Translocation of intertidal corals in highly urbanized Mumbai seascape: A pragmatic management initiative towards ecosystem conservation

Abstract

Coral reefs harbour rich biodiversity by increasing heterogeneous habitat and providing numerous ecosystem services and goods. However, they are highly threatened due to ongoing climate change and various anthropogenic activities. Therefore, the protection of corals is enforced by laws and legislative machinery around the globe. The present work is a case study in the highly urbanized Mumbai city, where a coastal road project required dredging and reclamation that overlapped with a coral habitat. A detailed environmental mitigation plan was undertaken to preserve the fragile corals at the proposed project site. A total of 329 colonies of Pseudosiderastrea tayamai Yabe & Sugiyama, 1935, were relocated from the project site to a recipient site after verifying the habitat suitability. Monthly coral health monitoring was conducted for one year after their relocation to the new habitat. After one year of translocation, 92.1% (n = 303) colonies survived and were in healthy state. Coral bleaching is a well-known phenomenon that occurs due to extreme variability in temperature, salinity and siltation etc. In the present study, coral bleaching was observed during monsoon (July – September 21) wherein maximum (94.83%) occurred in August 21 and minimum (4.86%) was in November 21. Algal overgrowth on coral colonies (maximum 38.9%), and sediment smothering (maximum 44.8%) were observed, but no colony mortality was noted (Jan – May 21). Whereas, 3.4% mortality was recorded during monsoon season only. The gross new recruitment (n = 22) of corals was also recorded collectively during the months of April, May and November 21. Therefore, the current study suggests that relocating corals from coastal development sites, where habitat loss is unavoidable, could be considered a tool that will aid in conservation of urban reefs. This study proves that only committed involvement of stakeholders and project proponents who have developmental perspective with environmental accountability can achieve the sustainability of rare and fragile ecosystems.