A comparison of ecological responses among aclonal (unitary), clonal and coalescing macroalgae

Based on growth patterns, regeneration capabilities and genetic make up, benthic macroalgae include three groups of species. Similar to land plants, they include clonal and aclonal species, and, similar to colonial aquatic animals, seaweeds also include coalescing species, that have the capacity to fuse forming composite (chimeric) entities. Since the awareness of the differences between these three kinds of seaweeds is rather recent, most ecological studies have not discriminated among them. However, ecological models based on one kind of seaweeds will not necessarily apply to all kinds of seaweeds. This study reviews ecological responses of algae at the individual and community levels, and describes similarities and differences among both the three algal groups and with parallel groups in land plants and chimeric marine animals. The ecological responses reviewed are plant sizes and shapes; patterns of resource acquisition; algal life phases, reproduction and dispersal; genetic variability, intraspecific and interspecific competition and herbivory. Analysis of these responses supports the idea in distinguishing among the above three algal group, reveals the need for numerous additional ecological studies and advices on incorporating concepts from the biology of chimeric aquatic animals and from clonal theory of land plants into the study of benthic macroalgae.