@article {147284, title = {Ascertaining the spatiotemporal variations in seaweed assemblages associated with the endemic seaweed Ulva ovata along selected locations of the Gulf of Khambhat, India}, journal = {AQUATIC ECOLOGY}, year = {2024}, month = {07/2024}, abstract = {

This investigation presents pioneering discoveries concerning the endemic seaweed Ulva ovata across multiple sites in the Gulf of Khambhat, India, going beyond its type locality, Gopnath. The primary objective of this research was to examine the substrate type and various environmental factors affecting seaweed diversity at five sites where endemic U. ovata was found. Identifying 11 seaweed species under Chlorophyta and Rhodophyta phyla, the study highlights rocky sites exhibiting higher Simpson (D) and Shannon (H {\textquoteright}) diversity indices, species richness, and percentage cover during cold months. k-dominance analysis indicates more species at Pingaleshwar, Unchakotda, and Gopnath. Bray Curtis similarity shows similarity in seaweed composition between Unchakotda-Pingaleshwar, and Kuda-Khadsaliya, whereas Gopnath forms a different cluster mode. Key species U. rigida and U. ovata, identified by SIMPER analysis, act as bio-indicators for future studies. Five sites demonstrate distinct seawater temperature, dissolved oxygen, light intensity, salinity, total dissolved solids (TDS), electrical conductivity (EC), wind velocity, UV index, nitrate (NO3-), and nitrite (NO2-) significantly impacting seaweed diversity. This study enhances understanding of seaweed distribution and environmental influences in the Gulf of Khambhat, offering insights into ecological dynamics and implications for marine conservation and management strategies.

}, doi = {10.1007/s10452-024-10127-0}, author = {Rathod, Sachin G. and Singh, Anshika and Mantri, Vaibhav A.} } @article {104419, title = {Differential tolerance capacity of intertidal organisms (sponge and zoanthid) to the environmental stresses: Preliminary Bndings from a rockpool transplantation experiment}, journal = {JOURNAL OF EARTH SYSTEM SCIENCE}, volume = {131}, year = {2022}, month = {03/2022}, abstract = {

Marine intertidal organisms face extreme environmental fluctuations due to tidal cycles. To investigate the impact of environmental changes (high salinity, sea surface temperature, and anthropogenic pollution) on the health of the coastal area, we selected the dominant intertidal organisms: sponge (Cinachyrella cf. cavernosa) and zoanthid (Zoanthus sansibaricus) as our model system from a rocky beach Anjuna, Goa, India. Sponges and zoanthids were transplanted from their natural habitat (mid-tide pools) to new habitat (upper-tide pools). The study was carried out for 15 days when these pools experienced flushing during the first and last 5 days (high tide was \>1.8 m) and no flushing during the middle 5 days (high tide was \<1.8 m). The indices of physiological response (such as in budding activity and oscular openings) in the sponge and (chlorophyll estimation and symbiotic zooxanthellae count) in zoanthid were estimated at natural and transplanted habitats. Upper intertidal pools experienced intense temperature (29.9-36.15 degrees C), salinity (35.03-46.7 ppt) and variability in dissolved oxygen (3.2-9.5 mg/l). The transplanted sponge did show the closure of oscula (90.62\%) and reduction in buds (40-94.9\%), but they could survive beyond 15 days. While transplanted zoanthid showed bleaching and did not survive beyond 72 h due to reduced chlorophyll content (up to 44.21\%) and zooxanthellae count (34.54\%). Our results depicted the differential tolerance capacity of sessile organisms like sponge and zoanthid to environmental changes, which govern the vertical zonation in the rocky intertidal region. It highlights the role of these sessile invertebrates as early indicators of environmental changes.

}, doi = {10.1007/s12040-021-01739-3}, author = {Singh, Anshika and Thakur, Narsinh L. and Sheikh, Farhan} } @article {96748, title = {Allelopathic interaction among rocky intertidal invertebrates: sponge Cinachyrella cf. cavernosa and Zooxanthellate zoanthids Zoanthus sansibaricus}, journal = {Hydrobiologia}, year = {2021}, month = {07/2021}, abstract = {

Intertidal sessile invertebrates experience tough competition for space which they avoid by releasing secondary metabolites (allelochemicals). We investigated the allelopathic interaction between sponge Cinachyrella cf. cavernosa and its neighbour zoanthids Zoanthus sansibaricus over a year on the rocky beach of Anjuna, (Goa) India. A major sterol (beta-sitosterol) was isolated from the sponge, and its natural variability was checked in tagged sponges with and without their competitor zoanthids during the reproductive and non-reproductive months of the sponges. The sponge showed significant variability in the production of beta-sitosterol owing to its spatial competition and asexual reproduction (budding) as predicted by the multiple regression analysis. Zoanthids are known to have dynamic mutualistic association with their autotrophic endosymbionts{\textquoteright} dinoflagellate (Symbiodinium, known as zooxanthellae), which are directly involved in their physiology. The phytagel (TM)-based field assay of sponge{\textquoteright}s bioactive compound (beta-sitosterol) was conducted to check its allelopathic impact on Z. sansibaricus and its symbiotic zooxanthellae (Symbiodinium sp.). Results showed significant bleaching (50-80\%) in the host Z. sansibaricus, resulting from a decrease in symbiotic zooxanthellae count, cell density, chl a and chl c content. This suggests the role of beta-sitosterol as allelochemical of the sponge in preventing the overgrowth of aggressive Z. sansibaricus, possibly by affecting its symbionts. This investigation is not only important to understand the ecological roles of marine-derived allelochemicals but also to allow sustainable bioprospecting of marine resources.

}, doi = {10.1007/s10750-021-04667-x}, author = {Singh, Anshika and Thakur, Narsinh L.} }