10.6.26

Gone fishin’ for survival

A coastal cutthroat trout in a holding tank.

The activities are as follows:

Climate change is affecting our world in many ways. Globally, we are experiencing more droughts and wildfires, shifting seasons, and rising sea levels. Species are responding as well. Some can shift their ranges to follow cooler temperatures. But what about organisms, like fish, that cannot easily move to a new location?

A group of scientists is studying fish in streams in central Oregon to learn more. The H.J. Andrews Experimental Forest, also called the Andrews, is a long-term research site in the Cascade Mountains of central Oregon. Scientists have been collecting data there for decades! The Andrews is an old-growth temperate rainforest with a dense canopy of trees. These trees block the sun’s heat, keeping the understory and streams below cool.

Ivan and his team electrofishing Mack Creek to sample the trout population.

Ivan is a biologist on this team who studies fish in these streams. Originally from southern Chile, he has spent decades studying ecology in both marine and freshwater environments. Ivan first came to Oregon to study how logging affects stream ecosystems. While working at the Andrews, he noticed that air temperatures in the forest were getting warmer over time. He wondered if the stream temperatures were warming too and whether this change might be affecting the fish that live there. He focused on coastal cutthroat trout living in Mack Creek, a stream within the Andrews.

Ivan started his exploration with data from historical surveys. For many years, scientists, staff, and students at the Andrews have been sampling coastal cutthroat trout in the streams. They collect data on their body size and other health measures. Ivan and his team found data on trout fork lengths, or the distance in millimeters (mm) from the tip of the fish’s snout to the center of its tail, dating back to the 1980s. Ivan used these data to calculate the median fork length of trout measured each year. The median is the middle value when all the trout are ordered from smallest to largest.

Each trout is measured before being released back into the creek.

Ivan also found data on Mack Creek water temperature for the same years as the fish length data. Ivan focused on summer water temperatures because these would be the warmest experienced by the trout each year. He found the highest water temperature recorded each summer day, called daily maximum temperature. He then averaged all the daily maximums for each summer, which gave him one temperature value for each year. This value is the average maximum summer water temperature.

Ivan predicted that he would see stream temperatures go up over time due to climate change impacting the Andrews. He also predicted that trout median fork lengths would be getting shorter over time. He based this idea on the temperature-size rule, a common pattern seen in fish. In warmer temperatures, fish metabolism speeds up, and animals with faster metabolisms often mature at a smaller body size. This would support the idea that climate change was leading to smaller fish in the Andrews.

Featured scientist: Ivan Arismendi from Oregon State University, H.J. Andrews Experimental Forest Long Term Ecological Research Site.

Written by Ryan Herlands (he/him) from Springfield Public Schools and Matthew Retterath (he/him) from Fridley Public Schools

Flesch–Kincaid Reading Grade Level = 9.2

Additional Teacher Resources:

You can learn more about the H.J. Andrews experimental forest here. This site is part of the long-term ecological research (LTER) network.

8.29.26

Time flies when you turn up the heat

A member of Richard’s lab recording data on the fruit fly population.

Aging is a natural process that happens in all living things. As organisms get older, their cells and DNA slowly become damaged. Some of this wear and tear happens naturally as cells do their jobs. Other damage can be brought on by stressful environmental conditions, such as high temperatures. 

Richard is a scientist interested in factors that affect aging. He is curious about why some individuals of the same species live longer than others. Similarly, some individuals reach maturity faster, or in other words, have shorter development time. These topics can be tricky to study because lifespan, or how long an organism lives, can take a long time to observe. For this reason, Richard studies aging in flies. Flies are especially useful for questions like these because they are small, easy to raise, and have short life cycles. This allows researchers to study growth, development, and aging in a short amount of time.

Each fruit fly is placed in their own container that is labeled with an assigned ID number, their sex, and the date they emerged as an adult. 

To start, Richard, along with members of his lab, wanted to look at how temperature affects development time and lifespan. Every organism has a range of temperatures where it grows and functions best. If the environment is much warmer or colder than that range, it can cause stress. Temperature also affects how quickly many biological processes happen. For example, in warmer temperatures, metabolism, or the process of turning food into energy, usually speeds up. Because of this, young organisms often grow and develop faster in warmer conditions. Faster development and metabolism can cause cell damage to build up more quickly.

Richard’s lab includes scientists at all stages – from undergraduates to graduate students, and researchers who already have advanced degrees. They worked together to investigate how temperature affects the development time and lifespan in a fruit fly species. They knew from previous studies that female fruit flies usually live longer than males. Richard’s lab wanted to build on past work and figure out how temperature affects this pattern. 

The vials with fruit flies inside are kept in incubators set to either 18°C or 22°C.

To test the effects of temperature, the research team raised fruit flies in two conditions: 18°C and 22°C. Female flies laid eggs, each in their own container, and the eggs were allowed to develop. Each day, the team recorded when adult flies emerged from their pupal cases and whether they were male or female. Development time was measured as the number of days it took each fly to grow from an egg into an adult.

After the flies emerged, they were moved to a separate container and kept at the same temperature treatment. This ensured the team could keep track of how long each fly lived. The adult flies were all given the same food and kept at the temperatures that they were raised in. Each day, members of the team would carefully check each vial and look for deaths. By knowing the dates that each fly had emerged as an adult and their death date, they could calculate lifespan. Throughout his experiment, the team measured lifespan and development time in thousands of male and female fruit flies!

Featured scientist: The Richard Meisel lab at the University of Houston

Flesch–Kincaid Reading Grade Level = 9.1

Additional Teacher Resources