SNAKEHEAD!

If you come and visit us at the Reed Center, you will be greeted by the newest resident of our 550-gallon tank: a Northern Snakehead fish. An object of lore and legend, the Northern Snakehead is known for being a foreboding invasive species of the Chespeake Bay’s rivers. Between the ability to eat fish up to a third of their body size (which can get up to 2 feet), and their ability to survive out of water if kept moist for up to four days (due to gills that resemble primitive lungs), these fish have acquired quite a reputation.

The Northern Snakehead that inhabits our large tank at the Reed Center. Say Cheese!
Photo Credit: Marlene Plumley (SERC Education Docent)

The Snakehead Saga:

The Northern Snakehead, Channa argus, originates from China, and was first spotted in Chesapeake waters in May of 2002, in Crofton, MD. Scientists quickly noticed that snakeheads had the potential to seriously disrupt natural food web systems, because as top-level predators, snakeheads were eating anything they could fit in their mouth. Snakeheads were quickly marked as an invasive species and eradication began. MDDNR posted signs telling the public to kill any snakehead they found and to alert MDDNR.

After two years of relatively no news of the snakeheads, they showed up in the Potomac River. However, because snakeheads prefer fresher waters, it was thought that the saltier waters of the Bay would keep the snakeheads from leaving the Potomac and spreading through the Bay. Essentially, the saltier waters of the Bay were to act like a barrier, made up of intolerable waters. However, increased spring runoff caused the salinity of the Bay to decline, expanded the area that the snakeheads’ could tolerate, and opened the opportunity for them to invade other tributaries.

This past summer (2011), SERC scientists and interns found a pregnant female snakehead in the Rhode River, here at SERC. Of course it made the news, and worried scientists that there was probably more than just the one individual present in the Rhode River and similar tributaries.

What’s going on now

Snakeheads are still found in the Potomac River, and MDDNR still offers a monetary reward for catching, killing, and reporting a snakehead catch. At SERC’s Family Day this year, the Fish and Invertebrate Lab had a Northern Snakehead from the Potomac River on display in a tank. Now, we have inherited the fancy fish and are telling everyone. By having the snakehead available for the public to view at the Reed Center, you can come by and see what a real one looks like, increase awareness of Northern Snakeheads, and drum up conversations about the ecological impacts of invasive species. Plus, the fish looks pretty cool (the name alludes to the awesome patterned coloration). Stop by and check it out!

Click here to view the blog post on SERC’s blog Shorelines about the snakehead they caught last summer, and here to read first-hand accounts of the people who caught it.

Oysters and Carbon Dioxide?

If you’ve been to SERC lately, you may have seen this strange plot off the right side of the dock:

Maybe you thought, ‘What are those blue and green pool noodles doing sitting so elegantly in square formation? Why are there interns in SCUBA gear pulling up oyster shells? What is going on?!’

Thanks to Chesapeake Quarterly, we have answers. That square plot is the where Whitman Miller, a SERC scientist, is doing research on how ocean acidification affects oyster populations.

At the water testing station of Estuary Chesapeake, we measure the pH of the Rhode River and discuss how any deviation from neutral conditions can have a negative effects on aquatic biological processes. Whitman has taken this question and turned it into a full-blown scientific investigation.

Here’s a link to a preliminary study:
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0005661.

Let’s break down his study into the parts of the scientific method:
Question, Background Research, Hypothesis, Test the Hypothesis/Method, Analyze, Report your findings 

Question: Since all good scientific study starts with a question, here’s Whitman’s: What would happen to oysters in an acidifying Chesapeake? 

Background Research: What information and observations lead him to ask this question?

SERC is home to the longest running CO₂ study on plant communities. In that study scientists created marsh chambers with elevated levels of CO₂ to simulate what the atmosphere could be like in the future.  Now Tom Arnold, a chemical ecologist from Dickinson College, and Whitman Miller are taking the same idea and applying it to an aquatic animal: the oyster.

Research has revealed that higher levels of CO₂ in the atmosphere are changing Earth’s climate. About a third of that CO₂ ends up getting absorbed into the world’s oceans, causing reactions to change the chemistry of the water. When CO₂ absorbs into water, it creates carbonic acid, which could make it hard for organisms like oysters to form their shells made of calcium carbonate. Here’s how it works:

To make matters worse, in areas like the Chesapeake Bay, an excess of nutrients like nitrogen and phosphorus can cause higher levels of CO₂. Studies have investigated this issue in a marine (or ocean) settings, but there isn’t enough research on coastal and estuarine settings (like the Rhode River).

Hypothesis: If the acidity of the Bay’s waters continue to increase, then the growth rate of young oyster shells will decrease.

Test the Hypothesis/Method: Whitman and Tom used tanks to pump CO₂ into the river bottom where baskets of young oysters were set up in order to raise the CO₂ levels and simulate future conditions. He then measures the surface area of the shells, how fast the shells are growing, how fast the larvae are growing, and the chemical makeup of the shells.

Analyze: Data has shown that estuarine shell-forming organisms are vulnerable to the effects of more CO₂ in the water, and that the effects are different across species- meaning, the conditions affect different types of oysters and other shelled organisms differently. However, Whitman has had to postpone research due to increased precipitation in early summer.

Report Your Findings: When charting the data he has so far, Whitman has found a 16% decrease in how fast native oyster mature in conditions simulating CO₂ levels of the year 2100, and a 42% decrease in the amount of calcium in the shells. Whitman is still collecting data, so more conclusions will come in the future.

This kind of study deserves a lot of attention. For one, it attacks a hole in aquatic chemical ecology. Before this study, research on acidification in oceans had been just beginning, but acidification in coastal and estuarine zones was barely existent.

The study also deserves attention because it has implications for both economic and restoration efforts surrounding the Bay’s oyster populations. If oysters aren’t going to be able to grow their shells as strong or large, there will be less to sell AND there will be less places for new baby oysters to hook onto (check out this video to learn more about the life of oysters).

On the Estuary Chesapeake Field trip, we tell you how you are investigating an estuary alongside SERC researchers. This study shows you just that-

We test pH, they test pH— Scientists use some of the same methods we use to test pH to answer some of the questions we hypothesize about in our discussions at Station 2: Water Testing.

We use oyster baskets, they use oyster baskets— The same kinds of baskets we use, the ones that are hanging off the dock at Station 3: Oyster Bar Community, are the same kinds that Whitman and his team used to house the young oysters that were receiving extra CO₂ gas.

We examine oyster shells, they examine oyster shells— The way we carefully make observations about the shape, size and organisms present on the oyster shells at Station 3: Oyster Bar Community is similar to how researchers examine the oysters that are part of their study.

If you and/or your class are interested in learning more about Whitman’s study, comment and ask some questions. We challenge you to trail blaze the issue of acidification in estuaries: come up with some great science questions that could lead to new research questions. Let these few questions get your brain moving…..

What other organisms might be affected? What other processes and conditions could make the situation worse? What can we do to help?

(Check out the original article published in Chesapeake Quarterly: An Acidifying Estuary? The “Other CO₂ Problem”)

Exploring Local Biodiversity Wrap Up

The past two weeks have been very busy on our education dock! Thursday, March 29 concluded a group of schools visiting SERC as part of an exciting collaborative education initiative between SERC, the National Zoological Park, Friends of the National Zoo, and DC teachers. Exploring Local Biodiversity aimed to train teachers from DC to develop inquiry-based science lessons focused on aquatic and terrestrial ecosystems around the Chesapeake Bay and the importance of biodiversity in a changing world.

This program built an important link between science education providers (SERC and the National Zoo) and local science teachers. The goal was to empower these teachers in providing Smithsonian resources to fill the gap between their existing science education framework and the expectations of new science standardized testing requirements.

At the crux of the program was a combination of teacher training sessions and student field trips at both the National Zoo and SERC. Applying techniques acquired in training sessions, teachers in the program developed classroom lessons that were supplemented by a field trip to the National Zoo’s Invertebrate exhibit and SERC’s Estuary Chesapeake program. These hands-on experiences connected the dots for students by putting scientific method-based learning into practice while exposing them first-hand to the broader concepts and issues of the Chesapeake Bay watershed.

In the span of just two weeks, over 450 students visited SERC as part of the Exploring Local Biodiversity program. We had a great time exploring new techniques and lessons. Hardy Middle School crossed into new territory by empowering eighth grade student leaders from their NEMO program to lead the stations. The DC Bilingual Public Charter School bumped up their lessons by spending half the day investigating earthworms, a topic they had been learning about in the classroom prior to their visit. Using a mustard water solution, students extracted, counted, and observed over 350 earthworms! Collectively, all students recorded data on the biodiversity in the Rhode River by investigating benthic oyster bar communities and seining (fishing with a seine net) in near-shore aquatic habitats. Their data can be found here.

Thanks to Alan Peters of the National Zoological Park, we have a photo slideshow that narrates DC Bilingual’s trip to SERC. Click on the first image (the bus) to see a larger version of the slideshow. Once in slideshow mode, click right to see more.

The DC Bilingual Public Charter school arrived in transportation provided by the National Zoo

As soon as the students arrived Jane Holly, the K-8 School Programs Coordinator, gave an introduction to the whole group. With the help of a fleet of trained docents, the students watch a demonstration on how to catch near-shore fish with a seine net.

The group split in half: while one half rotated through the 5 Estuary Chesapeake stations, the other half became young SERC scientists and investigated earthworms in an upland forest. Each small group was equipped with a data sheet and worm extraction materials.

The group was split up into smaller teams in which they investigated a ~1m x 1m plot.

Armed with plastic tweezers, students waited for earthworms to surface after dousing the plot with a mustard and water solution, an irritant for the earth worms.

Students counted and observed physical features of the earthworms in small collection containers.

Students compared the size and color of collected worms, as well as when it rose out of the ground (indicated how deep in the soil column it was).

The other half of the day was spent rotating through the five Estuary Chesapeake Stations. At Station 1: About Crabs, students discuss anatomy, diet, behavior, sex identification, and habitat of blue crabs, and then try three methods of catching crabs.

One of the DC Bilingual teachers lead the About Crabs station for this group, engaging in discussions supported by classroom lessons.

Students try catching crabs using the baited hand line method.

At Station 2: Water Testing students measure five parameters of the quality of the Rhode River. One of these five parameters is salinity, or how salty the water is. Students use hydrometers to measure the salinity of the Rhode River in parts per thousand (ppt).

At Station 3: Oyster Bar Community, students observe, sort, and identify organisms living in the benthic oyster bar community.

Students look through an oyster basket that hangs off the side of the dock and pull out any organisms they find.

One of our newest docents, a local oyster farmer and Bay enthusiast, helps this student take a closer look at an organism through a magnified viewer.

At Station 4: Investigating Plankton, students do a plankton tow to collect a sample containing plankton.

Back in the classroom, a station leader explains the importance of plankton and their role in the global ecosystem, right before letting each student observe the plankton that the group caught under a microscope.

At Station 5: Seining (Going Fishing) student put on chest waders to allow them to go out into the river without getting wet.

Students go out into the shallow waters of the seining beach to catch fish using a seine net.

Moving all the way up to the beach, students scoop up the net to reveal what they caught.

All students get the chance to go in the water to seine. Back at the beach, anyone not in the water helps to identify what fish were caught. Observed species are recorded on a data sheet.

After a wonderful day at SERC, we thank DC Bilingual Public Charter School for participating and encourage post-trip collaboration,

To see more photos from last week, check out our post about the first day of spring trips, or our photo gallery (a collection of all of our Estuary Chesapeake photos).

First day of spring field trips!

Grass shrimp, rotifers, and alewives, oh my!

Today, March 20th, was the first day of the spring 2012 season of Estuary Chesapeake field trips. When we scheduled these trips months ago, we feared the weather might be too cold for comfort, and that the Rhode River organisms might be sparse. But sure enough, these past few weeks rolled around and we had clear skies with highs near 70 and up. So when it rained last night we worried that we’d be sloshing in our galoshes, but the morning stayed dry the day ended sunny and warm, a great combination for the first day of Estuary Chesapeake.

At the water testing station we recorded a salinity of around 8 ppt, temperature of 20 degrees Celsius, depth of 190 cm, and light penetrating down the water column through about 85 centimeters. A lower salinity and low turbidity (deeper light penetration) are pretty typical conditions for this time of year, so we were glad to see the consistency.

As for the organisms, diversity was plentiful. If you check out the data we collected today on the spring 2012 page, you’ll see just that. Mating amphipods were swarming the oyster baskets. The students found 2 blennies and a few naked gobies in the oyster baskets, as well as some worms and grass shrimp. At the plankton station we saw a comb jelly, nauplia, rotifers, and mosquito larvae.

At the seining station we were excited to see the diversity of young fish expected at this time of the season. There were over 18 pumpkinseeds caught, over 50 silversides, and over 15 mummichogs caught today. In the afternoon, seiners caught 2 species that were pretty exciting- the alewife (10) and the spotted seatrout (3). Both species look similar to other close relatives, so Mark helped us out with identification. The alewife is part of the subfamily Alosinae, the same as the blueback herring and the more commonly known menhaden. One sure way to distinguish an alewife from a blueback herring is to open the abdomen, and look for characteristic coloration. When you open up the abdomen, alewives exhibit a white silvery region, while bluebacks have a dark/black region. Since our specimen did not survive the stress of the seining station, we were able to open it up postmortem and determine that it was an alewife. Click here to see a side by side comparison of the two fish on the Maryland Department of Natural Resources site: http://www.dnr.state.md.us/fisheries/fishfacts/herring.asp.

As for the spotted sea trout, it looks very similar to a weakfish. But small juvenile spotted   make their way into the Bay in April and like to live in shallow tidal creeks and beds of submerged aquatic vegetation. Weakfish don’t usually show up in the Rhode River until later in the year when they are larger juveniles. We used this information to identify our specimen as a spotted sea trout.

We noticed something interesting about the grass shrimp. At the oyster station, there were about 10 of them hanging out in the oyster baskets, but we caught zero at the seining station. Why do you think this is?

We hypothesized two options: the mesh in our net was too wide to catch the small grass shrimp, or they were choosing the benthic habitat of the oyster baskets over the seining beach shoreline. Why do you think they might be hanging out in the oyster baskets? Protection? Food availability? Tell us your hypotheses!

I want to give a shout out to the NEMO leaders from Hardy Middle School who did a great job teaching at all five of the stations. We were very impressed with your knowledge and leadership. It was a pleasure to work with you all- thanks for helping to make it a great first day!

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Spring Has Sprung!

It seems Father Time and Punxsutawney Phil didn’t get the memo from Mother Nature this year. Spring has sprung just a little early, and boy are we excited about it at SERC. How do we know that spring is just around the corner? For me, it’s the blooming pear trees that line the highways on my drive into work, the deafening calls of spring peepers on the way home, and the surge of mating amphipods that we are finding in the oyster baskets down at the dock. I asked around the office to find out what are some of SERC Education staff’s favorite indicators of spring, and we came up with a pretty great list.

Mating amphipods on the dock.

Karen, an avid amphibian admirer and advocate, said the sounds and sights of salamanders and frogs are some of her favorite tip offs that spring is here. Lucky for her, one of our staff’s favorite spring indicators showed up for the first time on her birthday: the osprey! We sighted our first osprey out over the South River on March 8th. Karen can’t wait for the pollinators, like bees and butterflies, to start doing their jobs. That’s when she knows that spring is official.

Wood frog spotted on SERC's back road. (Photo credit: Karen McDonald)

Julia uses her senses to feel out the start of spring. When she smells a combination of wet dirt, blooming pear trees, and pollen, hears the marsh crackle and wild turkeys’ mating calls, and sees the crocuses and daffodils burst, she knows spring has arrived. But Julia has an old standby to let her know spring is ringin- she looks out for the annual reveal of the pale-legged scientists who pull shorts out of their closets for the first time of the year.

Josh sees his asparagus eeking out of the garden and knows that a season of new tastes is in store. Soon fresh fruits and vegetables will be coming from some more local sources, followed by the long-awaited crab season. Most people get excited about the cherry blossoms popping with color, but Josh knows there’s another pink tree that puts on just as bright of a show: the redbuds. He says when he sees those trees he knows spring is here.

Eastern Redbud tree.

Our new intern Aaron came to us from Michigan, out in a more rural area. Aaron knows it’s spring when he hears and smells the neighbor’s lawn mowers cutting grass, and kids playing outside. The longer hours of daylight and the sounds of chirping insects and birds are some of Aaron’s favorite spring indicators, no matter which U.S. state he is in.

Jane’s signal of spring is simple: ospreys. Jane pulls out her spring wardrobe as soon as she watches those ospreys make their nests and hears their calls.

Osprey

There’s one other thing that Jane waits for this time of year: Estuary Chesapeake Field Trips. Months of planning and preparing bring us to Tuesday, the first day of our Estuary Chesapeake field trips, and we are thrilled. Starting out strong with a big group, we’ve already trained our station leaders from Hardy Middle School. This trip is unique- the station leaders are 8th grade students, who are part of the NEMO marine science program at Hardy. They are a great group of smart and enthusiastic students, and we are so excited to see how the program goes.

Since a new season of trips is upon us, we will be posting all the new data under a new page of “Spring 2012 Data.” This means that data from fall 2011 will move into “Past School Data.”

SO TELL US: What are some of your favorite indicators of spring? What are you most looking forward to this season? 

The Tiny Life of Oysters

Not sure how to start your discussions on oysters? Check out this video, The Tiny Life of Oysters:

Oysters may lead a tiny life, but their story has a long history and a big impact. This video mentions important concepts that we talk about at Station 3: Oyster Bar Community.

• Oyster reefs provide a habitat for benthic (bottom dwelling) organisms to live in and around.
• The oyster population is currently less 1% of its original size, which poses and environmental and economic threat to the Chesapeake Bay watershed.
• The decline in oyster population is due largely in part to over harvesting, diseases like MSX and Dermo, and habitat loss due to increased sedimentation and turbidity.
• Restoration efforts to increase the oyster population have been focused on building oyster reefs, so that oyster larvae have a surface to attach to in order to grow.

This video has some great visualizations, too. The idea of “oyster spat” is sometimes confusing. Oysters start their life as larvae, and are considered spat only for the first year of life, and only after they attach to a substrate. Although not labeled, around minute 1:20, there is a great visualization of larvae free-floating until they attach to the oyster reef.

To understand just how tiny the larvae are when they are released, check out the visual around minute 1:45. Once attached, oysters are sessile, or not moving, but as larvae, they are free-floating in the water column and moved around by currents.

Around minute 1:56 there is an awesome simulation of oyster larvae moving throughout the Choptank River, a river system that is part of the Chesapeake Bay watershed. The simulation ties it all together of how these tiny oyster larvae are the key to the success of building oyster reefs.

This video pairs well with one of the information sheets from the teacher packet that each teacher receives at their first training workshop. Curious? Check out the training workshop dates and contact Jane Holly to sign up!

Parent/Teacher Training Workshop Dates

The schedule for spring Parent/Teacher Training Workshops has been finalized. All new teachers, and all parents/chaperons should attend a training workshop before their field trip. Workshops are free, and generally last two hours.

Attending a workshop is essential to understanding the steps of the grand dance that is Estuary Chesapeake. We appreciate your time and assistance, and so we want to make the experience worthwhile for you, too.

To sign up for a workshop, contact Jane Holly at hollyj@si.edu or 443.482.2216

Wednesday March 21: 4pm-6pm

Thursday March 29: 11am-1pm

Tuesday April 10: 11am-1pm

Wednesday April 11: 4pm-6pm

Thursday April 12: 11am-1pm

Saturday April 14: 10am-12pm

Wednesday April 18: 4pm-6pm

Wednesday May 9: 4pm-6pm