Abstract
Metallothionein-like protein concentrations (MT) and three functionally defined fractions of cholinesterase activity (ChE) were quantified in gill and digestive gland homogenates of tropical cup oysters from 5 nearshore locations in the Colombian Caribbean and correlated with sediment and tissue metal (9 metals) and pesticide (22 organophosphates, OPs, and 20 organochlorines-OCPs), as well as water physical-chemical parameters (salinity, pH, temperature, and dissolved oxygen). Tissue and sediment pesticide concentrations were below detection limits in all samples, whereas sediment and tissue metal concentrations exceeded environmental thresholds at several locations. Tissue MT and ChE biomarkers varied by a factor of 5-6 between locations. Inhibition of cholinesterase activity was negligible for all 5 sites, despite spatial-temporal variation in ChE activity, consistent with below-detection OP concentrations. Tissue MT and ChE biomarkers correlated with tissue and metal sediment concentrations, yet, statistically significant covariance between biomarkers and water chemistry parameters was also observed, indicating that both, metal concentrations and physical-chemical variables, are likely to be responsible for generating the observed spatial-temporal variations in biomarker patterns.
Highlights
Tropical near shore ecosystems throughout the Caribbean have experienced significant modifications in recent decades, as consequence of human settlement and industrial and agricultural expansion
The aim of this study was to compare the variability of metallothionein-like proteins (MT) concentrations and cholinesterase activity (ChE) activity in cup oysters as indicator organisms along a presumed contamination gradient of metals and pesticides along the Colombian Caribbean, to assess their merit as a monitoring technique to evaluate the environmental health of coastal ecosystems in the Colombian Caribbean
This study demonstrated that MT and ChE activity in cup oysters varied significantly between stations and sampling dates, which was explained to a large extent by variations in environmental parameters, including physical-chemical water variables (T, S, pH and DO) and sediment and tissue metal concentrations, which differed among stations and sampling dates
Summary
Tropical near shore ecosystems throughout the Caribbean have experienced significant modifications in recent decades, as consequence of human settlement and industrial and agricultural expansion. In addition to global climate change, coastal ecosystems are threatened at the regional scale by habitat destruction, fragmentation and resource over-extraction, as well as by a plethora of biological, chemical, and physical contaminants derived from household, industrial, roadside, and agricultural runoff (Spaliding and Kramer, 2004). Notwithstanding these ever-increasing human influences, efforts to monitor their environmental impact have generally lagged developments, with much of previous monitoring activity having focused on determining concentrations of chemical contaminants in different environmental matrices (e.g., water, sediment, tissues, e.g., Fernandez-Maestre et al 2018). The employed methods span the gamut from analyses of specific metabolites to molecular, biochemical and histological techniques to detect exposure or effect at the cellular level, to biological population and community-scale health assessments, including reproduction, growth and species composition (Bernal et al, 2010; Dondero et al, 2010; Aceto et al, 2011; Cravo et al, 2012; Luo et al 2014; De Marchi et al, 2017)
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