Abstract Lophocladia lallemandii (Montagne) F. Schmitz is an invasive red alga which has recently become widespread in the Mediterranean Sea. Temporal variability in biomass of L. lallemandii across a depth gradient (10–30 m depth), as well as invasive potential by means of its reproductive output and recruitment abilities was assessed. No variability was found across the depth gradient, suggesting a homogenous pattern of invasion between the sampled depths. In contrast, all variables displayed a clear temporal pattern with higher growth and reproductive output with increasing temperatures, both in shallow and deep populations. The high total and relative biomass values of L. lallemandii confirm the invasive nature of this species. Likely, the high potential reproductive output by means of tetrasporocysts (41.8 ± 9.34 cm −2), together with the high recruitment abilities (352 ind. m −2) explains the great colonization capacity of L. lallemandii which prevents any kind of manual eradication.