Investigation on parasites of Octopus cyanea in Tanzania

Abstract

Abstract. Msongole PL, Kimbita EN. 2020. Investigation on parasites of Octopus cyanea in Tanzania. Ocean Life 4: 24-36. This study aimed to investigate parasites in Octopus cyanea (Gray, 1849) or Day octopus along the Indian Ocean of the Tanga region in Tanzania. Information from fishermen was required to determine their awareness of octopuses' parasitic infections. Twenty-five percent (25.3%) agreed on the presence of parasites in octopus skin and muscles, but these were not observed during laboratory investigation. Gamogony and sporogony of Aggregata sp. (Apicomplexa: Aggregatidae) were observed during histopathological examination of the digestive tracts of octopuses collected along the Tanga coastal area. The O. cyanea was infected with the coccidian parasite, Aggregata spp., with a prevalence of 41.1% (23 of 56 hosts examined). Oocysts were sub-spherical in the mucosa wall of the intestine and caecum, measuring 263-279 ?m. Sporocysts were smooth?surfaced, dark?staining, spherical, typically 10-15 ?m wide, and contained 9-22 banana-shaped sporozoites with a size of 2-6 ?m long and 0.2-0.3 ?m wide. The coccidian infection in octopuses is accompanied replacement of the infected cells with sporocysts. Parasite infection of Aggregata spp. was not significantly correlated with the weight of the octopus, study site, or sex of the host. Molecular analysis was used to confirm the parasite species, in which 68% of samples were positive. Molecular characterization revealed that the coccidian was the Aggregata octopiana (Schneider, 1875) Frenzel, 1885. Alignments revealed that the coccidian from O. cyanea resembled 89% with A. octopiana isolated from common Octopus in Spain. Despite the presence of A. octopiana in O. cyanea, the parasite does not cause effects on consumers unless the octopus is infected with another epizootiology agent.