Blue Crab invasion

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The Blue Crab, Callinectes sapidus, or Atlantic blue crab, is a species of crab native to the waters of the western Atlantic Ocean and the Gulf of Mexico and introduced internationally. Callinectes sapidus is of considerable culinary and economic importance in the United States, particularly in Louisiana, the Carolinas, the Chesapeake Bay, Delaware and New Jersey. It is the Maryland state crustacean and the state’s largest commercial fishery. Due to overfishing and environmental pressures some of the fisheries have seen declining yields, especially in the Chesapeake Bay fishery. Unlike other fisheries affected by climate change, blue crab is expected to do well; warming causes better breeding conditions, more survivable winters, and a greater range of habitable areas on the Atlantic coast. invasione di granchio blu

Blue Crab - Granchio blu o Granchio reale blu o Granchio azzurro - Callinectes sapidus - www.intotheblue.it

Blue Crab – Granchio blu o Granchio reale blu o Granchio azzurro – Callinectes sapidus – www.intotheblue.it

Whether this will have negative effects on the surrounding ecosystems from an increased crab population is still unclear. Callinectes sapidus is a decapod crab of the swimming crab family Portunidae. The genus Callinectes is distinguished from other portunid crabs by the lack of an internal cartilaginous spine on the carpus (the middle segment of the claw), as well as by the T-shape of the male abdomen. Blue crabs may grow to a carapace width of 23 cm. Callinectes sapidus individuals exhibit sexual dimorphism. Males and females are easily distinguished by the shape of the abdomen (known as the “apron”) and by color differences in the chelipeds, or claws.

Blue Crab - Granchio blu o Granchio reale blu o Granchio azzurro - Callinectes sapidus - www.intotheblue.it

Blue Crab – Granchio blu o Granchio reale blu o Granchio azzurro – Callinectes sapidus – www.intotheblue.it

The abdomen is long and slender in males, but wide and rounded in mature females. A popular mnemonic is that the male’s apron is shaped like the Washington Monument, while the mature female’s resembles the dome of the United States Capitol. Claw color differences are more subtle than apron shape. The immovable, fixed finger of the claws in males is blue with red tips, while females have orange coloration with purple tips. A female’s abdomen changes as it matures: an immature female has a triangular-shaped abdomen, whereas a mature female’s is rounded.

Blue Crab - Granchio blu o Granchio reale blu o Granchio azzurro - Callinectes sapidus - www.intotheblue.it

Blue Crab – Granchio blu o Granchio reale blu o Granchio azzurro – Callinectes sapidus – www.intotheblue.it

The crab’s blue hue stems from a number of pigments in the shell, including alpha-crustacyanin, which interacts with a red pigment, astaxanthin, to form a greenish-blue coloration. When the crab is cooked, the alpha-crustacyanin breaks down, leaving only the astaxanthin, which turns the crab to a bright orange-red color. Callinectes sapidus is native to the western edge of the Atlantic Ocean from Cape Cod to Argentina and around the entire coast of the Gulf of Mexico. It has recently been reported north of Cape Cod in the Gulf of Maine, potentially representing a range expansion due to climate change. It has been introduced (via ballast water) to Japanese and European waters, and has been observed in the Baltic North, Mediterranean and Black Seas. invasione di granchio blu

Blue Crab - Granchio blu o Granchio reale blu o Granchio azzurro - Callinectes sapidus - www.intotheblue.it

Blue Crab – Granchio blu o Granchio reale blu o Granchio azzurro – Callinectes sapidus – www.intotheblue.it

The first record from European waters was made in 1901 at Rochefort, France. In some parts of its introduced range, Callinectes sapidus has become the subject of crab fishery, including in Greece, where the local population may be decreasing as a result of overfishing. In Italy, public awareness of the detrimental impact of this species on local molluscs is rapidly growing and, especially in the Po delta area and on the Adriatic sea coast, eradication efforts are undergoing, both by local authorities and by local fishermen. From the 2000s until 2023 the species was reported throughout Italy. We met her in Rosignano Solvay in the Province of Livorno where we took the photos and video you are seeing.

(extract from Wikipedia)

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Fanino Cirivasi Fanino Cirivasi ha scritto / wrote 235 articoli / Posts.
Questo articolo è stato scritto il / This article was written on 19/06/2024
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