Humboldt-Universität zu Berlin - Behavioural Physiology

Humboldt-Universität zu Berlin | Department of Biology | Behavioural Physiology | Research | Ecophysiology of mormyrid weakly electric fish

Ecophysiology of mormyrid weakly electric fish

How are animal behaviour and physiology shaped by ecological constraints?

passbild_gross_stefan.jpgStefan Mucha, M. Sc.

How are animal behavior and physiology shaped by ecological constraints? Which strategies have evolved to facilitate survival in complex and challenging environments? In my research, I want to pursue these questions with a focus on African mormyrid weakly electric fishes.

Mormyrids - just like the independently evolved South American Gymnotiformes - use electrical discharges to navigate, hunt and communicate. The >200 known species of Mormyrids are endemic to freshwater systems of Sub-Saharan East Africa. These habitats are characterized by high competition for resources, high predation pressure and increasing human-driven environmental degradation. In my PhD project, I study how hypoxia (low oxygen availability) affects the physiology, morphology and behavior of mormyrid fishes. Oxygen is the primary source of metabolic energy, and the need to acquire enough oxygen to survive and reproduce is a key driver of animal behavior, inparticular in aquatic environments.

I conduct respirometry experiments to measure physiological properties of oxygen uptake (i.e. down to which oxygen concentration can these fish maintain aerobic metabolism?) and behavioral oxygen choice experiments (i.e. at which oxygen concentration do fish react to low oxygen, when do they start to avoid it?). As these fish do not usually live in laboratories, I conduct field experiments in Uganda near Lake Victoria to put my laboratory experiments in an ecological context.

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Figure: Stefan Mucha / Behavioral physiology
Hunting for weakly electric fish in the Lwamunda Swamp in eastern Uganda. With a simple amplifier/speaker, the electric discharges of the fish can be revealed as acoustic signals.