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PLANS, a NOAA B-WET Education Program that Partners Scientists, Teachers, and Students

Parameters: Chlorophyll

PLankton And Nutrient Studies for the Chesapeake Bay (PLANS) is a NOAA B-WET sponsored program designed to provide hands-on experience for Calvert County Public High School students by investigating nutrient enrichment/limitation, phytoplankton dynamics in the Chesapeake Bay, and the role that man plays in managing the Bay. This project teams Morgan State University Estuarine Research Center (ERC) and the Society for Ocean Sciences researchers/educators with the Calvert County Public School System. A distinctive strength of the program lies in the idea of scientists working directly with teachers and students on regionally important environmental issues. The program consists of field, laboratory and classroom components. The field part of the program is a cruise from the ERC facility into the Patuxent River for the Advanced Placement Environmental Science students from the four Calvert County, Maryland high schools. These trips enable the students to get hands-on experience with the collection of data from a water quality vertical profile, light attenuation profile, and chlorophyll a profile. These activities are followed by an interpretation of data that were collected. The second portion of the cruise moves from the deep channel of the river into the shallow reaches of an oyster bar. Here, an oyster dredge is towed and the contents analyzed for live/dead oysters and the associated catch During the cruise, the students divide up into three groups to sample for water quality, light and chlorophyll a. The water quality group uses a YSI 85 meter to measure temperature, salinity and dissolved oxygen at one meter intervals. The light attenuation group uses a LiCor underwater quantum sensor and data logger to measure light levels at 0.5m intervals. The chlorophyll group pumps water from depth with a bilge pump through a Turner Designs Model 10AU Fluorometer that is set up for flow-through capability. The data either shows a well-mixed water column or one that is stratified depending on the season. The in vivo fluorescence measured by the fluorometer at various depths is discussed in regards to the amount of algae present in the water column. During one of the cruises, the students noted that a large amount of phytoplankton was present near the surface, likely indicating a dinoflagellate bloom in the area. A live phytoplankton sample was collected from the surface before moving to the oyster bar on the other side of the river where an oyster dredge was performed and subsequent sorting of the catch.

Researcher explaining how the fluorometer works and student taking measurements.

The second half of the field trip involves an oyster grazing experiment and the microscopic examination of the live plankton samples that are collected during the cruise. The oyster grazing experiment is performed to illustrate the important role that oysters play in the ecosystem as the Bay’s filter. The experiment is designed with triplicate control tanks and two different treatments – tanks with one oyster and tanks with ten oysters. The same amount of phytoplankton is added to the tanks and fluorescence readings are taken every 30 minutes with the AquaFluor Handheld Fluorometer. The students are given a brief explanation of how the fluorometer works, what it measures, and how measurements are taken. Mean IVF values for each time period sampled are calculated for the three sets of tanks and entered onto a graph. By the end of the 2-hour experiment, the graph depicts three distinctly different line plots that are interpreted with the students input.

Students conducting the oyster filtering experiment - taking a sample, tank set-up, measuring fluorescence.

Data from oyster feeding experiment

Soon after the field trip, a nutrient limitation experiment using a natural water sample is scheduled for the classroom. The students are introduced to the idea of a nutrient limitation bioassay, the experimental design and procedure, how to use specific pieces of equipment (pipeters and the AquaFluor® Handheld Fluorometer used during the field trip), and how to record their data. The experiment is set up using a Patuxent River water sample collected by the students during their cruise. In the triplicate control (raw water) and treatment tubes (raw water +nitrogen, + phosphorus and + nitrogen and phosphorus) daily fluorescence readings were collected for 4-6 days and the results graphed by the students. Using a guide to nutrient limitation that shows graphs of different types of nutrient limitation that had been determined for the Bay, the students determine which type of limitation occurred in their bioassay and whether or not it is the limitation expected for the time of the year the experiment is performed.

Students performing the nutrient limitation bioassay- adding algae to different nutrient solutions, tubes incubating in growth box, recording fluorescence in each tube to monitor growth.

A unique strength in PLANS is the hands-on experience which enables the students to learn field and laboratory techniques. Allowing them to design experiments and use pieces of equipment, such as the fluorometers, to collect their data, gives them skills and a deeper understanding of methods used to address important issues that the Chesapeake Bay is facing.

Author: Stella Sellner

Institution: PLankton And Nutrient Studies for the Chesapeake Bay (PLANS), Chesapeake Bay, USA

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