Increasing depth reduces macrophyte coverage but increasing transparency promotes composition turnover through environmental thresholds

Abstract

Context Environmental filters modify the coverage and frequency patterns of macrophyte communities. Aims We characterised the thresholds in depth and transparency at which the macrophyte distribution shifted in an Atlantic Forested wetland. Methods Macrophyte communities were characterised in 150 plots divided into 6 transects. Key results Threshold indicator taxa analysis (TITAN) indicated that free-floating life forms respond negatively to depth and transparency increase. Rooted-floating species responded negatively to an increase in depth and transparency; by contrast, submerged species responded positively to increased transparency. Conclusion TITAN also highlighted that the entire macrophyte community responded negatively to increased depth but exhibited a synchronous turnover among species responding positively and negatively to transparency. Implications Our results demonstrated that macrophyte responses to increasing depth and transparency are non-linear and depend on species life forms.