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All issues Volume 39 (2026) Aquat. Living Resour., 39 (2026) 23 Full HTML
Open Access
Issue
Aquat. Living Resour.
Volume 39, 2026
Article Number 23
Number of page(s) 10
DOI https://doi.org/10.1051/alr/2026018
Published online 22 July 2026

© K. Bouhali et al., Published by EDP Sciences 2026

Licence Creative CommonsThis is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

1 Introduction

The blue crab, Callinectes sapidus Rathbun, 1896, is a Brachyuran Crustacean indigenous to the western Atlantic coast, with natural distribution spanning from the northeastern United States to Argentina (Williams, 1974; Millikin et al., 1984). In recent years, the blue crab population has increased significantly throughout the Mediterranean, further affecting the native fauna and local economies (Castriota et al., 2024). Its invasive capability is mainly due to numerous advantageous biological characteristics: significant resistance to environmental fluctuations (temperature, salinity, dissolved oxygen), substantial reproductive potential, and opportunistic feeding behavior (Nehring, 2011; Mancinelli et al., 2021). Owing to its broad ecological plasticity and predatory behavior, Callinectes sapidus has successfully colonized a wide range of coastal and estuarine habitats. Its presence has been linked to adverse effects on local fisheries, including predation on native or commercially valuable species and damage to fishing gear through entanglement (Tsirintanis et al., 2022).

Callinectes sapidus has predominantly expanded beyond its indigenous range inadvertently, mainly due to the release of ballast water from commercial ships (Nehring, 2011; Katsanevakis et al., 2014). Its first record in the Mediterranean occurred in 1949, within the Grado Lagoon in the Adriatic Sea (Mizzan, 1993). Since then, its presence has been extensively documented around the shores of Italy, Spain, Greece, Turkey, and Croatia (González Ortegón et al., 2022), underscoring a notable ability for biological adaptation. The species is imposing escalating ecological stress on the benthic populations of coastal estuarine systems in the Mediterranean Basin. It impacts these ecosystems through multiple mechanisms, including interspecific trophic competition, direct predation on indigenous species, and modification of benthic habitats. For instance, C. sapidus has been reported to prey on bivalves, small crustaceans, and juvenile fishes, while also competing with native benthic predators for food resources and disturbing sediments during foraging activities (Mancinelli et al., 2017; Kampouris et al., 2019; Marchessaux et al., 2023).

These disturbances disrupt local trophic networks and lead to a decline in available biological resources, particularly jeopardizing the sustainability of shellfish aquaculture (Cabiddu et al., 2025) and fisheries (Gavioli et al., 2025), with concerning socio-economic ramifications (Marchessaux et al., 2023; Nardelli et al., 2024).

In Algeria, C. sapidus was first documented in 2019 at Oued Zhor Wadi, located on Algeria's eastern coast (Benabdi et al., 2019). Its occurrence has been established in multiple estuarine and Lagoon environments, including Mafragh estuary (Hamida et al., 2021) and Mellah Lagoon (Kara & Chaoui, 2021), indicating a rapid establishment process. The occurrence of juveniles and ovigerous females indicates active local reproduction and successful establishment of C. sapidus in Mellah Lagoon (Kara & Chaoui, 2021; Bouhali et al., 2022).

A notable aspect of the ecological success of C. sapidus is its omnivorous diet. The species preys on a diverse array of organisms, encompassing crustaceans, mollusks, fish, plant matter, organic detritus, and conspecifics (Dittel et al., 2006; Seitz et al., 2011). This trophic plasticity allows for adaptation to available resources and the occupation of various ecological niches (González Ortegón et al., 2022). Recent studies have demonstrated that the invasion success of C. sapidus is largely driven by its exceptional trophic plasticity, aggressive foraging behaviour, high reproductive capacity, and broad environmental tolerance. Together, these attributes promote its successful integration into local food webs and can profoundly reshape trophic interactions and ecosystem functioning in both native and invaded habitats (Chkili et al., 2026).

Interspecific competition involving C. sapidus has been documented both in native estuarine systems (e.g., with Callinectes similis or Menippe mercenaria) and in invaded habitats where it interacts with native benthic crustaceans such as Carcinus aestuarii, Palaemon spp., and other portunids (Marchessaux et al., 2023). In Mediterranean lagoons, including Mellah, such competition may be intensified due to the confined nature of these ecosystems. Beyond its ecological impacts, increasing attention has recently been devoted to the valorization of the invasive blue crab as a fishery resource. Although the species causes substantial ecological and economic damage to fisheries and shellfish aquaculture, its commercial exploitation has been proposed as a complementary management strategy that may contribute to population control while generating economic opportunities for coastal communities affected by the invasion (Mistri & Munari, 2026).

Most of the research on the feeding ecology of C. sapidus has been performed either within its indigenous range or in specific invaded areas of Europe (Chainho & Gambi, 2011; Katsanevakis et al., 2011; Mancinelli et al., 2021). Conversely, there is a paucity of evidence regarding its trophic ecology along North African coasts. This study aims to examine the dietary composition and variations of C. sapidus in Mellah Lagoon according to season and sex. This lagoon, located in northeastern Algeria, is a Ramsar site and UNESCO biosphere reserve that forms part of El-Kala National Park. These data are crucial for understanding the ecological impact of this species in Mediterranean lagoons and for informing sustainable management strategies to protect native biodiversity from biological invasions.

2 Materials and methods

2.1 Study area

Mellah Lagoon (36°53′N, 8°19′E), is an estuary on the North African coast situated in the district of El-Tarf and is the sole Lagoon in Algeria (Fig. 1). The area encompasses around 865 hectares, featuring an average depth of 2.7 meters and a 900 m waterway linking it to the sea. The lagoon also receives freshwater inputs from three wadis that discharge into the system, contributing to seasonal variability in salinity and hydrological conditions. This hydrosystem undergoes significant seasonal environmental fluctuations (temperature: 10–30 °C; salinity: 25–35 psu), fostering the proliferation of diverse planktonic (Como et al., 2024) and macrobenthic communities (Embarek et al., 2017; Denis et al., 2023). The euryhaline and productive characteristics of this ecosystem (Chaoui et al., 2006a,b) render it conducive to the proliferation of the invasive species C. sapidus.

Thumbnail: Fig. 1 Refer to the following caption and surrounding text. Fig. 1

Geographical location of Mellah Lagoon, Algeria.

2.2 Sampling

Specimens of C. sapidus were gathered monthly during a one-year period, from February 2021 to March 2022. Adult crabs were captured via gillnets and baited traps set at depths between 0.5 and 2 meters, primarily along the lagoon's perimeter, next to vegetated or sandy-bottom environments. After capture, the individuals were conveyed alive to the laboratory in containers with brackish water. Upon arrival at the laboratory after about 1 hour, each crab was euthanized in accordance with ethical protocols, sexed, measured (carapace width in millimeters using a calibrated caliper), weighed (in grams), and thereafter stored at –20 °C until the analysis of stomach contents. Monthly sampling effort, including the number of males and females examined, their mean carapace width (±SD), the number of ovigerous and non-ovigerous females, and the number of prey items recorded, are summarized in Table S1 (Supplementary material).

2.3 Qualitative and quantitative analysis of stomach contents

A total of 287 individuals (carapace width >60 mm; males: 96, females: 191) had their stomachs dissected under a stereomicroscope at ×40 magnification. Prey items were identified utilizing appropriate taxonomic keys (Hyslop, 1980; Bouchereau et al., 1998). Species-level identification was conducted whenever the extent of digestion permitted. Upon identification, prey items were individually enumerated and weighed to the closest hundredth of a gram.

The quantitative dietary analysis involved calculating the stomach vacuity coefficient (VC%) to assess gut emptiness using the formula:

VC % = Number of empty guts Total number of guts examined  ×  1 00 , Mathematical equation

where the numerator represents the number of empty stomachs and the denominator the total number of stomachs analyzed, corresponding to the percentage of empty stomachs relative to all examined stomachs. Potential variations in vacuity rates were statistically assessed according to sex, season, and female reproductive status (ovigerous vs. non-ovigerous).

Ingested prey items were identified to the lowest possible taxonomic level. The numerical contribution (Cni%) of each prey category was calculated as the proportion of individuals relative to the total number of prey items:

Cni% = n i ∑ ​ n i   ×   100 , Mathematical equation

where ni is the number of individuals of prey category i.

The gravimetric contribution (Cpi%) was calculated as the weight of each prey category relative to the total prey weight in the stomach:

Cpi%  = Wi ∑ ​ Wi ×   100 , Mathematical equation

where: Wi is the total weight of prey category i.

Frequency of occurrence (Fi%) was calculated as the proportion of stomachs containing each prey category. These three indices were then combined to calculate the Index of Relative Importance (IRI): IRI = (Cni + Cpi) × Fi. This approach follows Pinkas et al. (1971) and the revision by Hacunda (1981).

2.4 Diet classification and statistical analyses

The categorization of food items into preferred, secondary, and occasional classifications was determined by their IRI percentage values, adhering to the standards established by Cortés (1997). The Index of Relative Importance (IRI%) was calculated as:

I R I %   =   ( I R I / ∑ ​ I R I )   × 100.Mathematical equation

The dietary habits of C. sapidus were analyzed based on sampling season, sex, and female reproductive status. Females were classified as ovigerous or non-ovigerous according to the presence or absence of an egg mass under the abdomen. This classification allows for comparison of stomach contents between females carrying eggs and those without eggs, without implying discrete reproductive periods, as C. sapidus exhibits a continuous reproductive cycle under favorable environmental conditions (Gelpi et al., 2009).

Owing to technical challenges encountered during lagoon sampling, blue crabs were collected over two consecutive years (2021–2022) in order to provide a representative coverage of the different sampling seasons. Sampling seasons were defined as follows: Spring (February–May 2021; March 2022), Summer (June–August 2021), Autumn (September–November 2021), and Winter (December 2021–February 2022). The number of individuals sampled per season and per month is provided in Table S1 (Supplementary material). Spring 2022 is represented by only one sampling month (March 2022), as the sampling cycle concluded at the end of the study period.

The statistical significance of dietary fluctuations was evaluated using Spearman’s rank correlation coefficient (Fritz, 1974), applied to the ranked significance of various prey items:

ρ =   1 − ( 6   Σ d ² ) / ( n 3 − n ) , Mathematical equation

where: n: number of prey categories, d: difference between the ranks of each prey item in the two compared samples.

Prey items were ranked in descending order of IRI to generate paired rank series. The ranks must be uniform across the compared samples; if a prey type was missing in one sample, it was nonetheless allocated a rank. In instances of tied IRI values within a taxonomic category, prey items were allocated the mean rank they would have occupied in the absence of ties. The statistical significance of r was evaluated using Student’s t-distribution with n – 2 degrees of freedom (Dagnélie, 1975).

t = [ ρ ( 1 − ρ 2 ) 1 / 2 . ] . ( n − 2 ) 1 / 2 .Mathematical equation

2.5 Trophic level estimation

The mean trophic level (TP) of C. sapidus was calculated by assessing the relative contribution of each prey item (based on IRI%) and the established trophic level (TP) of each prey category, in accordance with the methodology described by Dittel et al. (2006) and Seitz et al. (2011). The crab's trophic level was determined using the equation: TPcrab = 1 + Σ (proportioni × TPi). This trophic approach allows the ecological positioning of C. sapidus within the lagoon’s food web and helps anticipate its potential functional role in the ecosystem. All statistical analyses were performed using R software (version 4.2.2).

3 Results

3.1 Quantitative and qualitative composition

Among the 287 examined stomachs, 108 were empty, resulting in an overall vacuity index of 37.63%. Seasonal, sexual, and reproductive stage of females in stomach vacuity are reported in Table 1. The vacuity rate exhibited significant variation between seasons (χ2 = 20.91; p < 0.01) and between sexes (χ2 = 1.91; p < 0.05). No substantial difference in vacuity was noted between ovigerous and non-ovigerous females, Table 2 presents the qualitative and quantitative composition of the diet of C. sapidus in Mellah Lagoon during the sampling period. A total of 277 prey items were recorded across all examined stomachs, of which 94 were recorded in males and 183 in females, corresponding to an average of 1.54 prey items and 0.21 g of ingested material per stomach, respectively. Owing to the advanced stage of digestion of the majority of ingested prey, taxonomic identification was limited to the phylum level. Nine taxonomic groups were discovered and ranked by decreasing%IRI values: Arthropoda (37.42%), unidentified food particles (27.46%), Mollusca (15.47%), Chordata (11.49%), and Plantae (7.8%). The consumption of other phyla was deemed low dietary importance (%IRI < 0.2).

Table 1

Stomach vacuity values in the overall population and according to season, sex and reproductive periods of Callinectes sapidus in Mellah Lagoon. ORS: outside the reproductive season, RS: reproductive season, OP: overall population, M: males, F: females. *: significant, n.s: not significant.

Table 2

Diet composition of the blue crab Callinectes sapidus from the Mellah Lagoon and classification of ingested prey according to the percentage of relative importance index (% IRI).

3.2 Seasonal variations

The seasonal Spearman rank correlations of IRI values for C. sapidus (Fig. 2) showed the highest similarity between spring and summer (ρ = 0.6307). Correlations between winter and autumn (ρ = –0.8), winter and spring (ρ = 0.0286), and summer and autumn (ρ = 0.2) were low.

Thumbnail: Fig. 2 Refer to the following caption and surrounding text. Fig. 2

Seasonal comparisons of % IRI in the blue crab Callinectes sapidus of Mellah Lagoon.

3.3 Sexual variation

The comparison of IRI values according to sex (Fig. 3) demonstrated a robust Spearman correlation (ρ = 0.8857), signifying a trophic similarity. Nonetheless, the corresponding statistical test (tobs = 3.8158; tcritical = ± 2.7764; p = 0.0188; n = 6) indicated a significant disparity in the distribution of IRI%, implying that while both sexes consume analogous prey types, the relative significance of these prey items differ. Specifically, females primarily consumed arthropods (IRI% = 37.42), followed by unidentified organic matter (27.46%) and mollusks (15.47%), whereas males ingested mainly unidentified organic matter (IRI% = 40.59), followed by arthropods (24.54%) and teleost fish (14.33%). These results indicate that the diet of C. sapidus is structurally homogeneous (same prey categories present) but quantitatively heterogeneous, as the relative importance of prey items varies between sexes.

Thumbnail: Fig. 3 Refer to the following caption and surrounding text. Fig. 3

Sexual comparisons in the blue crab Callinectes sapidus of Mellah Lagoon.

3.4 Temporal variation

Temporal variation in the diet of C. sapidus was assessed both across seasons and according to female reproductive status. The Kruskal–Wallis test revealed no significant differences in the distribution of IRI% values among the four sampling seasons (χ2 = 0.508, df = 3, p = 0.917), indicating that the overall dietary composition of C. sapidus remained stable throughout the study period regardless of season.

Similarly, comparison of IRI values between the reproductive period (ovigerous females) and the non-reproductive period (non-ovigerous females) (Fig. 4) showed no significant differences in the ranking of consumed prey items (ρ = 0.4286; tobs = 0.9487; tcritical = ±2.7764; p = 0.3965; n = 6). Although minor variations were observed, particularly a moderate increase in plant material and unidentified food particles in ovigerous females, these differences did not result in any significant alteration of the overall dietary composition.

Thumbnail: Fig. 4 Refer to the following caption and surrounding text. Fig. 4

Comparison of prey importance (%IRI) in the diet of Callinectes sapidus from Mellah Lagoon during the reproductive season (RS) and outside the reproductive season (ORS).

3.5 Trophic level

The average trophic level (TL) of C. sapidus in Mellah Lagoon was calculated to be 3.3 (Tab. 3). The principal contributions to this trophic level were derived from arthropods (37.42%; TL = 2.5), followed by teleosts (11.49%; TL = 3.5), and mollusks (15.47%; TL = 2.1). The inclusion of low-trophic-level items, such as plant material (7.8%; TL = 1), signifies a level of dietary adaptability and opportunistic foraging behavior, especially during times of diminished animal prey availability.

Table 3

Contribution of different taxonomic phyla to the average trophic level in Callinectes sapidus from the Mellah Lagoon.

4 Discussion

The population of C. sapidus in Mellah Lagoon displays a moderate stomach vacuity rate (37.63%). This value is comparable to the vacuity rate recorded in Mar Menor Lagoon, Spain (39.5%; Öndes et al., 2025), but lower than that reported in Bardawil Lagoon, Egypt (46.6%; Rady et al., 2018). Vacuity rates varied across seasons but not between ovigerous and non-ovigerous females. The proportion of ovigerous females varied markedly across seasons, reaching a peak in summer (64.9% of females sampled), and declining substantially in winter (13.7%). This seasonal pattern is consistent with the reproductive cycle of C. sapidus in Mediterranean lagoons, where egg-bearing females are predominantly observed during warmer months (Gelpi et al., 2009). Seasonal variations suggest interactions between environmental parameters (temperature, salinity, dissolved oxygen, turbidity, prey availability,) and physiological conditions (ontogenetic development, molting cycles, reproductive state, prey digestion time). During winter, the reduced contribution of crustaceans to the diet coincided with lower water temperatures and salinity, which may have limited prey availability and feeding activity. Likewise, ovigerous females exhibited increased consumption of arthropods, which may reflect both the higher energetic demands associated with egg production and the greater availability of crustacean prey during summer, when the arthropod contribution to the diet reached its seasonal peak (IRI% = 45.14%). The co-occurrence of peak arthropod availability and the highest abundance of ovigerous females during summer suggests that this dietary pattern may result from opportunistic exploitation of seasonally abundant prey rather than active prey selection driven solely by reproductive energetic requirements. These patterns suggest that environmental conditions and physiological status jointly shape feeding behavior and trophic variability across seasons.

The diet of C. sapidus in Mellah Lagoon is primarily composed of crustaceans, mollusks, and teleost fish. This diet is consistent across several Mediterranean coastal ecosystems. In Bardawil Lagoon, Egypt, C. sapidus shows a consistent preference for mollusks, crustaceans, and fish regardless of sex (Rady et al., 2018). In the Mar Menor Lagoon, Spain, Chainho & Gambi (2011) reported similar trophic dominance of these three prey categories. Moreover, in the Aegean Sea, Aslan and Polito (2021) confirmed an opportunistic foraging behavior based on macrozoobenthic prey. Such diversity in feeding preferences across distant regions underscores the species’ trophic adaptability and highlights the ecological significance of macrozoobenthic resources in invaded environments.

While no significant qualitative differences in diet were observed between males and females of C. sapidus in Mellah Lagoon, quantitative disparities were evident. Males consumed proportionally more unidentified organic matter and teleost fish, whereas females showed relatively higher consumption of arthropods and mollusks (Tab. 2; Fig. 3). This sex-based trophic differentiation, whereby males tend to target more motile prey, has been reported in other Mediterranean populations, such as in the Adriatic Sea (Mancinelli et al., 2021) and the Gulf of Cádiz (Ortega Jiménez et al., 2025).

These differing patterns may reflect differing foraging strategies, mobility, or physiological constraints between sexes. Moreover, no substantial dietary differences were detected between ovigerous and non-ovigerous females. However, behavioral studies in the native range of C. sapidus, such as in Lake Mattamuskeet (North Carolina, USA), indicated that males typically exhibit a nomadic foraging strategy, while gravid females tend to adopt a sedentary behavior and aggregate in specific spawning grounds (Rinaldi et al., 2019). The spatio-temporal limitation of feeding activity in C. sapidus may be influenced by reproductive constraints. The effects of these constraints on the movement and diet composition of ovigerous females are supported by Aguilar et al. (2005), who studied naturally reproducing crabs. The consumption of large, hard-bodied carnivorous prey in Mellah Lagoon is facilitated by a well-developed and morphologically specialized gastric mill. The molariform structures of this species are adapted for mastication and mechanical fragmentation of resistant food items (Williams, 1974; Seed & Nickell, 1987). Rainer (1991) described the structural complexity of the gastric mill in C. sapidus, highlighting heavily calcified ossicles specialized in food breakdown. Rady et al. (2018) further demonstrated that the gastric mill consists of seven articulated ossicles within the cardiac stomach, allowing efficient fragmentation of firm-textured prey. These morpho-anatomical adaptations enable C. sapidus to exploit a wide range of prey, supporting its omnivorous diet and ecological flexibility. Similar functional adaptations have been reported in other carnivorous brachyurans (Saborowski et al., 2023). This structural-functional relationship provides insight into how C. sapidus can utilize diverse food resources, contributing to its invasive success in novel habitats.

The diet of C. sapidus in Mellah Lagoon exhibits marked seasonal variation, with the exception of spring and summer during which the dominance of Arthropods, particularly Decapod Crustaceans, remains constant. This is reflected in high Index of Relative Importance (IRI) values of 43.71% in spring and 45.14% in summer, suggesting that environmental conditions during these seasons favor an opportunistic feeding strategy centered on Crustacean prey. This trophic preference persists into autumn, coinciding with an increased abundance of Decapods in the macrobenthic community.

In winter and early spring, C. sapidus exhibits a dietary shift toward plant material and detritus, which may reflect a reduced availability or accessibility of animal prey, or an adaptive behavioral response to seasonal environmental constraints. Similar trophic adjustments have been observed in Bardawil Lagoon (Egypt), where low temperatures and fluctuating salinity influence feeding strategies (Abdel-Moati et al., 2024).

The multiple trophic levels occupied by the crabs are evidenced by gut content analysis. This intermediate trophic position underscores the potentially structuring role of C. sapidus in the Lagoon food web, where it functions both as a predator of benthic macrofauna and a contributor to organic matter recycling, particularly through the consumption of detrital or unidentified material (27.46%; estimated TL = 2.0).

In its native range, particularly in subestuaries of Chesapeake Bay (USA), C. sapidus exhibits a relatively stable diet throughout the year, primarily composed of mollusk bivalves, polychaetes, small crustaceans, and plant detritus (Hines et al., 1990). This trophic stability is largely attributed to the long-term co-evolutionary relationships with the prey, a well-structured benthic community, and the availability of refuges in structurally complex habitats (Eggleston et al., 1992).

The diet of C. sapidus is generally similar across sexes and reproductive stages, reflecting structural homogeneity, with both males and females primarily consuming decapod crustaceans and unidentified organic matter. Nevertheless, quantitative differences were evident: males ingested a greater proportion of organic matter, whereas females exhibited relatively higher consumption of decapod crustaceans during the reproductive period, indicating quantitative heterogeneity in diet composition. This trophic pattern remains steady throughout the reproductive cycle, indicating a conserved feeding approach that presumably sustains a consistent energy intake during reproduction. This behavior also reflects the species' adaptability in response to reproductive physiological demands. Zenetos et al. (2020) observed a comparable tendency in the eastern Mediterranean, where ovigerous females exhibit consistent feeding behavior, indicating an energy conservation strategy during reproduction.

The average trophic level of C. sapidus in Mellah (TL = 3.3) situates it as a secondary consumer and highlights its significant ecological function in the lagoon. Nonetheless, indigenous Portunids like C. aestuarii, occupying a similar trophic level, may compete for the same resources, thereby destabilizing the local food chain. Several studies have reported similar trophic levels between male and female C. sapidus across different regions, including Greece (Kampouris et al., 2019; Katsanevakis et al., 2024), Costa Rica (Dittel et al., 2006), and Italy (Mancinelli et al., 2017). These findings indicate that both sexes occupy comparable positions within the food web, consuming similar proportions of decapod crustaceans, teleost fish, and other prey types, despite minor quantitative differences in diet composition.

The findings of the present study are broadly consistent with the global synthesis recently published by Chkili et al. (2026), who conducted a scoping review of the trophic ecology of C. sapidus across native and invaded ecosystems based on 285 studies. These authors confirmed that C. sapidus consistently behaves as an opportunistic generalist predator across all invaded contexts, with benthic invertebrates, particularly bivalves and crustaceans, representing the most vulnerable trophic compartments. This pattern aligns with our results, where Arthropoda and Mollusca jointly accounted for over 52% of the diet by IRI% in Mellah Lagoon.

Furthermore, Chkili et al. (2026) highlighted that trophic studies in Mediterranean lagoons remain fragmented and largely descriptive, relying predominantly on stomach content analyses, the same methodological approach used in the present study. Our work therefore contributes to filling this identified knowledge gap in North African invaded ecosystems, for which no previous trophic data on C. sapidus were available.

Chkili et al. (2026) also emphasized that sex-related quantitative dietary differences are recurrently documented across invaded populations, a trend corroborated by the quantitative heterogeneity observed between males and females in the present study, despite structural homogeneity in prey categories consumed. Finally, the intermediate trophic level estimated in our study (TL = 3.3) is consistent with the mesopredator trophic position (TP = 3.2–3.6) reported by these authors across invaded Mediterranean ecosystems, reinforcing the classification of C. sapidus as a secondary consumer with a strong potential to restructure local benthic food webs.

Consistent data indicate that C. sapidus routinely adopts an opportunistic omnivorous diet in invaded coastal settings, confirming significant and enduring trophic plasticity. This corroborates the concept of a consistent trophic position for this species in invasion zones.

Data availability statement

The data supporting the findings of this study are available from the corresponding author upon reasonable request.

Supplementary Material

Table S1. Monthly sampling data for Callinectes sapidus in Mellah Lagoon, Algeria (February 2021 – March 2022). Access Supplementary Material

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Cite this article as: Bouhali K, Derbal F, Kara M.H. 2026. Composition and variation in the diet of the invasive blue crab Callinectes sapidus in Mellah Lagoon (north-eastern Algeria). Aquat. Living Resour. 39: 23. https://doi.org/10.1051/alr/2026018

All Tables

Table 1

Stomach vacuity values in the overall population and according to season, sex and reproductive periods of Callinectes sapidus in Mellah Lagoon. ORS: outside the reproductive season, RS: reproductive season, OP: overall population, M: males, F: females. *: significant, n.s: not significant.

In the text
Table 2

Diet composition of the blue crab Callinectes sapidus from the Mellah Lagoon and classification of ingested prey according to the percentage of relative importance index (% IRI).

In the text
Table 3

Contribution of different taxonomic phyla to the average trophic level in Callinectes sapidus from the Mellah Lagoon.

In the text

All Figures

Thumbnail: Fig. 1 Refer to the following caption and surrounding text. Fig. 1

Geographical location of Mellah Lagoon, Algeria.
In the text
Thumbnail: Fig. 2 Refer to the following caption and surrounding text. Fig. 2

Seasonal comparisons of % IRI in the blue crab Callinectes sapidus of Mellah Lagoon.
In the text
Thumbnail: Fig. 3 Refer to the following caption and surrounding text. Fig. 3

Sexual comparisons in the blue crab Callinectes sapidus of Mellah Lagoon.
In the text
Thumbnail: Fig. 4 Refer to the following caption and surrounding text. Fig. 4

Comparison of prey importance (%IRI) in the diet of Callinectes sapidus from Mellah Lagoon during the reproductive season (RS) and outside the reproductive season (ORS).
In the text

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