Ethohydraulics, to my knowledge, was first introduced by Beate Adam and Boris Lehmann in their 2011 book, “Ethohydraulik” (in German). In 2022, Lehmann et al. released an updated version of the book, “translated with DeepL”, under the title, “Ethohydraulics: A Method for Nature-Compatible Hydraulic Engineering“. Having been familiar with the term “Ecohydraulics” for more than a decade, I was intrigued by the term “Ethohydraulics” and wanted to explore what it entails and how it aligns with Ecohydraulics.
Wikipedia does not have an English entry for Ethohydraulics, but a German entry for Ethohydraulik. According to this entry, Ethohydraulics is an interdisciplinary field that combines principles from ethology (the study of animal behavior) and hydraulics (the study of fluids in motion) to understand and predict how aquatic organisms interact with their environment. Ethohydraulics focuses on the behavior of fish and other aquatic species in relation to water flow, habitat structure, and hydraulic conditions. By analyzing these interactions, researchers aim to develop more effective conservation strategies and sustainable management practices for aquatic ecosystems.
So I understand that there is a behavioral component of the aquatic individual, which is an emphasis of Ethohydraulics. But wasn’t this also an aspect of Ecohydraulics? To resolve my confusion, Wikipedia wasn’t enough, so I dug deeper into the two books. To put it in the words of ChatGPT & Co: “I delved into Ecohydraulics”.
According to the books, Ethohydraulics provides insights into the preferences and avoidance behaviors of species concerning water currents, turbulence, and habitat features such as substrate type and vegetation. This reflects the (in)famous link between functional and physical habitat, a connection sought in restoration efforts. Too often, the creation of functional physical habitats results more from a good amount of luck than from meticulous planning because we just don’t know what it feels like to be a fish. How does (dirty) water appear through the eyes of a fish – real fish eyes, not GoPro lenses? What constitutes a “good smell” from a fish’s perspective? Does the optical aesthetics of the environment influence a fish’s sense of comfort? These questions extend beyond fish to encompass animal perspectives in general, and possibly even human behavior. For instance, does my definition of “blue” internally match Greg’s definition of “green”? Returning to hydraulics, it seems that Ethohydraulics holds clues to one of my most pressing questions when I was dealing with river restoration: How can I set up an Amazon for (capitalist) fish? Seriously, this would finally provide a systematic understanding of what truly matters in river restoration. Ethohydraulics, therefore, is a fascinating field, and researchers in this field have been anything but idle, offering a lot of exciting insights.
The study of fish behavior regarding environmental factors has a rich history. As early as the 1970s, Russian researchers (Pavlov et al., 1972) analyzed fish responses to changes in lighting. In the United States, the Alden lab (Massachusetts) conducted research on the behavior of sturgeon and eel facing bar racks (Amaral et al. 2003). Swiss researchers are currently exploring the efficacy of electrified screens for guiding fish passage across dams (Meister et al. 2021). Being somewhat of a living animal myself, my instinctive guess is that fish probably do not enjoy being electro-shocked. But there are also masochist humans.
As I continued my readings, I discovered dozens of other studies on fish behavior, predominantly conducted in the US, Canada, and Europe. This made me wonder whether Western researchers are indeed the primary contributors to this field, or if my geographic statistics are biased by the languages I understand and a prominence of Western research in scientific literature. Unfortunately, my linguistic skills and resources for conducting a literature review for a blog post were insufficient to determine this. OK, this was not only for a blog post – I might have gotten a little too excited about it. If you, dear reader, know of studies from Asia, Africa, or any other region that might not have been accessible to me, please share your insights in the comments box below. I would be delighted to learn more about these studies!
This was a great read for me anyway. Although, I was wondering how Ethohydraulics relates to Ecohydraulics. Ethohydraulics still appears to be a subdiscipline of Ecohydraulics, despite Ethohydraulic research predating the term Ecohydraulics, which was coined in the 1990s. But research into the physical attributes of aquatic organisms has been conducted for much longer; for instance, Kreitmann’s 1932 study on the swimming strength of fish is one of the earliest examples, and Kreitmann (1932) points to an even older study from 1912 by Houssay. While these studies could be interpreted to adhere to Ecohydraulics only, physical aspects of fish can hardly be separated from their behavior. Therefore, a distinction between Ethohydraulics and Ecohydraulics had to be very nuanced, or it was just not meaningful.
This is what I retain: Ethohydraulics zooms in on behavioral responses of species to hydraulic conditions, and the term is primarily used by German-speaking folks. Ecohydraulics adopts a broader perspective, considering these behavioral responses within the wider context of ecosystem processes and functions. So, Ethohydraulics integrates into Ecohydraulics, aiming to understand how aquatic species interact with their environment. Combining the behavioral focus of Ethohydraulics with the presumably broader ecological and hydraulic-hydrological perspectives of Ecohydraulics helps us develop (more) effective strategies for conserving aquatic biodiversity and managing water resources. In conclusion, I look forward to integrated Ethohydraulic and Ecohydraulic research – and comments below!
References:
- Adam, Lehmann, Ethohydraulik – Grundlagen, Methoden und Erkenntnisse. Springer-Verlag, Berlin / Heidelberg, Germany (2011); https://doi.org/10.1007/978-3-642-17210-6
- Amaral, Winchell, McMahon, Dixon, Evaluation of angled bar racks and louvers for guiding silver phase American eels. Biology, Management and Protection of Catadromous Eels, 367–376 (2003); https://scholarworks.umass.edu/fishpassage_conference_proceedings/86
- Kreitmann, La vitesse de nage des poissons. Bull. Fr. Piscic., 145–150 (1932); https://doi.org/10.1051/kmae:1932004
- Lehmann, Bensing, Adam, Schwevers, Tuhtan, Ethohydraulics: A Method for Nature-Compatible Hydraulic Engineering. Springer Fachmedien Wiesbaden, Germany (2022); https://www.springerprofessional.de/en/ethohydraulics/20269252
- Meister, Moldenhauer-Roth, Beck, Selz, Peter, Albayrak, Boes. Protection and Guidance of Downstream Moving Fish with Electrified Horizontal Bar Rack Bypass Systems. Water 13, 2786 (2021).
- Pavlov, Sbikin, Vashchinnikov, Mochek. The effect of light intensity and water temperature on current velocities critical to fish. Vopr Ikhtiologii 12:769–778 (1972).
