The influence of geomorphological features on the distribution of Cystoseira populations along the coasts of four pristine islands in the Tyrrhenian Sea (Italy, central Mediterranean) was studied by means of a model-based statistical analysis. The most relevant trait that determined the presence of these populations was found to be the coastline slope at the level of the infralittoral fringe. Our findings indicate that slopes above 60 • reduce the likelihood of Cystoseira communities. The effects of the coastline slope on the CARLIT index are considered and discussed in view of these findings. Pending further studies on the implementation of the CARLIT index in the Mediterranean basin, we suggest that any changes to the procedure or the hasty multiplication of reference sites be avoided, and instead propose a simple empirical adjustment of the EQ values to be able to more accurately monitor coasts with steep slopes using this index.

Twenty-three freshwater springs of the Po plain (northern Italy) were surveyed and visited multiple times during 2011-2013 to assess water quality and algal taxa present. Despite poor water conditions of this human-altered floodplain, a relatively high number of taxa referable to the freshwater red algae, Batrachospermum and Sheathia, were observed. The identity of specimens collected was based on morphology and confirmed with sequence data. The specimens belonged to Sheathia arcuata, S. boryana, Batrachospermum atrum, B. gelatinosum and B. gelatinosum f. spermatoinvolucrum. This is the first report of B. gelatinosum f. spermatoinvolucrum outside North America. Niche analysis revealed a marked difference in the physical and chemical preferences of the freshwater red algae recorded. The occurrence of S. boryana was limited to relatively low nitrate and higher oxygen concentrations. Conversely, the spatial distribution of the other four taxa indicated that they were able to tolerate high concentrations of nitrate (up to 53.6 mg l -1 ) and low rates of dissolved oxygen saturation (as low as 3%). All the specimens of B. gelatinosum collected had few to many trichogynes deformed by a basal protuberance or knob, a structure previously unobserved in this species. No other taxa showed any deformities. The ecological analyses confirmed the existence of a relationship between the environmental conditions of the springs and the occurrence of knobs.

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