1. Plankton Ecology: Primary production, Phytoplankton and Zooplankton
Scripps Classroom Connection GK-12
Moira Décima, Scripps Institution of Oceanography Steve Halpern, San Diego High School (MVAS)
Summary: This is a four lesson unit that explores general plankton ecology and food web dynamics, with an emphasis on phytoplankton ecology. Students learn about phytoplankton and zooplankton, their interactions and importance in the marine pelagic food web. In addition students explore phytoplankton ecology, their distribution in a stratified and heterogeneous ocean, and the ecological traits evolved to survive in these habitats. This lesson was designed for 9-12 grade marine science and biology students, but is also relevant to earth science classes.
Day 1: The first lesson introduces the marine pelagic environment, explores marine primary production, phytoplankton and zooplankton. Students learn about photosynthesis, production in the ocean and food web dynamics that link phytoplankton to higher trophic levels, such as fish, birds and whales. Diversity within phytoplankton and zooplankton is introduced, and many of the important taxonomic groups are covered.
Day 2: A laboratory activity gives students hands on experience with the microscopic producers of the ocean: phytoplankton. Students get up close with three main groups of phytoplankton: diatoms, dinoflagellates and flagellates.
Students observe three mystery phytoplankton groups and based on the knowledge retained from the lecture of the previous day along with their personal observations, must guess which group of phytoplankton corresponds to each of the three mystery samples.
Characteristics of ecological importance – such as spines, swimming behavior, color, etc. – are used to infer the group of phytoplankton, as well as to hypothesize on the implications of these ecological traits.
CO2
Nutrients
Phytoplankton
Large zooplankton
Small zooplankton
Mystery Phyto 1
Mystery Phyto 2
Mystery Phyto 3
Day 4: The final lesson expands on material covered on the previous lecture, exploring consequences of a heterogeneous ocean on phytoplankton. The distribution, population growth rates and general ecology of phytoplankton is explored as a consequence of the heterogeneity of water masses. Students will learn how the environment determines a species distribution and persistence, with a final discussion and understanding that if and how the ocean changes will include drastic changes to the biological community it holds within. During this classroom activity they will plot and interpret growth rate data, and compare these phytoplankton characteristics among groups, understanding the importance of these within an ecological framework.
Day 3: The third lesson explores the consequences of a heterogeneous ocean on phytoplankton. Spatial heterogeneity in the ocean arises as a consequence of distance from shore as well as depth: water column stratification greatly affects the ecology and species distribution of phytoplankton. The distribution, population growth rates and general ecology of phytoplankton is explored as a consequence of the heterogeneity of water masses. Students learn how the environment determines a species distribution and persistence, with a final discussion and understanding that how the ocean changes in the future will include drastic changes to the biological community it holds within.
The lecture also explores horizontal spatial variability, and species distributions resulting as a consequence
This lecture relates ocean stratification to the environmental characteristics relevant to phytoplankton, linking physical stratification to biology. Ecological strategies of different groups coping with the stratification of nutrients, light and predators are explored.
Students understand measuring chlorophyll as a proxy for phytoplankton biomass. The analogy of using light from space to estimate the US population is given so students can understand the scientific practice of inferring information from correlated phenomena, when direct estimates are either cumbersome or impossible.
Students plot real phytoplankton growth data from each of the main 6 phytoplankton groups, and use this information (along with ecological characteristics) to guess the distribution (both in the vertical and horizontal) of the different phytoplankton groups.
Science standards addressed: The lesson touches on a number of California Earth Science and Biology standards. The Earth Science standards include: 4 b) Students know the fate of incoming solar radiation in terms of reflection, absorption, and photosynthesis.; 5 d) Students know properties of ocean water, such as temperature and salinity, can be used to explain the layered structure of the oceans, the generation of horizontal and vertical ocean currents, and the geographic distribution of marine organisms; 7 a) Students know the carbon cycle of photosynthesis and respiration and the nitrogen cycle; 7 b) Students know the global carbon cycle: the different physical and chemical forms of carbon in the atmosphere, oceans, biomass, fossil fuels, and the movement of carbon among these reservoirs; 7 c) Students know the movement of matter among reservoirs is driven by Earth's internal and external sources of energy;
The Biology standards include 1 f) Students know usable energy is captures from sunlight by chloroplasts and stored through the synthesis of sugar from carbon dioxide. 6 a) Students know biodiversity is the sum total of different kinds of organisms and is affected by alterations of habitats; 6 c) Students know how fluctuations in population size in an ecosystem are determined by the relative rates of birth, immigration, emigration and death; 6 f) Students know at each link in a food web some energy is stored in newly made structures but much energy is dissipated into the environment as heat. This dissipation may be represented in an energy pyramid.