A study of the uptake and excretion of inorganic mercury, and the long term effects of exposure to low levels of the metal in the lobster, homarus gammarus (L) White 1874

Abstract

The aim of this work has been to make an overall study of the uptake accumulation, and excretion of inorganic mercury, and the effects of long term exposure to the metal, in the lobster, Homarus gammarus, using relatively simple techniques considered appropriate to pollution studies. In this way it was hoped to gain an under- standing of the way in which the lobster deals with mercury and to be able to predict what organs were likely to be affected by low levels of mercury. The initial approach was to measure background levels in the different organs of the lobster, and also of lobsters exposed to 100ppb. and 10ppb. mercury for varying periods of time, using neutron activation analysis. These results were amplified by radioisotope tracer experiments so that besides the sites of principal accumulation being identified the route of uptake could be determined. By the same means, the ability of lobsters to excrete mercury was investigated. Long term studies of the effects of exposure to mercury on organs identified as being susceptible to damage because they were sites of uptake, major accumulation, or excretion were studied by histological techniques which were amplified in part by electron microscopical examination. Since it was likely that the lobster larvae might be weak links in the life history, measurements of mercury uptake by the larvae was attempted using X-ray microanalysis. This was unsuccessful, and studies of the effects of mercury on the survival of the lobster larvae were inconclusive. It was found by these varied approaches that uptake was mainly through the gills where highest levels of mercury accumulated, but it is probable that most of this mercury was bound to the cuticle or in the cells. A small proportion passes into the blood and is taken up and gradually excreted by the green glands, Long term damage is found in these organs but not in either the gills or the digestive gland. It is therefore suggested that damage due to mercury only occurs at sites of active control. The damage in the green glands due to exposure to levels even as low as 10ppb is likely to lead to death if exposure is prolonged, but a more important finding was evidence of greater susceptibility at different stages of the moult cycle. This is worthy of more detailed investigation.