LTER | Data Nuggets

4.26.16

Make way for mummichogs

Collecting mummichogs and other fish out of research traps.

The activities are as follows:

Salt marshes are important habitats and contain a wide diversity of species. These ecosystems flood with salt water during the ocean’s high tide and drain as the tide goes out. Fresh water also flows into marshes from rivers and streams. Many species in the salt marsh can be affected when the movement of salt and fresh water across a tidal marsh is blocked by human activity, for example by the construction of roads. These restrictions to water movement, or tidal restrictions, can have many negative effects on salt marshes, such as changing the amount of salt in the marsh waters, or blocking fish from accessing different areas.

Local managers are working to remove tidal restrictions and bring back valuable habitat. At the same time, scientists are working to study how the remaining tidal restrictions impact fish populations. To do this, they measure the number of fish found upstream of tidal restrictions, which is the side connected to the river’s freshwater but cut off from the ocean when the restriction is in place. By taking measurements before and after the restriction is removed, scientists can study the impacts that the restriction had on fish populations

Mummichogs are a small species of fish that live in tidal marshes all along the Atlantic coast of the United States.

Mummichogs are a small species of fish that live in tidal marshes all along the Atlantic coast of the United States. They can be found in most streams and marsh areas and are therefore a valuable tool for scientists interested in comparing different marshes. The absence of mummichogs in a salt marsh is likely a sign that it is highly damaged.

In Gloucester, MA, students participating in Mass Audubon’s Salt Marsh Science Project are helping Liz and Robert use mummichogs to examine the health of a salt march. In 2002 and 2003 Liz, Robert, and the students set traps upstream of a road, which was acting as a tidal restriction. These traps collected mummichogs and other species of fish. The day after they set the traps, the students counted the number of each fish species found in the traps.

Students participating in Mass Audubon’s Salt Marsh Science Project Count fish at Eastern Point Wildlife Sanctuary, Gloucester, MA

In December 2003, a channel was dug below the road to remove the tidal restriction and restore the marsh. From 2004 to 2007, students in the program continued to place traps in the same upstream location and collect data in the same way each year. Students then compared the number of fish from before the restoration to the numbers found after the restriction was removed. The students thought that once the tidal restriction was removed, mummichogs would return to the upstream locations in the marsh.

Featured scientists: Liz Duff and Robert Buchsbaum from Mass Audubon. Written by: Maria Maradianos, Samantha Scola, and Megan Wagner.

Flesch–Kincaid Reading Grade Level = 10.9

Additional teacher resources related to this Data Nugget:

Data is available at Mass Audubon’s Salt Marsh Science websites on the Salt Marsh Science Project and their Fish Results & Data.
To view images from the restoration, marsh, and data collection, check out our PowerPoint presentation to accompany this Data Nugget.
This research was funded by the National Science Foundation as part of the Plum Island Ecosystems Long Term Ecological Research site.

4.20.16

Bye bye birdie? Part II

In Part I, you examined the patterns of total bird abundance at Hubbard Brook Experimental Forest. These data showed bird numbers at Hubbard Brook have declined since 1969. Is this true for every species of bird? You will now examine data for four species of birds to see if each of these species follows the same trend.

Red-eyed vireo in the Hubbard Brook Experimental Forest

The activities are as follows:

It is very hard to study migratory birds because they are at Hubbard Brook only during their breeding season (summer in the Northern Hemisphere). They spend the rest of their time in the neotropics or migrating between their two homes. Therefore, it can be difficult to tease out the many variables affecting bird populations over their entire range. To start, scientists decided to focus on what they could study—the habitat types at Hubbard Brook and how they might affect bird populations.

Hubbard Brook Forest was heavily logged and disturbed in the early 1900s. Trees were cut down to make wood products, like paper and housing materials. Logging ended in 1915, and various plants began to grow back. The area went through secondary succession, which refers to the naturally occurring changes in forest structure that happen as a forest recovers after it was cut down or otherwise disturbed. Today, the forest has grown back. Scientists know that as the forest grew older, its structure changed: Trees grew taller, and there was less shrubby understory. It contains a mixture of deciduous trees that lose their leaves in the winter (about 80–90%; mostly beech, maples, and birches) and evergreen trees that stay green all year (about 10–20%; mostly hemlock, spruce, and fir).

Richard and his fellow scientists used their knowledge of bird species and thought that some bird species prefer habitats found in younger forests, while others prefer habitats found in older forests. They decided to look into the habitat preferences of four important species of birds—Least Flycatcher, Red-eyed Vireo, Black-throated Green Warbler, and American Redstart—and compare them to habitats available at each stage of succession.

Least Flycatcher: The Least Flycatcher prefers to live in semi-open, mid-successional forests. The term mid-successional refers to forests that are still growing back after a disturbance. These forests usually consist of trees that are all about the same age and have a thick canopy at the top with few gaps, an open middle canopy, and a denser shrub layer close to the ground.
Black-throated Green Warbler: The Black-throated Green Warbler occupies a wide variety of habitats. It seems to prefer areas where deciduous and evergreen forests meet and can be found in both forest types. It avoids disturbed areas and forests that are just beginning succession. This species prefers both mid-successional and mature forests.
Red-eyed Vireo: The Red-eyed Vireo breeds in deciduous forests as well as forests that are mixed with deciduous and evergreen trees. They are abundant deep in the center of a forest. They avoid areas where trees have been cut down and do not live near the edge. After an area is logged, it often takes a very long time for this species to return.
American Redstart: The American Redstart generally prefers moist, deciduous, forests with many shrubs. Like the Least Flycatcher, this species prefers mid-successional forests.

Featured scientist: Richard Holmes from the Hubbard Brook Experimental Forest. Data Nugget written by: Sarah Turtle and Jackie Wilson.

Flesch–Kincaid Reading Grade Level = 10.2

A view of the Hubbard Brook Experimental Forest

Additional teacher resource related to this Data Nugget:

For more information on this research, check out the Hubbard Brook Experimental Forest’s page on their songbird research
For more lessons created from data collected on birds at Hubbard Brook, check out the page “Migratory Birds Math and Science Lessons from Hubbard Brook”
For the full lesson plan, upon which this Data Nugget was based, check out this page: Bye Bye Birdie?

There are two publications related to the data included in this activity:

Holmes, R. T. 2010. Birds in northern hardwoods ecosystems: Long-term research on population and community processes in the Hubbard Brook Experimental Forest. Forest Ecology and Management doi:10.1016/j.foreco.2010.06.021
Holmes, R.T., 2007. Understanding population change in migratory songbirds: long-term and experimental studies of Neotropical migrants in breeding and wintering areas. Ibis 149 (Suppl. 2), 2-13

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4.20.16

Bye bye birdie? Part I

Male Black-throated Blue Warbler feeding nestlings. Nests of this species are built typically less than one meter above ground in a shrub such as hobblebush. Photo by N. Rodenhouse.

The activities are as follows:

The Hubbard Brook Experimental Forest is an area where scientists have collected ecological data for many years. It is located in the White Mountains of New Hampshire, and data collected in this forest helps uncover trends that happen over long periods of time. It is important to collect data on ecosystems over time, because these patterns could be missed with shorter experiments.

Richard Holmes is an avian ecologist who began this study because he was interested in how bird populations were responding to long-term environmental change.

Each spring, Hubbard Brook comes alive with the arrival of migratory birds. Many migrate from wintering areas in the tropics to take advantage of the abundant insects and the long summer days of northern areas, which are beneficial when raising young. Avian ecologists, scientists who study the ecology of birds, have been keeping records on the birds that live in the experimental forest for over 40 years. These data are important because they represent one of the longest bird studies ever conducted!

Richard is an avian ecologist who began this study. He was interested in how bird populations were responding to long-term environmental changes in Hubbard Brook. Every summer since 1969, Richard takes his team of scientists, students, and technicians into the field to count the number of birds that are in the forest and identify which species are present. Richard’s team monitors populations of over 30 different bird species. They wake up every morning before the sun rises and travel to the far reaches of the forest. They listen for, look for, identify, and count all the birds they find. The scientists record the number of birds observed in four different study areas, each of which are 10 hectare in size – roughly the same size as 19 football fields! Each of the four study areas contain data collection points that are arranged in transects that run east to west along the valley. Transects are parallel lines along which the measurements are taken. Each transect is approximately 500m apart from the next. At each point on each transect, an observer stands for ten minutes recording all birds seen or heard during a ten minute interval, and estimates the distance the bird is from the observer. The team has been trained to be able to identify the birds by sight, but also by their calls. Team members are even able to identify how far away a bird is by hearing its call! The entire valley is covered three times a season. By looking at bird abundance data, Richard can identify trends that reveal how avian populations change over time.

Featured scientist: Richard Holmes from the Hubbard Brook Experimental Forest. Data Nugget written by: Sarah Turtle, Jackie Wilson and Elizabeth Schultheis.

Flesch–Kincaid Reading Grade Level = 10.6

A view of the Hubbard Brook Experimental Forest

Additional teacher resource related to this Data Nugget:

For more information on this research, check out the Hubbard Brook Experimental Forest’s page on their songbird research
For more lessons created from data collected on birds at Hubbard Brook, check out the page “Migratory Birds Math and Science Lessons from Hubbard Brook”
For the full lesson plan, upon which this Data Nugget was based, check out this page: Bye Bye Birdie?

There are two publications related to the data included in this activity:

Holmes, R. T. 2010. Birds in northern hardwoods ecosystems: Long-term research on population and community processes in the Hubbard Brook Experimental Forest. Forest Ecology and Management doi:10.1016/j.foreco.2010.06.021
Holmes, R.T., 2007. Understanding population change in migratory songbirds: long-term and experimental studies of Neotropical migrants in breeding and wintering areas. Ibis 149 (Suppl. 2), 2-13

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4.8.16

LTER Data Nuggets: Breathing new life into long-term data

The original blog post can be found on the KBS LTER website here.

Each year the KBS LTER program awards graduate students summer fellowships. Here Elizabeth Schultheis and Melissa Kjevik, now both postdoctoral researchers with Michigan State University, describe the project their summer fellowship supported.

Today it is apparent that students and the public continue to struggle when faced with data and its interpretation. When asked to make sense of data taught in their science classrooms, gathered during classroom inquiry projects, or found in the news, students are unable to connect quantitative information to explanations of the way the world works. Without exposure and practice, a large dataset or complicated graph can seem insurmountable. In collaboration with K-12 teachers, the Kellogg Biological Station (KBS) GK-12 program, BEACON, and the LTER, we created Data Nuggets to help students overcome roadblocks when working with and interpreting data.

Data Nuggets are targeted classroom activities focused on developing quantitative skills for K-16 students. They are created from recent and ongoing research, bringing cutting edge science into the classroom and helping scientists share their work with broad audiences. The standard format of each Data Nugget provides background information about a scientist and their research, along with how they became interested in their research questions and system that they study. Each Data Nugget includes a real dataset for students to graph, interpret, and use to construct an explanation.

Scientist Mélanie Banville searching for reptiles in the Central Arizona-Phoenix LTER. Her and Heather Bateman’s Data Nugget, “Lizards, Iguanas, and Snakes! Oh My!”

LTER Data Nuggets

The collaboration between Data Nuggets and the LTER is a mutually beneficial fit. LTER scientists help strengthen the Data Nuggets project by increasing the diversity of data and research available to students. In turn, Data Nuggets provide an avenue for LTER scientists to share their work and findings with a broad audience of students, teachers, and fellow scientists. Sharing research findings with the non-science public is an important part of the science process, yet is often one of the most challenging to achieve. With broader impacts a factor in most grants, finding effective methods of communication and transmission is key. Researchers who create Data Nuggets must dig deep to uncover the core messages of their research and think back to the big question that got them passionate about the research in the first place. Also, by creating a Data Nugget and practicing communicating research to a 6th grader, scientists can rest assured that at their next conference they’ll be better able to discuss their work with collaborators and those outside their field!

Researcher Sam Bond taking Sediment Elevation Table measurements in Plum Island Ecosystems Long Term Ecological Research site. For more information on this research, check out Anne Giblin’s Data Nugget, “Keeping Up With the Sea Level”.

Most importantly, a great outcome of using LTER data to create Data Nuggets is that teachers and students will directly benefit from additional resources that highlight the importance of data and science in an authentic context. Activities aiming to improve quantitative skills are more effective if they’re grounded in real world situations that students can relate to. Connecting science to a student’s experiences and local ecosystems makes the content more accessible, particularly for culturally and linguistically diverse students. These connections also allow students to envision a place for themselves in science. To assist with place-based learning, each Data Nugget is categorized and searchable by the location where the study occurred, allowing teachers to connect data to their students’ environment. In this way, LTER Data Nuggets have the potential to increase interest and engagement with science and data, in both students and the public.

Robert Buchsbaum, from Mass Audubon, preparing his team for a morning of salt marsh bird surveys. Find out more about his research on the endangered Saltmarsh Sparrow in his Data Nugget, “Does Sea Level Rise Harm Saltmarsh Sparrows?”

Working with LTER Scientists and Educators

This past summer (2015), we received support from the LTER Summer Fellowship program. This support allowed us to continue our work with Data Nuggets, and to strengthen their connection to the vast stores of data available through the LTER, including the KBS site and the other 24 sites in the LTER Network. While the LTER Network has conducted over three decades of amazing research, spanning diverse ecosystems and taxa, LTER education and outreach specialists are still finding creative new ways to share this important research with the public. Data Nuggets can breath new life into long-term

datasets, opening them up to the public and future scientists. These funds were used to support training workshops at the LTER All Scientists Meeting (ASM) in Estes Park, CO in August and at KBS in July. These two workshops supported early and late career scientists (graduate students, postdocs, faculty, and REUs) and many LTER education and outreach specialists looking to broaden the impact of the LTER’s research and improve their communication skills. In addition, at the LTER ASM we participated in a poster session to reach out to those who were unable to attend our workshop. Our outreach efforts strengthened the connection between Data Nuggets and the LTER, and resulted in the creation of nine (and counting!) new Data Nuggets based on LTER research. Additionally, in August, we spoke to the teachers working with the KBS K-12 Partnership, connecting them with the LTER Data Nuggets and the vast pool of LTER data, freely available online.

When reflecting back on this summer, it was so great to work with a diversity of LTER scientists across the network. We enjoyed learning new science stories and are very happy to now include coastal, urban riparian, and other ecosystems in the Data Nuggets collection. Please feel free to contact Melissa or Elizabeth if you would like more information or to get started creating your own Data Nugget! For a list of all the Data Nuggets created by LTER scientists and outreach leaders, click here!

3.25.16

Keeping up with the sea level

A view of salt marsh hay (Spartina patens) growing in a marsh

The activities are as follows:

Salt marshes are ecosystems that occur along much of the coast of New England in the United States. Salt marshes are very important – they serve as habitat for many species, are a safer breeding location for many fish, absorb nutrients from fertilizer and sewage coming from land and prevent them from entering the ocean, and protect the coast from erosion during storms.

Unfortunately, rising sea levels are threatening these important ecosystems. Sea level is the elevation of the ocean water surface compared to the elevation of the soil surface. Two processes are causing sea levels to rise. First, as our world gets warmer, ocean waters are getting warmer too. When water warms, it also expands. This expansion causes ocean water to take up more space and it will continue to creep higher and higher onto the surrounding coastal land. Second, freshwater frozen in ice on land, such as glaciers in Antarctica, is now melting and running into the oceans. Along the New England coast, sea levels have risen by 0.26 cm a year for the last 80 years, and by 0.4 cm a year for the last 20 years. Because marshes are such important habitats, scientists want to know whether they can keep up with sea level rise.

Researcher Sam Bond taking Sediment Elevation Table (SET) measurements in the marsh

When exploring the marsh, Anne, a scientist at the Plum Island Ecosystems Long Term Ecological Research site, noticed that the salt marsh appeared to be changing over time. One species of plant, salt marsh cordgrass (Spartina alterniflora), appeared to be increasing in some areas. At the same time, some areas with another species of plant, salt marsh hay (Spartina patens), appeared to be dying back. Each of these species of plants is growing in the soil on the marsh floor and needs to keep its leaves above the surface of the water. As sea levels rise, the elevation of the marsh soil must rise as well so the plants have ground high enough to keep them above sea level. Basically, it is like a race between the marsh floor and sea level to see who can stay on top!

Anne and her colleges measured how fast marsh soil elevation was changing near both species of plants. They set up monitoring points in the marsh using a device called the Sediment Elevation Table (SET). SET is a pole set deep in the marsh that does not move or change in elevation. On top of this pole there is an arm with measuring rods that record the height of the marsh surface. The SETs were set up in 2 sites where there is salt marsh cordgrass and 2 sites where there is salt marsh hay. Anne has been taking these measurements for more than a decade. If the marsh surface is rising at the same rate as the sea, perhaps these marshes will continue to do well in the future.

Featured scientist: Anne Giblin from the Marine Biological Laboratory and the Plum Island Ecosystems Long-Term Ecological Research site

Flesch–Kincaid Reading Grade Level = 9.1

3.18.16

Does sea level rise harm Saltmarsh Sparrows?

Painting of the saltmarsh sparrow

The activities are as follows:

For the last 100 years, sea levels around the globe have increased dramatically. The cause of sea level rise has been investigated and debated. Data from around the world supports the hypothesis that increasing sea levels are a result of climate change caused by the burning of fossil fuels. As we warm the Earth, the oceans get warmer and polar ice caps melt. The dramatic increase in sea level that results could seriously threaten ecosystems and the land that humans have developed along the coast.

Salt marshes are plains of grass that grow along the east coast of the United States and many coasts worldwide. Salt marshes grow right at sea level and are therefore very sensitive to sea level rise. In Boston Harbor, Massachusetts, the NOAA (National Oceanic and Atmospheric Administration) Tide Gauge has measured a 21mm rise in sea level over the last 8 years. That means every year sea level has gone up an average of 2.6mm since 2008 – more than two and a half times faster than before we started burning fossil fuels! Because sea level is going up at such a fast rate, Robert, a scientist in Boston, became concerned for the local salt marsh habitats near his home. Robert was curious about what will happen to species that depend on Boston’s Plum Island Sound salt marshes when sea levels continue to rise.

Robert preparing his team for a morning of salt marsh bird surveys.

Robert decided to look at species that are very sensitive to changes in the salt marsh. When these sensitive species are present, they indicate the marsh is healthy. When these species are no longer found in the salt marsh, there might be something wrong. The Saltmarsh Sparrow is one of the few bird species that builds its nests in the salt marsh, and is totally dependent on this habitat. Saltmarsh Sparrows rely completely on salt marshes for feeding and nesting, and therefore their numbers are expected to decline as sea levels rise and they lose nesting sites. Robert heard that scientists studying Connecticut marshes reported the nests of these sparrows have been flooded in recent years. He wanted to know if the sparrows in Massachusetts were also losing their nests because of high sea levels.

For the past two decades Robert has kept track of salt marsh breeding birds at Plum Island Sound. In his surveys since 2006, Robert counted the number of Saltmarsh Sparrows in a given area. He did these surveys in June when birds are most likely to be breeding. He used the “point count” method – standing at a center point he measured out a 100 meter circle around him. Then, for 10 minutes, he counted how many and what kinds of birds he saw or heard within and just outside the circle. Each year he set up six count circles and performed counts three times in June each year at each circle. Robert also used sea level data from Boston Harbor that he can relate to the data from his bird surveys. He predicted that sea levels would be rising in Plum Island Sound and Saltmarsh Sparrow populations would be falling over time.

Featured scientist: Robert Buchsbaum from Mass Audubon. Written by: Wendy Castagna, Daniel Gesin, Mike McCarthy, and Laura Johnson

Flesch–Kincaid Reading Grade Level = 9.5

Additional teacher resources related to this Data Nugget include:

A PDF of the 2014 overview report on the Saltmarsh Habitat and Avian Research Program (SHARP) for the east coast marshes from Maine down to Maryland, which includes Massachusetts. The report may be helpful for students as they come up with other research questions.
A blog by SHARP, covering a wide diversity of salt marsh research!
Data from the Plum Island Sound LTER project.
Data from NOAA tide gauges in Boston Harbor. This data expands on that found in Table 1. Students can explore a longer-term dataset for Boston Harbor, or can explore other areas for independent research.

11.3.15

Lizards, Iguanas, and Snakes! Oh My!

The Common Side-blotched Lizard

The activities are as follows:

Throughout history people have settled mainly along rivers and streams. Easy access to water provides resources to support many people living in one area. In the United States today, people have settled along 70% of rivers.

Today, rivers are very different from what they were like before people settled near them. The land surrounding these rivers, called riparian habitats, has been transformed into land for farming, businesses, or housing for people. This urbanization has caused the loss of green spaces that provide valuable services, such as water filtration, species diversity, and a connection to nature for people living in cities. Today, people are trying to restore green spaces along the river to bring back these services. Restoration of disturbed riparian habitats will hopefully bring back native species and all the other benefits these habitats provide.

Scientist Mélanie searching for reptiles in the Central Arizona-Phoenix LTER.

Scientists Heather and Mélanie are researchers with the Central Arizona-Phoenix Long-Term Ecological Research (CAP LTER) project. They want to know how restoration will affect animals living near rivers. They are particularly interested in reptiles, such as lizards. Reptiles play important roles in riparian habitats. Reptiles help energy flow and nutrient cycling. This means that if reptiles live in restored riparian habitats, they could increase the long-term health of those habitats. Reptiles can also offer clues about the condition of an ecosystem. Areas where reptiles are found are usually in better condition than areas where reptiles do not live.

Heather and Mélanie wanted to look at how disturbances in riparian habitats affected reptiles. They wanted to know if reptile abundance (number of individuals) and diversity (number of species) would be different in areas that were more developed. Some reptile species may be sensitive to urbanization, but if these habitats are restored their diversity and abundance might increase or return to pre-urbanization levels. The scientists collected data along the Salt River in Arizona. They had three sites: 1) a non-urban site, 2) an urban disturbed site, and 3) an urban rehabilitated site. They counted reptiles that they saw during a survey. At each site, they searched 21 plots that were 10 meters wide and 20 meters long. The sites were located along 7 transects, or paths measured out to collect data. Transects were laid out along the riparian habitat of the stream and there were 3 plots per transect. Each plot was surveyed 5 times. They searched for animals on the ground, under rocks, and in trees and shrubs.

Featured scientists: Heather Bateman and Mélanie Banville from Arizona State University. Written by Monica Elser from Arizona State University.

Meet the scientist! Click here to watch a video where scientist Heather explains her research!

Flesch–Kincaid Reading Grade Level = 9.8

10.21.15

Is your salt marsh in the zone?

Scientist James collecting plants in a Massachusetts marsh, part of the Plum Island Ecosystems Long Term Ecological Research site

The activities are as follows:

Tides are the rise and fall of ocean water levels, and they happen every day like clockwork. Gravity from the moon and sun drives the tides. There is a high tide and a low tide, and the average height of the tide is called the mean sea level. The mean sea level changes seasonally due to the seasonal warming and cooling of the ocean, and annually due to the melting of glaciers and a long-term trend of ocean warming. The scientific evidence shows that sea level is rising faster now than it has in the past. As the climate continues to warm, it is predicted that the sea level will continue to rise.

Salt marshes are plains of grass that grow along much of the ocean’s coast worldwide. They grow between mean sea level and the level of high tide. Marshes flood during high tide, and are exposed to the air when the tide goes out. The health of a salt marsh is determined by where it sits relative to the tide (the “zone”) – a healthy marsh is flooded only part of the time. Too much flooding and too little flooding are unhealthy. Scientists wanted to know, can salt marshes keep up with current rates of sea level rise or will they loose their balance between high and low tides once sea levels are higher? How can this be measured?

A picture of James’ “marsh organ” which holds plants at different elevations relative to mean sea level. He gave it that name because it resembles organ pipes!

In the 1980s, scientist James Morris began measuring the growth of marsh grasses. He was surprised to discover that marsh grass growth was rising and falling every year, depending on mean sea level, and that there also was a long-term trend of increasing plant growth. Plant growth was greatest in years when the annual mean sea level was unusually high. He wanted to know whether marsh plants could continue this growth and handle rising sea levels. He thought that the long-term trend of increasing plant growth was symptomatic of the marsh surface not rising fast enough to keep up with increasing rates of sea-level rise. If this is the case, plants are growing the most in years where mean sea level is high to stay above the water surface. To test this, James measured elevations of the marsh surface every year and compared this with the elevation of mean sea level. He also made these same measurements in another marsh to determine if the patterns originally observed could be repeated.

James devised a method of growing a marsh at different elevations within the vertical range of the tides. He invented a device that he called the “marsh organ” which is made from PVC pipes that stand at different elevations and are filled with marsh mud and planted with marsh vegetation. The marsh organ design allowed him to experimentally control the elevation. He then measured the growth of the vegetation in the pipes. If higher water levels stimulated growth, then pipes at lower elevations should support more plant growth than pipes higher elevations.

Featured scientist: James Morris from the University of South Carolina

Additional teacher resource related to this Data Nugget: Jim has created an interactive salt marsh model called the “marsh equilibrium model”. This online tool allows you to plug in different marsh levels to explore potential impacts to the salt marsh. To explore this tool click here.

To read more about Jim’s research on “tipping points” beyond which sediment accumulation fails to keep up with rising sea level and the marshes drown, click here.

There are two publications related to the data included in this activity:

Morris, J.T., Sundberg, K., and Hopkinson, C.S. 2013. Salt marsh primary production and its responses to relative sea level and nutrients in estuaries at Plum Island, Massachusetts, and North Inlet, South Carolina, USA. Oceanography 26:78-84.
Morris, J.T., P.V. Sundareshwar, C.T. Nietch, B. Kjerfve, D.R. Cahoon. 2002. Responses of coastal wetlands to rising sea level. Ecology 83:2869-2877.

8.24.15

Urbanization and Estuary Eutrophication

Charles Hopkinson out taking dissolved O2 measurements.Student activity, Graph Type A, Level 4

The activities are as follows:

An estuary is a habitat formed where a freshwater river or stream meets a saltwater ocean. Many estuaries can be found along the Atlantic coast of North America. Reeds and grasses are the dominant type of plant in estuaries because they are able to tolerate and grow in the salty water. Where these reeds and grasses grow they form a special habitat called a salt marsh. Salt marshes are important because they filter polluted water and buffer the land from storms. Salt marshes are the habitat for many different kinds of plants, fish, shellfish, and birds.

Hap Garritt removing an oxygen logger from Middle Road Bridge in winter.

Scientists are worried because some salt marshes are in trouble! Runoff from rain washes nutrients, usually from lawn fertilizers and agriculture, from land and carries them to estuaries. When excess nutrients, such as nitrogen or phosphorus, enter an ecosystem the natural balance is disrupted. The ecosystem becomes more productive, called eutrophication. Eutrophication can cause major problems for estuaries and other habitats.

With more nutrients in the ecosystem, the growth of plants and algae explodes. During the day, algae photosynthesize and release O₂ as a byproduct. However, excess nutrients cause these same algae grow densely near the surface of the water, decreasing the light available to plants growing below the water on the soil surface. Without light, the plants die and are broken down by decomposers. Decomposers, such as bacteria, use a lot of O₂because they respire as they break down plant material. Because there is so much dead plant material for decomposers, they use up most of the O₂ dissolved in the water. Eventually there is not enough O₂for aquatic animals, such as fish and shellfish, and they begin to die-off as well.

Two features can be used to identify whether eutrophication is occurring. The first feature is low levels of dissolved O₂ in the water. The second feature is when there are large changes in the amount of dissolved O₂ from dawn to dusk. Remember, during the day when it’s sunny, photosynthesis converts CO₂, water, and light into glucose and O₂. Decomposition reverses the process, using glucose and O₂ and producing CO₂ and water. This means that when the sun is down at night, O₂ is not being added to the water from photosynthesis. However, O₂ is still being used for decomposition and respiration by animals and plants at night.

The scientists focused on two locations in the Plum Island Estuary and measured dissolved O₂ levels, or the amount of O₂in the water. They looked at how the levels of O₂ changed throughout the day and night. They predicted that the upper part of the estuary would show the two features of eutrophication because it is located near an urban area. They also predicted the lower part of the estuary would not be affected by eutrophication because it was farther from urban areas.

A view of the Plum Island estuary

Featured scientists: Charles Hopkinson from University of Georgia and Hap Garritt from the Marine Biological Laboratory Ecosystems Center

Flesch–Kincaid Reading Grade Level = 9.6

8.18.15

Can a salt marsh recover after restoration?

Students collecting salinity data at a transect point. The tall tan grass is Phragmites.

The activities are as follows:

In the 1990s, it was clear that the Saratoga Creek Salt Marsh in Rockport, MA was in trouble. The invasive plant, Phragmites australis, covered large areas of the marsh. The thick patches of Phragmites crowded out native plants and reduced the number of animals, especially migrating birds, because it was too thick to land in. Salt marshes are wetland habitats near ocean coasts that have mostly water-loving, salt-tolerant grasses. Human activity was having a huge effect on the health of the Saratoga Creek Salt Marsh by lowering the salinity, or salt concentrations in the water. Drains built by humans to keep water from rainstorms off the roads changed how water moved through the marsh. The storm drains added a lot of runoff, or freshwater and sediments from the surrounding land, into the marsh after rainstorms. Adding more freshwater to the marsh lowers salinity. The extra sediment that washed into the marsh raised soil levels along the road. If the soil levels get too high, the salty ocean water does not make it into the marsh during high tide. Perhaps these storm drains were changing the salinity of the marshes in a way that helped Phragmites because it grows best when salinity levels are low.

In 1998, scientists, including members of the Rockport Conservation Commission and students from the Rockport Middle School science club, began to look at the problem. They wanted to look at whether freshwater runoff from storm drains may be the reason Phragmites was taking over the marsh. They were curious whether the salinity would increase if they made the storm water drain away from the marsh. They also thought this would stop the runoff sediments from raising soil levels. If so, this could be one way to restore the health of the salt marsh and reduce the amount of Phragmites.

In 1999, a ditch was dug alongside the road to collect runoff from storm drains before it could enter the marsh. A layer of sediment was also removed from the marsh so ocean water could reach the marsh once again. Students set up transects, specific areas chosen to observe and record data. Then they measured the growth and abundances of Phragmites found in these transects. They also measured water salinity levels. Transects were 25 meters long and data were collected every meter. The students decided to compare Phragmites data from before 1999 and after 1999 to see if diverting the water away from the marsh made a difference. They predicted that the number and height of Phragmites in the marsh would go down after freshwater runoff was reduced after restoration.

View of Saratoga Creek Salt Marsh several years after restoration, showing location of one of the transects. Native grasses are growing in the foreground.

Featured scientists: Liz Duff from Mass Audubon, Eric Hutchins from NOAA, and Bob Allia and 7th graders from Rockport Middle School

Written by: Bob Allia, Cindy Richmond, and Dave Young

Flesch–Kincaid Reading Grade Level = 9.5

For more information on this project, including datasets and more scientific background, check out their website: Salt Marsh Science