climate (Köppen BSh) characterised by sweltering summers, hot winters and occasional heavy rain during the northeast monsoon. Summer extends from March to June when the climate is very humid. Thoothukudi registers a maximum temperature of and a minimum temperature of . The city receives adequate rainfall only during the months of October and November. The city receives around rainfall from the Northeast monsoon, during summer, during winter and during the South-west monsoon season. The coolest month is January and the hottest months are from May to June. The city has a very high humidity being in the coastal sector. The 21 islands between Thoothukudi and Rameswaram shores in the Gulf of Mannar are notified as the first Marine Biosphere Reserve of India. About 36,000 species of flora and fauna exist in the region covered with mangroves, sandy shores, sea grass beds that are conducive for turtle nesting. The region around the Thoothukudi shores are home to rare marine flora and fauna. Coral reefs and pearl oysters are some of the exotic species while algae, reef fish, holothurians, shrimps, lobsters, crabs and Mollusca are very common. Out of 600 recorded varieties of fish in the region, 72 are found to be commercially important. The thermal discharge from the thermal plants and excessive brine run off from the salt pans impact the flora and fauna in the region to a large extent. Demographics Thoothukudi was a port town during the period of Portuguese, Dutch and British in the 16th–19th centuries. The city expanded after 1907 due to the presence of public establishments. Residential and industrial growth was maximum around Palayamkottai and Ettaiyapuram roads between 1907 and 1930. According to 2011 census, Thoothukudi city had a population of 237,830 with a sex-ratio of 1,010 females for every 1,000 males, much above the national average of 929. Thoothukudi had an average literacy rate of 92.10% with male literacy being 94.84%, and female literacy being 89.37%. A total of 24,959 were under the age of six, constituting 12,684 males and 12,275 females. Scheduled Castes and Scheduled Tribes accounted for 7.42% and 0.1% of the population, respectively. The city had a total of 60,714 households. There were a total of 83,669 workers, comprising 114 cultivators, 154 main agricultural labourers, 1,498 in house hold industries, 77,420 other workers, 4,483 marginal workers, 69 marginal cultivators, 25 marginal agricultural labourers, 280 marginal workers in household industries and 4,109 other