Air Quality Criteria for Lead Volume II of II - (NEPIS)(EPA) - US ...

Lefcort et al. (1998) exposed spotted frogs (Rana luteiventris) to 0.05 to 50 ppm Pb in
water for 3 weeks. High levels of Pb reduced the fright response of tadpoles; suggesting a
reduced avoidance of predators.
Bullfrog larvae exposed to Pb in water (0.78 mg/L) and high or low dissolved oxygen
were monitored for respiratory surfacing behavior (Rice et al., 1999). Larvae had a significantly
increased number of trips to the water surface regardless of oxygen content. Thus, the authors
suggest that Pb may affect oxygen uptake such that larvae are under greater predation pressure
due to increased time spent at the surface.
Weis and Weis (1998) evaluated the effect of Pb exposure on mummichog (Fundulus
heteroclitus) larvae prey capture rate, swimming behavior, and predator avoidance. Prey capture
rates were affected after 4 weeks exposure at 1.0 mg Pb/L. The larvae were also more
vulnerable to predation by grass shrimp (Palaemonetes pugio) at 1.0 mg Pb/L. Finally, the
swimming behavior of mummichog larvae was affected at 0.3 and 1.0 mg Pb/L. Once the larvae
were no longer exposed to Pb, they recovered their ability to capture prey and avoid predators.
Clearly, exposure to Pb does affect the predator-prey interactions and the ability of prey to
avoid predators. The effect of Pb on these ecological functions may alter community dynamics.
AX7.2.5.3 Summary
The effects of Pb have primarily been studied in instances of point source pollution rather
than area-wide atmospheric deposition; thus, the effects of atmospheric Pb on ecological
condition remains to be defined. The evaluation of point source Pb within the EPA Ecological
Condition Framework has been examined primarily in relation to biotic conditions. The
available literature focuses on studies describing the effects of Pb in natural aquatic ecosystems
with regard to community composition and species interactions. The effects of Pb on the biotic
condition of natural aquatic systems can be summarized as follows: there is a paucity of data in
the general literature that explores the effects of Pb in conjunction with all or several of the
various components of ecological condition as defined by the EPA. However, numerous studies
are available associating the presence of Pb with effects on biotic conditions.
In simulated microcosms or natural systems, environmental exposure to Pb in water and
sediment has been shown to affect energy flow and nutrient cycling and benthic community
structure. In field studies, Pb contamination has been shown to significantly alter the aquatic
AX7-209