animals ‣ Data Nuggets

3.25.14

Won’t you be my urchin?

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.

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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3.25.14

Coral bleaching and climate change

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

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.

Kenkel CD, E Meyer, MV Matz (2013) Gene expression under chronic heat stress in populations of the mustard hill coral (Porites astreoides) from different thermal environments. Molecular Ecology 22:4322-433
Kenkel CD, G Goodbody-Gringley, D Caillaud, SW Davies, E Bartels, MV Matz (2013) Evidence for a host role in thermotolerance divergence between populations of the mustard hill coral (Porites astreoides) from different reef environments. Molecular Ecology 22:4335-4348

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!

A video in BioInteractive’s “Scientists at Work” series showing researchers working on the same hypothesis in another part of the world: Steve Palumbi & Megan Morikawa Study Coral Reef Damage in American Samoa

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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3.17.14

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!

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.

1.7.14

Dangerously bold

An aquarium filled with young bluegill sunfish. Bluegills are a common type of fish that live in freshwater lakes in the eastern United States.

The activities are as follows:

Just as each person has her or his own personality, animals of the same species can behave very differently from one another! For example, pets, like dogs, have different personalities. Some have a lot of energy, some are cuddly, and some like to be alone. Boldness is a recognized behavior that describes whether or not an individual takes risks. Bold individuals take risks while shy individuals do not. The risks animals take have a big impact on their survival and the habitats they choose to search for food.

Bluegill sunfish are a type of fish that lives in freshwater lakes and ponds across the world. Open water and cover are two habitat types where young bluegill are found. The open water habitat in the center of the pond is the best place for bluegill to eat a lot of food. However, the open water is risky and has very few plants or other places to hide. Predators, like large birds, can easily find and eat bluegill in the open water. The cover habitat at the edge of the pond has many plants and places to hide from predators, but it has less food that is best for bluegill to grow fast. Both habitats have costs and benefits—called a tradeoff.

To determine their personality, Melissa observed bluegill sunfish in the aquarium lab.

Melissa is a scientist who is interested in whether differences in young bluegill behavior changes the habitats in which they choose to search for food. First, she looked at whether young bluegill have different personalities by bringing them into an aquarium lab and watching their behavior. Melissa observed that, just like in humans and dogs, bluegill sunfish have different personalities. She noticed that some bluegill took more risks and were bolder than others. Melissa wanted to know if these differences in behavior could also be observed in her experimental pond. She reasoned that being in open water is risky, but results in more access to food. Therefore, bold fish should take more risks and use the open water habitat more than shy fish, giving them more food, allowing them to grow faster and larger, but exposing them to more predation. Just the opposite should be true about shy fish: more time for them in the cover habitat of the pond exposing them to less predation, but also giving them less access to food and an overall smaller body size than bold fish. A tradeoff for both types of fish based on personality.

Melissa designed a study to test the growth and survival of bold and shy fish. When she was watching the fish’s behavior in the lab, she determined if a fish was bold or shy. If a fish took the risk of leaving the safety of the vegetation in a tank so that it could eat food while there was a predator behind a mesh screen, it was called bold. If it did not eat, it was called shy. She marked each fish by clipping the right fin if it was bold or the left fin if it was shy. She placed 100 bold and 100 shy bluegill into an experimental pond with two largemouth bass (predators). The shy and bold fish started the experiment at similar lengths and weights. After two months, she drained the pond and found every bluegill that survived. She recorded whether each fish that survived was bold or shy and measured their growth (length and weight).

Featured scientist: Melissa Kjelvik from Michigan State University

Flesch–Kincaid Reading Grade Level = 7.3

A view of the aquarium tank used to determine fish personality. A largemouth bass is placed to the left of the barrier, while 3 bluegill sunfish are placed to the right. If a sunfish swims out of the vegetation and eats a bloodworm dropped near the predator, it is considered bold.

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