Miniview: What effects the forces required to break or dislodge macroalgae?
Faculty of Computing, Health and Science
School of Natural Sciences
The forces required to break or dislodge benthic macroalgae can be linked to many important ecological processes such as survival, transport and dispersal, and it is, therefore, important to understand what factors affect these forces. We review existing studies, using simple vote-counting, to establish what ecological factors have been found to influence macroalgal break forces. We also used the compiled information to test for the existence of a general allometric relationship between thallus area and break force. We found 30 studies reporting break forces for 27 species of macroalgae from 118 populations. Species within the orders Laminariales, Fucales and Gigartinales were well studied whereas other orders had been neglected. Two-thirds of all studies were from rocky intertidal habitats and two-thirds were from North American coastlines. The most frequently tested ecological factor was wave exposure (14 studies with 7 significant effects). Other factors that were found to affect break force significantly in at least one study included time of sampling, thallus size, substratum and species. Generally, most factors had been addressed only a few times, emphasizing a need for further study. We found a highly significant positive relationship between thallus size and break force across a wide range of species and ecological conditions, providing evidence that size alone is an important determinant of macroalgal break force. To strengthen inferences and ensure that meta-analyses can be conducted, we suggest that future studies (i) use nested replication in space and time, (ii) include taxa and regions that have not been studied in detail, and (iii) report, as a minimum, corresponding information on break forces, thallus sizes, substratum type, wave exposure and time of sampling.