Contaminants in aquaculture: Overview of analytical techniques for their determination
Introduction
Aquaculture is one of the pillars of the European Union Blue Growth Strategy and its development can contribute to the Europe 2020 Strategy [1]. The aquaculture is defined as the rearing or cultivation of aquatic organisms using techniques designed to increase the production of those organisms beyond the natural capacity of the environment [2]. Aquaculture is also known as fish and shellfish farming under controlled conditions in marine or freshwater environments. Marine aquaculture usually occurs in cages on the seafloor or suspended in the water column, and the species most produced are oysters, clams, mussels, shrimp and salmon; freshwater aquaculture usually occurs in ponds or recirculating aquaculture tanks, and the species most produced are catfish, trout, tilapia and bass [3].
According to the last issue of ‘The State of World Fisheries and Aquaculture’ published by the Food and Agricultural Organization of the United Nations [4], the aquaculture is continuing its impressive growth, in both increased quantity and improved quality. The world aquaculture production attained 90.4 million tons in 2012 including 66.6 million tons of food fish (e.g., finfishes, crustaceans, molluscs and amphibians) for human consumption [4]. The world food fish aquaculture production has continuously increased from approximately 13 million tons in 1990 to 32 million tons in 2000 and to 67 million tons in 2012 [4]. The average annual rate for the aquaculture production has increased from 5.7% in 2008 to 6.9% in 2012 [4]. Higher production is observed in Asian countries with 88.4% in 2012, where China alone accounted for 61.7% of the total production; Europe accounted 4.3% of the total global aquaculture production in 2012 [4]. The main species produced in European aquaculture in terms of weight (in 2011) are mussels (mainly Mytilus galloprovincialis and Mytilus edulis, 456,000 tons, 36% of the total EU (European Union) production), rainbow trout (mainly Onchorynchus mykiss, 179,000 tons, 14% of the total EU production), Atlantic salmon (mainly Salmo salar, 171,000 tons, 13% of the total EU production), Pacific cupper oysters (mainly Crassistrea gigas and Ostrea edulis, 104,000 tons, 8% of the total EU production), gilthead sea bream (Sparus aurata, 99,000 tons, 8% of the total EU production), European sea bass (Dicentrarchus labrax, 73,000 tons, 6% of the total EU production) and common carp (Cyprinus carpio, 62000 tons, 5% of the total EU production) [5].
The aquaculture production can be developed in extensive or intensive systems, according to the respective low or higher fish density. In extensive systems, organisms grow in lagoons or brackish waters naturally fed, while in intensive systems, they are bred in tanks and fed with special feeds according to each single species; the semi-intensive systems can also occur when the natural diet is supplemented with special feeds [6].
The main objective of aquaculture is the production of high nutritional value foods for human consumption. However, apart from its valuable food supply and economic support for many countries, the aquaculture practice can cause environmental problems such as pollution of the surrounding waters with nutrients, solid wastes and chemicals (e.g., antibiotics) that are used for disease control in the aquaculture tanks. Regarding chemical contaminants (concentration and duration of exposure), the ingredients of commercial animal feeds can be responsible for food safety risks in aquaculture; the major animal feed contaminants reported are veterinary drug residues, persistent organic pollutants, pesticides, metals and mineral salts (mercury, lead, cadmium, hexavalent chromium, arsenic and selenium) [7]. The typology of feeds and the quality of waters can be considered to be important critical factors in fish farming [8]. The exchanges between fish body, water and food can be described by uptake via food and water, and losses via metabolism, growth dilution, egestion and gills [9]. The contaminants present in aquaculture, whether intentionally or unintentionally, can be metabolized and excreted (such as veterinary drugs), detected at residual levels, or accumulated in fish. The bioaccumulation of toxic contaminants by farmed fish, bivalves, crustaceans and molluscs becomes a serious environmental problem mainly related to human supply. As stated by the European Food Safety Authority [10] and Håstein et al. [11], the contaminant concentration in farmed fish and shellfish depends on various factors such as the species, the capture season, the origin, the development state, and the tissue, and the levels vary within species and between species in both wild and farmed fish [10]. Comparative studies have demonstrated that man-made contaminants such as pesticides, polybrominated biphenyl ethers (PBDE) and polychlorinated biphenyls (PCB) were found at higher concentrations in farmed fish than in wild fish (salmon, catfish, turbot and sea bass) [12], but there is a need for the standardization of sampling procedures before a robust comparison of wild and farmed fish can be made [10].
The sample preparation is an important step in the analysis of contaminants from environmental samples due to the occurrence of matrix effects which are directly associated with the complexity of such environmental matrices [13]. Regarding the determination of contaminants in aquaculture matrices, it is well known that such matrices are complex and the large amounts of fat and other interfering substances present are co-extracted with the analytes of interest. Thus, the choice of the extraction method or combination of extraction methods together with the clean-up procedures should be well defined to obtain extracts with minimal fat content for further efficient analysis of contaminants. The determination of contaminants in aquaculture is crucial to the control of food safety of the produced organisms. The organic enrichment of aquaculture waters from sediments is also an important topic, and the analysis of contaminants in water and sediments is also required for monitoring the water quality.
This study aims to review the state-of-the-art current analytical techniques published in the recent period of 2008–2015, which are used for the determination of contaminants, that is, polycyclic aromatic hydrocarbons (PAHs), brominated flame retardants (BFRs), PCBs, organochlorinated pesticides (OCPs), potentially toxic elements and residues of veterinary drugs and antibiotics, in various samples from aquaculture such as fish, crustaceans and molluscs. The occurrence of such contaminants in aquaculture and the analytical procedures required before analysis, such as extraction and clean-up, are also discussed.
Section snippets
Occurrence of contaminants in aquaculture
Aquaculture has been increasingly used to produce foodstuffs such as fish and shellfish and it has been strictly controlled by global and European regulations in order to define maximum levels of substances in such products. For example, the EC 1881/2006 regulated the maximum levels of contaminants such as metals (Pb, Hg and Cd) and PAHs in foodstuffs such as muscle of fish, crustaceans and bivalve molluscs [14]; the EC 1259/2011 regulated the maximum levels for dioxins, dioxin-like PCBs and
Sampling, extraction and clean-up methods
Table 1 displays results of the recent works on the determination of contaminants in aquaculture samples, where extraction and clean-up methods are also identified.
For the majority of the works reported in Table 1, the following procedures have been considered: a) fishes were collected from the aquaculture sites and transported alive to the laboratory in ziplock polyethylene bags or wrapped in an aluminium foil. b) Fishes were eviscerated and peeled and their edible tissues such as muscle,
Separation, detection and determination of contaminants in aquaculture
Various analytical techniques were suggested for the determination of contaminants in the aquaculture samples (Table 1). Liquid (LC) or gas chromatography (GC) with MS detection is proposed as a suitable confirmatory method for organic residues or contaminants in foodstuffs [65]. Effectively, approximately 54% of the works analysed in this review used the GC or LC combined with MS for the determination of organic compounds in fish or shellfish, as shown in Table 1. The GC–ECD (electron capture
Quality assurance and quality control
The representativeness is important for the reliability of analytical information. A representative sample is a sample that is typical of the parent material for the characteristics under inspection. The aquaculture samples taken into consideration in this review are associated with a very dynamic system, as the sample at any instant is characteristic of the sampling moment and in a particular location. Thus, the sampling plan should be well defined for identifying the exact geographic location
Conclusions and future perspectives
Although the aquaculture production has been increased both at a global state and in the European countries, constituting a valuable food supply and also promoting the economic development, potential contamination of the aquaculture products by animal feed, veterinary drugs and/or the neighbouring environmental conditions of aquaculture sites still remains. Some works reported levels of contaminants higher than those established in global or European legislations, which should arouse further
Acknowledgements
This work was funded by the Portuguese Science Foundation (FCT) through scholarships (ref. SFRH/BPD/95961/2013, SFRH/BD/84524/2012 and SFRH/BPD/73781/2010) under POCH funds, co-financed by the European Social Fund and Portuguese National Funds from MEC. This work was also funded by national funds through FCT/MEC (PIDDAC) under project IF/00407/2013/CP1162/CT0023. Thanks are also due, for the financial support to CESAM (UID/AMB/50017), to FCT/MEC through national funds, and the co-funding by the
References (74)
- et al.
Persistent halogenated compounds in aquaculture environments of South China: implications for global consumers' health risk via fish consumption
Environ. Int
(2011) - et al.
Aquaculture: environmental, toxicological, and health issues
Int. J. Hyg. Environ. Health
(2009) - et al.
Achievements and future trends in the analysis of emerging organic contaminants in environmental samples by mass spectrometry and bioanalytical techniques
J. Chromatogr. A
(2012) - et al.
Organochlorine levels in adipose tissue of woman from a littoral region of Argentina
Environ. Res
(2006) - et al.
Fish intake and serum levels of organochlorines among Japanese women
Sci. Total Environ
(2006) - et al.
Persistent organic pollutants in breast milk of mothers residing around an open dumping site in Kolkata, India: specific dioxin-like PCB levels and fish as a potential source
Environ. Int
(2010) - et al.
Chemical and biochemical tools to assess pollution exposure in cultured fish
Environ. Pollut
(2008) - et al.
Aquaculture effects on environmental and public welfare – The case of Mediterranean mariculture
Chemosphere
(2011) - et al.
Trace minerals in fish nutrition
Aquaculture
(1997) - et al.
Aquatic accumulation of dietary metals (Fe, Zn, Cu, Co, Mn) in recirculating aquaculture systems (RAS) changes body composition but not performance and health of juvenile turbot (Psetta maxima)
Aquacult. Eng
(2014)
Chemometric techniques in distribution, characterisation and source apportionment of polycyclic aromatic hydrocarbons (PAHs) in aquaculture sediments in Malaysia
Mar. Pollut. Bull
Dietary uptake of polybrominated diphenyl ethers (PBDEs), occurrence and profiles, in aquacultured turbots (Psetta maxima) from Galicia, Spain
Chemosphere
Assessment of contaminants and biomarkers of exposure in wild and farmed seabass
Ecotoxicol. Environ. Saf
Persistent halogenated compounds in two typical marine aquaculture zones of South China
Mar. Pollut. Bull
Temporal trends of PCBs in feed and dietary influence in farmed rainbow trout (Oncorhynchus mykiss)
Food Chem
Occurrence and distribution of antibiotics in the Beibu Gulf, China: impacts of river discharge and aquaculture activities
Mar. Environ. Res
Steroids in marine aquaculture farms surrounding Hailing Island, South China: occurrence, bioconcentration, and human dietary exposure
Sci. Total Environ
Investigating the presence of organochlorine pesticides and polychlorinated biphenyls in wild and farmed gilthead sea bream (Sparus aurata) from the Western Mediterranean sea
Mar. Pollut. Bull
Performance evaluation of commercial ELISA kits for screening of furazolidone and furaltadone residues in fish
Food Chem
Determination of nitroimidazole residues in aquaculture tissue using ultra high performance liquid chromatography coupled to tandem mass spectrometry
J. Chromatogr. B
Multi-residue determination of seventeen sulfonamides and five tetracyclines in fish tissue using a multi-stage LC-ESI-MS/MS approach based on advanced mass spectrometric techniques
Anal. Chim. Acta
Heavy metal (Pb, Co, Cd, Cr, Cu, Fe, Mn and Zn) concentrations in harvest-size white shrimp Litopenaeus vannamei tissues from aquaculture and wild source
J. Food Compos. Anal
Persistent organic pollutants and trace metals in sediments close to Scottish marine fish farms
Aquaculture
Aquaculture-derived enrichment of hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) in coastal sediments of Hong Kong and adjacent mainland China
Sci. Total Environ
Enrichment of polycyclic aromatic hydrocarbons (PAHs) in mariculture sediments of Hong Kong
Environ. Pollut
Detection of nitrofurans and their metabolites in pond water and sediments by liquid chromatography (LC)-photodiode array detection and LC-ion spray tandem mass spectrometry
Int. Biodeter. Biodegrad
Green analyrtical chemistry
Trends Anal. Chem
Occurrence of androgens and progestogens in wastewater treatment plants and receiving river waters: comparison to estrogens
Water Res
Trace analysis of 28 steroids in surface water, wastewater and sludge samples by rapid resolution liquid chromatography–electrospray ionization tandem mass spectrometry
J. Chromatogr. A
A paradigm shift in safe seafood production: from contaminant detection to fish monitoring – application of biological warning systems to aquaculture
Trends Food Sci. Tech
Trends in quality in the analytical laboratory. II. Analytical method validation and quality assurance
Trends Anal. Chem
Communication from the Commission to the European Parliament, the Council, the European Economic and Social Committee and the Committee of the Regions
Council Directive 2006/88/EC on animal health requirements for aquaculture animals and products thereof, and on the prevention and control of certain diseases in aquatic animals
Off. J. Eur. Union
What is Aquaculture?
The State of World Fisheries and Aquaculture Opportunities and Challenges
Scientific, Technical and Economic Committee for Fisheries (STECF) – The Economic Performance Report on the EU Aquaculture sector (STECF-13-29)
Heavy metal bioaccumulation and metallothionein content in tissues of the sea bream Sparus aurata from three different fish farming systems
Environ. Monit. Assess
Cited by (65)
Laser-Induced graphene-based Fabry-Pérot cavity label-free immunosensors for the quantification of cortisol
2024, Sensors and Actuators ReportsDelineation of trace metal level in fish feed and farmed fish, Tilapia (Oreochromis mossumbicus) and their consequences on human health
2024, Regional Studies in Marine ScienceRecent developments in biosensing strategies for the detection of small molecular contaminants to ensure food safety in aquaculture and fisheries
2023, Trends in Food Science and Technology