January 21st, 2021
The article I chose to read this week was “Evaluation of the influences of dam release types, land use, and habitat affecting abundance, richness, diversity, and community structure of larval and juvenile fish” by Daniel Hanks and Kyle Hartman. It was published in the Canadian Journal of Fisheries and Aquatic Sciences, which “publishes perspectives, discussion, articles...relating to current research on...processes that affect aquatic ecosystems.” ¹ The purpose of this article was to “evaluate the influence of dams on downstream aquatic habitat and early life stage fish” from two different types of discharges (epilimnetic and hypolimnetic)⁴. Epilimnetic discharges are flows of warm water from the part of the lake that’s just above the thermal layer. On the other hand, hypolimnetic discharges are flows of stagnant and uniform temperature water from the part of the lake below the thermal layer.
I found this article in the Gale in Context: Science database, using the search terms dams, fish, and ecosystems. Some of the key terms in this article were epilimnetic versus hypolimnetic, larval fish, and juvenile fish.
The two authors of this article are Daniel R. Hanks and Kyle J. Hartman. Hanks is currently researching and working as an aquatic ecologist at the company Weyerhaeuser. Up until November 2020, he worked at Clemson University as a post-doctoral researcher and he received his Ph.D. in Wildlife and Fisheries Resources from West Virginia University in 2016. He has 19 publications (composed of articles and conference papers), and his impact lies in helping “develop products that inform on the ground conservation efforts.” ² Hartman has been a professor of Wildlife and Fisheries Resources at West Virginia University since 1996 ³. He received a Ph.D. in Marine Ecology from the University of Maryland and has about 130 publications (composed of articles, conference papers, and presentations). His articles are all peer-reviewed and he serves as a faculty advisor to more than 30 graduate students, on top of researching “ecology and management of aquatic systems and biota” ³.
The study they’re conducting is sampling larval and juvenile fish from six dammed streams (three of each type of discharge), as well as one control stream, that are all from the mid-Atlantic region of the US⁴. 16 different sampling sites were set up at each stream, the first one located directly below the dam; 100 m was the distance between the first seven sites while 500 m was the distance between the remaining nine⁴. Additionally to analyzing landscape habitat variables (which were divided into developed, forested, and agricultural grassland), “average substrate diversity...and overall habitat diversity (...for substrate, depth, and flow) was [also] calculated for each site” in order to make up for any differences between sites⁴. The results from the experiment showed that the greatest difference in richness and diversity of fish between epilimnetic and hypolimnetic releases was “at moderate distances from dams” but effects were still seen at larger distances (like 2100 m) from the dam⁴. However, both discharges showed far lower numbers than the control stream. While the fish in a regular stream had an average richness of 7.5, an abundance of 100, and diversity of 1.5, fish experiencing epilimnetic discharge had values of about 3.5, 50, and 0.75 (respectively) and fish experiencing hypolimnetic discharge had even lower values of 2.5, 40, and 0.5 (respectively)⁴. It can be concluded from these results that dams that cause more hypolimnetic discharge (which is a water flow of lower temperature) have even greater impacts on the richness, abundance, and diversity of fish than other dams. While this study provides very good information that can be used when constructing dams, the effect that even warmer waters have on fish was not tested. All the streams that were tested were “transitional, cool water systems”, meaning that these fish were readily adapted to cooler waters. If dams potentially heat up water (even though the discharge can be either of warmer or cooler water) further than normal, or there’s a pollution of streams by factories, would this have further effects on the fish?
My research question for this midterm is “To what extent do dams negatively impact the surrounding wildlife/animal habitats?”. The research provided by this article was most definitely relevant to this question, as I did not know that there were two possible types of discharges that dams could produce. However, this article also pointed out “that larval and juvenile fish communities are structured by dam release type, land use, and habitat type”, and that they adapt differently according to how far away from the dam they are (there are more drastic changes immediately following the dam and those changes get more gradual further downstream)⁴. I think this is an important fact to keep in mind: while a general agreement that fish populations downstream of dams suffer can be reached, there are other factors that play into affecting these fish populations--as in all aspects of life.
Canadian Journal of Fisheries and Aquatic Sciences (n.d.). Gale In Context: Science (accessed January 21, 2021). https://link.gale.com/apps/pub/5AHB/SCIC?u=nysl_ca_guild&sid=SCIC.
“Daniel Hanks.” Employee Profiles | College of Agriculture, Forestry and Life Sciences | Clemson University, South Carolina. Clemson University. Accessed January 21, 2021. https://www.clemson.edu/cafls/faculty_staff/profiles/rhanks.
“Hartman, Kyle.” Hartman, Kyle | Davis College of Agriculture, Natural Resources and Design | West Virginia University. West Virginia University. Accessed January 21, 2021. https://www.davis.wvu.edu/faculty-staff/directory/kyle-hartman.
Hanks and Hartman "Evaluation of the influences of dam release types, land use, and habitat affecting abundance, richness, diversity, and community structure of larval and juvenile fish."
Bibliography:
“Daniel Hanks.” Employee Profiles | College of Agriculture, Forestry and Life Sciences | Clemson University, South Carolina. Clemson University. Accessed January 21, 2021. https://www.clemson.edu/cafls/faculty_staff/profiles/rhanks.
Canadian Journal of Fisheries and Aquatic Sciences (n.d.). Gale In Context: Science (accessed January 21, 2021). https://link.gale.com/apps/pub/5AHB/SCIC?u=nysl_ca_guild&sid=SCIC.
Hanks, R. Daniel, and Kyle J. Hartman. "Evaluation of the influences of dam release types, land use, and habitat affecting abundance, richness, diversity, and community structure of larval and juvenile fish." Canadian Journal of Fisheries and Aquatic Sciences 76, no. 8 (2019): 1388+. Gale In Context: Science (accessed January 21, 2021). https://link.gale.com/apps/doc/A594831829/SCIC?u=nysl_ca_guild&sid=SCIC&xid=474999fa.
“Hartman, Kyle.” Hartman, Kyle | Davis College of Agriculture, Natural Resources and Design | West Virginia University. West Virginia University. Accessed January 21, 2021. https://www.davis.wvu.edu/faculty-staff/directory/kyle-hartman.