Sublethal Effects of Petroleum Hydrocarbons on Adult American Lobsters (Homarus americanus)

Abstract

A suite of 56 different parameters including biochemical, physiological, and morphological indices were investigated in lobsters chronically exposed to a low level of petroleum hydrocarbons. General condition indices were unaffected and no oil-induced differences were noted in serum values for most of the electrolytes, except calcium, which was elevated in both sexes. Serum freezing-point depression decreased in both sexes of the experimental group. Considering the four major serum parameters, protein, lipid, glucose, and amino nitrogen, oil exposure had a significant effect on plasma protein and lipid values in the females. Chronic exposure to oil also had a marked impact on blood hemocytes in which lipid values were reduced by approximately one-half in both sexes. Three different types of oil-induced effects were noted for the essential amino acids, including (a) change in one sex only, (b) change in both sexes, and (c) interaction between sex and oil exposure. The only nonessential amino acid significantly affected by oil exposure was alanine. The differences observed in amino acid analogs, namely the elevation of serum levels of methionine sulfoxide and methylhistidine, have been discussed on the basis of mammalian studies as possible stress-related effects. One of the most interesting effects observed at the organismal level was gill browning, which markedly increased in the oil-exposed animals. This particular sublethal effect, possibly more than any other, could be considered pathological in nature. Gill browning is readily measurable and provides one suitable biological response for monitoring point sources of petroleum pollution in lobster habitats.