About This Project

Freshwater ecosystems are considered highly vulnerable to global climate change, and will face chemical, physical, and biological transformations. In southern California, extreme drought conditions have gripped the region between 2012 - 2016. During this time, continuous water temperature data was collected in two creeks. This study will determine if thermal conditions were altered by drought, and consider implications for resident trout.

Ask the Scientists

What is the context of this research?

In the currently modeled climate change regime, mean air temperatures are predicted to increase over the next hundred years as a 6.4 oC increase worldwide. While a warmer Planet Earth will have widespread effects on human life and civilization, wildlife will be impacted significantly as well. For fish and other cold-blooded animals, the biochemical reactions of life that direct growth, reproduction, and more, are directly correlated to the temperature of the surrounding environment. If thermal limits are exceeded, fish could be extirpated from native ranges. In southern CA, the federally endangered Steelhead Trout will be especially vulnerable to warming waters. This study focuses on temperature in freshwater habitat of this imperiled fish.

What is the significance of this project?

We know increasing temperatures will affect freshwater resources and their management. However, how freshwater temperatures will change is not so clear. For example, are maximum temperatures, which if exceed fish tolerance levels can prove fatal, increasing at the same rate as minimum temperatures, which influence availability of thermal refuge? Important questions as to the magnitude, timing, frequency, duration, and rate of change of temperature increases persist. Determining how temperature conditions in our streams are responding to drought or other climate phenomenon will be critical to understand how to best respond and manage streams to protect biodiversity.

What are the goals of the project?

This project will utilize temperature data collected between 2012-2016 in two coastal creeks in southern California to determine how freshwater temperatures have responded to extreme drought conditions. Temperature was collected at 30 minute intervals in four locations per creek. This data will be analyzed to determine the magnitude (how many degrees difference in temperature?) timing (earliest/latest occurrence of extreme temperatures), frequency (number of extreme temperature days), and rate of change (degrees per year) of temperature change. These metrics will be compared year to year, as well as between creeks. Extreme temperatures will be defined as those above the thermal maximum for Steelhead Trout, which has been determined to be above 30 degrees C.