Revealing the illegal harvesting of Manila clams (Ruditapes philippinarum) using fatty acid profiles of the adductor muscle
Introduction
Marine bivalves, such as oysters, mussels, cockles and clams are among the most consumed seafood products worldwide. The Manila clam (Ruditapes philippinarum) is one of the most representative of such bivalves, with a production in 2017 of over 35.000 tons in Europe alone (FAO, 2019). Native from South-east Asia (Indo-Pacific), R. philippinarum is an invasive species in European coasts (Humphreys et al., 2015), where it was introduced in the early 1970's. In Iberian Peninsula, this species has been reported since late 1980's (Campos & Cachola, 2005; Chiesa et al., 2017), presenting currently well-stablished populations which turned it an important economic resource in this area (FAO, 2019).
Despite their high nutritional value, bivalves can at times threaten human health. Due to their suspension feeding nature, bivalves can accumulate pathogenic bacteria, being this especially dangerous for human health if consumed raw or lightly cooked (Cook, 1991, pp. 19–39; Wright, Fan, & Baker, 2018), as well as metals and metalloids present in the water (Karouna-Renier, Snyder, Allison, Wagner, & Ranga Rao, 2007; Velez, Figueira, Soares, & Freitas, 2015). These issues are related with water and sediment quality of the harvesting location (Li, Yu, Song, & Mu, 2006; Stabili, Terlizzi, & Cavallo, 2013). In order to safeguard public health, the European Union (EU) already produced several pieces of legislation (Regulation (EC) No 853/2004, No 854/2004, No 2073/2005 and No 1021/2008) classifying bivalves harvesting areas according to the levels of Escherichia coli they display per g of bivalves flesh and intravalvular liquid (EC, 2004a; 2004b, 2005, 2008). Moreover, to ensure the traceability of each batch of seafood traded in the European Union, it also stablished several labelling regulations (Regulation (European Commission (EC)) No 104/2000 and No 1224/2009; Regulation (EU) No 404/2011 and No 1379/2013) (EC, 2000, 2009; EU, 2011, 2013). The more recent and demanding of these labeling regulations (Regulation (EU) No 1379/2013) (EU, 2013) stipulates, among other specifications, that marketed seafood products need to display the catch area, production method and fishing gear used. In this way, the development of traceability tools for origin certification is paramount to avoid seafood mislabeling, being key to ensure safety for human consumption (Leal, Pimentel, Ricardo, Rosa, & Calado, 2015; Moretti, Turchini, Bellagamba, & Caprino, 2003).
Environmental factors, such as temperature, salinity and sediment type, influence the spatial distribution of bivalves (Gosling, 2003) modulating their fatty acids (FA) profile (Calado & Leal, 2015). For instance, high salinity fluctuations and low temperatures influence the structure and fluidity of cell membranes. This results in a lower saturated FA (SFA) content, that stabilize bilayer cellular membranes, with these biomolecules being replaced by polyunsaturated FA (PUFA), which allow higher membrane fluidity (Fokina, Ruokolainen, Bakhmet, & Nemova, 2015; Nemova, Fokina, Nefedova, Ruokolainen, & Bakhmet, 2013). Other driving factor of the FA composition in bivalve tissues is trophic history, with the predominance of certain FA revealing their dietary regimes (Calado & Leal, 2015; Prato, Danieli, Maffia, & Biandolino, 2010). The FAs 16:0, 16:1n-7 and 20:5n-3 (eicosapentaenoic acid, EPA) in bivalves tissues reveal the consumption of diatoms, while PUFA 18:3n-3 and 18:2n-6 of green microalgae, 22:6n-3 (docosahexaenoic acid, DHA) and 18:4n-3 of dinoflagellates, and odd chain FA (15:0 and 17:0) and 18:1n-7 of detritus/bacteria (among others, Calado & Leal, 2015; Dalsgaard, John, Kattner, Müller-Navarra, & Hagen, 2003; Ezgeta-Balić, Najdek, Peharda, & Blažina, 2012; Fujibayashi, Nishimura, & Tanaka, 2016; Nerot et al., 2015). These indicative features allow to apply the profiling of FA signatures of tissues from different marine species for multiple scopes, such as identifying their feeding habitats (e.g. Coelho et al., 2011; Xu, Xu, Zhang, Peng, & Yang, 2016), diet composition (e.g. Bosley, Copeman, Dumbauld, & Bosley, 2017; White et al., 2017), seasonal variations in dietary habits (e.g. Soler-Membrives, Rossi, & Munilla, 2011) or trace their geographic origin (Ricardo et al., 2015; Ricardo, Maciel, Domingues, & Calado, 2017; Zhang, Liu, Li, & Zhao, 2017).
The FA profile of the adductor muscle (AM) proved to be suitable in geographic origin traceability studies targeting diverse bivalve species, such as cockles (Cerastoderme edule; Ricardo et al., 20157, 2015), scallops (Pecten maximus; Grahl-Nielsen, Jacobsen, Christophersen, & Magnesen, 2010) and clams (Astarte sulcata; Olsen, Grahl-Nielsen, & Schander, 2009). The AM is of particular interest in traceability studies, mainly due to its high content in polar lipids, which prevents short-term turnover in the FA profile related to dietary shifts (Grahl-Nielsen et al., 2010; Leal et al., 2015; Olsen et al., 2009).
To avoid the fraudulent mislabeling of seafood geographic origin, it is important to develop and refine traceability tools. Therefore, the present study aimed to develop a model based on the FA profile of the AM that could indicate the most likely harvesting location of four batches of R. philippinarum suspected of having been illegally harvested from the Tagus estuary (where the harvesting of Manila clams is forbidden due to food safety issues). A two-step approach was employed to develop this model: i) Manila clam samples harvested from three ecosystems (the Tagus estuary and Ria de Aveiro, two Portuguese ecosystems that supply ~95% of the whole Manila clam traded in Portugal, and Ría de Vigo, a Spanish ecosystem that is also an important supplier of this species to the Portuguese market) were used to validate a predictive model to trace their geographic origin; and following the validation of the predictive model ii) the FA profile of the AM of clams suspected of originating from the Tagus estuary were screened to verify if these clams had indeed been harvested in this area where their capture is illegal.
Section snippets
Study areas and clam collection
Thirty specimens of R. philippinarum were collected in May 2018 in the Tagus estuary (Te, Portugal), Ria de Aveiro (RAv, Portugal) and Ría de Vigo (RV, Spain) (3 ecosystems X 30 replicates = 90 samples; Fig. 1). These ecosystems play an important role in the Portuguese trade of R. philippinarum, with these clams being intensively harvested in these locations. However, it must be highlighted, that regardless of the Tagus estuary being the main source of Manila clams supplying the Portuguese
Results
The mean relative abundance of each FA per sampling group is presented in Table 1. A total of 26 FAs were identified, being HUFA the most dominant class (50–53%), with eicosapentaenoic (20:5n-3; EPA) and docosahexaenoic (22:6n-3; DHA) acids being the most relevant ones, followed by SFA (22–26%), with the predominance of palmitic (16:0; PA) and stearic (18:0) acids. The least represented classes were MUFA (13–18%), mostly present due to oleic (18:1n-9) and eicosenoic (20:1n-9/11) acids, and PUFA
Discussion
The fraudulent mislabeling of geographic origin is a well-known problem in the seafood trade (Leal et al., 2015). The significant differences recorded in the FA profiles of the AM of Manila clams originating from the three ecosystems surveyed in the present study, confirmed the potential of this biochemical tool to trace the geographic origin of bivalves, as already highlighted by previous studies (Grahl-Nielsen et al., 2010; Olsen et al., 2009; Ricardo et al., 2017, 2015).
The FA profile of the
CRediT authorship contribution statement
Renato Mamede: Conceptualization, Methodology, Data curation, Formal analysis, Writing - original draft, Writing - review & editing, Data curation. Fernando Ricardo: Conceptualization, Methodology, Data curation, Writing - review & editing, Project administration. Andreia Santos: Methodology, Writing - review & editing. Seila Díaz: Methodology, Writing - review & editing. Sónia A.O. Santos: Methodology, Writing - review & editing. Regina Bispo: Formal analysis, Writing - review & editing. M.
Declaration of competing interest
The authors declare that they have no conflict of interest.
Acknowledgements
This work was financially supported by project TraSeafood (Tracing the geographic origin of seafood as a pathway towards the smart valorization of endogenous marine resources) (PTDC/BIA-BMA/29491/2017), funded by FEDER, through PT2020 Partnership Agreement and Compete 2020 and by national funds (OE), through FCT/MCTES. This work was also funded by the Integrated Programme SR&TD ‘Smart Valorization of Endogenous Marine Biological Resources Under a Changing Climate’ (Centro-01-0145-FEDER-000018),
References (50)
- et al.
Evaluation of a methylation procedure to determine cyclopropenoids fatty acids from Sterculia striata St. Hil. Et Nauds seed oil
Journal of Chromatography A
(2004) - et al.
Trophic ecology of benthic marine invertebrates with bi-phasic life cycles: What are we still missing?
(2015) - et al.
Metals and As content in sediments and Manila clam Ruditapes philippinarum in the Tagus estuary (Portugal): Impacts and risk for human consumption
Marine Pollution Bulletin
(2018) - et al.
A history of invasion: COI phylogeny of Manila clam Ruditapes philippinarum in Europe
Fisheries Research
(2017) - et al.
Fatty acid profiles indicate the habitat of mud snails Hydrobia ulvae within the same estuary: Mudflats vs. seagrass meadows
Estuarine, Coastal and Shelf Science
(2011) - et al.
Fatty acid trophic markers in the pelagic marine environment
(2003) - et al.
Seasonal fatty acid profile analysis to trace origin of food sources of four commercially important bivalves
Aquaculture
(2012) - et al.
Fatty acid composition in adductor muscle of juvenile scallops (Pecten maximus) from five Norwegian populations reared in the same environment
Biochemical Systematics and Ecology
(2010) - et al.
Accumulation of organic and inorganic contaminants in shellfish collected in estuarine waters near Pensacola, Florida: Contamination profiles and risks to human consumers
Environmental Pollution
(2007) - et al.
Seafood traceability: Current needs, available tools, and biotechnological challenges for origin certification
Trends in Biotechnology
(2015)
Fatty acids as trophic markers of phytoplankton blooms in the bahia blanca estuary (buenos aires, Argentina) and in trinity bay (newfoundland, Canada)
Biochemical Systematics and Ecology
Spatial changes in fatty acids signatures of the great scallop Pecten maximus across the Bay of Biscay continental shelf
Continental Shelf Research
Population study of Astarte sulcata, da Costa, 1778, (Mollusca, Bivalvia) from two Norwegian fjords based on the fatty acid composition of the adductor muscle
Biochemical Systematics and Ecology
Spatio-temporal variability in the fatty acid profile of the adductor muscle of the common cockle Cerastoderma edule and its relevance for tracing geographic origin
Food Control
Feeding ecology of Ammothella longipes (arthropoda: Pycnogonida) in the mediterranean sea: A fatty acid biomarker approach
Estuarine, Coastal and Shelf Science
Spatial distribution and bioaccumulation patterns in three clam populations from a low contaminated ecosystem
Estuarine, Coastal and Shelf Science
Consumption of aquaculture waste affects the fatty acid metabolism of a benthic invertebrate
The Science of the Total Environment
Identification of the geographical origins of sea cucumber (Apostichopus japonicus) in northern China by using stable isotope ratios and fatty acid profiles
Food Chemistry
A comparison of lipids and fatty acids of the ocean quahaug, Arctica islandica, from nova scotia and new brunswick
Journal of the Fisheries Board of Canada
PERMANOVA+ for PRIMER: Guide to software and statistical methods
Identification of burrowing shrimp food sources along an estuarine gradient using fatty acid analysis and stable isotope ratios
Estuaries and Coasts
The introduction of the Japanese carpet shell in coastal lagoon systems of the algarve (south Portugal): A food safety concern
Internet Journal of Food Safety
PRIMER v7: User manual/tutorial
Microbiology of bivalve molluscan shellfish
Microbiology of marine food products
Council Regulation (EC) No 104/2000 of 17 December 1999 on the commomn organisation of the markets in fishery and aquaculture products
Official Journal of the European Communities
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2022, Aquaculture ReportsCitation Excerpt :Ruditapes philippinarum, a kind of marine bivalve, is widely distributed in coastal area for its good adaptability to temperature and salinity (Mamede et al., 2020; Nie et al., 2017).