Impacts of dugong foraging on seagrass habitats: observational and experimental evidence for cultivation grazing

Abstract

In Moreton Bay, Australia, dugongs Dugong dugon often graze in large herds at the same location for weeks to months. The species composition of seagrass meadows can be altered by intensive grazing, which favours rapidly growing, early pioneer species, such as Halophila ovalis at the expense of lower growing but dominant species such as Zostera capricorni. H. ovalis is the most nutritious (high nitrogen, low fibre) and the most preferred seagrass grazed by dugongs. Z. capricorni is the least preferred species. By preventing the expansion of Z. capricorni and increasing the abundance of H. ovalis dugongs have adopted a grazing system, termed cultivation grazing, which can improve the quality of their diet. -from Author