G. Goldbouchot et al., HISTOPATHOLOGICAL EFFECTS OF PETROLEUM-HYDROCARBONS AND HEAVY-METALS ON THE AMERICAN OYSTER (CRASSOSTREA-VIRGINICA) FROM TABASCO, MEXICO, Marine pollution bulletin, 31(4-12), 1995, pp. 439-445
Oyster tissues may be affected by the concentration of ions in the wat
er (i.e. salinity) and by contaminants such as petroleum hydrocarbons
and heavy metals. Oyster populations from three coastal lagoons (Mecoa
can, Camen and Machona) in the Mexican state of Tabasco, in the southe
rn Gulf of Mexico, were sampled for pollution studies during June, Sep
tember and November 1992 and May 1993, No statistically significant re
lationships were found between the concentration of contaminants in th
e body tissues of organisms and their shell length, soft tissue weight
and particulate matter; however, a significant correlation was found
between condition index and salinity (r = -0.72). Generally, the lowes
t weights, shell lengths and indices of condition were found in Mecoac
an. The concentrations of cadmium and zinc were inversely related to s
alinity (r = -0.52 and r = -0.32, respectively), so a riverine input i
s suspected. On average, 63% of the individual oysters showed histopat
hological lesions, which can be related to salinity and to the concent
rations of cadmium and the unresolved fraction of hydrocarbons (UCM).
The response of each of the tissues analysed was different. The percen
tage of individuals with damage in the digestive diverticulum increase
d linearly with UCM (r = 0.71), but in a saturation-response fashion (
r = B-0 - B-0/(1 + X(B1)), r = 0.66) with cadmium, The percentage of i
ndividuals, with damage in the gills increased linearly with weight (r
= 0.68), cadmium (r = 0.60) and UCM (r = 0.60). The lesions in the co
nnective tissue decreased Linearly (r = -0.82) with salinity, but incr
eased in a saturation-response way (r = 0.83) with cadmium. Finally, t
he percentage of individuals with lesions in the digestive tube decrea
sed linearly with salinity (r = -0.59). Only the damage to the gills a
nd digestive diverticula were dependent on gonadal maturity, while dam
age to the connective tissue was dependent on the sex of the individua
l.