Variations in cardiac activity following acute exposure to copper in three co-occurring but differently zoned Mediterranean limpets.
The cardiac activity of three limpets (Patella rustica, P. caerulea and P. aspera), having a different vertical zonation on the Mediterranean rocky shores, was monitored using a non-invasive technique, during 6 h exposure to copper solutions (0.1 and 0.5 ppm), and after return to copper-free conditions. At 0.1 ppm no significant variation of heart rate was observed in the three species with respect to control conditions, while after 3 h at 0.5 ppm a consistent bradycardia was evident in P. caerulea and P. aspera, but not in P. rustica. After 6 h at 0.5 ppm most of the specimens of the three species were acardic but still reactive to mechanical stimulation. Tests on the resumption of cardiac activity after 6 h exposure to 0.5 ppm showed that even after a prolonged cessation of cardiac activity, limpets quickly resumed heartbeating once returned to clean seawater. However, recovery of heart-beating was faster in the mid- and high-shore species (P. caerulea and P. rustica, respectively) than in the lower-shore P. aspera. Moreover, the cardiac pattern upon recovery was definitely bradycardic in P. aspera, while the other two species showed a significant overshooting in heartbeating rate. Measurement of body burdens of copper showed that P. rustica and P. caerulea were faster in removing the excess of copper than the lower-shore P. aspera. In conclusion, this study showed that taxonomically close and syntopic species having a different zonal distribution exhibit different cardiac responses to water-borne copper and stresses the importance of comparative studies on physiological responses of organisms to metal pollution.
De Pirro
M
M
Dipartimento di Biologia Animale e Genetica, Università degli Studi di Firenze, Italy.
Chelazzi
G
G
Borghini
F
F
Focardi
S
S
D000818:Animals; D003300:Copper / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D004781:Environmental Exposure; D006339:Heart Rate / Q000187:drug effects; D007700:Kinetics; D008974:Mollusca / Q000502:physiology*; D013045:Species Specificity
D003300:Copper