Complex Residences and Sociality: How Coral Structure and Social Environment Influence Occupation Patterns in Gobiodon in Aquaria

TL;DR

This study shows how coral structure complexity and social status affect the habitat choices of coral-dwelling gobies in aquaria.

Contribution

The study introduces 3D-printed coral structures to precisely manipulate complexity and observe social behavior in reef fish.

Findings

Individuals were observed more frequently in high complexity coral structures.

Breeders preferred high complexity structures even when their size was reduced.

Subordinates switched habitats more frequently than breeders.

Abstract

Habitat size and complexity are two of many important characteristics that can have profound effects on individual survival, growth, and reproduction. However, little is known about the influence these characteristics may have on sociality and how this may be altered in response to environmental stress. Among marine fishes, coral‐dwelling gobies are highly specialized cryptobenthic fish that live almost exclusively between the branches of Acropora corals, on which they rely for survival and reproduction. The study investigated whether grouping patterns and habitat choice decisions of a facultatively social species,
Gobiodon quinquestrigatus
, were influenced by habitat complexity and size. Coral structures were 3D printed with eco‐friendly polymers to create high and low complexity Acropora structures, allowing coral complexity and size to be precisely manipulated. Replicated trials consisted of three sequential 24‐h treatments: (1) breeder pair only, (2) breeder pair with the addition of a subordinate, and (3) breeder pair and subordinate with a reduced size of the high complexity coral structure. All individuals were observed more frequently in the high complexity coral structure. Females chose the high complexity structure most frequently, with males and subordinates less likely to choose the high complexity structure. Breeders were more likely to occupy the high complexity coral structure even when the size of the high complexity coral structure was reduced. Breeders were observed switching more frequently in their first round (breeder pair only) compared to the latter rounds when the subordinate was added and when the coral size was reduced. Breeder males switched marginally more than breeder females. However, subordinates performed the most switches consistently throughout the two rounds they were present. These results highlight the dynamic relationship between sociality and structural complexity in a habitat specialist reef fish, with implications for our understanding of social maintenance in response to climate change and habitat loss.

Using the novel methodology of 3D printing, we precisely and accurately manipulated complexity to observe habitat choice behavior in coral‐dwelling gobies. The social status and complexity of the coral structure influenced the choice of the individuals.

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