Can kelp help the plovers? 

Beach hopper on a sidewalk

The activities are as follows:

It’s a beach day! You’re walking through the sand on a southern California beach, looking for a place to put your things. You notice there are clumps of dried-up seaweed everywhere. As you brush aside some of these clumps to lay out your towel, a shrimp-like bug jumps out at you and bounces off your hand! With smelly dried seaweed, small birds skittering across the sand, and hopping bugs, you wonder, is this beach healthy? Yes! These are all parts of a thriving food web.

Beaches are home to many important species that each play a role in the ecosystem. On the Pacific Coast of California, the dried-up seaweed is typically made up of several species of kelp. Kelp captures the sun’s energy through photosynthesis. Beach hoppers, the little jumping “bugs”, are actually small crustaceans
that feed on the kelp. In turn, these beach hoppers are the main food source for birds.

Snowy plovers are a type of bird that loves to eat beach hoppers. This shorebird species is threatened in California due to habitat loss. The sandy beaches where the plovers live and nest are also places where people like to walk and play. Scientists want to better understand what makes up the base of the food web that supports plovers to help their populations recover.

High school seniors, Mari and Azra, visited beaches in Lompoc, a coastal city in California, many times with their science classes. They wanted to learn more about the sandy beach ecosystem, so they read an article from a local research group at the University of California-Santa Barbara. On one of their field trips, they learned about a scientist named Jenny Dugan. Jenny and members of her lab study the beach hoppers’ important role in the sandy beach ecosystem. The Dugan lab had done a series of experiments to see what types of kelp beach hoppers liked to eat.

Azra (left) and Mari (right) working with kelp.

Mari and Azra wanted to set up a similar experiment to see if the beach hoppers in the Lompoc area preferred the same species of kelp. Their teacher, Ms. Moore, collected beach hoppers, sand, and kelp on her way to school one day. Mari and Azra set up ten plastic containers by measuring an equal amount of damp sand and punching holes in the lids. Then they tried to put 10 beach hoppers into the container. But it was hard to know the exact number until the very end of the experiment because some would hop out before the lid was on! At the end of the study, the number ranged from 8-15 beach hoppers in each container. Finally, Mari and Azra weighed out 15.0 grams of kelp and put it on top of the sand in the containers. They put one type of kelp in each container. Four containers had feather boa kelp, Egregia, four containers had giant kelp, Macrocystis, and two containers had Laminaria, another type of kelp. Mari and Azra also set up controls for each type of kelp with sand and kelp, but no beach hoppers. This container would tell them how much kelp weight was lost to water evaporation over the 3 days of the experiment, and not due to being eaten.

Trial 1: Mari and Azra placed the containers outside in a shady spot for three days. On the third morning, they opened up the containers to weigh the kelp that remained. Before weighing the kelp, they rinsed it to remove excess sand and dried it gently to remove excess water. Finally, they counted the beach hoppers that were in the container.

Trial 2: After reviewing their results from this experiment, Mari and Azra realized the beach hoppers did not like Laminaria at all. They decided to repeat the experiment using kelp and beach hoppers from a different beach, and did not include Laminaria as a food source.

Featured scientists: Mari and Azra from Lompoc High School, California. Jenny Dugan from the University of California-Santa Barbara. Written by: Melissa Moore from Lompoc High School.

Flesch–Kincaid Reading Grade Level = 8.1

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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