Stegastes adustus
A study of territory loyalty

Organisms choose a home based on its needs. When those needs are removed, the organism has two options. The organism can either move and look for a new home that meets its needs, or it can stay and facilitate rehabilitation of the resources to the territory. Stegastes adustus is well known for protecting their territory. Inside of a S. adustus territory, the fish maintains an algae patch that it takes care of and protects from other grazers. The hypothesis of this paper is that at a critical reduced algal level, S. adustus will move on to a new site. This is a problem because when the S. adustus moves on, any algae left is open to grazing and will also be lost. The drop in biomass can then lead to a decreased productivity level of the area. After testing 13 sites by gradually removing percentages as well as taking all of the algal mass on an area at once, only 7.7% of fish abandon their sites. This data suggests that S. adustus in fact does not abandon their territories in a number that would make a difference to productivity.

– Matt