Biodiversity assessment and spatio-temporal dynamics of gastropods with 66 new records to Sri Lanka

Uventhikka Sivanantham; Sutharshiny Sathyaruban; Kuddythamby Gunaalan; Sivashanthini Kuganathan

doi:10.17017/j.fish.1136

Uventhikka Sivanantham Department of Fisheries, Faculty of Science, University of Jaffna, Jaffna, Sri Lanka
Sutharshiny Sathyaruban Department of Fisheries, Faculty of Science, University of Jaffna, Jaffna, Sri Lanka
Kuddythamby Gunaalan Department of Fisheries, Faculty of Science, University of Jaffna, Jaffna, Sri Lanka
Sivashanthini Kuganathan Department of Fisheries, Faculty of Science, University of Jaffna, Jaffna, Sri Lanka

DOI: https://doi.org/10.17017/j.fish.1136

Keywords: Cerithiidae, diversity indices, gastropods, tidal zone, water quality

Abstract

The present study aims to investigate the gastropod diversity in Mathagal (MAL), Kankesanthurai (KKS), Akkarai (AKI), and Mandaithivu (MAU), along the Northern coast of Sri Lanka. A systematic monthly survey was conducted from December 2022 to November 2023 using fifteen 0.5 m² quadrats per location. Gastropod shells were quantitatively sampled and taxonomically identified. Additionally, key water quality parameters were measured to determine their influence on the abundance of gastropods. A total of 92 gastropod species from 43 families comprising 1962 individuals were identified. The present study authenticated 66 new species to Sri Lanka’s gastropod database and 12 new locality records to Jaffna. Significant spatial variation in gastropod abundance was observed among sites. MAU exhibited the highest dominance (0.202), indicating potential environmental stress or habitat homogeneity favouring particular species. KKS showed the highest evenness (0.841), suggesting a well-balanced community structure, while MAL demonstrated the highest species richness despite moderate evenness (0.688). The Shannon index ranged from 2.52 (KKS) to 2.09 (MAU), reflecting moderate to high biodiversity across all sites. These diversity patterns suggest heterogeneous habitat conditions, with some locations supporting more equitable species distributions while others are dominated by few taxa. No significant differences among the sites for water quality, suggesting these parameters are not influencing gastropods’ abundance. This research provides an essential baseline for implementing targeted conservation strategies to protect these organisms from growing anthropogenic pressures, while the substantial number of new records highlights previously underestimated malacological richness of Sri Lanka’s northern coastal waters.

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