Page 28 - AT

A28 SCIENCE
Saturday 28 december 2019
Scientists struggle to save seagrass from coastal pollution

By MICHAEL CASEY and More than $2.5 billion was
ANDREW SELSKY spent on upgrades to sew-
DURHAM, N.H. (AP) — Peer- age treatment plants, mea-
ing over the side of his skiff sures to address stormwater
anchored in the middle of runoff and curbs on nitro-
New Hampshire’s Great gen emissions from power
Bay, Fred Short liked what plants. That resulted in two-
he saw. thirds less nitrogen going
Just below the surface, into the bay compared to
the 69-year-old marine the 1970s, according to Ed
ecologist noticed beds Sherwood, executive direc-
of bright green seagrass tor of the Tampa Bay Estu-
swaying in the waist-deep ary Program.
water. It was the latest Seagrass area nearly dou-
sign that these plants with bled to about 63 square
ribbon-like strands, which miles (163 square kilome-
had declined up to 80% ters). The water quality im-
since the 1990s, were start- provement along with a gill
ing to bounce back with net ban has contributed to
improved water quality. the recovery of several fish
Seven rivers carry pollution species including striped
from 52 communities in mullet, red drum and spot-
New Hampshire and Maine In this undated photo provided by the Massachusetts Division of Marine Fisheries, a winter flounder ted sea trout.
into the 1,020-square-mile rests in a restored eelgrass meadow in the outer Boston Harbor. But such stories can’t mask
(2,650-square-kilometer) the challenges.
watershed for the bay. cies of seagrasses are ning speed. Central Cali- gen do result in the eco- Some recoveries such as
“It actually looks better among the most poorly fornia’s scenic Morro Bay system starting to come those in parts of the Boston
than it did last year at this protected but widespread has lost more than 90% of back,” Moraff said. Harbor and the Great Bay
time and better than has in coastal habitats — more its eelgrass since 2007. Studies have documented are at risk from dredging. In
many years,” said Short, a than 116,000 square miles “It’s certainly not a pretty seagrass recovery in Bos- other places, such as Ches-
noted seagrass expert who (300,000 square kilome- picture and may not get ton, Tampa Bay and Long apeake Bay, a decline
coordinates the monitor- ters) have been mapped, any prettier because of the Island Sound. in nitrogen has benefited
ing of 135 sites around the though there could be 10 climate change issues we Boston Harbor was once many underwater plants
world from his University of times that. They are found are all dealing with,” said known as the dirtiest harbor but not eelgrass, which has
New Hampshire lab. along coastlines around Virginia Institute of Marine in America because most declined since the 1990s.
“You see here,” he said, the world except Antarc- Science’s Robert Orth, a waste went into the waters Brooke Landry, a Maryland
glancing into the water. tica’s. professor who has stud- untreated. Department of Natural Re-
“It’s nearly 100% cover. You Seagrasses, which cover ied seagrass for decades. Then the state invested $3.8 sources biologist who moni-
look to the bottom. You less than 0.2% of the world’s “These plants are very sensi- billion in a treatment facil- tors the bay’s underwater
can’t see the mud. You oceans, store twice as tive to environmental char- ity on Deer Island that was vegetation, said that eel-
just see eelgrass. That is as much carbon in a given acteristics — water quality, completed in 2001 and al- grass, a coldwater species,
dense as it gets. That’s a re- area as temperate and temperature.” lowed wastewater to be may be more susceptible
ally good sign.” tropical forests, a study by In parts of the United States piped almost 10 miles (16 to heat events as seen in
Seagrass beds in New the United Nations-affiliat- and other developed kilometers) out into Mas- 2005 and 2010 — or to over-
Hampshire and along ed Blue Carbon Initiative countries, there is growing sachusetts Bay. The state ly cloudy waters in the bay.
shorelines around the world found. But seagrass mead- recognition of the impor- has documented an 80% Scientists are also struggling
are important because ows in many places are tance of seagrass and its decline in nitrogen levels in to understand why eelgrass
they have been found to imperiled by coastal devel- sensitivity to nitrogen-rich the harbor. hasn’t come back in Cali-
provide food and shelter opment, overfishing, runoff runoff from sewage treat- Tay Evans, a seagrass spe- fornia’s Morro Bay.
for fish, shellfish and sea from farm waste, and the ment plants and other cialist with the Massachu- “We have some theories,”
turtles. They also blunt the growing threat from cli- sources. Too much nitrogen setts Division of Marine said Jennifer O’Leary, who
impacts of ocean acidifi- mate change. They have can spike algae growth, Fisheries, said there has studied the bay as a Cali-
cation, reduce coastal ero- declined roughly 7% annu- which clouds the water been a corresponding 50% fornia Sea Grant research-
sion and keep the water ally since the 1990s, a peer- and blocks the sunlight increase in eelgrass from er. She said the eelgrass
clean by filtering out exces- reviewed study found. That seagrass needs to grow. 2006 to 2016. Now seagrass decline has occurred in
sive nutrients. is on par with the declines “We think this is a problem is growing in Governors Is- waters that are warmer,
Their comeback in the of tropical rain forests and that has to be solved,” said land Flats near Logan Inter- saltier, cloudier and less
Great Bay gives hope for coral reefs. Ken Moraff, water division national Airport. oxygenated than the bay’s
recovery elsewhere. Some seagrass declines director for U.S. Environmen- “It was astounding me,” mouth, where eelgrass did
The more than 70 spe- have occurred with stun- tal Protection Agency’s Evans said. “I dove there well.
New England region. Com- and saw what we would In New Hampshire, eelgrass
munities around the Great call a moonscape that was has recovered about 20%
Bay have spent about $200 just mud. You come back in parts of the Great Bay,
million to upgrade waste- and it’s a lush meadow though it hasn’t returned to
water treatment plants, re- and then you’re going to several areas.
sulting in some cutting nitro- see all the animals — the Some conservationists ar-
gen releases by up to 70%, winter flounder swimming gue that bayside com-
according to EPA and of- through there, lobster walk- munities need to further
ficials in several Great Bay ing around.” reduce nitrogen releases
communities. In Tampa Bay, seagrass through tens of millions of
“We’ve seen other areas beds are reaching levels dollars in treatment plant
where reductions in nitro- not seen since the 1950s. improvements.q