Communication is key, and to this rule electric fish are no exception. In the last post I briefly defined what communication is in terms of a signaler and a receiver I also touched on why communication is important due to the environment. In this post, I will be touching on communication from the cellular and ecological viewpoint and how climate change may have an effect on communication.
When thinking about communication in electric fish it is important to realize that there much be a system in place that helps maintain a synchronize pattern to allow the signaler to send out and the receiver to gather accurate information. In weakly electric fish this system is found in the pacemaker nucleus (Lucas et al. 2019). The pacemaker nucleus allows neurons to release high-frequency discharges to the electrical discharge organ (EDO) (Lucas et al. 2019). The pacemaker cells have a similar function to pacemakers that doctors implant into patients with arrhythmia. Communication in electric fish (chirps) must be accurate to capture prey, navigate dirty water, and communicate with others.
Jamming avoidance in electric fish is when they can shift the frequency of their EOD so that the wave does not interfere with the signals of other conspecifics. An ethorobotical study was done with living weakly electric fishes and a robot which simulated another fish (Worm et al. 2018). The study found that the electric fish were able to shift their frequency almost perfectly to the electric field that the robotic fish was emitting (Worm et al. 2018).
Cdh8 Carl D. Hopkins; Department of Neurobiology and Behavior, Cornell University, Ithaca, NY (https://commons.wikimedia.org/wiki/File:Jamming_Avoidance_Response_Eigenmannia.png), „Jamming Avoidance Response Eigenmannia“, https://creativecommons.org/licenses/by/3.0/legalcode
Electric fish can differentiate between different chirps due to the different frequency and amplitude of the produced electric field. Chirps are so fast that they must be measured in sub-microseconds which to put that into numbers is about less than .0000002 seconds (that is a small amount of time) (Lucas et al. 2019).
It is believed that in some species of electric fish can communicate their sex through their electric organ discharge frequency (EODf) (Smith et al. 2018). This difference in frequency can be linked to gonadal steroid hormone which is different between sexes. A study done at Indiana university showed that the cells in the pacemaker nucleus have receptors for androgen and estrogen which suggest that they have a role in courtship and aggression (Life Science, 2018).
Global climate change may influence how well electric fish are able to communicate with each other. Climate change may cause water temperature and levels to raise which may cause problems since communication in electric fish has to be very precise in frequency to avoid jamming with others (Tal 2018). Climate change could also make differentiating between males and females much more difficult. As I said earlier electric fish are able to differentiate between sexes with different electric organ discharge frequencies which when in higher water temperatures may make it difficult for that specific frequency to travel through water efficiently.
Literature Cited
1. Findings from Indiana University Update Understanding of Physiology (Genes linked to species diversity in a sexually dimorphic communication signal in electric fish). Life Science Weekly. 2018 Feb 20:1918.
2. Lucas KM, Warrington J, Lewis TJ, Lewis JE. Neuronal Dynamics Underlying Communication Signals in a Weakly Electric Fish: Implications for Connectivity in a Pacemaker Network. Neuroscience. 2019;401:21–34. doi:10.1016/j.neuroscience.2019.01.004
3. Neuroethology: Jamming Avoidance Response in Electric Fish. [accessed 2019 Apr 17]. http://nelson.beckman.illinois.edu/courses/neuroethol/models/jamming_avoidance/JAR.html
4. Smith GT, Proffitt MR, Smith AR, Rusch DB. Genes linked to species diversity in a sexually dimorphic communication signal in electric fish. Journal of Comparative Physiology A. 2018;204(1):93–112. doi:10.1007/s00359-017-1223-3
5. Tal A. The implications of climate change driven depletion of Lake Kinneret water levels: the compelling case for climate change-triggered precipitation impact on Lake Kinneret’s low water levels. Science of The Total Environment. 2019;664:1045–1051. doi:10.1016/j.scitotenv.2019.02.106
You bring some some really interesting implications of climate change on electric fish behavior. I would love to hear more about why you think temperature changes would affect their communication signals, and how much their signals might be affected based on the anticipated temperature changes we are facing.