E. M. Garcia

Metal Content on the Reef Coral Porites astreoides: an Evaluation of River Influence and 35 Years of Chronology

Ten metals (Al, Ca, Cd, Cu, Cr, Fe, Hg, Pb, V and Zn) were analysed in skeletal sections of the coral Porites astreoides. Each skeletal section comprised five years of growth, and a total of 35 years of carbonate deposition was analysed from 1960 to 1995. The skeletal sections were determined through the analysis of growth bands using tomography. The corals were taken from two localities that differ in their sedimentation rate and closeness to river inputs that were considered as factors that could lead to differences in coral metal content. The concentration of most metals did not differ throughout the period of time analysed. This, together with the fact that most metals showed concentrations higher than others reported for pristine locations in the Caribbean, suggests a relatively chronic contamination of the study site established at least since 1960 for the metals analysed. Only the skeletal content of Al, Fe, Cr and Ca differed significantly between localities: (a) corals from the locality closer to the river inputs had a greater concentration of Al and Fe; (b) the difference in Cr was only due to an increased concentration in one colony, although detectable in 3 skeletal sections (15 years), and; (c) the skeletal Ca difference could be associated with different growth rates between localities.

Sedimentation Rates and Metal Content of Sediments in a Venezuelan Coral Reef

The sedimentation rate and metal content in trapped sediments were determined at four localities at the Parque Nacional Morrocoy and for a sampling period of 1 year. The sedimentation rate was inversely related to the distance from the main terrestrial sources of sediment and ranged from 44+7 to 281+46 g m-2d -n (mean+SE) for the farthest two localities (11 km apart). February through May showed the highest sedimentation rate considering all localities. Except for Ca and Hg, metals in sediments also varied inversely to the distance from terrestrial sources and ranged as follows: AI 1.01-2.57, Fe 0.70-2.08, Ca 22.3-34.8 in %; and Zn 44.6-77.9, V 19.9-41.8, Pb 18.1-35.6, Cr 18.1-31.9, Cu 6.8-40.3, Hg 0.269-0.325 in lag g i based on dry weight. A common source of metal pollution is suggested from the positive and significant correlation found between the concentrations of most metals. Only Hg was not correlated with any other metal and its concentration was relatively constant for all localities. Based on our results we speculate that reef environments of P.N. Morrocoy are being affected by long-term continuous load of sediment moderately contaminated, brought about by drainage of the neighboring rivers.

Chronology of mercury enrichment factors in reef corals from western Venezuela.

Mining and deforestation in the early 20th century, the development of petrochemical industries during the 1950s, and the constant weathering of natural deposits of cinabrium (HgS) have made Golfo Triste, Venezuela, a region impacted by mercury (Hg). We studied the chronology of Hg in coral skeletons of Siderastrea siderea (1 colony, 1900-1996) and Montastraea faveolata (2 colonies, 1930-1999) from Parque Nacional San Esteban. Maximum values of Hg/Ca ratios and standard deviations of Hg enrichment factors occurred in the 1940s, 1960s, and 1980s, and matched maxima of decadal rainfall. Values from the 1950s and 1970s matched periods of abundant but constantly decreasing rainfall and hence were best explained by the combination of runoff and the sudden bioavailability of Hg in the region. This sudden availability likely was associated with activities of the chlorine-caustic soda and fertilizer plants of Morón petrochemical complex, industries that started producing large amounts of Hg in 1958.

The ability of the unicellular giant alga Acetabularia sp. to bioconcentrate aquatic mercury in whole and anucleated cells

The uptake of mercury by the marine alga Acetabularia sp. was studied using mercury chloride (HgCl2). The algae were exposed to water contaminated with HgCl2 for various periods of time: 5 min. ‐ 6 h. and 1 day ‐ 7 days. Hg was measured by cold vapor atomic absorption spectrophotometry and the results obtained indicate that Acetabularia is a good absorbent of aquatic mercury. Moreover, the uptake of Hg appeared not to be highly affected either by the presence of a protein synthesis inhibitor (Cycloheximide), or by the absence of the nucleus in long term contamination.

Induction of mercury‐binding peptide in whole cells and anucleated cells of Acetabularia calyculus

The present study reports the isolation and partial purification of a mercury‐binding polypeptide in whole and anucleated cells of Acetabularia calyculus. Sephadex G‐75 Gel filtration showed that cells exposed to Hg exhibit a major peak of protein(s) concomitant with both, a major peak of Hg (revealed by atomic absorption spectroscopy), and the major peak of mercury‐thiolate complex (based on a high 254 nm absorbance) accompanied by high content of SH groups. SDS‐Page electrophoresis showed that this peak contains one major polypeptide of apparent molecular weight 27.000 dalton. These results are in agreement with our previous finding of unusually high bioconcentration factor of Hg in Acetabularia related to the induction of a polypeptide in both, whole and anucleated cells of Acetabularia, in presence of Hg.

Bioconcentration of hg in acetabularia calyculus: Evidence of a polypeptide in whole cells and anucleated cells

Whole cells and anucleated cells of Acetabularia calyculus, were exposed to concentrations of 1 mg/l and 10 mg/l of mercury chloride (HgCl2) during 3 days. The bioconcentration factor (BCF) was not significantly different between both concentrations, reaching a saturation level in the uptake of mercury. The cytoplasm protein fraction (CPF) of whole cells and anucleated cells treated with 10 mg/1 of (HgCl2) was analyzed by SDS‐Page electrophoresis. Results obtained indicated that, at this experimental concentration of Hg, Acetabularia calyculus synthesizes a polypeptide with a molecular weight apparent of 27.000 Dalton. This polypeptide was absent in the control experiments, where cells were not treated with Hg. These results suggest that the great ability of Acetabularia to bioconcentrate Hg (high BCF) could be related to the synthesis of this Hg induced Polypeptide (HgIP).

Phase I and II biotransformation and antioxidant enzymes in the coral Siderastrea siderea act as biomarkers for reproductive condition and habitat quality

Abstract In this study we examined the behaviour of biomarkers in corals combining the reproductive status of colonies and reef sites with different levels of contamination. The content of P450 and P420 and the activities of NADPH c reductase, glutathione S-transferase (GST), catalase (CAT) and superoxide dimutase (SOD) were measured in the coral Siderastrea siderea at two marine parks. Parque Nacional Morrocoy (PNM) encompasses a continental marine ecosystem largely influenced by anthropogenic impacts. In contrast, Parque Nacional Archipielago Los Roques (PNALR) is 160 km offshore and relatively less impacted. As these enzymes are also affected by reproduction, samples were taken in both parks during the reproductive and non-reproductive seasons. In both parks, NADPH c reductase and GST were higher in the reproductive than in the non-reproductive season. Differences in enzymatic content or activity in corals from the two parks were usually more prominent during the reproductive season. Hence, P450 and P420 were undetectable during the non-reproductive season, while during the reproductive season, P420 was highest in colonies from the most impacted park (PNM). Activities of NADPH c reductase, CAT and SOD were also higher at PNM than at PNALR, while GST was an exception to this trend. Our results show that the aforementioned enzymes act as biomarkers in the coral S. siderea, changing in relation to its reproductive status and with the habitat quality.

Caribbean yellow band disease compromises the activity of catalase and glutathione S-transferase in the reef-building coral Orbicella faveolata exposed to anthracene

Healthy and diseased corals are threatened by different anthropogenic sources, such as pollution, a problem expected to become more severe in the near future. Despite the fact that coastal pollution and coral diseases might represent a serious threat to coral reef health, there is a paucity of controlled experiments showing whether the response of diseased and healthy corals to xenobiotics differs. In this study, we exposed healthy and Caribbean yellow band disease (CYBD)-affected Orbicella faveolata colonies to 3 sublethal concentrations of anthracene to test if enzymatic responses to this hydrocarbon were compromised in CYBD-affected tissues. For this, a 2-factorial fully orthogonal design was used in a controlled laboratory bioassay, using tissue condition (2 levels: apparently healthy and diseased) and pollutant concentration (4 levels: experimental control, 10, 30 and 100 ppb concentration) as fixed factors. A permutation-based ANOVA (PERMANOVA) was used to test the effects of condition and concentration on the specific activity of 3 enzymatic biomarkers: catalase, glutathione S-transferase, and glutathione peroxidase. We found a significant interaction between the concentration of anthracene and the colony condition for catalase (Pseudo-F = 3.84, df = 3, p < 0.05) and glutathione S-transferase (Pseudo-F = 3.29, df = 3, p < 0.05). Moreover, our results indicated that the enzymatic response to anthracene in CYBD-affected tissues was compromised, as the activity of these enzymes decreased 3- to 4-fold compared to healthy tissues. These results suggest that under a potential scenario of increasing hydrocarbon coastal pollution, colonies of O. faveolata affected with CYBD might become more vulnerable to the deleterious effects of chemical pollution.

Monitoring coastal pollution associated with the largest oil refinery complex of Venezuela

This study evaluated pollution levels in water and sediments of Península de Paraguaná and related these levels with benthic macrofauna along a coastal area where the largest Venezuelan oil refineries have operated over the past 60 years. For this, the concentration of heavy metals, of hydrocarbon compounds and the community structure of the macrobenthos were examined at 20 sites distributed along 40 km of coastline for six consecutive years, which included windy and calm seasons. The spatial variability of organic and inorganic compounds showed considerably high coastal pollution along the study area, across both years and seasons. The southern sites, closest to the refineries, had consistently higher concentrations of heavy metals and organic compounds in water and sediments when compared to those in the north. The benthic community was dominated by polychaetes at all sites, seasons and years, and their abundance and distribution were significantly correlated with physical and chemical characteristics of the sediments. Sites close to the oil refineries were consistently dominated by families known to tolerate xenobiotics, such as Capitellidae and Spionidae. The results from this study highlight the importance of continuing long-term environmental monitoring programs to assess the impact of effluent discharge and spill events from the oil refineries that operate in the western coast of Paraguaná, Venezuela.