Wafa RJIBA BAHRI, CHAFFAI A., GHANEM R., BEN SOUISSI J.
Laboratory of Biodiversity, Biotechnology and Climate change LR11ES09, University
Tunis El Manar, Tunis, Tunisia
E-mail: wafa.rjiba@yahoo.fr
EAT ALIEN INVASIVE BLUE CRABS: YES, BUT WITHOUT
RUNNING HEALTH RISKS!
Abstract
The non-indigenous blue crabs (Portunus segnis and Callinectes sapidus) represent an emerging
fishery in Tunisia, which can effectively contribute to food security in the context of local resources
scarcity. In 2019, catches reached 14 000 T in this country, and were mainly exported worldwide.
These crabs have a high nutritional value and are considered as a new source of
proteins for
Tunisian consumers. Nevertheless, some trace elements may constitute a threat to human health at
high concentrations and heavy metals are toxic even at very low contents (bioaccumulation via the
food chain). This work aims to evaluate and compare the concentration of nine trace metals (Fe, Cu,
Zn, Mn, Ni, Co, Cr, Cd and Pb) in various tissues (muscles, hepatopancreas and exoskeleton) of C.
sapidus using Inductively Coupled Plasma Mass Spectrometer. Samples (n=33) were collected in
Tunis southern lagoon by fyke nets during eel fishing campaign (from October 2020 to July 2021).
Results highlighted that metal concentrations differed significantly according to tissues (p<0.05). The
exoskeleton of the crab accumulated the highest levels for all the elements followed by hepatopancreas
and pereiopods’ muscles. The Metal Pollution Index was 3.73± 0.19, 0.26± 0.04 and between 0.11
and 0.16 respectively for exoskeleton, hepatopancreas and muscles. Zn was the most abundant in the
different tissues with a highest concentration in the exoskeleton (11.19± 2.49 mg/100g, 14.69± 1.10
mg/100g, 13.74± 0.98 mg/100g and 168.95± 19.1mg/100g respectively in claws, locomotion
pereiopods, hepatopancreas and exoskeleton). Regarding highly toxic metals (Pb and Cd),
concentrations were under the admissible limits of the European Union except for hepatopancreas
and exoskeleton with a significant difference between them (p<0.05). Indeed, the most consumed
tissues (muscles) are the least affected and targeted by Pb and Cd. More controls are strongly needed
to guarantee human health safety. Biomonitoring must cover all fishing sites, especially polluted
areas, and must take into account seasonal variations, sex and crab physiology.
Key-words: Bioinvasion, Heavy metals, Callinectes sapidus, Food safety, Invasivorism
Introduction
Biological invasions have been considered worldwide as a major driver of change in
Mediterranean marine biodiversity (Azzurro et al., 2019). Managing invasive nonindigenous species (NIS) represent a challenge for biodiversity conservation. Different
approaches are used for control such as mechanical and physical removal (Nunez et al.,
2012). Furthermore, eating edible NIS or “invasivorism” to reduce invasive populations
is gaining popularity (Franke, 2007). In addition, turning invasive species into gourmet
meals may contribute to food security and is an opportunity to boost local economy
(Nunez et al., 2012).This approach was presented as a win-win for consumers and
environmental stakeholders (Franke, 2007). Several promoting campaigns for NIS
consumption, namely “Eat Those Invasives”, “Eat Lionfish” and “Fighting invasive
species, one bite at a time” were carried out (Nunez et al., 2012). In addition, many
cookbooks focused on recipes based on NIS (Franke, 2007; Leone, 2020). Alien portunid
crabs are regularly caught and landed by small-scale fisheries in Tunisia since 2015 for
2nd Mediterranean Symposium on the Non-Indigenous Species (Genoa, Italy, 22-23 September 2022)
62
Laboratory of Biodiversity, Biotechnology and Climate change LR11ES09, University
Tunis El Manar, Tunis, Tunisia
E-mail: wafa.rjiba@yahoo.fr
EAT ALIEN INVASIVE BLUE CRABS: YES, BUT WITHOUT
RUNNING HEALTH RISKS!
Abstract
The non-indigenous blue crabs (Portunus segnis and Callinectes sapidus) represent an emerging
fishery in Tunisia, which can effectively contribute to food security in the context of local resources
scarcity. In 2019, catches reached 14 000 T in this country, and were mainly exported worldwide.
These crabs have a high nutritional value and are considered as a new source of
proteins for
Tunisian consumers. Nevertheless, some trace elements may constitute a threat to human health at
high concentrations and heavy metals are toxic even at very low contents (bioaccumulation via the
food chain). This work aims to evaluate and compare the concentration of nine trace metals (Fe, Cu,
Zn, Mn, Ni, Co, Cr, Cd and Pb) in various tissues (muscles, hepatopancreas and exoskeleton) of C.
sapidus using Inductively Coupled Plasma Mass Spectrometer. Samples (n=33) were collected in
Tunis southern lagoon by fyke nets during eel fishing campaign (from October 2020 to July 2021).
Results highlighted that metal concentrations differed significantly according to tissues (p<0.05). The
exoskeleton of the crab accumulated the highest levels for all the elements followed by hepatopancreas
and pereiopods’ muscles. The Metal Pollution Index was 3.73± 0.19, 0.26± 0.04 and between 0.11
and 0.16 respectively for exoskeleton, hepatopancreas and muscles. Zn was the most abundant in the
different tissues with a highest concentration in the exoskeleton (11.19± 2.49 mg/100g, 14.69± 1.10
mg/100g, 13.74± 0.98 mg/100g and 168.95± 19.1mg/100g respectively in claws, locomotion
pereiopods, hepatopancreas and exoskeleton). Regarding highly toxic metals (Pb and Cd),
concentrations were under the admissible limits of the European Union except for hepatopancreas
and exoskeleton with a significant difference between them (p<0.05). Indeed, the most consumed
tissues (muscles) are the least affected and targeted by Pb and Cd. More controls are strongly needed
to guarantee human health safety. Biomonitoring must cover all fishing sites, especially polluted
areas, and must take into account seasonal variations, sex and crab physiology.
Key-words: Bioinvasion, Heavy metals, Callinectes sapidus, Food safety, Invasivorism
Introduction
Biological invasions have been considered worldwide as a major driver of change in
Mediterranean marine biodiversity (Azzurro et al., 2019). Managing invasive nonindigenous species (NIS) represent a challenge for biodiversity conservation. Different
approaches are used for control such as mechanical and physical removal (Nunez et al.,
2012). Furthermore, eating edible NIS or “invasivorism” to reduce invasive populations
is gaining popularity (Franke, 2007). In addition, turning invasive species into gourmet
meals may contribute to food security and is an opportunity to boost local economy
(Nunez et al., 2012).This approach was presented as a win-win for consumers and
environmental stakeholders (Franke, 2007). Several promoting campaigns for NIS
consumption, namely “Eat Those Invasives”, “Eat Lionfish” and “Fighting invasive
species, one bite at a time” were carried out (Nunez et al., 2012). In addition, many
cookbooks focused on recipes based on NIS (Franke, 2007; Leone, 2020). Alien portunid
crabs are regularly caught and landed by small-scale fisheries in Tunisia since 2015 for
2nd Mediterranean Symposium on the Non-Indigenous Species (Genoa, Italy, 22-23 September 2022)
62