Effects of the rainy season and urbanization on the phenology and richness of the community of Dictyotales (Phaeophyceae) on Brazilian tropical reefs

The phycological diversity of Dictyotales, macroalgal species with great biotechnological potential, is still unknown in Alagoas, Brazil. Therefore, we carried out a phenological survey of Dictyotales and provided ecological comments. Samples were collected at four stations during the dry season (November and December 2013 and January 2014) and the rainy season (May–July 2014). Eighteen species were identified, five of which were recorded for the first time in Alagoas (Canistrocarpus crispatus, Dictyopteris jamaicensis, D. polypodioides, Dictyota pinnatifida and Padina antillarum). Canistrocarpus cervicornis and Dictyopteris delicatula made the highest biomass contribution in all the stations in both seasons. The stations studied showed differences between them, except for stations with less anthropogenic interference and offer greater local species diversity. This highlights that in Maragogi and Pajuçara Stations aspects of urbanization could negatively affect the Dictyotales community, such as the disappearance of endemic species. Sporophyte phase and fertility showed differences between stations and seasons. In both analyses, the rainy season collected the most of the records. The analysis of richness showed that the rainy season had higher values. Thus, the rainy season is the time when Dictyotales invest in reproduction and we find higher biodiversity. Therefore, phenological studies, biodiversity research and commercial research of Dictyotales should take place during the rainy season.