Size-Dependent Habitat Selection in a Tropical Freshwater Crayfish: Preference for Vegetated Refugia

Area of Science:

• Ecology
• Aquatic Biology
• Conservation Biology

Background:

• Habitat selection is vital for freshwater species' early survival and recruitment.
• Distinguishing active habitat preference from mere accessibility is challenging.

Purpose of the Study:

• To experimentally determine habitat selection preferences in freshwater crayfish (Cherax quadricarinatus) across early life stages.
• To assess if habitat selection is size-dependent and if structurally complex habitats are preferred.

Main Methods:

• Laboratory choice and no-choice arenas were used to quantify habitat selection.
• Two early life stages, craylings and juveniles, were tested.
• Habitat use patterns across vegetated, sand, and gravel substrates were analyzed.

Main Results:

• Both craylings and juveniles demonstrated a clear preference for vegetated habitats.
• Juveniles exhibited a significantly stronger preference for vegetation (60.0%) compared to craylings (10.7%).
• Habitat use in no-choice arenas was more uniform, indicating active selection rather than accessibility.

Conclusions:

• Vegetated habitats serve as critical refuges for early-stage freshwater crayfish.
• Juveniles show a much stronger preference for vegetation than craylings, highlighting size-dependent selection.
• Loss of habitat complexity threatens crayfish recruitment and population viability in tropical ecosystems.