The Gulf of Heraklion is one of the most well-studied coastal marine ecosystems in the eastern Mediterranean. It is an oligotrophic area, exposed to wave action where muddy sediments prevail and its coastal zone is relatively unaffected by major riverine inputs. However, it faces pressures deriving from urbanisation, tourism, small-scale fisheries and climate change. Amongst its biological components, macrobenthos is an important component of soft-bottom habitats of the continental shelf and considered to be an indicator of environmental and human-induced disturbance. Nevertheless, long-term data are limited, thus restricting our understanding of their temporal trends. This is of particular importance for the Mediterranean Sea which is characterised as a hot spot of biodiversity and climate change impacts on its biota.<br> The macrοbenthic faunal communities were investigated in the continental shelf of Heraklion Bay within the framework of the European funded project entitled MARine Biodiversity and Ecosystem Functioning leading to Ecosystem Services (MARBEFES), with the objective to enhance the understanding of marine biodiversity, ecosystem functioning and the ecosystem services they provide. Additional studies, with the same objectives, were carried under national and local monitoring programmes. Samples were collected from a specific transect of stations, named H2 (10, 20, 30, 40, 50, 100 and 200 m depth), located in the wider marine area of the wastewater treatment plant of Heraklion City. The transect was sampled during three different sampling surveys and periods: June 2010, June 2015 and August 2024.<br> A total of 30,280 individuals were examined belonging to the taxonomic groups of Annelida, Crustacea, Mollusca, Echinodermata, Nemertea and varia. The identification of the key taxonomic classes (Polychaeta, Bivalvia, Gastropoda, Scaphopoda and Malacostraca) revealed 231 macrobenthic taxa. Out of the 231 taxa, only 30 were common amongst all the three sampling periods, while Polychaeta was the most abundant macrobenthic group in all sampling periods.
