Portunus segnis (Forskål, 1775) and later for the Atlantic crab Callinectes sapidus (C.
sapidus) Rathbun, 1896 (Ben Souissi et al., 2017; Katsanevakis et al., 2020). Actually,
more than 28 processing units and export companies have been implemented in Tunisia
and crab exports increased 100 times between 2015 and 2019 to more than 20 destinations
all over the world (GIPP, 2019). The exported quantities reached 3500 tons for more than
12 million euros in 2019 (export price is between 2.5 and 4 €/kg depending on products)
(GIPP, 2019). These crabs have a high nutritional value and considered as a new source
of minerals for Tunisian consumers. Some trace elements are essential for the metabolism
of the organism but may constitute a threat to human health at high concentrations. Other
metals have no known biological functions and are toxic even at very low contents
because of their toxicity, and biomagnification in the food chain (Barat Kumar et al.,
2019). C. sapidus is omnivorous predator, feeding on bivalves, fish, gasteropods, and
other crustaceans, as well as algae (Kampouris et al. 2019). Since accumulation of trace
metals in aquatic organisms has been correlated to their feeding habits (Barat Kumar et
al., 2019), it seems necessary to evaluate trace element contents, especially heavy metals,
in crab tissues to estimate his potential toxic effect. Therefore, this work is the first one
dealing with trace elements uptake on the invasive decapod C. sapidus in Tunisia.
Materials and methods
Crab sampling and preparation: Specimens of C. sapidus (n=33) were collected from the
Southern lagoon of Tunis (north eastern of Tunisia) by fyke nets of 18 mm mesh size during
eel fishing campaign (from October 2020 to July 2021). Samples were then transferred alive
to the laboratory to be measured and classified into males and females. After morphometric
caracterisation, adult crabs were euthanized by thermal shock (-20°C for 10 min) and divided
randomly into three homogeneous groups. Then, exoskeleton, hepatopancreas and muscles
from thoracic sterna, claws (chelipeds) and locomotion pereiopods of each group were handpicked and blended to homogenize (Khamassi et al., 2022).
Trace element analysis: The metal analysis was made according to Canli and Atli (2003).
The carapace, hepatopancreas and muscle samples (0.1 g dry weight each) were dried at
150 °C until reaching constant weight. Then concentrated nitric acid (4 mL, Merck,
Darmstadt, Germany) and perchloric acid (2 mL, Merck) were added to the samples,
which were put on a hot plate set to 150 °C until all tissues were dissolved. Inductively
coupled plasma mass spectrometer ICP-MS, Agilent, 7500ce Model) was used to
determine elements (Fe, Cu, Zn, Mn, Ni, Co, Cr, Cd and Pb) concentrations. detected as µg
metal g
-1 dry weight. The mean value of the measured concentrations in the crab tissues
are used in this work. High purity multi standard (Charleston, SC, USA) was used for
determination of the metals.
Statistical analysis: A one-way ANOVA was performed after normal distribution data
analysis. Duncan’s multiple range test was assessed to separate differences among means.
All statistical analysis was tested at the 0.05 level of probability with the software
Statistical Analysis System (SAS 9.1.3, 2002-2003, Institute Inc., Cary, NC, USA).
Results
First occurrences of C. sapidus in the Mediterranean Sea are summarized in Figure 1.
Actually, this species is present in 19 out of the 23 countries surrounding the
Mediterranean Sea. Since its first record in 1949, the crab has colonized almost the entire
Mediterranean basin (Figure 1).
2nd Mediterranean Symposium on the Non-Indigenous Species (Genoa, Italy, 22-23 September 2022)
63
sapidus) Rathbun, 1896 (Ben Souissi et al., 2017; Katsanevakis et al., 2020). Actually,
more than 28 processing units and export companies have been implemented in Tunisia
and crab exports increased 100 times between 2015 and 2019 to more than 20 destinations
all over the world (GIPP, 2019). The exported quantities reached 3500 tons for more than
12 million euros in 2019 (export price is between 2.5 and 4 €/kg depending on products)
(GIPP, 2019). These crabs have a high nutritional value and considered as a new source
of minerals for Tunisian consumers. Some trace elements are essential for the metabolism
of the organism but may constitute a threat to human health at high concentrations. Other
metals have no known biological functions and are toxic even at very low contents
because of their toxicity, and biomagnification in the food chain (Barat Kumar et al.,
2019). C. sapidus is omnivorous predator, feeding on bivalves, fish, gasteropods, and
other crustaceans, as well as algae (Kampouris et al. 2019). Since accumulation of trace
metals in aquatic organisms has been correlated to their feeding habits (Barat Kumar et
al., 2019), it seems necessary to evaluate trace element contents, especially heavy metals,
in crab tissues to estimate his potential toxic effect. Therefore, this work is the first one
dealing with trace elements uptake on the invasive decapod C. sapidus in Tunisia.
Materials and methods
Crab sampling and preparation: Specimens of C. sapidus (n=33) were collected from the
Southern lagoon of Tunis (north eastern of Tunisia) by fyke nets of 18 mm mesh size during
eel fishing campaign (from October 2020 to July 2021). Samples were then transferred alive
to the laboratory to be measured and classified into males and females. After morphometric
caracterisation, adult crabs were euthanized by thermal shock (-20°C for 10 min) and divided
randomly into three homogeneous groups. Then, exoskeleton, hepatopancreas and muscles
from thoracic sterna, claws (chelipeds) and locomotion pereiopods of each group were handpicked and blended to homogenize (Khamassi et al., 2022).
Trace element analysis: The metal analysis was made according to Canli and Atli (2003).
The carapace, hepatopancreas and muscle samples (0.1 g dry weight each) were dried at
150 °C until reaching constant weight. Then concentrated nitric acid (4 mL, Merck,
Darmstadt, Germany) and perchloric acid (2 mL, Merck) were added to the samples,
which were put on a hot plate set to 150 °C until all tissues were dissolved. Inductively
coupled plasma mass spectrometer ICP-MS, Agilent, 7500ce Model) was used to
determine elements (Fe, Cu, Zn, Mn, Ni, Co, Cr, Cd and Pb) concentrations. detected as µg
metal g
-1 dry weight. The mean value of the measured concentrations in the crab tissues
are used in this work. High purity multi standard (Charleston, SC, USA) was used for
determination of the metals.
Statistical analysis: A one-way ANOVA was performed after normal distribution data
analysis. Duncan’s multiple range test was assessed to separate differences among means.
All statistical analysis was tested at the 0.05 level of probability with the software
Statistical Analysis System (SAS 9.1.3, 2002-2003, Institute Inc., Cary, NC, USA).
Results
First occurrences of C. sapidus in the Mediterranean Sea are summarized in Figure 1.
Actually, this species is present in 19 out of the 23 countries surrounding the
Mediterranean Sea. Since its first record in 1949, the crab has colonized almost the entire
Mediterranean basin (Figure 1).
2nd Mediterranean Symposium on the Non-Indigenous Species (Genoa, Italy, 22-23 September 2022)
63