Marvelous mud

mud

You can tell that the mud in this picture is high in organic matter because it is dark brown and mucky (in real life you’d be able to smell it, too!)

The activities are as follows:

The goopy, mucky, often stinky mud at the bottom of a wetland or lake is a very important part of the ecosystem. Wetland mud is much more than just wet dirt. For example, many species of microbes live in the wetland mud where they decompose (breakdown) dead plant and animal material to obtain energy. This dead plant and animal material is called organic matter. However, the wetland mud microbes do not have all the oxygen they need to decompose the plant and animal tissues quickly and efficiently. Because of this, the dead material in wetland mud decomposes much more slowly than similar dead material in dry soil.

A successful core! You can see that the tube has mud, as well as some of the water from the wetland that was on top of the mud.

A successful core! You can see that the tube has mud, as well as some of the water from the wetland that was on top of the mud.

As a graduate student, Lauren became fascinated with wetland mud and its interesting properties. She wanted to know how important all the mud and its organic matter is for wetlands. By talking with other members of her lab and reading scientific papers, Lauren learned that wetland mud can often be high in the element phosphorus and that phosphorus acts as a fertilizer for plants, including wetland plants and algae. However, nutrients, such as phosphorus can build up in wetland mud. Lauren thought it might be possible that the organic matter in the mud was the source of all the phosphorus in some wetlands. She predicted that wetlands with more organic matter would have more phosphorus. If her data support her hypothesis, it could mean that organic matter is very important for wetlands, because nutrients are needed for algae and plants to grow.

Although most mud is high in organic matter and nutrients, not all mud is the same. There is natural variation in the amount of organic matter and nutrients from place to place. Even within the same location mud can be very different in spots. Lauren used this variability to test her ideas. She measured organic matter and phosphorus in mud from 16 freshwater locations (four lakes, five ponds, and seven wetlands). She took cores that allowed her to sample mud deep into the ground. She then brought her cores back to the lab and measured organic matter and phosphorus levels in her samples.

Featured scientist: Lauren Kinsman-Costello from Kent State University

Flesch–Kincaid Reading Grade Level = 9.8

More photos associated with this research can be found here. There is one scientific paper associated with the data in this Data Nugget. The citation and PDF of the paper is below:

Kinsman-Costello LE, J O’Brien, SK Hamilton (2014) Re-flooding a Historically Drained Wetland Leads to Rapid Sediment Phosphorus Release. Ecosystems 17:641-656

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Won’t you be my urchin?

The vegetarian sea urchin Diadema antillarum.

The vegetarian sea urchin Diadema antillarum.

The activities are as follows:

Éste Data Nugget también está disponible en Español:

Imagine you are snorkeling on a coral reef where you can see many species living together. Some animals, like sharks, are predators that eat other animals. Other species, like anemones and the fish that live in them, are mutualists and protect each other from predators. There are also herbivores, like urchins, that eat plants and algae on the reef. All of these species, and many more, need the coral reef to survive.

Experimental setup with tiles in bins. Some bins have sea urchins and some do not.

Experimental setup with tiles in bins. Some bins have sea urchins and some do not.

Corals are the animals that build coral reefs. They are very sensitive and can be hurt by human activity, like boating and pollution. Coral reef ecosystems are also in danger from warming waters due to climate change. Sadly, today many coral reefs around the world are dying because the places they grow are changing. Sarah is a marine biologist who is determined to figure out ways to save coral reefs. Sarah wants to understand how to help the dying corals so they can keep building important and diverse coral reef habitats.

Corals compete with large types of algae, like seaweed, for space to grow on the reef. Corals are picky and only like to live in certain places. If there is too much algae, corals will have no place to attach and grow. Sea urchins are important herbivores and one of the species that like to eat algae. Sarah thought that when urchins are present on the reef, corals will have less competition from algae for space, and thus more room to grow. Maybe adding urchins to a coral reef is a way to help corals!

To test her idea Sarah set up an experiment. She set 8 bins out on the reef. Into half of the bins, Sarah added urchins. She left the other half without urchins as a control. Sarah put tiles into all of the bins. Tiles gave an empty space for coral and algae to compete and grow. After a few months, Sarah looked at the tiles. She counted how many corals were growing on each tile. Sarah predicted that more corals would grow on the tiles in bins with sea urchins compared to the control bins with no sea urchins.

B. Photograph of Agaricia juvenile on experimental substratum. C. Photograph of Porites juvenile on experimental substratum

B. Photograph of coral species Agaricia juvenile on experimental tile. C. Photograph of coral species Porites juvenile on experimental tile.

Featured scientist: Sarah W. Davies (she/her) from the University of Texas at Austin

Flesch–Kincaid Reading Grade Level = 6.5

There is one scientific paper associated with the research in this Data Nugget. The citation and PDF of the paper is below.

Davies SW, MV Matz, PD Vize (2013) Ecological Complexity of Coral Recruitment Processes: Effects of Invertebrate Herbivores on Coral Recruitment and Growth Depends Upon Substratum Properties and Coral Species. PLOS ONE 8(9):e72830

After students have completed the Data Nugget, you can have them discuss the management implications of this research. Watch the news story below and have students consider how urchins can be used as a management tool to help restore coral reefs!

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Coral bleaching and climate change

A Pacific coral reef with many corals

A Pacific coral reef with many corals

The activities are as follows:

Éste Data Nugget también está disponible en Español:

Corals are animals that build coral reefs. Coral reefs are home to many species of animals – fish, sharks, sea turtles, and anemones all use corals for habitat! Corals are white, but they look brown and green because certain types of algae live inside them. Algae, like plants, use the sun’s energy to make food. The algae that live inside the corals’ cells are tiny and produce more sugars than they themselves need. The extra sugars become food for the corals. At the same time, the corals provide the algae a safe home. The algae and corals coexist in a relationship where each partner benefits the other, called a mutualism: these species do better together than they would alone.

When the water gets too warm, the algae can no longer live inside corals, so they leave. The corals then turn from green to white, called coral bleaching. Climate change has been causing the Earth’s air and oceans to get warmer. With warmer oceans, coral bleaching is becoming more widespread. If the water stays too warm, bleached corals will die without their algae mutualists.

Scientist Carly working on a coral reef

Scientist Carly working on a coral reef

Carly is a scientist who wanted to study coral bleaching so she could help protect corals and coral reefs. One day, Carly observed an interesting pattern. Corals on one part of a reef were bleaching while corals on another part of the reef stayed healthy. She wondered, why some corals and their algae can still work together when the water is warm, while others cannot?

Ocean water that is closer to the shore (inshore) gets warmer than water that is further away (offshore). Perhaps corals and algae from inshore reefs have adapted to warm water. Carly wondered whether inshore corals are better able to work with their algae in warm water because they have adapted to these temperatures. If so, inshore corals and algae should bleach less often than offshore corals and algae. Carly designed an experiment to test this. She collected 15 corals from inshore and 15 from offshore reefs in the Florida Keys. She brought them into an aquarium lab for research. She cut each coral in half and put half of each coral into tanks with normal water and the other half into tanks with heaters. The normal water temperature was 27°C, which is a temperature that both inshore and offshore corals experience during the year. The warm water tanks were at 31°C, which is a temperature that inshore corals experience, but offshore corals have never previously experienced. Because of climate change, offshore corals may experience this warmer temperature in the future. After six weeks, she recorded the number of corals that bleached in each tank.

 Featured scientist: Carly Kenkel from The University of Texas at Austin

Flesch–Kincaid Reading Grade Level = 8.0

There are two scientific papers associated with the data in this Data Nugget. The citations and PDFs of the papers are below. 

If your students are looking for more data on coral bleaching, check out HHMI BioInteractive’s classroom activity in which students use authentic data to assess the threat of coral bleaching around the world. Also, check out the two videos below!

  • Another BioInteractive video, appropriate for upper level high school classrooms. Visualizes the process of coral bleaching at different scales. Video includes lots of complex vocabulary about cells and the process of photosynthesis.

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Finding a Foothold

The activities are as follows:

Have you ever noticed that the ground at a beach has rocks of many different sizes? These rocks, sand, and dirt are all called substrates. The types of substrate we see are described by the size of the particles that cover the ground. These can range from large boulders down to fine grains of sand and dirt, with many sizes in between. No matter what type of substrate you see at the beach, you can find organisms that will live in or on it. Just like there are different types of substrates, there are different types of organisms that can live there. How can we determine which types of organisms prefer which types of substrates? That is the job of field researchers!

mollusk-3

Students collecting mollusk data on different beach substrates.

Students and teachers at Kentridge High School have made many field trips to the beach and have seen lots of organisms. Normally, they just noticed what they could see easily in front of them. Students became interested to know how the type of substrate influences which organisms will live there. They noticed that the snails in the aquarium at school like to stick to the glass walls of the tank. Do snails and other shelled mollusks found near the ocean, like chitons, periwinkles, whelks and limpets, also like to live on large, stable substrates? The students went to beach to find out!

Mollusks have a “foot” which may be able to attach more securely to larger substrates, such as boulders, and allow them more room to move. So, the students expected to find more mollusks on boulders than on other types of substrates. To gather the data needed to answer this question, the students went to a local beach. They looked at sections of the beach with substrates of all types. On these different substrates, they kept track of all the different types of organisms that were present. They measured the frequency that they observed four types of mollusks (chitons, limpets, whelks, and periwinkles) on the following substrates: boulder, gravel, pebble, logs, sand, and shell debris. Frequency was measured as the proportion of times that a particular organism was present on a substrate type, out of the total number of observations. For example, if they observed 2 boulders and saw limpets on 1, the frequency would = ½ or 0.5.

Featured scientists: Darrel Nash and Sarah Hall from Kentridge High School, Washington

Flesch–Kincaid Reading Grade Level = 7.4

For more information on the Seattle Aquarium’s citizen science project, and to download the dataset from this project, click here

Float down the Kalamazoo River

Morrow Lake, a reservoir created along the Kalamazoo River. The water is held in a reservoir by a dam. When water flows into the reservoir it slows, potentially letting some of the total suspended solids settle to the bottom of the river.

Morrow Lake, a reservoir created along the Kalamazoo River. The water is held in a reservoir by a dam. When water flows into the reservoir it slows, potentially letting some of the total suspended solids settle to the bottom of the river.

The activities are as follows:

Ever since she was a kid, rivers have fascinated Leila. One of her hobbies is to kayak and canoe down the Kalamazoo River in Michigan, near where she lives. For her work, she researches all the living things in the river and how humans affect them. She is especially interested in changes in the river food web, caused by humans building dams along the river, and an oil spill in 2010.

Leila knows there is a lot more in river water than what meets the eye! As the river flows, it picks up bits of dead plants, single-celled algae, and other living and nonliving particles from the bottom of the river. The mix of all these particles is called total suspended solids (TSS) because these particles are suspended in the river water as it flows. The food web in the Kalamazoo River depends on the particles that are floating in the water. Invertebrates eat decomposing leaves and algae, and fish eat the invertebrates.

Leila showing off some of the cool invertebrates that can be found in the Kalamazoo River.

Leila showing off some of the cool invertebrates that can be found in the Kalamazoo River.

As you float down the river, particles settle to the river bottom and new ones are picked up. The amount of suspended solids in a river is influenced by how fast the water in the river is flowing. The faster the water flows, the more particles are picked up and carried down the river. The slower the water flows, the more particles will settle to the bottom. Discharge is a measure of how fast water is flowing. You can think about discharge as the number of cubes (one foot on each side) filled with water that pass by a point every second. During certain times of the year, water flows faster and there is more discharge. In spring, when the snow starts melting, a lot of water drains from the land into the river. There also tends to be a lot more rain in the fall. Things humans build on the river can also affect discharge. For example, we build dams to generate hydroelectric power by capturing the energy from flowing water. Dams slow the flow of river water, and therefore they may cause some of the suspended solids to settle out of the water and onto the bottom of the river.

Leila wanted to test how a dam that was built on the Kalamazoo River influenced total suspended solids. If the dam is reducing the amount of total suspended solids, it could have negative effects on the food chain. She was also curious to see if the dam has different effects depending on the time of year. On eight different days from May to October in 2009, Leila measured total suspended solids at two locations along river. She collected water samples upstream of the dam, before the water enters the reservoir, and samples downstream after the water has been in the reservoir and passed over the dam. She also measured discharge downstream of the dam.

KalamazooRiver

Featured scientist: Leila Desotelle from Michigan State University

Flesch–Kincaid Reading Grade Level = 8.7

If your students are looking for more information on how the amount of water flowing in the river affects the food chain and the health of the ecosystem overall, check out the video below!