First Report of Grandidierella japonica Stephensen, 1938 (Amphipoda: Aoridae): A Non-native Species in Vellar estuary, Southeast Coast of India

Authors : Vengatesan Sanjaikumar, Subramanian Anbuselvan, Gothandapani Jana, Abul Abbas Mohamed Shafick, Muthusamy Thangaraj

Pages : 215-223

Doi:10.46384/jmsf.1742078

View : 32 | Download : 144

Publication Date : 2025-12-22

Article Type : Other Papers

Abstract :The present study reports the first confirmed occurrence of the non-indigenous amphipod Grandidierella japonica Stephensen, 1938 in the Vellar Estuary, located along the southeast coast of India. Systematic benthic sampling conducted between August 2024 and April 2025 revealed established populations of G. japonica, evidenced by the presence of ovigerous females and juvenile stages. Population density ranged from 1300 to 1800 ind./m², comparable to other introduced countries. Morphological examination confirmed the identity of the species based on diagnostic characters of gnathopod 1, which exhibited an oval-oblong shape consistent with native Japanese populations. Uropod 3 was uniramous, a trait separating it from most other aorid amphipods. The sex ratio was highly female-biased, and the highest abundance was recorded at Station S2. This record represents a significant range extension for G. japonica, highlighting the potential for estuarine systems impacted by aquaculture and tidal dynamics to serve as gateways for marine bioinvasions. Potential ecological impacts include competition with native amphipods such as Atylus minikoi, Idunella chilkensis, Orchestia platensis, and Eriopisa chilkensis. This finding highlights the importance of ongoing monitoring and biosecurity measures to track the spread and assess the ecological effects of non-indigenous species in Indian estuarine ecosystems.
Keywords : Grandidierella japonica, amfipot, yabancı tür, Vellar Lagünü, Hindistan, bentik topluluk, biyolojik istila, akuakültür vektörü

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