2020 to 3,235 acres in 2021. In Mobjack Bay, underwater grass acreage increased from 7,440 acres in 2020 to 8,355 acres in 2021.

Grass is quite variable from year to year, with, as usual, weather, not long-term water quality trends  being the culprit in most cases. It is also complicated by the fact that there are numerous grass species in different area, and they are clearly to different factors. That being said, if the long term goal is 180,000 acres, and in a 'good' year, we're achieving 67,000, we're a long way from getting to the 2025 goals for fixing the Bay.

I would like to add, that by personal observation, and comments from Pete, this year, large areas of the middle Bay are showing less grass cover than in a few previous years, so next year might be a set back.

Doomed! The Bay is Doomed!

But aren't we all, in the long run? The talk of the bay newsfeed today is that the underwater grasses (aka submerged aquatic vegetation, SAV) underperformed expectations 2 years in a row. From MDE, Lingering Impacts from Extreme Weather Events Affect Chesapeake Bay Underwater Grasses in 2020

The Maryland Department of Natural Resources (DNR) reports a third consecutive year of underwater grass loss in Maryland’s portion of the Chesapeake Bay in 2020. During the annual survey, 34,882 acres of underwater grasses were mapped in Maryland, representing 44% of the state’s 2025 restoration target and 30% of the ultimate restoration goal of 114,065 acres.

Record high rainfall and stream flows into the Chesapeake Bay in 2018 and 2019 led to higher levels of nutrient and sediment pollution, changes in salinity, and poorer water clarity in many of Maryland’s waterways. Habitat conditions remained poor in 2020, and underwater grass abundance declined 13% overall from the previous year.

After years of significant gains, more than 3,000 acres of underwater grasses were lost in the mid-Bay region, specifically the lower Chester River, Eastern Bay, the mouth of Choptank River, and the Little Choptank River. These declines were primarily in widgeon grass, a species that can rapidly increase or decrease from year to year with changes in water quality.

As usual, we find that weather conditions exert the most influence over year to year variation in the seagrasses. 

Some areas of Maryland’s portion of the Bay showed improvements in underwater grass abundance. The iconic beds in Tangier Sound and the Susquehanna Flats, along with those on the Potomac River, including Mattawoman and Piscataway creeks, increased in 2020.

Underwater grasses were observed in the Wicomico River on the Eastern Shore for the first time since the survey began in 1984.

“Efforts underway by Maryland and our Bay partners to reduce nutrients in our waterways remain critical to our goal of increasing submerged aquatic vegetation in the Bay,” Maryland Natural Resources Secretary Jeannie Haddaway-Riccio said. “While extreme weather has had a real impact on our state’s underwater grasses, SAV are aiding in improving water quality and do provide important habitat in many of our waterways.”

“The improvements seen in Tangier Sound and on the Susquehanna Flats highlight the resilience of Maryland’s large, stable underwater grass beds, and emphasize the importance of protecting and preserving them,” said Becky Raves Golden, Living Resource Assessment Program Manager for DNR. “Many of the losses observed in 2020 were in areas where gains had been made in recent years, suggesting that recovering populations are more affected by the stress of poorer water quality than stable, resilient beds. There is still work to do to mitigate the impacts of multiple stressors on Maryland’s recovering underwater grasses.”

Despite the overall decline in statewide underwater grass abundance, underwater grasses in all or part of four Maryland rivers surpassed their restoration goals. These included the Northeast River at 122%; the Bush River at 127%; the middle Chester River at 287%; and the tidal fresh portion of the Chester River at 16,554% (the percentage of the goal attained is so high due to a very small segment restoration goal). An additional six river segments in Maryland reached 75% or more of their restoration goals, including the northern Chesapeake Bay, the upper Chesapeake Bay, Gunpowder River, Northeast River, Mattawoman Creek, and Wicomico River.

I also appreciate the recognition that because the weather conditions have differing local effects, and different species of seagrass respond differently, that there is substantial regional variation in the response.

Other flavors of coverage at Bay Journal - Chesapeake Bay grass beds decline for second year in a row, Baltimore Sun - Underwater grass abundance, 'critical' to the Chesapeake Bay's ecosystem, is down but may be stabilizing, Chesapeake Bay Program - Acreage of underwater grasses in the Chesapeake Bay decline for second straight year

Do You Miss Taking Care of Your Lawn in Winter?

If so, fear not, you can grow grass for Chesapeake Bay, Volunteers are needed to grow Chesapeake Bay seagrasses in their homes, classrooms and offices

The Chesapeake Bay and its tidal river systems once teemed with underwater grasses, but pollution and devastating storms decimated them until today they cover only about 10% of their historic range.

Restoration has been underway for decades and in many forms, including an effort called Grasses for the Masses that enlists volunteers to sprout seagrass seeds in classrooms, homes and workplaces for transplant to special restoration sites in the James, Rappahannock, Chickahominy and Potomac rivers.

Now in its 20th year, the program is seeking volunteers throughout the state for the next round of homegrown underwater grasses. A local how-to workshop is set for 2-4 p.m. Feb. 8 at the Williamsburg Regional Library. Registration is required.

“I’ve grown grasses in my office, and I think it’s surprisingly easy,” said Kenny Fletcher, spokesman at the Chesapeake Bay Foundation, which heads the effort. “I haven’t found it to be any more difficult than growing a houseplant. And the sense of satisfaction it 

Some of us aren't all that good with houseplants. And my fish eat any plants I try to put in the aquarium. However, the species of grass they are growing, wild celery, aka Vallisneria americana, is a common freshwater aquarium plant, and fairly easy to grow.

“It’s neat to see on social media people posting pix of their first sprouts and become proud of their grasses that they’re growing themselves,” said Fletcher.

When the seedlings are ready, hundreds of volunteers gather to transplant them into permitted sites at the Westover Plantation and Virginia Commonwealth University Rice Rivers Center on the James River, the Chickahominy Riverfront Park, Rappahannock River Valley National Wildlife Refuge and Mason Neck State Park on the Potomac.

The program initially began as Grasses for the Classes and enlisted school volunteers before expanding to the general public.

“Now about half our participants are educators and students," said Troutman. “And the other half are generally volunteers who are just really interested in finding a way that they could do something on a personal level that’s at the right scale for them to feel like they made a difference in their local rivers.”

Given the thousands of acres of SAV in the Chesapeake Bay, it's hard to imagine that this program will make much difference, but it won't hurt, and it makes people feel good.

Extra Wet Year Affects Bay

Bay health impacted by record flows - Largest amount of fresh water to enter the Chesapeake Bay since 1937

In 2019, more fresh water flowed into the Chesapeake Bay than it has in any of the past 82 years. The average freshwater streamflow into the Bay over the past year was 130,750 cubic feet per second—the highest since data collection began in 1937. To put this into perspective, 130,750 cubic feet is about 978,077 gallons. In comparison, an average Olympic-sized swimming pool holds approximately 660,253 gallons of water. That’s more than one pool entering the Bay every second!

These historic flows, which followed the record-breaking rainfall seen in 2018, caused Bay-wide changes in salinity. The extreme rainfall also washed nutrient and sediment pollution into the Bay, which depleted dissolved oxygen that aquatic species depend on for survival, and dramatically impacted the Bay’s underwater grass habitat and other living resources.

Hmm. That's interesting, since 2009 until now, 20 year, we've had 5 years below normal and 5 years above. Sound's like things are going on about normal.

However, the extreme amounts of rain that led to these heavy flows of freshwater between 2018 and 2019 dramatically impacted salinity levels throughout the entire Bay. Beginning in May 2018, salinity levels in the middle of the Chesapeake Bay were below-average, a situation which persisted for 17 consecutive months. A record-low level of salinity was observed in February 2019 in this area, and the months that followed continued to hover near record-low levels.

As of October 2019, waters in the lower Bay have returned to their normal salinity levels. However, the months of high flows has dramatically impacted plant and animal life in these regions. This has impacted the habitat for spawning fish, the distribution of underwater grasses and oysters, and increased the presence of Dermo and MSX, which are oyster-killing parasites.

Some effects:

After a promising year, underwater grasses have taken a step back . . .

Oysters restoration heavily impaired in upper Bay . . .

Blue crab populations are improving . . .

Invasive species are taking advantage of increased freshwater flows . . .

Dead zones continue to grow . . .

Which, other than crabs improving, are all sort of what you'd expect from an exceptionally wet year.  One of these years soon, we'll have a drought, and then they'll be complaining about all the bad things droughts cause, too

Rains No Help to Chesapeake Lawn

Scientists fear steep loss of Bay grasses lies ahead

Portions of the Chesapeake Bay’s underwater grass meadows appear to be headed for steep declines this year, a delayed response to the torrential rains that poured vast amounts of water-fouling sediments and nutrients into the estuary during 2018.

Initial reviews of this year’s aerial survey show significant losses of underwater grass beds in parts of the Mid Bay, where the bulk of the Chesapeake’s underwater grass beds are located.

At the same time, preliminary reviews of the aerial images show that portions of the Upper Bay survived last year’s deluge of muddy water surprisingly well, with grass beds even expanding in some areas.

“It’s going to be a mixed story, as it always is,” said Bob Orth, the Virginia Institute of Marine Science researcher who has been overseeing the aerial survey since its inception in 1984.

The full analysis of this year’s survey, which is still under way, won’t be available until early next year. But the broad picture is starting to emerge as Orth and others pore over the hundreds of aerial images gathered thus far.

Underwater grasses are one of the Bay’s most critical habitats, providing food for waterfowl, juvenile blue crabs and many types of fish. Because they require clear water to survive, they are a closely watched indicator of the Bay’s health.

Grass beds had been steadily expanding in recent years. They covered 104,843 acres in 2017, which was the largest amount observed since Bay cleanup efforts began in the mid 1980s.

It's no great shock. Hurricane Agnes, in 1972 is widely credited with devestating the underwater grasses of the Chesapeake for years, as a result of massive freshwater and mud.

Excess Rain Waters Bay Grasses

An interesting case of science reporting by press release. VIMS released it's annual report on the state of submerged aquatic vegetation in the Bay, and other outlets picked up the news. First, VIMS: Survey indicates slight decline in underwater grass abundance

Despite record-rainfall in 2018, underwater grass abundance remains strong
An annual survey led by researchers at the Virginia Institute of Marine Science mapped an estimated 91,559 acres of underwater grasses in the Chesapeake Bay and its tidal tributaries in 2018.

While this acreage is less than the previous year, it is likely that substantially more submerged aquatic vegetation (SAV) grew in the Bay than the mapped acreage suggests: frequent rain, cloudy water, and security restrictions prevented researchers from successfully collecting aerial imagery over 22% of the monitored area, including the Potomac River near the Patuxent Air Base; portions of the Susquehanna Flats; Mattaponi, Middle, Choptank, and Honga rivers; and Fishing Bay.

In 2017, these unmapped portions of the Bay supported more than 17,401 acres of grasses. Adding this value to the 2018 estimate would bring the estimated total for 2018 to 108,960 acres—a 4% increase from 2017 levels and a 59% achievement of the Chesapeake Bay Program’s 185,000-acre 2025 goal. The 2017 total was the greatest amount of underwater grasses ever recorded by VIMS’ SAV Monitoring and Restoration Program, and the first time total grass abundance surpassed 100,000 acres. VIMS scientists began monitoring the Bay in 1979. . . . 

As reported by the Bay Journa (EPA Bay Programs bought and paid for media arm) is less optimistic: Bay grasses survived 2018 deluge, but losses expected this year

The full impact of last year’s high flows on the Chesapeake’s underwater grasses, one of the Bay’s most critical habitats, remains murky as scientists try to assess the full impact of last year’s record rainfall.

But the full story is far from clear. Most of that survey was finished before unrelenting rains began in late July. The continual downpours flushed huge amounts of water-clouding sediment and nutrients into the Bay, which can be lethal to grass beds.The good news, according to the results of the 2018 aerial survey, is that underwater grass acreage increased overall from 2017 in areas where the survey was completed.

Scientists say grasses stressed by poor conditions last year may not bounce back this summer. As a result, the impact of those high river flows may not be known until after the 2019 survey is complete.

“Everyone is wondering what will happen in 2019 and how these plants will react,” said Bob Orth, the Virginia Institute of Marine Science researcher who has been overseeing the aerial survey since its inception in 1984. . . .

The local CBS station in Balmer is really upbeat:  Measured Acreage Of Underwater Grasses Decline Slightly In The Bay, But Could Be Highest Amount Ever

In 2018, an estimated 91,559 acres of underwater grasses were mapped in the Chesapeake Bay and its tidal tributaries.

While this acreage is less than the previous year, it is likely that substantially more submerged aquatic vegetation (SAV) grew in the Bay than the mapped acreage suggests.

If the acreage of grasses that these unmapped portions of the Bay supported in 2017 is considered, the estimated total for 2018 could be as high as 108,960 acres.

This would be an increase from the previous total, which was the highest amount of underwater grasses ever recorded in the Bay since monitoring began over 30 years ago.

Experts believe it is likely that the actual expanse of underwater grasses in 2018 ranged between 91,559 and 108,960 acres.

The growth and survival of underwater grasses are sensitive to the impacts that extreme weather conditions have on Bay water quality. In the past, underwater grass populations have taken several years to recover from the effects of hurricanes or high-temperature events. . . .

The same basic facts, with three different spins.

Did the 2018 Rains Drown the Bay's Progress?

We recorded 73 inches of rain here. Washington and Baltimore both had record years. Scientists waiting to see if record 2018 rainfall dampens Bay recovery in the Bay Journal. 

The water-fouling nutrients and sediment that were also flushed into the Bay by record-setting rainfall throughout the region will test the staying power of recent water quality improvements to the nation’s largest estuary.

At risk are improving trends for the Chesapeake’s fish-stressing “dead zone” and the restoration of its vital underwater grass beds and oyster populations.

Some cleanup efforts seemed to withstand the repeated downpours, but others faltered. Farmers struggled to plant pollution-absorbing cover crops, for instance.

It will be months before anyone can fully gauge the impact of higher-than-normal river flows that began flooding the Chesapeake in May and persisted through the rest of the year. August, September and November all set records for freshwater flows into the Bay, and December flows were running far above normal in its three largest tributaries, the Susquehanna, Potomac and James rivers.

The one thing about the higher flows is that it will cause the Bay to flush out faster. I suspect there will be some shorter term damage in the upper Bay, with excess freshwater and sediment having set back SAV and oysters, but a recovery will be rapid. It has been observed that high flow years generally lead to improved Striped Bass recruitment, so that's a positive.

A Good Sign: Bay Grasses Up Again

Underwater grasses up 8%; acreage is highest in decades

Underwater grasses, one of the most closely watched indicators of Chesapeake Bay health, surged to the highest levels seen in decades, according to survey results for 2016.

This is the second straight year that grasses have set a record.

Nearly 100,000 acres of the Bay’s and its tidal tributaries were covered by the underwater meadows, which provide habitat for juvenile fish and blue crabs, as well as food for waterfowl.

That was an 8 percent increase over 2015, and more than twice what was in the Bay just four years ago. “It was an impressive year following a previously impressive year and we are at numbers that we’ve not seen — ever,” said Bob Orth, an underwater grass expert with the Virginia Institute of Marine Science who oversees the annual aerial survey, which began 33 years ago.

 I would hate to be overly optimistic, but my feeling that the bay has turned a corner (for the better) is being reinforced. I'll be fishing on the Eastern Shore Saturday, and maybe we'll see some.

Green Alien Dominates the Potomac

What’s up with the green stuff invading the Potomac River?

Last month, Joe McMullin, coach of the freshman boys rowing team at Bethesda-Chevy Chase High School, sent his boats out into the Potomac only to have one get stuck in a green mat floating near Roosevelt Island. The mass extended off the island’s bank and into the river.

“It was also growing up near the steps near the Lincoln Memorial,” McMullin told Answer Man as the team assembled this past week at Thompson Boat Center.

As Answer Man looked across the Potomac, he could see a thin green margin edging Roosevelt Island.

“Two weeks ago, the heavy rains cleared it out,” Joe said. “It was pretty bad the first two or three weeks of September.”

The tide was rising, which was another reason the green carpet was not as visible as it often is, for it grows up from the river bottom. Biologists call it submerged aquatic vegetation, SAV for short.

The SAV in the DMV includes the invasive species hydrilla along with such mellifluously named native species as small pondweed, spiny naiad, water stargrass, wild celery and coontail. It’s all thriving, which has divided experts.
. . .
Dean blames the increased SAV on pollution, namely nutrient runoff: fertilizer, farm waste, pet waste and the overflow from combined storm water and sewage systems in the District and Alexandria. All of it washes into the river and encourages the growth of SAV. In warm, stagnant or slow-moving water, algae will often bloom atop the vegetation

Well, yes, plants need nutrients, and the added nutrients from all the shit coming in from up stream do contribute to the growth of the plants, but in so doing, the plants take nutrients out of the water, and at least temprorarily sequester it, moderating its influence farther down stream

But others feel that the increase in the Potomac’s SAV — including hydrilla, a once much-maligned species whose reputation has improved in recent years — is because the river is actually cleaner. Improvements in wastewater treatment have reduced the overall nutrient load. And a Potomac strewn with vegetation is actually more natural, said R. Christian Jones, a freshwater ecologist and director of George Mason University’s Potomac Environmental Research and Education Center.

“Our best guess is that all of the shallow areas of the Potomac were covered with submerged aquatic vegetation when the Europeans first came to the area,” Jones said.

Mattawoman Creek, a Potomac tributary south of Washington, is just loaded with Largemouth Bass and Northern Snakeheads.

Bay Grasses Had a Good Year

Underwater grass abundance in the Chesapeake Bay increased 24 percent between 2012 and 2013, reversing the downward trend of the last three years.

Because underwater grasses are sensitive to pollution but quick to respond to water quality improvements, their abundance is a good indicator of Bay health. Aerial surveys flown from last spring to last fall showed an almost 12,000-acre increase in grass abundance across the Bay, which scientists attribute to the rapid expansion of widgeon grass in the saltier waters of the mid-Bay and the modest recovery of eelgrass in shallow waters where the species experienced a “dieback” after the hot summers of 2005 and 2010. Scientists also observed an increase in the acreage of the Susquehanna Flats.

I would hasten to add that the grasses are also very weather/climate dependent, and wide variation from year to year are the norm.  It's good to see such an increase, but as they say regarding the stock market "past performance is no guarantee of future results." 

“The mid-Bay has seen a big rise in widgeon grass,” said Robert J. Orth, Virginia Institute of Marine Science (VIMS) professor and coordinator of the school’s Submerged Aquatic Vegetation Survey, in a media release. “In fact, the expansion of this species in the saltier waters between the Honga River and Pocomoke Sound was one of the driving factors behind the rise in bay grass abundance. While widgeongrass is a boom and bust species, notorious for being incredibly abundant one year and entirely absent the next, its growth is nevertheless great to see.”

What I said.

There's a tendency in writing up this stuff to claim good years as proof the current Bay restoration efforts are working - keep them up, and in bad years to say it's all the weather's fault, and we need to try harder.

As to 2014?  We'll see.  I'm moderately optimistic; we haven't (yet?) had the huge deluges that wash in massive sediment loads, and nutrients, which are important pollutants from the point of view of a sea grass.

DNA Used to Track Renegade Pond Weed

From the USGS: New DNA Tool Helps Scientists Identify Invasive Species of Aquatic Plants

A new DNA protocol developed by the U.S. Geological Survey helps biologists distinguish between native and invasive species of aquatic vegetation that have almost identical appearances. Until now, measuring the dispersal of these various invasive plants has been hampered by confusion about where and when the plants arrived.

Invasive aquatic plants from Korea, Brazil, and the Indian subcontinent have been spreading through U.S. waterways for decades. The new DNA protocol will help biologists identify species, track their progress, and provide facts to local managers who can develop appropriate control measures.

“When invasive plants appear in a body of water, local people naturally are alarmed” said Nancy Rybicki, the USGS biologist who teamed up with molecular biologists to develop the new DNA testing technique. “Enormous amounts of money are spent on control. Some species may look very nearly identical, but they have unique reproductive and growth characteristics. Identification, the first step for control or eradication, needs to be precise.”

Using this new protocol, Rybicki determined that hydrilla arrived in both the Potomac River and Chesapeake Bay earlier than previously thought, a finding that revises earlier ideas of how it was first introduced into the area.

The authors found that hydrilla was in the Potomac River in 1976. Thus, the original introduction of hydrilla to the Potomac was not from National Park Service experiments conducted in 1980 at Dyke Marsh on the tidal Potomac River as previously thought. It is probable that hydrilla was already present, but was misidentified. It may still be undiscovered in many locations today.

Huge beds of Hydrilla are widely credited with helping to clean up portions of the Potomac River. And they make good habitat for another invader, the Chinese Snakehead.

The two biotypes of hydrilla, one first introduced into Florida and the other first introduced into Washington, DC, are both spreading toward Canada, well beyond their predicted range.

“We anticipate that hydrilla will continue to move into colder regions, including, the Great Lakes, where a native plant called elodea is common,” Rybicki explained. “Without DNA verification, misidentification of the two plants is likely.”

New technologies are nice, but it's kind of sad when it gets to where scientists are relying on DNA tests instead of whipping out the cheap dichotomous key and learning what traits distinguish the two species.

Can Bird $#!* Save the Bay?

Eelgrass in Long Island Sound

Scientists discover that marine animals disperse seagrass

...a recent study in Marine Ecology Progress Series documents that several species of marine animal are key to dispersing seagrass, overturning the assumption that seagrass was largely dispersed by abiotic methods (such as wind and waves).

"Traditional thinking is that eelgrass disperses by abiotic mechanisms such as floating seeds, floating reproductive shoots, or currents pushing seeds along the seafloor," explains lead author Sarah Sumoski with the Virginia Institute of Marine Science. "Our study shows that eelgrass seeds can also be dispersed through consumption and excretion by fish, terrapins, and birds—providing a means to bring seeds to isolated areas."

The researchers studied eelgrass (Zostera marina), a type of seagrass, in the Chesapeake Bay in the eastern U.S. Feeding nearly two thousand eelgrass seeds to five species—including three fish, one turtle, and one seabird—the researchers found that the seeds survived the passage through the animal's guts and germinated successfully. But survival isn't the only important thing to a plant: distance also matters. If a plant species is to colonize new areas it will need to ensure its seeds can go far.

"We estimate that the fishes could disperse eelgrass seeds 10s to 100s of meters, while the maximum dispersal distance for terrapins is around 1,500 meters, or about a mile. The scaup [seabird] was the champ, with a maximum dispersal distance of more than 10 miles," explains Sumoski.

While dispersal by winds and currents are also likely important, Sumoksi says that seagrass seeds dispersed by animals may have a better chance for survival.

"[Animals] prefer to live under the conditions that favor seagrass growth and thus will tend to carry seeds to areas where they'll germinate. Wind and currents can easily disperse seeds into areas unsuitable for seagrass growth."

The last is an important concept; seeds dispersed to unfavorable areas is wasted.  With an animal vector, the chance of the seed finding suitable habitat for living is much increased.  This reminds me of the old biblical passage, the parable of the sower, Mark 4:8.

And some fell among thorns, and the thorns grew up, and choked it, and it yielded no fruit. And other fell on good ground, and did yield fruit that sprang up and increased; and brought forth, some thirty, and some sixty, and some an hundred.

 I don't plan to make biblical quotes a habit.