The seasonal cycle of copper concentration in Busycon canaliculatum L.

Abstract

Individual tissues of approximately 100 whelks were analyzed for copper content. Tissue copper concentrations showed a high degree of individual variation, but seasonal trends were evident. In the digestive gland, the organ with the highest copper concentration, the mean monthly concentrations were about 5 to 10 times higher in the summer (400-900 µg Cu/g fresh weight) than in the winter (65-120 µg Cu/g). Gut concentrations followed the same seasonal trend. The copper concentration in the gonad increased in the early spring and then decreased in the late spring and summer to low fall and winter values. The total copper in the gonad increased 6-fold during the spring and summer, however, because of large increases in size as late summer spawning approached. The total copper in the gonad dropped off after the spawning season. Monthly average blood copper and protein concentrations followed the same seasonal pattern as the digestive gland and gut, with copper ranging from a monthly average of 42 µg/ml in February to 175 µg/ml in June. Nearly all the blood protein present was hemocyanin, and there was no apparent seasonal change in the ratio of copper: protein. The copper concentration of the kidney was similar to that of the blood during most of the year, but in late summer and fall it increased to a maximum (171 µg/g in Oct.), while that of the blood and other tissues was decreasing. Whelks in Narragansett Bay usually begin to feed in late May or early June; the general early summer increases in the copper concentration of most tissues correlated with this commencement of feeding.