Breaking: Invasive Atlantic Blue Crab Reproductive Migration in Spanish Mediterranean
Murcia, Thursday, June 26, 2025 – Research personnel from the Oceanographic Center of Murcia of the Spanish Institute of Oceanography (IEO, CSIC), in collaboration with the University of Alicante, have just released findings from a comprehensive two-and-a-half-year study on the populations, fisheries, and management of the invasive Atlantic blue crab (Callinectes sapidus) in the Spanish Mediterranean. This breakthrough research, which has significant implications for ecological management and fisheries, was presented today.
Reproductive Migration and Fertility Rates
The study reveals that the reproductive migration of the Atlantic blue crab occurs from the lagoon to the Mediterranean, with females exhibiting an exceptionally high fertility rate of up to 3.6 million eggs. This information is crucial for understanding and managing this species in invaded areas.
Background and Historical Context
The Atlantic blue crab, native to the American East Coast, is known for its economic significance in the United States, where its fishery generates over $100 million annually. It is believed to have arrived in the Mediterranean around 75 years ago via ballast water. Its presence has become increasingly noticeable in recent years, particularly in the Mar Menor and other Spanish regions.
Study Focus and Key Findings
The investigation was concentrated in the Mar Menor and specific areas in the province of Alicante, including the Salinas de Santa Pola, the Laguna de El Hondo, and the mouth of the Segura River in Guardamar. These locations are interconnected, facilitating the blue crab’s movement across varying salinity levels.
One of the most intriguing findings is that, unlike its behavior in its native habitat or other Spanish regions, the reproductive migration of the blue crab in the Mar Menor occurs in a negative salinity gradient, from the lagoon to the Mediterranean. The study also notes that adult females are present in the lagoon from May to November, with fertility rates ranging from 300,000 to 3.6 million eggs. However, no larvae have been observed in the lagoon, suggesting that the crabs enter as juveniles and seek refuge in shallow areas with high plant cover.
Ecological Impact and Future Research
The species is omnivorous and exhibits opportunistic trophic behavior, with prawns being a favored prey in the Mar Menor. While the presence of the blue crab adds pressure to the ecosystem, environmental variability appears to be a more significant factor in observed trends than the crab itself. Further long-term data is necessary to fully assess its impact.
Elena Guijarro, responsible for the project at the Oceanographic Center of Murcia, emphasizes the need for continued study: “It is unquestionable that the crab is an added pressure, but the lagoon has suffered numerous anomalous events over the last decade. To determine the impact of the crab, a longer series of data with less environmental variability is needed.”
Collaboration and Funding
The study was co-directed by Elena Guijarro from the Oceanographic Center of Murcia and Alfonso Ramos from the University of Alicante. It was part of the Ecese project: ecology and impact of the blue crab of the Atlantic in coastal lagoons, estuaries, and adjacent waters of the Spanish Mediterranean. Funding was provided by the Ministry of Science, Innovation, and Universities under the 2020 R&D projects call.
This groundbreaking research underscores the importance of continuous ecological monitoring and management strategies to mitigate the impact of invasive species. Stay tuned to archyde.com for more updates on this developing story and other breaking news in the world of ecology and marine science.
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