2. 2019 Collection
3. Chlorophyll-a in upwelling vs. stratified temperate regions
4. Instructor's Guide

Summary

Time series data is utilized to connect lecture discussion on ocean currents, upwelling/downwelling, seasonal variability, ocean chemistry, and productivity. Students are given the opportunity to explore these learning outcomes and to draw their own predictions on the graphs and view if their predictions resemble the observed data. Students contrast and compare selected time series data from the Coastal Endurance (Pacific Ocean) and Coastal Pioneer (Atlantic Ocean) Array and determine if the data follows predicted patterns. They examine the Array time series data and identify time frames where the data follow expected trends and make predictions about these time frames. This exercise is a case study that, if used in full, takes students through the entire learning cycle from invitation to reflection as applied to continental margins in temperate environments that either do or do not experience seasonal upwelling. Pieces of the exercise can be used as appropriate to meet instructor goals.

• Students access their previous learning on primary production through images depicting varying ocean color (Invitation). (See Teaching Notes below for concepts your students should be familiar with before starting this exercise.)
• Some time series data from the Oregon Shelf are presented and students are asked to speculate on the relationships between variables. (Exploration)
• Students are asked to describe a potential mechanism for the relationships. Afterward, they are shown figures of coastal upwelling and the relationship of winds with temperature off Oregon. (Concept Invention)
• After learning about upwelling, students are challenged to apply what they have learned to a time series from the Massachusetts coast during seasonal stratification. (Application)
• Students are asked to reflect on the interaction between wind, water properties, and biology, and about what they have learned about this complexity. (Reflection)

Enduring Understandings

Students should ultimately understand that:

1. Increases in dissolved oxygen are a consequence, not a cause of primary productivity.
2. Density stratification works to separate phytoplankton from the two things they need for primary productivity: light and nutrients.

Learning Goals and Assessments

After engaging with the Data Exploration a student will be able to:

• Interpret basic time-series data visualizations and identify patterns and anomalies.
• Compare time-series sea surface temperature, salinity, dissolved oxygen, and chlorophyll data at a Pacific Ocean coastal site and Atlantic Ocean coastal site over time to explore the data for changes and patterns both temporally and spatially.
• Discuss the role of water chemistry (dissolved oxygen, temperature, and salinity) on the amount of phytoplankton. [The amount of chlorophyll is heightened at times of cooler temperatures and higher salinities.]
• Mechanistically explain the relationship between sea surface temperature, salinity, dissolved oxygen, and chlorophyll during late summer - early fall at a Pacific Ocean coastal site and Atlantic Ocean coastal site.
• Explain the driving mechanism and relationship between primary productivity and temperature. [Temperature influences density and thus stratification.]
• Explain the role of upwelling/downwelling, longshore transport, and density stratification on phytoplankton abundance.
• Describe the importance of proxy data and predict phytoplankton concentrations using proxy data as a tool.

Context for Use

These data explorations were designed for implementation in an introductory oceanography course (majors and/or non-majors). These activities would be appropriate for exercises in reading and interpreting graphical data as well as examining the processes that affect primary production, focusing on spatiotemporal variations such as the spring bloom in temperate environments and the high productivity of upwelling regions.

Teaching Notes

Students will need to be familiar with concepts from earlier in the semester including: density stratification; the vertical distribution of oxygen, carbon dioxide, and nutrients, and what affects them; Ekman Transport and upwelling.

At any level, this activity requires synthesis of a variety of concepts that may not have been considered together previously. While the hope is to guide students to a more scientifically accurate understanding, the broader learning goal is in making these connections.

The Data Exploration activities require access to an internet-ready computer or tablet. Ideally each student or pairs of students would have a computer or tablet to use to engage with the activity. Alternatively, if no internet access is available for each student or pairs of students, graphs of the specific time periods of interest and variables could be printed onto plastic overlays for each student or group of students. Note, the Data Explorations use authentic raw data. Many of the datasets have been downsampled for simplicity and to ensure that the interactives load quickly in your browser.

Subject / Topics

Introduction to Oceanography

• Ocean currents: surface currents, upwelling/downwelling, Ekman transport
• Water chemistry: temperature, salinity, density, dissolved gases
• Primary production: what it is, regional and seasonal variability
• Marine fisheries

Grade Level

Undergraduate students in Introduction to Oceanography courses (for either marine science majors or non-science majors)

Data Scope

Our scope in exploring ways to use professionally-collected data in our teaching:

• Using professionally-collected data in teaching of concepts
• Visualizing data in a user-friendly and authentic way
• Enabling students to interactively engage with data in their learning to see the patterns as they are learning the why

Quantitative Skills

Most of the quantitative reasoning in this exercise revolves around reading and interpreting graphs.

• Water quality is determined by interpreting a time series of chlorophyll concentration. Students are asked to read the graph to determine axes, the date range, chlorophyll units, and minimum and maximum values.
• Students must examine multiple time series with the widget to deduce the relationship between chlorophyll and water temperature, salinity, and dissolved oxygen. They should see that there is a strong correlation between all three of these variables.
• They must also articulate temporal patterns in the data presented.
• Longshore wind direction is presented in a graph and students must make the connection between the direction on a graph and Ekman transport and associated upwelling and downwelling. [N-to-S winds cause upwelling while S-to-N winds cause downwelling.]
• Students compare and contrast U.S. west and east coast regions by making a prediction for east coast temperature using the relationship with chlorophyll that they generated for the west coast.
• Students compare and contrast U.S. west and east coast regions over time and in scale (magnitude) with respect to chlorophyll, water temperature, salinity, and dissolved oxygen.

Expansion ideas

• Use future data to examine nutrient concentration (phosphate and/or nitrate) and pH.

Science Explanation

TBD

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