New Phyto-Finders Tackle Improvements for Better Phytoplankton Sampling

Lexi M. Foster, Phyto-Finder, First Flight High School, Kill Devil Hills, North Carolina USA

 First Flight High School (FFHS), located on the barrier islands of North Carolina, sets a high bar with their Phyto-Finders Club. Club members take advantage of their unique location and resources by collecting phytoplankton with a student-designed and student-fabricated tow frame, which they deploy along local piers. Their main objective is to detect toxic algal blooms, which are a threat to human and ecosystem health. When examining their samples using microscopes and through DNA analysis, the Phyto- Finders are able to detect harmful organisms, such as Pseudo-nitzschia, which can produce domoic acid, a potent neurotoxin. Their results are reported directly to the National Oceanic and Atmospheric Administration (NOAA) Plankton Monitoring Network (PMN). This school year (2019-2020), the club has an almost entirely new team with creative ideas to improve the capabilities of the tow frame.

INTRODUCTION

In the beginning, 2005, as the Phyto-Finders Club first began to take shape, collecting phytoplankton was as simple as dropping a net at the US Army Corps of Engineers Field Research Facility (FRF) pier in the town of Duck, NC, or at Jennette’s Pier in the town of Nags Head, NC. This technique had some flaws, mainly the inability to control the orientation of the net’s mouth, through which the phytoplankton are collected. Over a decade later, the process was updated with the construction of the tow frame, Bagel, which Phyto-Finders described in a paper presented at OCEANS ’18 in Charleston, SC. Since then Bagel has been used for every sample collection, but phytoplankton sampling remains a difficult task.

COLLECTING SAMPLES AND REVIEWING BAGEL

First, one person must throw a bucket into the water to collect a preliminary water sample. This is done in case there is a toxic bloom in progress; significant discoloration of the water would warn us that special precautions or backing off entirely is necessary. It then takes two people to complete one sample, by steadily towing the frame, to which a rope bridle is attached, over a fixed distance alongside the pier.  Although this technique does control the mouth of the net, a major improvement, it is inconsistent in poor weather conditions, such as high winds and strong waves. And, even in good conditions, it is difficult to get the net and the sample bottle located at the end of the net to submerge, because of trapped air.

Club members have found through experience that winds mixed with choppy water make it nearly impossible to collect a consistent, usable sample. The net mouth was connected in the center on the original frame and the net body and sample bottle could move freely, having no surrounding support. Scenarios such as an inside-out net or a breached bottle, which can force termination of the sample tow, are far too frequent. Air gets trapped and breaches the bottle when Bagel’s net isn’t completely vertical as it makes contact with the water, especially if the speed of immersion cannot be controlled due to wind and waves. An inside-out net is caused when currents, winds, and waves conspire to push the bottle forward through the mouth of the net before the tow can start. If either failure occurs, the tow must be scratched and restarted.

Figure 1: Two club members pull Bagel up after a successful tow (top panel). Students then cap the bottle (bottom panel) and apply a label with the date and location before beginning a new tow further along the pier.

To address these issues, the club brainstormed ideas for potential improvements during a December 2019 visit by IEEE Oceanic Engineering Society (OES) mentors, Drs. Todd and Hilary Morrison.

DECEMBER 2019 VISIT

During the Morrisons’ two-day visit to the Outer Banks of North Carolina, Todd and club members worked together to assess towing techniques, particularly with new members, and discussed ideas for improving the performance and behavior of Bagel. And all Phyto-Finders had the opportunity to learn DNA extraction protocols from Hilary in the FFHS lab of our AP science teacher and club advisor, Katie Neller.

Figure 2: Bagel has a breached net and bottle, which calls for a restart of the tow. Students must repeatedly dunk the frame until it is submerged properly, a frustrating exercise that potentially compromises the sample even during relatively good conditions.

While collecting samples from the piers, experienced students taught collection techniques to new members. All of us shared ideas for overcoming the observed problems of breaching and inversion.  We discussed and refined these ideas with Todd, who encouraged us to start trials of our best ideas.

We decided that supporting the net and bottle with a rigid frame was a particularly promising approach, but were uncertain how to fabricate one. We also anticipated that transporting and handling the combination of tow and net frames would be awkward and that releasing the sample bottle without compromising the sample would be difficult. We believe we can solve the fabrication problem by using a tomato cage, available from gardening stores. Credit to an unnamed Phyto-Finder for a creative and easily implemented solution!

For the other problems, we are still talking and planning and intend to have these advancements developed and in use by next school year. Once we have that enhancement working reliably, our next planned development is a Bagel that can be configured to sample at different depths, not just at the surface.

Every week during the school year (when there isn’t a pandemic) we examine our phytoplankton samples under microscopes, typically the day after collecting them. We look for a number of different species using a reference sheet that identifies which species produce toxins. And then we document our observations and send the results to NOAA.

Taking an even deeper look into our local waters, Dr. Hilary Morrison taught club members how to extract DNA from phytoplankton and other organisms in our samples. The process requires precision and care, but we worked diligently with Hilary and with each other to get it right.

The finished product, about 30 µl of liquid containing the DNA from many different organisms, is sent to Hilary’s lab at the Marine Biological Laboratory in Woods Hole, MA. There it can be processed to identify, with very high sensitivity, the microbial, planktonic, and macroscopic species present in the waters of the Outer Banks of North Carolina. Soon, we hope, some of us will be able to travel to Woods Hole to participate directly in that processing.

ACKNOWLEDGEMENTS

The Phyto-Finders would first like to recognize and thank the IEEE Oceanic Engineering Society for graciously supporting and funding our research. Next, to our advisor, Ms. Katie Neller, thank you for opening our minds and supplying us with everything necessary to succeed. Lastly, a special thanks to Drs. Todd and Hilary Morrison for their advice, guidance, and knowledge.