Meeting Abstract
South American weakly electric fish use self-generated electric fields, known as electric organ discharges (EODs), to navigate their environment and communicate. These fish are categorized either as wave-type fish that produce EODs at continuous frequencies of ~100-2000 Hz, or as pulse-type fish that generate EODs at low intermittent rates of ~10-100 Hz. EOD production incurs significant metabolic costs, as high as 30% of the daily energy budget in wave fish and 20% of the daily energy budget in pulse fish. Water conductivity in some Neotropical habitats varies with natural seasonal rainfall/drought and human inputs (e.g., agricultural runoff, industrial waste disposal). Changing water conductivity alters the fish’s electric field volume (EFV). Increased conductivity shrinks the EFV, while decreased conductivity expands the EFV. The resulting changes in EFV likely affect sensory and communication performance. We have found that, following a conductivity increase, some species compensate by increasing the EFV over the course of a week possibly by increasing the EO power output. Here we investigated whether this compensation impacts metabolic investment in EOD production. We used intermittent-flow respirometry to measure metabolic rate across different conductivities in both pulse-type and wave-type fish. Metabolic rate increased in both wave-type and pulse-type fish within days of exposure to increased water conductivity. Preliminary results indicate that pulse-type fish increase the EFV after exposure to high-conductivity water, but wave-type fish do not.
