Baseline Survey on Coral Diseases, Stress Factors and New Threats in Coral Reefs of Gulf of Mannar Marine Biosphere, India

Gulf of Mannar Marine Biosphere Reserve (GOMMBRE) is the first marine biosphere reserve in India and Southeast Asia. It has a rich marine biodiversity including coral reefs, but now facing threats from different environmental factors and anthropogenic interferences. Particularly, coral reefs distributed in the 21 islands under the Gulf of Mannar (GoM) region are facing critical threats. Although several institutions and authors have studied various aspects on corals, direct and indirect influences of natural and anthropogenic catastrophes on corals have been poorly understood. Therefore, the main objective of this study was to identify the anthropogenic disturbances, biological stress factors and diseases on fringing reefs of GoM. The present study reveals that dead coral reefs are being replaced by assemblage of marine algae. Although several diseases were recorded during this study, pink line disease is wide spread in all the islands. Porites sp. and Acropora sp. were the more affected corals. This baseline data lays foundations to survey and to assess the rapid changes that occur over a period of time in coral reefs of GoM.

Exhibition of Bleaching Resistance Via Adaptive Bleaching Pattern by Coral Reefs of the Gulf of Mannar during Massive Bleaching Event 2019

Coral reefs in the Gulf of Mannar(GoM)and Palk Bay regions are facing potential threats from climate change,sedimentation and anthropogenic activities.Considerably,coral reefs in these two regions are highly damaged due to frequent bleaching events caused by increased sea surface temperature(SST)recorded over the past two decades.Recently,during February to May 2019,mass bleaching event of corals was documented again in GoM and Palk Bay regions due to increased sea surface temperatures ranged between 32°C to 36°C.Despite of completely bleached corals,some coral colonies of the same bleached coral species have displayed adaptive bleaching pattern(ABP)for survival.This incidence is displayed by the symbiotic zooxanthellae to protect coral polyps from environmental stress such as elevated temperatures.These observations infer that coral colonies with preferential bleaching pattern ability would serve as environmental stress resisting coral colonies which can be used for restoration activities and cryopreservation.Further studies are needed to explain the potential mechanisms or specific environmental drivers responsible for ABP.

Characterization and seasonal distribution of microplastics in the nearshore sediments of the south-east coast of India,Bay of Bengal

In view of increasing Microplastics(MPs)contamination in the marine environment and dearth of baseline data,a study was conducted on the abundance,characterization,and seasonal distribution of MPs in the nearshore sediments of the south-east coast of India.Sediment samples(n=130)were collected at a distance of 1 km and 10 km from the shore region at varying depths(8–45 m)along the Chennai to Puducherry coast(165 km stretch),representing two seasons,i.e.,south-west(July 2019 and July 2020)and north-east(January 2020)monsoons.The average abundance of MPs at the 22 offshore sites along the Chennai to Puducherry coast varied from 9±4.3 to 19±12.9 particles/50 g dry weight,in July 2019 and January 2020,respectively.July 2020 had an average abundance of 10±4.5 particles/50 g dry weight.Spatially,high levels of MPs were found at 1km stations and transects in proximity to the river inlets,and temporally,the north-east month recorded the maximum concentration.The dominant morphotype was the filament,and the major polymers were polyethylene and polypropylene.Scanning Electron Microscope(SEM)images revealed the surface irregularity and degradation of MPs due to weathering.The study highlights that high sediment contamination by MPs occurs during heavy rainfall and accumulates closer to river inlets.Eventually,this study suggests that appropriate management of plastic wastes on the landside will reduce MP contamination in the marine environment.