California Current Ecosystem Plankton Food Web

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1 TEACHER PAGES What role do plankton play in the food web? California Current Ecosystem Plankton Food Web and the Beth Simmons Education and Outreach Coordinator, CCE LTER, Scripps Institution of Oceanography, and Christy Millsap Rancho Bernardo High School San Diego, California What is a food web? Habitats within California s ocean ecosystems contain rich and productive marine communities. Many of the species present here are able to exploit the rich coastal upwelling that brings nutrients to the sunlit ocean waters at the ocean's surface. A food chain represents one possible pathway for the transfer of energy and nutrients from plants to herbivores to carnivores and top predators. However, most organisms eat more than one type of prey and are fed upon by more than one type of predator. When these multiple food chains are put together, they form a complicated web that explains the different pathways through which energy and nutrients move within an ecosystem. Every drop of water in the top 100 meters of the ocean contains thousands of free-floating, single-celled microscopic living organisms: plant-like phytoplankton and animal-like zooplankton. Together they fuel life in the ocean. Plants, the primary producers in ecosystems, use the sun s energy during a process known as photosynthesis to build raw materials (glucose). Animals are organisms that do not have the ability to make their own food and therefore must consume other organisms in order to obtain energy. The level at which an organism consumes is referred to as a trophic level; in other words, how far removed their food source is from the primary producer. A primary consumer is also referred to as an herbivore - as they eat only plants. A secondary consumer is an animal that feeds on herbivores. Tertiary consumers feed on secondary consumers. Energy is lost as it moves from one trophic level to the next. This means that it takes more primary producers to support tertiary consumers Figure 1: An example of a marine pelagic food web. Credit: From "Fishing down marine food webs' as an integrative concept" by Daniel Pauly (University of British Columbia, Canada), Proceedings of the EXPO'98 Conference on Ocean Food Webs and Economic Productivity, online at the Community Research and Development Information Page. than the primary producers needed to support their immediate consumers. This is why few ecosystems can support trophic levels further than a quaternary or fourth-level consumer. In order to understand how food webs are formed, it is essential to understand how species interact. In marine ecosystems, phytoplankton hold the position of primary producers and are thus essential for the health and maintenance of the entire marine food web. 1

2 TEACHER PAGES What role do plankton play in the food web? Objective: To determine the possible effect of fewer phytoplankton in the CCE food web. Hypothesis: Predict what might happen to an oceanic food web if phytoplankton numbers were drastically reduced. Materials: : California Current Ecosystem Plankton Food Web Article: Ocean warming's effect on phytoplankton: NASA satellite data show how global climate change hurts marine food chain CCE food web cards (Illustrated by Kirsten Carlson, 2010) and the Beth Simmons Education and Outreach Coordinator, CCE LTER, Scripps Institution of Oceanography, and Christy Millsap Rancho Bernardo High School San Diego, California California Current Ecosystem Illustration (Illustrated by Kirsten Carlson, 2010) Target audience: Grade 9-12 Biology, Marine Science, or Environmental Science Time Frame: 60 min class period CA standards addressed: Life Science standards- 1f,1g, 6b, 6d. Earth Science Standard 7a. Investigation and Experimentation 1a, 1b, 1c, 1d, 1j, 1k,1m. National Science Standards: NS SCIENCE AS INQUIRY- Abilities necessary to do scientific inquiry, understandings about scientific inquiry NS LIFE SCIENCE- Interdependence of organisms Procedure: Note: Before beginning, have students cut out all the species identification cards. 1. Read the article titled Ocean warming s effect on phytoplankton... As you read the article, write down any organisms that are affected by the decline in phytoplankton abundances. 2. Use the CCE LTER marine ecosystem illustration to help you construct a food pyramid using the species identification cards. Lay out the cards according to their trophic levels and then transfer their names onto your data sheet. 3. Label each level of the pyramid on your data sheet with the appropriate trophic level (producer, primary consumer, secondary consumer, tertiary consumer, quaternary consumer) 4. Draw arrows to show the direction that energy would move through the food web (what eats what). (Teacher Reference Sheet provided). 2

3 Ocean warming's effect on phytoplankton / NASA satellite data show how global climate change hurts marine food chain. December 07, 2006 / By Jane Kay, Chronicle Environment Writer When the climate warms, there is a drop in the abundance of the ocean's phytoplankton, the tiny plants that feed krill, fish and whales, according to scientists who say new research offers the first clues to the future of marine life under global warming. Ocean temperatures have generally risen over the last 50 years as the atmosphere warms. And now nine years of NASA satellite data published today in the journal Nature show that the growth rate and abundance of phytoplankton around the world decreases in warm ocean years and increases in cooler ocean years. The findings are crucial because they show a consequence of the changing global climate at the most fundamental level. Scientists estimate that phytoplankton is responsible for about half of Earth's photosynthesis, a process that removes carbon dioxide from the atmosphere and converts it into organic carbon and oxygen that feeds nearly every ocean ecosystem. Fewer phytoplankton consume less carbon dioxide, aggravating a cycle that can lead to even more warming. Over the past decades, California scientists have linked declining plankton numbers to El Niños and other warm-water years in the Pacific Ocean, which set off a domino effect of fewer krill and young fish and eventually failed reproduction of seabirds and even deaths of seals and sea lions. "What's amazing is this is the first time we see it on a global scale," said Dave Siegel, professor of marine science at UC Santa Barbara and a study author. "We have an inkling now what will happen to the ocean's biology in future climates." The scientists report that the relationship between warmer ocean waters and fewer plankton holds strongly for three-quarters of the world's oceans. Oceanic plant growth increased from 1997 to 1999 as the oceans cooled as a result of one of the strongest El Niño-to-La Niña transitions on record, said NASA officials. Since 1999, the climate has been in a period of warming that has seen the health of ocean plants diminish, they said. When the climate warms, the ocean's upper layer where the phytoplankton proliferate becomes separated from the denser, colder ocean water below in a sort of a stratification effect. The ocean can't mix as well, and the plankton don't reach the nutrients in the deeper, colder waters that they use as a food supply. For the first time, the NASA data set "is long enough and good enough so that we can evaluate the global links between climate and productivity," Siegel said. The NASA satellite data measure the oceans' color and helps scientists determine the amount of phytoplankton and the growth rates, he said. "We can know the amount of plants in the ocean by looking at the ocean's color. A blue ocean has no phytoplankton in it. The beautiful tropical oceans that you see on postcards have little in it. The green ocean is chock-full of phytoplankton." There is a consensus among the world's experts that carbon dioxide, methane and other greenhouse gases emitted from the burning of fossil fuels have added to natural carbon dioxide levels. The carbon dioxide concentrations measured in ice cores in Antarctica are the highest in 640,000 years. Gene Carl Feldman, NASA scientist and a study author, said in a statement Wednesday that only by understanding how climate and life on Earth are linked "can we realistically hope to predict how the Earth will be able to support life in the future. 3

4 Hypothesis: Predict what might happen to an oceanic food web if phytoplankton abundance were drastically reduced. Students predictions (on data sheet) should look something like this: 4

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