Tadpole swimming performance and activity affected by acute exposure to sublethal levels of carbaryl

Abstract

Abstract-General activity and swimming performance (i.e., sprint speed and distance) of plains leopard frog tadpoles (Rana blairi) were examined after acute exposure to three sublethal concentrations of carbaryl (3.5, 5.0, and 7.2 mg/L). Both swimming performance and spontaneous swimming activity are important for carrying out life history functions (e.g., growth and development) and for escaping from predators. Measured tadpole activity diminished by nearly 90% at 3.5 mg/L carbaryl and completely ceased at 7.2 mg/L. Sprint speed and sprint distance also decreased significantly following exposure. Carbaryl affected both swimming performance and activity after just 24 h, suggesting that 24 h may be an adequate length of exposure to determine behavioral effects on tadpoles. Slight recovery of activity levels was noted at 24 and 48 h post-exposure; no recovery of swimming performance was observed. Reduction in activity and swimming performance may result in increased predation rates and, because activity is closely associated with feeding, may result in slowed growth leading to a failure to emerge before pond drying or an indirect reduction in adult fitness. Acute exposure to sublethal toxicants such as carbaryl may not only affect immediate survival of tadpoles but also impact critical life history functions and generate changes at the local population level.

A dilution effect in the emerging amphibian pathogen Batrachochytrium dendrobatidis

“…Larval amphibians alter their behavior in response to their biotic and abiotic environment (39,40). Different densities of conspecifics or the presence of other species may alter behaviors such as schooling or foraging, which could change their likelihood of encountering Bd or transmitting it to other individuals.…”

Predator-induced stress makes the pesticide carbaryl more deadly to gray treefrog tadpoles ( Hyla versicolor )

“…LC50 estimates have been extremely useful in determining the relative lethality of different pesticides and the relative susceptibility of different organisms. However, the lethality of very low concentrations of pesticides (Ͻ ϽLC50) is often unknown (12,13).…”

“…Whereas myriad tests of carbaryl toxicity have been conducted on birds, mammals, fish, and invertebrates, there are few published studies on amphibians. Past studies of amphibian responses to carbaryl have found that carbaryl reduces tadpole activity and growth, and LC50 estimates vary between 2.5 and 20.6 mg͞liter (12,13,15,23).…”

Amphibians as indicators of changes in aquatic and terrestrial ecosystems following GM crop cultivation: a monitoring guideline

“…Pesticides are well known to affect amphibians (Bridges 1997;Brunelli et al 2010;Davidson 2004, Howe et al 2004Paganelli et al 2010;Relyea 2005a;Relyea 2005b;Relyea et al 2005). Though effects on individuals do not necessarily impair population viability (Forbes and Calow 2002;Rohr et al 2006;Schmidt 2004), an ultimate deterioration cannot be excluded.…”