The reef-building serpulid polychaete Ficopomatus enigmaticus is an invasive species in brackish waters in tropical and temperate zones worldwide and often has massive impacts on ecosystems and anthropogenic activities. In Prokopos Lagoon in Greece, the species has constructed large reefs over the past few decades which occupy a large area of the lagoon. In this study, we used high-resolution aerial photography to map the distribution of these reefs, and conducted a one-year field survey to investigate settlement and growth parameters, including abundance, biomass and body length, using artificial settlement panels. We correlated our findings with physicochemical measurements, specifically focusing on temperature, salinity and dissolved oxygen. Salinity exhibited marked and rapid fluctuations, ranging from less than 2 to over 42 Practical Salinity Units (PSU). These variations did not affect the adult population, but settlement only occurred at salinities above approximately 10 PSU and only when water temperatures surpassed 18-20 °C. Settlement was reduced when temperatures were high (> 28 °C) but was not affected by high salinity. The maximum abundance measured was 880 000 individuals m2, and reefs attained a weight of 18 kg m2 in 11 months. This study contributes further to understanding the species? environmental tolerances and life cycle, which in turn may help to design future management measures.
