MONITORING THE EFFECTS OF ENVIRONMENTAL ANTIBIOTIC CONTAMINATION ON NON-TARGET MACROALGAE THROUGH BIOMARKERS RESPONSE

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Tissue depletion of five antibiotic residues in farmed European seabass (Dicentrarchus labrax)

Publication . Rosa, João; Leston, Sara; Freitas, Andreia; Barbosa, Jorge; Rema, Paulo; Dias, Jorge; Lemos, Marco F. L.; Pardal, Miguel Ângelo; Ramos, Fernando

Concerns about antibiotic use led to stricter legislations and overall better practices in aquaculture production. However, depletion time periods in tissues vary greatly with different antimicrobials, fish species, or experimental setup. In the present work, five drugs (sulfadiazine (SDZ), trimethoprim (TRI), flumequine (FLU), oxolinic acid (OXO), and oxytetracycline (OTC)) were incorporated into medicated feed, and their retention in European seabass muscle tissues assessed. Juveniles were placed in 300 L tanks at 18 °C and were manually fed with medicated feeds for a 7 day period (two concentrations per antimicrobial, ranging from 6 to 220 mg kg−1 , which were based on previous studies on the occurrence of these antimicrobials). Residues were analyzed through a multi-class quantification method (UHPLC-MS/MS). Data on residues concentration through time followed a one-compartment model, with TRI concentrations above the established Maximum Residue Level (MRL) throughout the experiment. Similarly, OTC concentrations at the highest dose were also above 100 μg kg−1 up to 14 days after the medication period. Results obtained for TRI may indicate the presence of a dose dependency for this antimicrobial. FLU concentrations in muscle samples were the lowest through time (Cday7 of 279.70 and 386.63 μg kg−1 , for prophylactic and therapeutic treatments, respectively). Half-life values of 14.37, 10.87, 5.36, 7.20, and 27.22 h (prophylactic treatment), and 20.95, 8.41, 5.61, 11.22, and 17.99 h (therapeutic treatment), were determined for SDZ, TRI, FLU, OXO, and OTC, respectively. Withdrawal times of 0, 2, and 5 days were determined for FLU, OXO, and SDZ, but sampling times for OTC and TRI should be longer, since antimicrobial concentrations were above the MRL 14 days after the end of the feeding period with medicated feed. Therefore, special attention should be given since they are the most used antibiotics in aquaculture and European seabass plays a major part in human nutrition in the Mediterranean region.

2019Journal article

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Uptake of enrofloxacin from seawater to the macroalgae Ulva and its use in IMTA systems

Publication . Rosa, João; Leston, Sara; Crespo, Daniel; Freitas, Andreia; Pouca, Ana Sofia Vila; Barbosa, Jorge; Lemos, Marco F.L.; Pardal, Miguel Ângelo; Ramos, Fernando

Integrated multi-trophic aquaculture systems can minimize the environmental impacts of aquaculture, while delivering economical benefits. However, the use of extractive species such as seaweeds can accumulate pharmaceuticals commonly used in these systems. Therefore, this work evaluated the exposure of the seaweed Ulva to enrofloxacin (ENR), a vastly used antimicrobial in aquaculture, at two dosages (C1, 7.5 μg L−1 and C2, 15 μg L−1), and concentrations in water and in Ulva were measured through time. Traditional endpoints such as growth and mortality were assessed as ENR effects in the macroalgae. Enrofloxacin presented good stability in seawater, and degradation rates were influenced by the presence of seaweed at the lowest concentration tested. The seaweed was able to assimilate the antibiotic, reaching internal concentrations of 7.76 ± 1.11 ng g−1 WW after 30 min of exposure for C1, and 14.51 ± 1.22 ng g−1 WW, after 15 min for C2. Lowest concentrations detected at the end of experimental time were 4.08 ± 0.42 ng g−1 WW and 5.09 ± 1.57 ng g−1 WW for C1 and C2, respectively, which nonetheless, corresponds to ∼5% of the maximum residue limit established for fish for ENR by the European regulation. The presence of ENR stimulated Ulva growth, with differences observed 96 h after the beginning of the trial.

2020Journal article

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Integrated multitrophic aquaculture systems: potential risks for food safety

Publication . Rosa, João; Lemos, Marco F.L.; Crespo, Daniel; Nunes, Margarida; Freitas, Andreia; Ramos, Fernando; Pardal, Miguel Ângelo; Leston, Sara

Background: The demand for fish and fish products is now higher than ever. However, several problems such as nutrient loading or excessive use of resources can be associated with the intensification of aquaculture systems. Integrated multitrophic aquaculture systems (IMTAs) refer to the co-culture of different species belonging to different trophic levels, and offer a sustainable approach to aquaculture development. In these systems, organic and inorganic extractive species will feed on other species waste or on uneaten feed nutrients, acting as bioremediators. Scope and approach: The extractive capacity that these organisms have to take up nutrients from the water also means they will accumulate chemicals that are often administered in intensive productions. The present review describes a vast number of substances that can be found in IMTAs, either intentionally administered or resulting from contamination, and subsequently accumulated in species reared afterwards in these systems. The presence of such chemicals in organisms produced in IMTAs raises several food safety and human health concerns, which need to be addressed. Key findings and conclusions: Although IMTAs still face many challenges in terms of large scale production, legislations are not yet ready to comprise co-cultivation of multiple species in proximity. Also, maximum residue limits already existent for fish must be set for other organisms also produced in IMTAs in order to protect consumer's health. An increase in extractive species consumption (e.g. seaweeds) has been noticed during the past few years, and as IMTAs gain importance as a sustainable production method, food safety issues must be tackled.

2020Journal article

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Oxytetracycline accumulation in the macroalgae Ulva: Potential risks for IMTA systems

Publication . Rosa, João; Leston, Sara; Freitas, Andreia; Pouca, Ana Sofia Vila; Barbosa, Jorge; Lemos, Marco F. L.; Pardal, Miguel A.; Ramos, Fernando

Oxytetracycline (OTC) is one of the most used antibiotics in aquaculture. With the development of Integrated Multitrophic Aquaculture (IMTA) systems in order to mitigate some aquacultures' adverse effects, attention needs to be shifted to other co-cultured species that can also accumulate such pharmaceuticals and pose a risk to human consumption. Therefore, the present work evaluated the exposure of the seaweed Ulva to OTC at two realistic concentrations (0.040 and 0.120 mg L1 ). Oxytetracycline degradation rates in seawater were dependent on the initial concentration but were not influenced by the presence of Ulva. The macroalgae presented good assimilation rates of OTC, with internal concentrations reaching 40.9934 ng g1 WW for the lowest concentration tested and 108.6787 ng g1 WW for the highest, with a steep decrease after 48 and 24 h, respectively. Nonetheless, concentrations were still half of the Maximum Residue Limit set for fish (100 mg kg1) 48 h after C2 treatment. The highest dosage tested stimulated growth 96 h after the beginning of the trial, although some signs of decay could also be found in Ulva's fronds.

2019-07Journal article

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