Морской биологический журнал (May 2024)
The infestation status of symbiotic crustaceans on the swimming crab Charybdis truncata (Fabricius, 1798) from Nha Trang Bay, Vietnam (the East Sea)
Abstract
Symbioses are common relationships between organisms in marine ecosystems. Out of crabs belonging to the family Portunidae, an economically important one, Charybdis truncata (Fabricius, 1798) is a widely distributed species. However, the studies on its symbiotic assemblages are still limited. A total of 408 C. truncata were sampled in Nha Trang Bay (Khanh Hoa province, Vietnam, the East Sea) in January–August 2022. Symbionts were classified based on morphological characters. Statistical analysis was applied to compare the infestation status of symbionts. Six symbiotic species were detected, including four epibiotic barnacles [Octolasmis angulata (Aurivillius, 1894), Octolasmis alata (Aurivillius, 1894), Octolasmis warwicki Gray, 1825, and Dianajonesia tridens (Aurivillius, 1894)] and two obligate unidentified parasites [Cancrion sp. and Sacculina sp.]. Out of them, O. alata and Cancrion sp. were recorded on C. truncata for the first time. The overall prevalence of symbionts on the swimming crab hosts was 13%, and the number of infecting symbiont species on hosts ranged within 1–4. O. angulata was the dominant species, with the prevalence of 6.9%. The prevalence of this symbiotic species was significantly higher in ovigerous female crabs compared to non-ovigerous ones. Moreover, there was a noticeable rise in O. angulata prevalence rates as crab size increased. No significant differences were revealed in the mean intensity of symbionts by sex, reproductive status of females, and size of the crab hosts. The initial morphological modifications caused by infecting parasites, Cancrion sp. and Sacculina sp., were recorded and described. These findings provide data on the status of natural infection of symbiotic species on C. truncata as a basis for the management of commercial species and aquaculture development.
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