Changing Tides: Intertidal Invertebrates, Bears, and People
Visitors view a bear foraging for clams and other invertebrates in the mudflats of Chinitna Bay in Lake Clark National Park and Preserve.
NPS Photo/J Pfeiffenberger
In the summer of 2015, the National Park Service embarked on a new multi-year study to investigate the unique link between the terrestrial and the nearshore environment, specifically between coastal brown bears and intertidal invertebrates. Clams and other marine invertebrates are known to be an important food source for coastal brown bears. Natural and human-related pressures can impact the health of these intertidal invertebrate communities, which can in turn affect those species that rely on them.
This study aims in part to identify just how important these invertebrate resources are for brown bears and how threats to the marine environment might affect them. Elements of the study are taking place at both Katmai and Lake Clark National Park and Preserve.
You can use the links below to explore this study and follow along as we learn more about how bears, clams, and people interact along Alaska's coasts! Project updates after 2017 have been incorporated into the park's Natural Resource newsletters.
Locations:Katmai National Park & Preserve, Lake Clark National Park & Preserve
Although remote, the Alaska Peninsula is still vulnerable to natural and human-caused disturbances. These disturbances could affect the amount of food available for brown bears. As part of a larger project looking at the nearshore environment of the peninsula, biologists will outfit 12 bears with GPS collars, to track their movements between different habitats, and conduct direct observations on these bears to collect data on their foraging behavior.
The Changing Tides project is a three-year study examining the link between the marine and terrestrial environments, specifically between coastal brown bears, clams and mussels, and people. It is a cooperative project of the National Park Service, U.S. Geological Survey, Alaska Sealife Center, and Washington State University.
Locations:Katmai National Park & Preserve, Lake Clark National Park & Preserve
Southwest Alaska’s coastal brown bears are the largest of their kind in the world, deriving much of their bulk from the abundant salmon resources that pulse into the rivers from the sea each summer. Bears also use intertidal resources such as clams and mussels. Along the shores of Lake Clark National Park and Preserve and Katmai National Park and Preserve, bears spend hours in the mudflats digging, chomping, slurping, and digging again.
Locations:Katmai National Park & Preserve, Lake Clark National Park & Preserve
Browse articles related to the Changing Tides project. This is a research study in Southwest Alaska exploring the connections between coastal brown bears, invertebrates like clams and mussels, and what influence human activities have on bear ecology.
Locations:Katmai National Park & Preserve, Lake Clark National Park & Preserve
The Changing Tides project is a three-year study examining the link between the marine and terrestrial environments, specifically between coastal brown bears, clams and mussels, and people. It is a cooperative project of the National Park Service, U.S. Geological Survey, Alaska Sealife Center, and Washington State University. Preliminary data from the summer of 2015 creates more questions to study.
Highlights from this year's study so far include taking tissue samples from bivalves (e.g., clams), assessing bear health and discovering with a camera trap that bears may be actively predating upon otters!
For the second consecutive summer, researchers are putting GPS collars on coastal bears in Katmai as part of the Changing Tides project. The May 2016 collaring effort was a great success, with near-perfect weather aiding in the outfitting of ten bears with GPS collars.
Several months into the Changing Tides project, scientists are beginning to see patterns in the foraging movements of collared bears along Katmai's coast. The bears being studied gained significant weight already, even before salmon runs had reached area streams. Data like this will help scientists analyze just how important invertebrates like mussels and clams are to grizzly bear health and their success raising cubs.
By tracking the movements of bears and assessing body composition, biologists can examine their use of different foraging areas and the importance of different food to overall bear health and survival. This July 2015 update explores the first steps taken in the "Changing Tides" project.
