A. Calabrese

The toxicity of heavy metals to embryos of the American oyster Crassostrea virginica

The acute toxicity of 11 heavy metals to embryos of the American oyster Crassostrea virginica was studied and the concentrations at which 50% of the embryos did not develop were determined. The most toxic metals and their LC50 values were mercury (0.0056 ppm), silver (0.0058 ppm), copper (0.103 ppm) and zinc (0.31 ppm). Those metals that were not as toxic and their LC50 values were nickel (1.18 ppm), lead (2.45 ppm) and cadmium (3.80 ppm). Those metals that were relatively non-toxic and their LC50 values were arsenic (7.5 ppm), chromium (10.3 ppm) and manganese (16.0 ppm). Aluminum was non-toxic at 7.5 ppm, the highest concentration tested.

Survival and growth of bivalve larvae under heavy-metal stress

In a study of the toxicity of mercury, silver, copper, nickel, and zinc to larvae of the American oyster Crassostrea virginica and hard clam Mercenaria mercenaria, the concentrations at which 5% (LC5), 50% (LC50), and 95% (LC95) of the larvae died were determined, as well as growth at the LC5 and LC50 values. The order of toxicity for oyster larvae was Hg>Ag>Cu>Ni, and for clam larvae Hg>Cu>Ag>Zn>Ni. Growth of larvae of both species, with the exception of clam larvae in nickel-treated water, was not reduced at the LC5 values, but was markedly reduced at the LC50 values.

Biochemical and ultrastructural observations of long-term silver accumulation in the mussel, Mytilus edulis

Abstract The cellular distribution and chemical forms of Ag were determined in mussels after accumulation of the metal from sea water. The major accumulations were either in the vacuoles of connective tissue macrophages, where it was associated with S, or in deposits in the fibrillar layer of the basement membranes of the digestive diverticulum and kidney epithelia, where it was bound to the sulphydryl and sulphate groups of glycoproteins and proteoglycans. In acutely exposed animals, about 10 % of the accumulated Ag was found in a (Ag, Cu)-binding protein with characteristics indicating that it may be a metallothionein. There was a concomitant increase in the body Cu levels after Ag exposure and 40 % of this was bound to this low molecular weight metal-binding protein.

Effect of heavy metals on bay scallops, surf clams, and blue mussels in acute and long-term exposures.

JuvenileArgopecten irradions andSpisula solidissima were exposed to Cu, Pb, Se, or Zn in a 96-hour static bioassay. The order of toxicity for both bivalve species was the same: Cu > Se > Zn > Pb. With the exception of lead,A. irradians was more sensitive thanS. solidissima to the metals tested.JuvenileMytilus edulis were exposed in 96-hour static bioassays to Cd, Cu, Hg, or Ag. The order of toxicity was Cu = Hg = Ag > Cd.M. edulis was less sensitive to Ag and Hg when compared toA. irradians and less sensitive to Cu thanA. irradians orS. solidissima. M. edulis was as sensitive to Cd asA. irradians.In a 126-day exposure, 45 young-of-the-yearA. irradians orS. solidissima, or 45 adultM. edulis were exposed to Cu, using a proportional diluter apparatus. Copper was added to test tanks at concentrations of 0.002, 0.010, or 0.020 mg/L, while control tanks received untreated seawater. Of the three species exposed to the three concentrations of Cu, young-of-the-yearS. solidissima were the most sensitive, followed by young-of-the-yearA. irradians. Least sensitive was the adultM. edulis.

Physiological response of juvenile striped bass,Morone saxatilis, to low levels of cadmium and mercury

Juvenile striped bass,Morone saxatilis, were exposed to 0.5, 2.5, and 5.0 parts per billion (ppb) cadmium as cadmium chloride for 30–90 days and to 1.0, 5.0, and 10.0 ppb mercury as mercuric chloride for 30–120 days. Following the longest exposure to each metal, the fish were allowed to recover for 30 days in running seawater. Gill-tissue respiration, glucose-6-phosphatase, malic enzyme, aspartate aminotransferase, and magnesium activation of AAT were measured. Animals exposed to either metal exhibited changes in gill-tissue respiration. There was no significant difference in enzyme activity during exposure to either metal; however, fish cleared for 30 days following exposure to cadmium exhibited a slight drop in liver AAT and G6PdH.

RESPONSE OF EMBRYOS OF THE AMERICAN OYSTER, CRASSOSTREA VIRGINICA, TO HEAVY METALS AT DIFFERENT TEMPERATURES

ABSTRACT The acute toxicity of four heavy metals (copper, mercury, silver, and zinc) added individually to embryos of the American oyster, Crassostrea virginica , in natural seawater was studied at 20, 25, and 30°C. The toxicity of copper-zinc and mercury-silver mixtures to oyster embryos at the above temperatures was also determined. All of these metals, added either individually or in combination, were less toxic at 25°C than at either 20 or 30°C, suggesting that oyster embryos are more susceptible to metal toxicity at either 20 or 30°C than at 25°C. Less than additive effects were observed at 20 and 25°C with mercury and silver in combination. Simple additive effects were noted at 30°C for the mercury-silver mixture and at 20, 25, and 30°C for the copper-zinc mixture.

Mercury stress on juvenile bay scallops, Argopecten irradians, under various salinity-temperature regimes

Survival of juvenile bay scallops, Argopecten irradians, after 96 h of exposure to mercury at various salinity and temperature regimes was studied. Scallop survival was significantly affected by mercury concentration and by salinity, as well as by the interaction between temperature and concentration and between temperature and salinity. Toxicity of mercury at low concentrations was enhanced by high temperature and low salinity, whereas at high mercury concentrations this effect diminished.

Mercury-binding proteins in the slipper limpet, Crepidula fornicata, exposed to increased soluble mercury

Crepidula fornicata were held in a flow-through bioassay system and exposed to sand-filtered seawater to which no soluble mercury (control) was added or to which either 5, 25, or 50 μg 1−1 soluble Hg was added. At specific intervals during the 16-week experiment, a group of limpets was removed from each tank; one subgroup was exposed for 48 h to high concentrations of Hg, and another was analyzed for Hg-binding proteins by gelpermeation chromatography and spectrometry. Mortality from exposure to Hg in the 48-h acute toxicity tests was related to concentrations of Hg experienced both during the long-term exposure period and the 48-h exposure period. Chronic exposure to low levels of Hg resulted in increased amounts of total Hg in the whole body and in the low-molecular-weight Hg-binding proteins. No evidence was found for increased tolerance to Hg with preexposure.

The Development of Methods for Rearing the Coot Clam, Mulinia Lateralis, and Three Species of Coastal Bivalves in the Laboratory

The importance of selecting appropriate biological material for commercial cultivation or for experimentation cannot be overemphasized. Selection of a species for commercial propagation consists of balancing the economic liabilities of hatchery and field cultivation with various aspects of marketing economics. For experimental use, one can dispose of the commercial aspects in selecting experimental material and concentrate on finding organisms most amenable to controlled culture. Characteristics to be considered should include the availability of adults, the necessity for and ease in conditioning the adults for spawning, spawning methods, the success of larval culture, the growth rate of the immature animals, and the total generation time for the animals. In this presentation, these aspects will be considered for a non-commercial estuarine species, Mulinia lateralis, and three commercial coastal zone bivalves, Spisula solidissima, Arctica islandica, and Placopecten magellanicus.