**2. Study areas**

The coral reefs are geographically located at different latitudes on the Indian coast, and are highly important ecosystem for ecosystem service and economy. The climate over Indian coral reef regions is tropical, hot, and humid. Species diversity and reef structure in Indian coral reefs vary significantly between the areas due to differences in the reef extent and environmental conditions. This study was carried out at the Gulf of Kachchh and Malvan Marine Sanctuary, which lies in the Arabian Sea on the Indian coast and harbor some of the most northern reefs in the world [27]. The coral reefs in the Gulf of Kachchh is located between 22° 15' N to 23° 40' N Latitude and 68° 20′ E to 70° 40′ E Longitude to the north of Saurashtra Peninsula of Gujarat state (**Figure 1**). This region is very rich in terms of biodiversity value and supports varied coastal habitats, including coral reefs, mangroves, creeks, mudflats, islands, rocky shores, sandy beaches, etc. (Arora et al.*,* 2018) and mostly consisting of dead coral boulders and rubbles. The coral species over the Gulf of Kachchh region belonging to the common genera of *Coscinaraea, Favia, Goniastrea, Gonipora, Leptastrea, Porities, Turbinaria*, etc.

It extends over 170 kilometers in length (NNE–SSW) and about 75 kilometers in width (NNW–SSE), covering an area of approximately 7350 km2 with a mean depth of 30 meters. A total of 76 species of stony coral (Scleractinian) belonging to 30 genera and 12 families [28] and 12 species of soft corals are found in this region [29]. On the other hand, the Malvan Marine Sanctuary, a Marine Protected Area (MPA), is located in the Central West coast of India along the Eastern Arabian Sea, spreads over a 29.122 km2 area. The marine wildlife sanctuary harbor near shore patch coral reefs mostly dominated by massive and encrusting *Porites* species and

#### **Figure 1.**

*Study area of Gulf of Kachchh and Malvan Marine Sanctuary, which lies in the EAstern Arabian Sea on the Indian coast.*

foliose *Turbinaria mesenterina;* other species includes *Porites lichen, Porites lutea, Porites compressa, Pseudosiderastrea tayami, Siderastrea savignyana, Coscinaraea monile, Favites melicerum, Favites halicora, Cyphastrea serailia, Plesiastrea versipora, Goniopora sp., Tubastraea coccinea* [25, 30]*.* Corals in the Gulf of Kachchh and Malvan regions are surviving through extreme environmental conditions such as high temperature, high solar radiation, turbidity, salinity changes, and high suspended sediment loads [28, 31]. Both the regions have been designated as a Marine Protected Area (MPA). However, in the Malvan Manrine Sanctuary, the absence of a robust management system and opposition of the MPA from the local population resulted severe local disturbances includes fishing, wastewater drainage, and unregulated recreational activities along with climate change disturbance [30, 32].
