Plankton underpin pelagic food webs and play fundamental roles in energy transfer and global biogeochemical cycling. Their generally short generation times, small body sizes and limited capacity for directed movement relative to ocean currents make many planktonic organisms highly responsive to environmental variability. Consequently, plankton are widely regarded as valuable indicators of environmental change and are increasingly incorporated into models of ecosystem structure and function. Yet, understanding plankton dynamics remains challenging because of their immense diversity, heterogeneous spatial distributions and pronounced temporal variability. These challenges are particularly acute in coastal waters, where interacting physical, chemical and biological processes strongly influence planktonic feeding, growth, reproduction, survival and community assembly. For the past 15 years, the SAEON Elwandle Coastal Node and its partners have maintained a standardised plankton sampling programme in Algoa Bay, providing an increasingly valuable long-term perspective on coastal plankton dynamics. Here, I present selected insights from this time series, focusing on the mesozooplankton component and exploring patterns of variability and potential drivers. I will also reflect on the logistical challenges associated with managing a long-term plankton observatory and share opportunities and priorities for the next phase of plankton observation in Algoa Bay.