No abstract

Understanding the effects of chronic chemical contamination on natural populations of marine organisms is complex due to the combined effects of different types of pollutants and environmental parameters that can modulate the physiological responses to stress. Here, we present the effects of a chronic contamination in a marine bivalve by combining multiple approaches that provide information on individual and population health. We sampled variegated scallops (Mimachlamys varia) at sites characterized by different contaminants and contamination levels to study the short and long-term (intergenerational) responses of this species to physiological stress. We used biomarkers (SOD, MDA, GST, laccase, citrate synthase and phosphatases) as indicators of oxidative stress, immune system alteration, mitochondrial respiration and general metabolism, and measured population genetic diversity at each site. In parallel, concentration of 14 trace metals and 45 organic contaminants (PAHs, PCBs, pesticides) in tissues were measured. Scallops were collected outside and during their reproductive season to investigate temporal variability in contaminant and biomarker levels. Our analyses revealed that the levels of two biomarkers (Laccase-type phenoloxidase and malondialdehyde) were significantly correlated with Cd concentration. Additionally, we observed significant seasonal differences for four of the five biomarkers, which is likely due to the scallop reproductive status at time of sampling. As a source of concern, a location that was identified as a reference site on the basis of inorganic contaminant levels presented the same level of some persistent organic pollutants (DDT and its metabolites) than more impacted sites. Finally, potential long-term effects of heavy metal contamination were observed for variegated scallops as genetic diversity was depressed in the most polluted sites.

Objectives were to compare circulating progesterone (P4) profile and pregnancies per AI (P/AI) of two commercial intravaginal P4 devices (PRID-Delta(®) vs CIDR(®)). In Experiment 1, ovariectomized dairy cows (PRID-Delta, n=6 vs CIDR, n=6) were sampled throughout 7 days to measure circulating P4. In Experiment 2 (PRID-Delta, n=399 vs CIDR, n=375), cows were assigned to treatments, as follows: D0, an intravaginal P4 device containing 1.38g of P4 (CIDR) or 1.55g of P4 (PRID-Delta); D6: 25mg PGF2α (Dinoprost) and P4 devices were removed 24h later. Insemination was performed at 56h after P4 removal. Cows visually detected in estrus between days 18 and 24 after 1st synchronized AI were re-inseminated. PRID-Delta produced greater circulating P4 compared to CIDR, particularly within 4 days after insertion (P<0.01). The logistic regression analysis indicated a tendency for improved P/AI at 1st AI in PRID-Delta cows compared to CIDR (36% vs 31%, P=0.10). More cows were detected in estrus in the following cycle nearly 21d after 1st AI when treated with PRID-Delta (28% vs 16%), but P/AI in the returning-natural estrus breedings did not differ (PRID-Delta=56% vs CIDR=55%; P=0.91). As a result, final cumulative P/AI was greater in cows receiving PRID-Delta (46% vs 37%, P=0.02). These results indicate that PRID-Delta seem to maintain greater circulating P4 levels as compared to CIDR in non-lactating dairy cows. This might explain potential benefits in fertility of dairy cows found in Experiment 2. Underlying physiological consequence of greater circulating P4 during synchronization programs in lactating cows in terms of oocyte quality and other reproductive structures warrants further investigation.

Coral reefs around the world are under threat due to anthropogenic impacts on the environment. It is therefore important to develop methods to monitor the status of the reefs and detect changes in the health condition of the corals at an early stage before severe damage occur. In this work, we evaluate underwater hyperspectral imaging as a method to detect changes in health status of both orange and white color morphs of the coral species Lophelia pertusa . Differing health status was achieved by exposing 60 coral samples to the toxic compound 2-methylnaphthalene in concentrations of 0 mg L −1 to 3.5 mg L −1 . A machine learning model was utilized to classify corals according to lethal concentration (LC) levels LC5 (5% mortality) and LC25 (25% mortality), solely based on their reflectance spectra. All coral samples were classified to correct concentration group. This is a first step towards developing a remote sensing technique able to assess environmental impact on deep-water coral habitats over larger areas.

The ecological and economic importance of fish act as a brake on the development of chemical dispersants as operational instruments following oil spills. Although a valuable and consistent body of knowledge exists, its use in spill response is limited. The objective of the present study was to increase current knowledge base to facilitate the translation of published data into information of operational value. Thus we investigated the dose-response relationship between dispersant-treated oil exposure and ecologically relevant consequences by combining laboratory and field experiments. Effects were examined over almost a year using juveniles of the slowly growing, commercially important European sea bass (Dicentrarchus labrax). A reliable interpretation of biomarker responses requires a complete knowledge of the factors likely to affect them. Interpopulational variability is of particular importance in environmental impact assessment because biomarker responses from a population collected in an impacted area are classically compared with those collected in a clean site. Our study revealed no effect of the exposure to dispersant-treated oil on fish hypoxia tolerance and temperature susceptibility at 1 and 11 mo post exposure. Similarly, no effect of the exposure was observed on the ability of the fish to cope with environmental contingencies in the field, regardless of the dose tested. Thus we feel confident to suggest that a 48-h exposure to chemically treated oil does not affect the ability of sea bass to cope with mild environmental contingencies. Finally, investigation of interpopulation variability revealed large differences in both hypoxia tolerance and temperature susceptibility among the 2 populations tested, suggesting that this variability may blur the interpretation of population comparisons as classically practiced in impact assessment. Environ Toxicol Chem 2018;9999:1-12. © 2018 SETAC.