Event name: Linking watersheds, wetlands, headwater streams and juvenile salmon - Kenai Lowlands, Alaska
Event speaker: Dr. Dennis Whigham from the Smithsonian Environmental Research Center
Event time and place: 3:00 pm - 4:00pm on October 30th; 0408 Animal Science Building, University of Maryland
The presentation occurred as part of the Environmental Science & Technology Weekly Seminar series and discussed the Smithsonian Environmental Research Center’s Salmon and People Project. The goal of the project is to understand ecology and communicate with policymakers and the public regarding maintaining a sustainable salmon industry. Dr. Whigham discussed his work in Alaska, where he monitored unprotected streams. He observed vegetation and fish species in these streams. He found that high-gradient streams and low-gradient streams had distinct differences in aquatic organisms and vegetation surrounding the streams. He specifically began to look at the alder coverage of the streams. Alder is a plant with nitrogen-fixing bacteria in its root nodules, so he studied the relationship between the plant’s coverage and the available nitrogen in the stream. He also conducted a stream dosing project with nitrogen and carbon to determine impacts on stream metabolism. Unfortunately, the nitrogen results were lost to a rain event, but the carbon results showed that calamagostis coverage increased, causing photosynthesis at the bottom of the stream to decrease. Ultimately, he determined that sites with alder had more nitrogen. When there’s no nitrogen, plants have more roots stretching out into the streams because they have to work harder to search for available nitrogen. This can have negative impacts on the productivity of the stream.
I found the main points he presented very convincing. Dr. Whigham presented research on his work in Alaska and briefly discussed its relevance to influencing conservation policies and education. The streams were unprotected at the beginning of their research, but their findings on prominent salmon presence was used to establish new laws that would protect these smaller streams. They were also able to meet with a local tribe and host educational events to encourage a mindset of conservation when it comes to the salmon industry. He mentioned that these results could be applied to streams all over the world and the Chesapeake Bay research could provide influence on other parts of the world. It may have been due to time constraints, but he failed to provide adequate evidence of this point. In the introduction, he mentioned how understanding how the landscape supports fish in the Chesapeake Bay is what inspired his initial interest in the Alaskan streams, however, a link between the results of these studies was not provided. It would have been interesting to hear more about the link between salmon and wetlands and how this can be applied to other types of wetlands in different climates. His claim that degrading wetlands influences stream ecology and negatively impacts fish populations was supported. This main point was convincing and was a significant part of his support for the application of these very different estuaries. If there had been more time, I would have liked to learn more about how abundant vegetation in the Chesapeake Bay watershed impacts specific stream ecology and species diversity. I didn’t notice any logical fallacies in his work, though I noticed he didn’t discuss other potential sources of nitrogen within the streams. Again, this may have been due to time constraints or the research may not have been done. This is an ongoing project, with researchers still doing stream work in Alaska, so more experimental data is being collected. Similarly, it would be interesting to see other wetland characteristics considered to determine what nutrients and factors are having the greatest impacts on the stream ecology. Finally, he provided a lot of background on salmon fishing, but not much background on wetland and stream ecology. His argument was convincing overall, but missing some relevant information. We were not presented with the laws and education initiatives before his team’s discoveries. Thus, we cannot know for certain how much has changed at both the governmental and public knowledge levels. It is difficult to fully accept his argument when I still have several questions about the work. Overall, his research was well presented and explained, I just wish he had spent more time relating the work back to the overarching questions and goals.