Gerardo Gold-Bouchot

Histopathological effects of petroleum hydrocarbons and heavy metals on the American Oyster (Crassostrea virginica) from Tabasco, Mexico

Abstract Oyster tissues may be affected by the concentration of ions in the water (i.e. salinity) and by contaminants such as petroleum hydrocarbons and heavy metals. Oyster populations from three coastal lagoons (Mecoacan, Camen and Machona) in the Mexican state of Tabasco, in the southern Gulf of Mexico, were sampled for pollution studies during June, September and November 1992 and May 1993. No statistically significant relationships were found between the concentration of contaminants in the 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 lowest weights, shell lengths and indices of condition were found in Mecoacan. The concentrations of cadmium and zinc were inversely related to salinity (r = −0.52 and r = −0.32, respectively), so a riverine input is suspected. On average, 63% of the individual oysters showed histopathological lesions, which can be related to salinity and to the concentrations of cadmium and the unresolved fraction of hydrocarbons (UCM). The response of each of the tissues analysed was different. The percentage of individuals with damage in the digestive diverticulum increased linearly with UCM (r = 0.71), but in a saturation-response fashion ( Y = B 0 − B 0 (1 + X B1 ) r = 0.66) with cadmium. The percentage of individuals 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 connective tissue decreased linearly (r = −0.82) with salinity, but increased in a saturation-response way (r = 0.83) with cadmium. Finally, the percentage of individuals with lesions in the digestive tube decreased linearly with salinity (r = −0.59). Only the damage to the gills and digestive diverticula were dependent on gonadal maturity, while damage to the connective tissue was dependent on the sex of the individual.

Polynuclear Aromatic Hydrocarbons in American Oysters Crassostrea virginica from the Terminos Lagoon, Campeche, Mexico

Abstract The concentrations of polynuclear aromatic hydrocarbons in oyster tissues from one of the most productive shrimp-fishing and oyster-farming areas in the coastal Gulf of Mexico, the Terminos Lagoon, were measured to assess the impact that offshore crude oil production on the continental shelf of Campeche might have on local resources. Total PAH concentrations in oyster tissues ranged from 2470 to 42,500 ng/g during this six-month study. The predominance of low and medium molecular weight alkylated compounds over their parent compounds indicates the petrogenic source of these PAHs. The apparent correlation between the geographical distributions of the measured PAH concentrations and the distinctive circulation pattern into and inside the lagoon suggests that offshore oil activities are the source of these PAHs to local oysters. Although comparable, the concentrations reported in this study are on the high side of those reported earlier in samples from the same general area and from the northern coast of the Gulf of Mexico. This should be a cause for concern in a protected area where oysters are farmed for human consumption and should result in the implementation of monitoring programs.

Trace metals in sediment cores from the Campeche shelf, Gulf of Mexico

Abstract Trace metals in sediment cores from the Gulf of Mexico, in the Campeche shelf area were studied to investigate possible variations in their vertical and/or horizontal sedimentary distributions. Possible links to petroleum sources were investigated as this area contains very productive oil explotation and transportation activities. Sediments were collected undisturbed using a vegematic type box corer. The upper 10 cm. were collected and cut in sections of 2 cm each. Incomplete, open vessel sediment digestion and atomic absorption was used for trace element determination. Particular interest was placed on vanadium and nickel concentrations as they have been associated to oil. Several metals were measured and representative distributions are presented. Horizontal distributions appear to conform to predominant current circulation patterns reported and closeness to sources of sedimentary materials. Vertical distributions are discussed. The vertical distributions were strikingly constant. Correlation among metals are also presented. Fe was used as a normalizing agent and the carbonate content was acting as a diluter of total trace metal content.

Environmental monitoring using acetylcholinesterase inhibition in vitro. A case study in two Mexican lagoons

Cholinesterase inhibition is considered a specific biomarker of exposure and effect for organophosphorous pesticides. Its use for monitoring has been hindered, particularly in tropical countries where organophosphates are widely used for malaria and dengue control, because of the frequent lack of suitable controls. An in vitro technique is proposed as a biochemical method for monitoring pollutant mixtures in sediment toxicity tests. Brain homogenate from the fish Oreochromis niloticus is used as the enzyme source. Optimum incubation time, extraction solvent and effect of crude oil on acetylcholinesterase (AChE) are reported. The method described was used in sediments from two Mexican lagoons, located in an oil extraction area where pesticides are used in agriculture and vector control campaigns. AChE inhibitions from 3 to 21% were found in these lagoons, even in the presence of high concentrations of petroleum.

Organochlorine pesticide residue concentrations in biota and sediments from Río Palizada, Mexico

The Mexican State of Campeche is one of the major rice producers in Mexico, accounting for 9.3 to 20.0% of the total production during in the period of 1982-1986 (INEGI, 1990). Another important crop is sugar cane, with an average annual yield of 28,000 ton from 60,000 ha (INEGI 1990). Most of these crops come from the Palizada river basin (Figure 1). This drainage basin, with a surface area of 2,460 km 2, is the main riverine discharge into Laguna de Terminos, representing 70% of the total freshwater discharge of 6 x 109 m3/year (Vera-Herrera et al. 1988). 20% of the basin is devoted to rice production, with an annual use of 3,000 ton of fertilizers and 37 ton of pesticides (Benitez et al. 1993). Within the framework of the joint IOC/UNEP Program for Marine Pollution Assessment and Control for the Wider Caribbean (CEPPOL)(IOC 1990), a pilot study was established to assess the concentrations of organochlorine pesticide residues in recent sediments and oysters (Crassostrea virginica), mussels (Brachidontes recurvus), and juvenile shrimps (Penaeus setiferus) in the Palizada river. The results of previous samplings have been reported elsewhere (GoldBouchot et al 1993). MATERIALS AND METHODS Sediment and biota samples (where available) were collected at nine sampling stations along the Palizada river and the main lagoons close to its mouth in December, 1992, as shown in Figure 1. Sediment samples were collected with a 0.1 m 2 Van Veen grab, shrimp by trawling and bivalves (mussels and oysters) manually. Sediment samples were placed in glass jars cleaned with chromic acid and hexane. Organisms were wrapped in aluminum foil, previously cleaned with hexane and heated at 450~ for two hours. The samples were transported under refrigeration to Merida for further analysis. The solvents used were distilled twice in an all-glass still. Florisil was purified by extracting it for 8 hours with hexane in a Soxhlet apparatus. All samples were freeze-dried upon arrival at the laboratory. Correspondence to: G. Gold-Bouchot

CICHLIDOGYRUS SCLEROSUS (MONOGENEA: ANCYROCEPHALINAE) AND ITS HOST, THE NILE TILAPIA (OREOCHROMIS NILOTICUS), AS BIOINDICATORS OF CHEMICAL POLLUTION

Experimental results showed that the gill monogenean Cichlidogyrus sclerosus and its host, the Nile tilapia Oreochromis niloticus, exhibited significant numerical and physiological responses after exposure to sediments polluted with polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls, and heavy metals in comparison with control fishes. After 15 days of exposure, C. sclerosus abundance significantly increased in treatments with low to fairly high sediment pollutant concentrations, but declined at high sediment pollutant concentrations. Hypertrophy and hyperplasia in secondary gill lamellae and the spleen melanomacrophage centers were significantly higher at extremely high sediment pollutant concentrations compared with the controls. Spleen lymphocyte and monocyte counts were significantly lower at extremely high sediment pollutant concentrations and were significantly correlated with high fluorescent aromatic compound concentrations measured as PAH exposure indicators. A multivariate redundancy analysis showed significant statistical association between sediment pollutant concentration, C. sclerosus abundance, and tilapia physiological variables. The polluted sediments negatively affected monogenean abundance and induced immunosuppression in hosts, consequently increasing histological damage in hosts and allowing persistent C. sclerosus infection. This study documents evidence suggesting that C. sclerosus and its host are indeed excellent models to test environmental quality in tropical freshwater ecosystems.

Biomarkers and pollutants in the Nile Tilapia, Oreochromis niloticus, in four lakes from San Miguel, Chiapas, Mexico

The effects of the oil industry and environmental pollutants present in four lakes from Reforma, Chiapas, Mexico, were assessed via ethoxyresorufin O-deethylase activity (EROD), PAH metabolites, and butyrylcholinesterase activity (BChE) in Nile Tilapia, Oreochromis niloticus. Fish were collected during two seasons (the rainy season in September 2000 and the dry season in May 2002) from the lakes Caracol, Rio, Enmedio, and Limon. Fish were sacrificed and EROD activities, hydrocarbons, organochlorine pesticide and heavy metal concentrations were determined in the liver, while PAH metabolites and cholinesterase activity were measured in bile and muscle, respectively. Hydrocarbon concentrations in fish liver were moderately high, as compared with results reported for the other species in different coastal ecosystems in Mexico. The highest concentrations of total hydrocarbons were found in fish captured in Lake Limon, and the lowest in Lake Caracol. The highest EROD and PAH metabolites were found in fish collected from Limon and Enmedio lakes. A Spearman test showed significant negative correlations between EROD and BChE activity with fish weight. EROD correlated with total hydrocarbons, the metabolites of pyrene and benzo[a]pyrene, and negatively with polychlorinated biphenyls (PCBs), endosulphan, hexachlorobenzene (HCB), and pentachloroanisol. BChE activity in the four lakes was lower than the activity measured in laboratory cultured tilapias, indicating the presence of anti-cholinergic pollutants in the area; Caracol was the lake with the lowest enzyme activity. This study demonstrated that high concentrations of contaminants can cause effects on fish metabolism, and that tilapia can be used as a test organism in tropical ecosystems.

Potential interactions between metazoan parasites of the Mayan catfish Ariopsis assimilis and chemical pollution in Chetumal Bay, Mexico

The effect of pollutants on the intensity of infection of metazoan parasites in the Mayan catfish, Ariopsis assimilis was investigated. Data were collected on pollutants and metazoan parasites from 76 catfish from five localities in Chetumal Bay in October, 1996. Nineteen pollutants (pesticides, polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs)) were found in the catfish livers. Heavy metal content was not determined. Nineteen metazoan parasite species were recovered. After controlling for fish length and sampling station, there was a significant negative linear relationship between the intensity of the larval digenean Mesostephanus appendiculatoides and 1,1,1,-trichloro-2,2-bis (4-chlorophenyl) ethane (DDT) concentrations. This negative relationship may be explained either by the effect of the pesticide on the mortality of (i) free-living larval forms, (ii) metacercariae in the fish, (iii) infected fish or (iv) intermediate host snails. There were significant differences between fish parasitized and not parasitized with M. appendiculatoides with respect to their DDT concentrations. There were also significant differences between the variances of the mean Clarks coefficient of condition values between catfish parasitized and not parasitized by M. appendiculatoides, with the variance of non-parasitized catfish being significantly larger. The results provided statistical evidence that DDT has a detrimental effect on M. appendiculatoides infection intensity. Furthermore, the significantly larger variance value of Clarks coefficient for non-parasitized fish suggested that DDT affects both the parasite and general host condition.

The checkered puffer (Spheroides testudineus) and its helminths as bioindicators of chemical pollution in Yucatan coastal lagoons

The suitability of using helminth communities as bioindicators of environmental quality of the Yucatan coastal lagoons status was tested on the checkered puffer (Spheroides testudineus) in four coastal lagoons along the Yucatan coast. The concentration of chemical pollutants in sediments, water quality parameters, helminth infracommunity characteristics, as well as fish physiological biomarkers, including EROD (7-ethoxyresorufin-O-deethylase) and catalase activities, were measured. Results from sediment analyses demonstrated the presence of hydrocarbons, organochlorine pesticides and polychlorinated biphenyls at varying concentrations, some of which exceeded the Probability Effect Level (PEL). Significant negative associations among organochlorine pesticides, infracommunity characteristics and fish physiological responses were observed in most of the lagoons. Results suggest that EROD activity and parasite infracommunity characteristics could be useful tools to evaluate the effects of chemical pollutants on the fish host and in the environment. Importantly, certain parasites appear to influence biomarker measurements, indicating that parasites should be considered in ecotoxicological studies.

Chlorinated pesticides in the Rio Palizada, Campeche, Mexico

The main objective of this study is to assess the concentration of organochlorine pesticides in recent sediment, oysters (Crassostrea virginica), clams (Rangia cuneata), mussels (Brachidontes recurvus) and juvenile shrimps (Penaeus setiferus) in Rio Palizada, Campeche, Mexico