University Of Tasmania
143059 - Ontogenetic shifts in social aggregation and habitat use in a temperate.pdf (2 MB)

Ontogenetic shifts in social aggregation and habitat use in a temperate reef fish

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posted on 2023-05-20, 21:26 authored by Fobert, EK, Reeves, SE, Swearer, SE

Cover, both from physical structure or association with social groups, can reduce predation risk and increase foraging, leading to enhanced growth and survival, and is therefore a critical aspect of the niche for many organisms. However, the need for cover, or the need for a specific type of cover, may change as an individual grows in size, leading to niche shifts throughout development to meet these changing needs. In this study, we examine ontogenetic shifts in cover use by wild populations of a temperate reef fish, the southern hulafish, Trachinops caudimaculatus, a small, abundant planktivorous social aggregator found on temperate reefs in southern Australia. Through repeated in situ surveys, we found clear evidence of ontogenetic shifts in both microhabitat use and aggregation patterns by T. caudimaculatus juveniles in the first three months on the reef. The microhabitat associations of juvenile T. caudimaculatus became more similar to those of adult conspecifics over the study period, and over the same time frame, juveniles increasingly aggregated with adult shoals. Our findings also suggest that trade‐offs between structural and social cover are context‐dependent, with juveniles relying on structural cover longer when adult conspecific density (and thus intra‐specific competition) and/or habitat complexity (and thus the availability of shelter) is high. These findings provide rare and important observations into the complex interplay of social aggregations, habitat use, and ontogeny in wild fish populations.


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Institute for Marine and Antarctic Studies


Ecological Society of America

Place of publication

United States

Rights statement

© 2020 The Authors. This is an open access article under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) License, ( which permits use, distribution and reproduction in any medium, provided the original work is properly cited

Repository Status

  • Open

Socio-economic Objectives

Marine biodiversity