An integrated biomarker approach: Non-monotonic responses to cadmium exposure in the suckermouth catfish Hypostomus plecostomus.

Environmental risk assessment in aquatic ecosystems typically uses biomarkers to detect interactions between potential hazards and biological systems. Next to knowing environmental contaminant levels in tissues and the environment, it is important to link to potentially deleterious effects at higher levels of biological organization such as biochemistry, physiology, and overall health status. In this laboratory study we assessed the toxicity of waterborne cadmium (Cd) over an exposure range of 0 - 100 µg l-1 for nine days to the loricariid suckermouth catfish Hypostomus plecostomus. We evaluated the integrated response of the fish at the biochemical to physiological level by means of a suite of tissue biomarkers of exposure and effects, including Cd concentrations in gills, liver metallothioneins (MT) and cholinesterase activity (ChE) in brain, before and after the inhibition of the alkaloid eserine, as well as whole-fish resting oxygen consumption rates and ingestion rate. Tissue biomarkers (MT and ChE) showed a non-monotonic relationship, with maximum/minimum responses at intermediate doses. i.e. 10 and 50 µg l-1, whereas biomarker responses of fish exposed at 100 µg l-1 more closely resembled biomarker responses seen at lower concentrations (< 10 µg l-1). Conversely, the oxygen consumption rate peaked at 100 µg l-1, suggesting a higher metabolic cost for higher metal exposure, with no significant correlation with fish body condition and food intake. Integrated Biomarker Response (IBR) values peaked at the intermediate exposure concentration of 50 µg l-1 Cd. The non-monotonic dose-response of the biochemical biomarkers of exposure, together with the higher metabolic rates of fish exposed to 50 - 100 µg l-1 of Cd and the non-significant effects on the more relevant physiological and histological variables suggests that H. plecostomus is capable of biochemically and physiologically regulating moderately high Cd concentrations, thus representing a suitable indicator organism to monitor metal pollution by Cd.

Monitoring metallothionein-like protein concentrations and cholinesterase activity in tropical cup oysters as biomarkers of exposure to metals and pesticides in the southern Caribbean, Colombia.

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.

Cholinesterase activity in the cup oyster Saccostrea sp. exposed to chlorpyrifos, imidacloprid, cadmium and copper.

In the present study, the sensitivity and concentration dependence of three functionally-defined components of cholinesterase activity (total: T-ChE; eserine-sensitive: Es-ChE; and eserine-resistant: Er-ChE) were quantified in the gill, digestive gland and adductor muscle of the tropical cup oyster Saccostrea sp., following acute (96h) aqueous exposure to commercial formulations of the organophosphate (OP) insecticide chlorpyrifos and the neonicotinoid (NN) imidacloprid (concentration range: 0.1-100mg/L), as well as to dissolved cadmium and copper (concentration range: 1-1000µg/L). Oysters (1.5-5.0cm shell length), field-collected from a boating marina in Santa Marta, Colombia (Caribbean Sea) were exposed in the laboratory to each substance at five concentrations. T-ChE, Es-ChE, and Er-ChE activity were quantified in the three tissues in pools of 5 individuals (3 replicates per concentration), before and after inhibition with the total cholinesterase inhibitor eserine (physostigmine, 100µM). Oysters exposed to chlorpyrifos, imidacloprid and Cd showed reduced T-ChE and Es-ChE activity in gills at highest exposure concentrations, with Es-ChE activity being inhibited proportionally more so than T-ChE, whereas Er-ChE activity showed no significant concentration-response. Digestive gland also showed diminished T-ChE, Es-ChE and Er-ChE activity for highest chlorpyrifos and Cd concentrations relative to controls, but an increase of T-ChE and Er-ChE activity at the highest imidacloprid concentration (100mg/L). For Cu, T-ChE, Es-ChE and Er-ChE activities in gills and digestive gland were elevated relative to controls in oysters exposed to Cu concentrations > 100µg/L. In adductor muscle, T-ChE, Es-ChE and Er-ChE activity showed no apparent pattern for any of the four xenobiotics and concentration levels tested. Although this study confirms acute (96h) concentration-dependent reduction of tissue T-ChE and Es-ChE activity in gills and digestive glands of Saccostrea sp. exposed to high concentrations of chlorpyrifos (100mg/L), significant changes in T-ChE, Es-ChE and Er-ChE were also caused by exposure to Cd and Cu at concentrations > 100µg/L and by exposure to imidacloprid (100mg/L), indicating that cholinesterase activity is not a specific biomarker of organophosphate exposure in this species, but, rather, a biomarker of diverse xenobiotic exposure.

Presence of Ruvettus pretiosus (Gempylidae) in the Colombian continental Caribbean / Presencia de Ruvettus pretiosus (Gempylidae) en el Caribe continental colombiano / Presencia de Ruvettus pretiosus (Gempylidae) no Caribe continental colombiano

The first record of Ruvettus pretiosus Cocco, 1833 for the Colombian continental Caribbean is presented. The specimen was collected at Los Cocos, department of Magdalena (11° 16' 33, 84'' N 73° 53' 33, 01'' W), using a demersal longline gear placed at 100 m depth. Biometrics, diagnosis and comments regarding its distribution, ecology and biology are included in the description. This new record expands the distribution of the species in the Caribbean Sea and increases the reported number of gempylids for Colombia to five.

Se presenta el primer registro de Ruvettus pretiosus Cocco, 1833, para el Caribe colombiano continental. El especimen fue colectado en Los Cocos, Departamento de Magdalena, (11° 16' 33, 84'' N 73° 53' 33, 01'' W), usando un palangre sumergible colocado a 100 m de profundidad. En la descripción se incluye biometría, diagnóstico y comentarios sobre su distribución, ecología y biología. Este nuevo registro amplía la distribución de la especie en el Mar Caribe e incrementa a cinco el número de gempílidos reportados en Colombia.

É apresentado o primeiro registro de Ruvettuspretiosus Cocco, 1833, para o Caribe Colombiano continental. O espécime foi capturado na vereda Los Cocos, Departamento de Magdalena (11° 16' 33, 84'' N 73° 53' 33, 01'' W), utilizando palangres horizontais demersales a uma profundidade de 100 m. Estao incluídos neste manuscrito dados biométricos, diagnóstico das espécies e comentários sobre a sua distribuiclo, ecología e biología. Com este novo reporte a distribuiclo das espécies no Mar do Caribe se expande, aumentando para cinco o números de espécies da família Gemphelidae na Colombia.