The Behavioral Responses Of Two Appalachian Crayfish To Cool And Warm Spectrum LED Light At Night

Ecological light pollution is increasing worldwide, and the use of artificial lighting is expected to increase during the coming decades. It is not clear how the different spectral emissions produced by the two most common LED categories will affect freshwater animals. The New River crayfish (Cambarus chasmodactylus) and the spiny stream crayfish (Orconectes cristavarius) are important ecosystem engineers with influences on food webs, community structure and nutrient processing. I used artificial stream microcosms to expose both species to cool (5000 K) and warm (3000 K) spectrum lights at intensities of 15 lux. I recorded crayfish behaviors under each light treatment and in a dark control during the first and third hours after artificial dusk. In addition, I quantified total substrate displacement for C. chasmodactylus in these treatments. I found that O. cristavarius sheltering behavior significantly increased and locomotor activity decreased while exposed to both 5000 K and 3000 K light. Cambarus chasmodactylus significantly increased sheltering behavior and exhibited decreased mobility in response to 5000 K but not 3000 K lights. Substrate displacement by C. chasmodactylus was not affected by light treatments. Reduced crayfish mobility may lead to fewer foraging opportunities and reduced bioturbation in light-polluted streams.