Lab 7.2 – THE GULF STREAM PART 2: IDENTIFYING INTRUSIONS AND PLANKTONIC IMPACTS

Fundamental concept: TBD
Estimated time to complete: 45 minutes
Data skills preparation: TBD
Materials needed: None

Lab 7.1 Introduced the Gulf Stream and explored an intrusion event along the New England Shelf. Now let’s see if you can spot another example of a saltwater intrusion event due to the Gulf Stream coming close to shore.  In 2022-2024, the Pioneer Array of instruments was moved from its initial location on the New England Shelf to its new location in the southern part of the Mid-Atlantic Bight off the coast of North Carolina near Cape Hatteras.  Below, data from this new location are shown in interactive graphs for you to explore.

The top graph shows salinity profiles over time and the middle graph shows temperature profiles over time.  In these two graphs, each day is shown as a vertical bar that is color coded to show the salinity or temperature of the water from near the surface at 28m to the bottom at about 80m. The lower graph shows a time series of the salinity, temperature, and density near the surface at 7 m depth.  Observe the data, zoom in and out, and see if you can find evidence of another event where Gulf Stream water was detected by these sensors, which are located on continental shelf. Answer the questions that follow the graphs.

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Orientation Questions

  1. What are the starting and ending dates of the time period shown on these graphs?
  2. What is the range of depth shown on the y axes of the top two graphs?
  3. What are the maximum and minimum values for temperature shown on the third graph?
  4. What are the maximum and minimum values for salinity shown on the third graph?

Interpretation Questions

  1. Think about the location where this dataset was collected:
    1. In which hemisphere is the Coastal Pioneer array located?
    2. Which coast of the United States is this data from?
    3. Which side of the Atlantic Ocean is this data from?
  2. Focus on the bottom two graphs showing a time series of temperature, salinity and density at the surface in this location.  Compare temperature to the density: What happens to the water density as the temperatures cool
  3. Focus on the bottom two graphs showing a time series of temperature, salinity and density at the surface in this location.  Compare salinity to the density: What happens to the water density as the salinity increases?

Application Questions

  1. Gulf Stream water is warmer and has a higher salinity; describe how these characteristics would combine to affect density.
  2. What dates show evidence that the Gulf Stream water passed by the sensors at 7 m depth (shown in the third graph)?
  3. On the dates you identified, how deep did the warmer, saltier Gulf Stream water extend? How do you know?

In Lab 7.1 we highlighted how the Gulf Stream can impact fish populations but changes in the Gulf Stream movement could also have effects on other marine life.  Planktonic organisms form the base of marine food webs and changes in planktonic communities can have cascading effects in marine ecosystems. A 2024 paper by Pereira et al. studied plankton communities in meanders of another surface current known as the Brazil Current. and found a unique assembly of phytoplankton associated within different parts of the meanders. 

The new location of the Pioneer array near Cape Hatteras, North Carolina is an ideal spot to study Gulf Stream meanders and eddy formation and differences in marine life within each. Pereira et al.(2024) point out that taxonomic identification will be important for understanding how the phytoplankton community varies in such meanders. The instrumentation of the Pioneer MAB array includes an Imaging FlowCytobot (IFCB); This oceanographic sensor uses video imaging to capture high-resolution images of microscopic aquatic life (mainly phytoplankton) (see image of sample data below) which allows identification of the plankton.

Pictures of Plankton from the Imaging Flow Cytobot (IFCB) on the Pioneer MAB Array

Pictures of Plankton from the Imaging Flow Cytobot (IFCB) on the Pioneer MAB Array

After running for a full year, the instrument was recovered in April 2025, and its data are now publicly available to researchers and educators alike.

Reflection Question

  1. Imagine you were an oceanographer interested in this topic; brainstorm how this new instrument could help us understand how Gulf Stream meanders and intrusions affect plankton communities and possibly higher levels of the food web. Summarize your ideas here.

 

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