Chesapeake Bay

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Stomachs, Ear Bones and Electrofishing: Dissecting the Invaders

Friday, June 28th, 2013

By Katie Sinclair

SERCterms Mark and Brooke weigh and measure a bluecatfish.

SERC interns Mark and Brooke weigh and measure a blue catfish.

Ever wonder what a catfish eats? The blue catfish, invasive to the Chesapeake, is not a picky eater.

This voracious predator eats pretty much anything that can fit in its mouth.  By digging into their stomachs, a process vaguely reminiscent of high school biology classes, researchers can figure out the impact this species has on the ecosystem.

 In order to get some fresh catfish stomachs, researchers working in the Fish and Invertebrate Lab at SERC set up a “Gon’ fishing” sign and hit the field.

 Using a technique known as “electrofishing,” researchers stun the fish with electric currents in the water and collect them from several sites along the Chesapeake and rivers that feed into the Bay. Once the fish are caught, they place them into a cooler. The frozen fish are then identified by species, weighed and measured. Each fish varies tremendously: From a few ounces to over 10 lbs., a wide range of maturities and sizes are represented.

Paige and Mike begin to dissect the fish.

Paige and Mike begin to dissect the fish.

 A closer look at the stomach

A closer look at the stomach

The ecologists then remove the fish’s stomach,  taking great care to keep it intact. (Though frozen, the contents of a fish’s lower intestines tend to have a rather unpleasant smell). As fishermen know, gutting catfish can get messy, especially when the interns get involved.

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New Genome Helps Crack Methylmercury Code

Friday, April 15th, 2011

A bacterium called Desulfovibrio desulfuricans strain ND132 can transform elemental mercury into methylmercury, a human neurotoxin. Credit: Oak Ridge National Laboratory.

A newly decoded bacterial genome brings scientists one step closer to unlocking the secret behind the production of methylmercury, the chemical notorious for contaminating tuna and other seafood.

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Smithsonian Study Measures Watershed-wide Effects of Riparian Buffers on Nutrient Pollution

Wednesday, October 27th, 2010
Aerial photo of farmland and streams - with trees growing in between them.

Well-developed riparian forests outline streams and help protect stream water quality.

Most of the time, nutrients are viewed as a positive and essential part of life. However, excess amounts of a nutrient, like nitrogen, can create major ecological problems for the Chesapeake Bay and other aquatic ecosystems. Too much nitrogen leads to an abundance of microscopic plant growth in the water. When the algae die and decay, they consume the oxygen that other organisms need to thrive.

Much of the Bay’s nitrogen pollution comes from farms where rainwater carries nitrate, a form of nitrogen, from fields into streams that drain into the Bay. For years, ecologists have noted that forests and wetlands growing between croplands and streams can reduce the amount of nitrate that reaches the waterways. Scientists have measured nitrate removal by these “riparian buffers,” but only in small study areas.
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Eco Trekking across the Chesapeake Bay Watershed

Thursday, September 2nd, 2010
Sunset on Smith

Sunset on canoes in Tylerton, MD

This summer from August 7th through August 13th, 9 students went on a journey through the Chesapeake Bay watershed. This trip was organized and led by Josh Falk, an Education Specialist at SERC, and Kevin Schabow, an educator at the NOAA Chesapeake Bay Office. The purpose of this trip was to immerse high school age students in the complex nature of the science, culture and natural resources that the Bay’s watershed has to offer. This year, the students were assigned to report on what they learned and what they did. Here is their story.
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Seagrasses and Sunlight: Rethinking Water Quality Measurements

Wednesday, July 14th, 2010

Photo of eelgrass growing in the water.

Around the world seagrasses are being lost. Turbidity is one factor that impedes their growth. However, in some places water quality has improved, but the grasses have not rebounded. SERC scientists wonder if a 'carpet of fluff'—a mix of organic and inorganic particles that floats just above the sediment—is blocking the sunlight seedlings need to grow. Photo: Tim Carruthers courtesy of IAN/UMCES.

Peculiar phenomena have always brought researchers together. For SERC senior scientist Chuck Gallegos and Danish PhD student Troels Møller Pedersen it was a mutual interest in the “carpet of fluff” that floats just above the sediment in estuaries like the Chesapeake Bay. The fluff is a soupy mix of organic and inorganic particles. These particles pose a problem to underwater vegetation because they cloud-out sunlight that the plants, particularly seedlings, need. No one has documented just how much light this layer blocks. Pedersen and Gallegos hope to change this.
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A census of a different sort

Tuesday, April 27th, 2010

If you’re a fish or crab living in the Chesapeake Bay, it’s quite possible that at some point during your life, you’ll make your way into one of the creeks, rivers or subestuaries that feed the Chesapeake. These areas provide important nursery and spawning habitat for many of the Bay’s aquatic residents. For more than 25 years, researchers from the Smithsonian Environmental Research Center’s Fish and Invertebrate Ecology Lab have taken a weekly survey of the species that make their way into and out of one of these creeks. Its name is Muddy Creek and it feeds into the Rhode River, which flows into the Chesapeake Bay.


View Muddy Creek and the Rhode River in a larger map

To survey the animals swimming up and down Muddy Creek, the researchers use a fish weir — an expanse of nets, gates and boardwalks — that temporarily blocks aquatic traffic. Once a week, the researchers close the weir, set out the nets and identify and count all the species that get trapped. Their data go back to 1983.

This type of fine-scale surveying, that’s done on a weekly basis, is rare. It’s even more unique to have such long-term data. Many ecological studies are funded for just a few years at a time. These short time frames can make it difficult for scientists to observe changes and patterns in species populations and composition.

Human activity and environmental conditions can affect which species are swimming in Muddy Creek. The water is brackish and salinity levels change seasonally and from year to year. During winter and early spring, when freshwater flow is usually the highest, researchers will generally catch more freshwater species like bluespotted and banded sunfish – two protected species in Maryland. During periods of high salinity, researchers can catch many species indicative of the higher saline lower Bay such as, red drum, spotted sea trout, and Spanish mackerel.

In honor of the 2010 U.S. Census, we thought we’d share photos from one of this month’s surveys. The salinity on this April day was fairly low (~ 5 ppt) and nearly a dozen golden shiners (a freshwater minnow) were caught along with several estuarine-resident and a few diadromous (fish that migrate between fresh and saltwater) species. Among the highlights: a sizeable snapping turtle, many white perch in spawning condition, juvenile American eels and a parasite.

You can read more about SERC’s Muddy Creek survey on our Web site.

Phragmites australis: Genetic analysis reveals the promiscuous nature of the invasive reed

Friday, March 12th, 2010

Phragmites australis growing in a subestuary of Chesapeake Bay.

The non-native strain of Phragmites australis dominates many Chesapeake Bay wetlands. Photo Melissa McCormick.

Phragmites australis took its sweet time taking over East Coast wetlands. A non-native strain of the reed arrived in the U.S. around 1800, likely stowed away in the ballast material of European ships. For nearly two centuries the plant grew in relatively small pockets along the coast. Today it’s a poster child for invasive species. In some states along the Atlantic, it covers as much as a third of the tidal wetland acreage. Among other impacts, it challenges native plants for turf. The European strain has even out-competed North America’s native P. australis.
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Climate change may drastically alter Chesapeake Bay, scientists say

Thursday, December 3rd, 2009

Smithsonian researchers Lori Davias and Jenna Malek collect oysters on an intertidal reef in the Chesapeake Bay. It is difficult to predict the effect of climate change on oyster populations because increasing temperatures will likely have at least two opposing effects. On one hand, intertidal oyster populations may be able to expand northward as winter temperatures rise. On the other hand, increasing summer temperatures are likely to worsen the problem of low oxygen concentrations and may reduce the extent or suitability of some subtidal habitat currently used by oysters. At this point, scientists are unable to predict whether the combination of these two factors will result in a net increase or net loss of habitat.  Photo: Sean Fate

Smithsonian researchers Lori Davias and Jenna Malek collect oysters on an intertidal reef in the Chesapeake Bay. It is difficult to predict the effect of climate change on oyster populations because increasing temperatures will likely have at least two opposing effects. On one hand, intertidal oyster populations may be able to expand northward as winter temperatures rise. On the other hand, increasing summer temperatures are likely to worsen the problem of low oxygen concentrations and may reduce the extent or suitability of some subtidal habitat currently used by oysters. At this point, scientists are unable to predict whether the combination of these two factors will result in a net increase or net loss of habitat. Photo: Sean Fate

It is one of the largest and most productive estuaries in the world, yet dramatic changes are in store for the Chesapeake Bay in coming decades if climate change predictions hold true, say a team of scientists from the Smithsonian Environmental Research Center, the University of Maryland, Pennsylvania State University, and other research organizations in a recent paper published in the journal “Estuarine, Coastal and Shelf Science”

Using forecasts of atmospheric carbon dioxide production for the coming century, the scientists predict the water of the Bay will see rising levels of dissolved carbon dioxide and higher water temperatures. As a result, climate change is expected to worsen problems of low dissolved oxygen concentrations in the Chesapeake’s water and cause sea levels to rise.
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‘Tidal Freshwater Wetlands’ gives an overlooked ecosystem its due

Tuesday, November 17th, 2009

Tidal Freshwater Wetlands book cover

Tidal Freshwater Wetlands

There are certain obstacles you have to embrace if you are going to edit a book about tidal freshwater wetlands. They include: mud, mosquitoes and leeches. Smithsonian plant ecologist Dennis Whigham has accepted all three and then some.

Whigham, along with colleagues Aat Barendregt from Utrecht University and Andy Baldwin from the University of Maryland, has edited the new book Tidal Freshwater Wetlands. It’s a weighty work containing more than 20 chapters written by more than 40 authors. For the first time ever, they have systematically peeled back the layers of these overlooked coastal ecosystems. The book explores how these wetlands work, the animal and plant life they support, and the threats they face.
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