Two laboratory experiments were conducted at the National Oceanography Centre in Southampton from June 2021 - April 2022 to investigate intraspecific variability in functional trait expression in marine bioturbating benthic invertebrate fauna. The macroinvertebrate species Amphiura filiformis, Amphiura chiajei, Turritellinella tricarinata, Edwardsia claparedii, Sternapsis scutata, Paraleptopentacta elongata, Hediste diversicolor and Nephtys hombergii were collected from different locations around the UK (Plymouth, Oban and Newcastle) and in two different seasons. In laboratory experiments ranging in duration from 2 - 3 months we investigated how individual densities, season and future vs ambient climate treatments impacted functional bioturbation behaviour and ecosystem functioning (nutrients release and community respiration).