Hamline News

Biology Summer Research Notes: Spencer Larson and Professor Leif Hembre


Summer is a great time for students to conduct collaborative research at Hamline University. Student Spencer Larson and Professor Leif Hembre have made the most of it by spending time lakeside collecting samples for their research collaboration. Recently, Larson shared insights the project, which is supported by the Kerr Fund.

 What is the title of your project?

“Using zooplankton remains and sediment composition to investigate the effects of fisheries management practices on the trophic state of lakes”

How would you explain your project to a person who knows nothing about it?

We want to find out how the ecology of two lakes (Square Lake and Big Carnelian Lake, in Washington County, MN) has changed over the past several centuries. To reconstruct how these lakes have changed over time we are using clues from materials that have been sunken out of the water and become deposited in the lakes’ sediments (mud!) year after year. The main things we are looking at are the remains of different types of zooplankton, small animals that live in the open water of the lakes. In lakes, zooplankton eat algae in the water and are, in turn, consumed by fish. The abundances and sizes of these zooplankton remains gives us clues about how fertile the lakes have been through time and how much predation the zooplankton were experiencing from fish.

The reason that we are interested in these two lakes is because the two lakes have a different fisheries management history. Square Lake was stocked with rainbow trout by the Minnesota Department of Natural Resources for more than 30 years (1981-2012), while Big Carnelian Lake has never been stocked with trout. Otherwise, Big Carnelian is similar to Square Lake. It is less than two miles away from Square Lake and is similar to Square Lake in its depth, size, and water quality.

How has the COVID-19 pandemic affected your research methods?

We have had to be careful when working together in the lab to prevent potential spread of the virus (e.g., wearing masks, staying > 6 ft apart, sanitizing surfaces). Wearing masks when working together makes communication somewhat difficult, and not being able to share the same microscope when looking at samples has made our collaboration in the laboratory cumbersome at times.

What is the biggest challenge of your project?

One of the biggest challenges we’ve had to address and resolve was a problem with the quantity (counts) of remains found. For context, our work this summer is a continuation of a research project that began 3 years ago, and we wanted to make sure the counts we found were close to what was found previously by looking at slides that were documented beforehand. To our surprise, they were drastically different from what was previously found, and this is a major issue because it could call into question the validity of the data collected up to this point in the project. We are working with Professor Hembre’s former research student, Michael Gilray ‘18, to solve this problem.

Once this problem is solved, the next challenge will be to dig into the samples and do A LOT of microscope work!

What has surprised you about the project?

I was surprised to have encountered such a major problem right out of the gate; not too long after I started working on this project with Professor Hembre, we found the massive discrepancies between these counts, and our plans for the project were quickly put on hold as a result. There was now an emphasis on finding a solution to this problem, rather than expanding upon what was found 3 years ago. This has, however, shed light on a very important aspect of doing research: A lot of times, problems like these will occur, and one must always be prepared to address and solve any potential issues that may arise during the process. It may be quite the issue, but I am glad to have this kind of experience under my belt because learning ways to solve unanticipated problems is incredibly important in the research process, and it is no doubt very applicable to many aspects of life.

How does the project fit with your academic or career goals?

The world of research is one of great interest to me, and I want to be as prepared as I can be when I go to graduate school and do work reminiscent of this project with Professor Hembre. It just so happens that this work is centered around one of my favorite fields of biology: Ecology. It is a subject I want to continue to study in graduate school and in the future. I would love to have a career tailored to it and have the opportunity to advance the field to new heights, and I am grateful to have such an amazing professor who has supported me and my goals ever since my freshman year. I have nothing but respect for Professor Hembre and the guidance he has given me so I can continue to pursue my aspirations. He is truly an inspiration, and a person I look up to.


Written by Larson and Hembre in response to staff questions.