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Impact of artificial coastal protection structures on Ascidians settlement along the Tamil Nadu coast, India

Jebarathanam Prince Prakash Jebakumar, Nandhagopal Ganesan, Rajan Babu Bose, Ragumaran Shunmugavel, Ramakritinan Chokalingam Muthiah, Ali Abdul Jaffar, Arshan Mohammed Kaleem, Ravichandran Vijaya

Oceanologia

2019

No. 61 (1)

60--67

Ascidians are one of the dominant marine sedentary filter feeders recorded more frequently as introduced species than other taxa. It is renowned that artificial structures offer novel niches to the non-native species. A yearlong investigation was carried out to understand the role of ascidian colonization on various artificial structures located along 84 stations stretched on the 1076 km long Tamil Nadu coast of South India. It revealed the occurrence of 26 ascidian species, among these18 specimens were identified to species level, 8 were identified to genus level based on morphological characters. As on origin and nativity, out of the total 26,3 species were classified as introduced, 8 specieswere classifiedas native and 15 as cryptogenic species. Interestingly, Polyclinum isipingense and Diplosoma variostigmatumwere reported first time inIndianwaters.Thecryptogenic and colonial forms of ascidians are dominant in the artificial structures. There were significant differences observed between artificial structure type, geographic locations ( p = 0.0071) and between ascidians forms as well as geographic areas ( p = 0.00375). This study also confirms the artificial structures offer new niches for non-native ascidian colonization. The influence of the substrate (structure type) aswell as geographic locations on the biotic assemblage was also observed.

Stone-dwelling leeches (Hirudinea, Clitellata) of Lake Hańcza (Poland) : different sampling methods determine different taxonomic structures

Koperski P.

Polish Journal of Ecology

2003

Vol. 51, nr 3

353-361

The work concerned the taxonomic structure and densities of assemblages of leeches inhabiting the stony littoral of oligotrophic Lake Hańcza in North-Eastern Poland. Samples collected manually from stone surfaces were compared with those found on artificial structures made of PVC. The differences between the assemblages sampled by these different methods were much greater than those between assemblages sampled manually from natural stones at most of sampling sites. Such differences make it clear that artificial substrates differ from a littoral stone surface in the way they are colonized by leeches to the extent that using artificial substrates did not prove to be a good method for study the leech community in a stony littoral.