I need a source for functional traits of gastropods and bivalves, specially life history traits. but i think the benthic species of my study area ,which is mangroves of northern Indian Ocean, are not well studied.
https://www.routledge.com/Biology-and-Evolution-of-the-Mollusca/Ponder-Lindberg-Ponder/p/book/9781032400310 is a good recent review of the Mollusca overall, and would be a good starting place. Although the particular species that you have may not have been studied in detail, there are a number of studies on functional morphology of mollusks that might give useful ideas for you.
Back in 2000 I created these trait databases (before trait databases were a 'thing') for Neogene to recent molluscs of tropical America: https://nmita.rsmas.miami.edu/database/mollusc/mollusclifestyles.htm
They should be useful at the very least as an example of building a database of 'universal' traits.