The conceptualization of trace element flows within Posidonia oceanica meadows: a collaborative proposal to fill knowledge gaps

The Mediterranean seagrass Posidonia oceanica (L.) Delile is regarded as a relevant indicator of bioavailable trace elements (TEs) since it efficiently and proportionally bioaccumulates these chemicals from its surrounding environment. Recent studies have further brought supplementary insights in our understanding of the processes driving TE kinetics within that species. But at a higher degree of organization, the distribution and flows of TEs between P. oceanica meadow components, i.e. seagrass shoots, epiphytes, associated algae and animals and detritus, have not been investigated yet. The present study therefore aims to propose a conceptualization model of P. oceanica meadows, regarded as the juxtaposition of the 5 separate components listed above exchanging flows of TEs between themselves and with their environment, i.e. water and sediment. This model can be drawn in energy circuit language. By writing such a model, one in essence is writing equations describing a system. To be relevant, its elaboration requires the compilation of a large amount of quantitative data. This conceptualization can thus be regarded as a collaborative innovation requiring scientists to fill the model through the continuous supplement of new data. In fine, this model will lead to the exact quantification of the role played by P. oceanica meadows in the coastal biogeochemistry of TEsin the Mediterranean.