Wetland-lake complexes, like the quarry lakes at Barton-under-Needwood, provide multiple roles of biodiversity, aesthetic value, ecosystem services, flood prevention and alleviation, which need to be balanced against each other. High biodiversity quarry lakes are very desirable systems that contribute much to regional biodiversity in river-floodplain environments and the Barton quarry lake system provides a rare opportunity to explore the development of an ecosystem type which is increasingly rare in the UK. This proposal will provide valuable long-term data for a largely neglected and yet important artificial aquatic habitat by examining the naturally deposited sediment archive in these lakes, focussing on (1) the development of the sedimentary diatom (algal) community as an indicator of changing aquatic biodiversity over time, and (2) applying the novel research field of microplastic/fibre pollution by assessing the inventory (and possible impact) of these relatively recent anthropogenic markers in these sediments. Together, this will allow an assessment of how these lakes have developed over time, and of the role that anthropogenic pollution (likely mainly from the adjacent River Trent from nutrient and microplastic/fibre inputs) plays in their diatom algal biodiversity. It will help establish the longer-term ecological development of these ecosystems which will support and inform the optimal management of these potentially important regional and national habitats.