Aggression plays a role in the fine-scale partitioning of damselfishes: a story of coexistence

New research from Coral CoE, led by Jacob Eurich, Prof Mark McCormick and Prof Geoffrey Jones, suggests that similar species are able to live along side one another in coral reef fish communities with limited resources by finding unique habitat within the reef matrix and aggressively defending their space against intruders. The research team found that in Kimbe Bay, Papua New Guinea (PNG) ‘niche partitioning,’ or adapting to the unique resources and species in the environment to minimize overlap, is a result of competition between species.

The extent of this partitioning amongst varying species of coral reef fishes was previously a matter of debate, yet the roles of habitat selectivity and conflict/aggression between species received little attention. The new study, published in Marine Ecology Progress Series, comprehensively addresses this knowledge gap and reports that the distribution of adult fish is a result of competition for space. The fish that were the most aggressive occupied more suitable habitat on the reef and inferior competitors were pushed into other reef zones.

In this study, the researchers used the fine-scale partitioning of seven territorial damselfish along a physical reef and depth gradient to assess the ecological importance of habitat partitioning and interspecific competition. This represents the finest scale of habitat partitioning yet documented for this guild of fishes. Additionally, the team used a ‘bag experiment’ (pictured) in the field to investigate the competitive interaction network. This multi-species comparison helps explain the unique diversity and distributions of ecologically similar fishes in PNG.

The paper “Habitat selection and aggression as determinants of fine-scale partitioning of coral reef zones in a guild of territorial damselfishes” provides a framework to investigate ecological partitioning along depth and reef profile gradients in the natural environment. As coral bleaching and anthropogenic threats increase on shallow exposed reefs, it is important to understand how fishes partition space along these gradients.

Read the full research paper here.