Summary of the Penn State Study on Flathead Catfish in the Susquehanna River
This article details a new study conducted by Penn State researchers investigating the impact of invasive flathead catfish on the food web of the Susquehanna River. Here’s a breakdown of the key findings and methods:
Key Findings:
* Flathead catfish occupy the highest trophic position: They are apex predators in the river, impacting the food web significantly.
* Expansion of Isotope Niche: The presence of flathead catfish leads to a broader range of resource use (indicated by isotope analysis) within the river ecosystem. This suggests they are altering how native species interact and compete.
* Changes in Native Species: The study aims to understand how the invasive catfish affect the diets, habitat use, and potential competition for resources among native species.
Methods:
* Comparative Analysis: Researchers compared sections of the river with and without flathead catfish presence.
* Focus Species: the study focused on:
* Flathead catfish: The invasive predator.
* Channel Catfish & Smallmouth Bass: Potential prey species.
* Coral Shrimp & Small Fish: Lower trophic level prey.
* Stable Isotope Analysis: This was the primary method used. It involves:
* Analyzing carbon and nitrogen isotopes in fish tissue.
* Nitrogen isotopes reveal diet.
* Carbon isotopes reveal habitat use.
* Comparing isotope signatures across diffrent regions to understand fish movement and habitat shifts.
* Sample Collection: 279 fish (including 79 flathead catfish) and 64 coral shrimp where collected. Samples were processed into powder and sent for isotope analysis.
Importance:
The study provides valuable insight into how invasive species can restructure river ecosystems. By understanding the trophic relationships and resource use patterns, researchers can better predict and possibly mitigate the impacts of invasive species like the flathead catfish.
Funding & Contributors:
* Funding: Pennsylvania Sea Grant and US Geological Survey.
* Key Researchers: Sydney Stark,Olivia C. Hodgson, megan Schall, Geoffrey Smith, kelly Smalling, and Tyler Wagner.
