Food and feeding habits of the blue crab,Callinectes sapidus (Crustacea: Decapoda: Portunidae) with special reference to the gastric mill structure

Abstract

Blue crab Bardawil Lagoon Feeding habits Gastric mill Stomach contents of 161 specimens of Callinectes sapidus(Crustacea: Decapoda: Portunidae)from Bardawil Lagoon were examined from November 2016 to July 2017. The percentage point (% P) and percentage frequency of occurrence (% F) methods were used for stomach contents analysis. Out of the 161 individuals 75 (46.58 %) had empty stomach. Mollusca, Crustacea and Pisces dominated the diet of this species. According to points method Mollusca, Crustacea and Pisces scored 44.83%, 18.1% and 16.24% points in malesand 47.2%, 21.62% and 11.03% points in females, respectively. Consumed tissues of other benthic invertebrates were also present in verylow ratios, while algal fragments were occurred in low quantitiesin few stomachs. Sediments were also detected in considerable ratios. Results of the present study suggest that the blue crab C. sapidusis a carnivore. The remarkable seasonal fluctuations in the diet composition and stomach fullness of this species during the present studywere detected For understanding the mechanism of feeding, gastric mill structure was morphologically investigated and all its seven articulated ossicles were examined and photographically illustrated.

Diet of the Invasive Atlantic Blue Crab Callinectes sapidus Rathbun, 1896 (Decapoda, Portunidae) in the Guadalquivir Estuary (Spain)

“…The FS was assessed visually and consisted of six levels according to the quantity of food in the stomach (Hines 2007;Rady et al 2018) -State 0: empty stomach; State 1: food occupies less than 5% of the stomach; State 2: food occupies between 5 and 35% of the stomach; State 3: food occupies between 35 and 65% of the stomach; State 4: food occupies between 65 and 90% of the stomach; and State 5: food occupies 90 to 100% of the stomach. The FI was estimated with Eq.…”

“…For example, to estimate the FO some authors exclude stomachs with FS ≤ 3 (Reichmuth et al 2009). In the case of the RP index, the total food item abundance adjustment based on the FS (Hines et al 1990;Rady et al 2018) is done to normalize the relative importance of prey for the total diet (Williams 1981).…”

“…To ensure comparability with other studies, we corrected the RP using the FS as a weighting factor by multiplying the RP of each food item in each stomach by levels of (1) FI = food weight (g) crab weight(g) × 100 punctuation related to its FS as defined by Wear and Haddon (1987) (see Rady et al 2018). The FS punctuation depends on the stomach's relative degree of fullness, as follows: FS 0 = 0.00 points, FS 1 = 0.02 points, FS 2 = 0.25 points, FS 3 = 0.50 points, FS 4 = 0.75 points, and FS 5 = 1 point.…”

“…Mollusks are a common prey and, in some situations, they can be more frequent than fish (Hines 2007;Rady et al 2018). The most representative groups are gastropods and bivalves of multiple families (Van Engel 1958;Seed 1980;Micheli 1995;Wright et al 1996;Brown et al 2011).…”

“…The Atlantic blue crab occasionally presents a scavenger behavior upon dead fish, prawns, and crabs (Van Engel 1958;Scherer et al 2017). In the Mediterranean basin, Atlantic blue crabs show similar feeding habits as in their native area, feeding mainly on mollusks (Pla et al 2018;Rady et al 2018;Gil 2018;Prado et al 2021), fish, and crabs (Carrozzo et al 2014). The Atlantic blue crab diet is influenced by environmental conditions, such as salinity and temperature (Seitz et al 2011;Mancinelli et al 2017c), seasonal variation in food items (Laughlin 1982;Haefner 1990;Hsueh et al 1992), and energy requirements (Rosas et al 1994).…”