To date, the majority of studies investigating marine mammal distribution and behavior take a single-species perspective, which is often driven by the logistic difficulties of collecting appropriate data at sea. Passive acoustic monitoring tools, provided these exhibit sufficient bandwidth, have the potential to provide insights into community structure as devices operate autonomously simultaneously collecting data on baleen, pinniped and toothed whale acoustic presence. Data can provide information on local species diversity, residency times and patterns in species co-occurrence. Using multi-year passive acoustic data from 6 sites in the Weddell Sea, Atlantic sector of the Southern Ocean, we here explore how local marine mammal community compositions develop over time. We show that the effective number of species exhibited little variation over time, reflecting that species remain in Antarctic waters throughout austral winter. Community composition showed almost complete seasonal overturn, recognizing that species replace each other throughout the year. For all 6 sites, community dissimilarity increased with increasing temporal distance reflecting temporal trends in community composition beyond seasonality. Several species exhibited significant positive or negative co-occurrence patters over time, suggesting predator-prey relationships, competition for prey species as well as acoustic interference between co-occurring species. These seasonal associations were consistent across and between all oceanic sites, but partly inversed at the Western Antarctic Peninsula recording site. This study shows that the application of biodiversity metrics to PAM data can foster insights to the timing of behaviors and community composition, which can boost the interpretation of responses in the light of ongoing environmental changes.