How the diversity of constructed wetlands improves the plankton communities discharged into a protected Mediterranean wetland

The effectiveness of constructed wetlands (CWs) created to improve water quality has been demonstrated. However, their role in enhancing biodiversity, such as in plankton communities, is still understudied. To assess this, we analysed, over two years, the plankton of three structurally different CWs which are intermediaries between low-quality waters and a protected Mediterranean wetland ( Albufera de València Natural Park). We estimated the alpha-diversity of each CW and the beta-diversity among their different sectors. In two CWs, the diversity decreased as water flowed from the Inlet (a species mix from anthropically disturbed environments) to the Outlet, due to natural assembly processes. In the other CW, as it received water dominated by a few species, the emerging assemblages increased the diversity. Moreover, comparing the three CWs, the most divergent communities were those in the outlets (due to the emergence of exclusive species, biovolume differences, etc.). Therefore, they contributed to beta-diversity as they acted as generators of communities, which were characterized by the loss of cyanobacteria and chlorophytes, the dominance of large copepods or cladocerans and the presence of unshared species. We emphasize the importance of having structurally and functionally different CWs to enhance biodiversity and improve biological water quality in natural parks.