An invasive polychaete species found in living marine stromatolites

This study represents the first report of an invasive species associated with modern, living stromatolites. The presence and potential impacts of the reef-forming tubeworm Ficopomatus enigmaticus (Fauvel, 1923) in unique stromatolite ecosystems of South Africa are addressed. Data on F. enigmaticus populations and a suite of environmental variables were collected on a monthly basis in 2014, at three sites along the Eastern Cape coast. Results are interpreted in terms of known environmental tolerance, reproductive strategy and environmental impacts of F. enigmaticus around the world. A combination of variables influenced the F. enigmaticus populations, particularly temperature and the availability of substrates for settlement. Low water temperatures (< 20°C) in winter appeared to limit the species growth and reproduction. Small populations of adult individuals were however able to persist all year round in habitats that exhibit favourable environmental conditions. These stromatolite pools appear to function as unique ecosystems that provide refuge for estuarine species, thus acting as stepping stones facilitating the dispersal and range expansion of estuarine fauna along the coast, including invasive species.