Phylogeny and ecology of the green seaweed Ulva

Due to their crucial role in coastal ecosystems and their burgeoning commercial use for aquaculture, Ulva spp.have become the focus of many (applied) scientific studies (Bolton et al. 2016;Simon et al. 2022;Steinhagen et al. 2021;Wichard 2023).The cultivation of seaweed for food, feed and useful chemicals has the potential to increase significantly and sustainably.It could provide alternative protein sources, alleviate food shortages and meet increasing demand by utilizing the largely untapped aquatic environment (Barbier et al. 2020;Buck and Shpigel 2023).In any case, the reliable identification of the morphologically variable species and ecotypes of Ulva remains of particular interest and a prerequisite for many applications (Steinhagen et al. 2019).Despite their paramount importance, a comprehensive understanding of the ecology, phylogeny, and key characteristics across various Ulva species remains elusive.Advancements in cutting-edge technologies and sophisticated molecular techniques have propelled scientific research, unlocking some of the mysteries of this ecologically and economically significant genus.The quest to unravel the complexities of Ulva continues.This Special Issue consolidates pertinent scientific contributions spanning species-specific ecological traits, intricate phylogenetic aspects, and insightful aquaculture case studies.Acknowledging the considerable interest and commitment demonstrated by all contributors to this Special Issue,