Highlights
- Reduced pH disrupted early development, causing brood failure and incomplete eggs.
- Broods and cohorts showed high mortality, limited growth and irregular sex traits.
- Reduced pH altered behaviours, with sex-specific substrate use and slower escape.
- Multilevel responses suggest reduced pH may affect population stability and invasion.
Abstract
Non-indigenous species (NIS) and reduced pH conditions are key stressors shaping coastal biodiversity and population performance. We examined how decreased pH influences developmental, demographic, and behavioural traits of the non-indigenous amphipod Melita palmata from the Mar Chiquita coastal lagoon (Argentina). Individuals, broods, and cohorts were reared under current pH (8.07) and a reduced pH scenario (7.5) to assess egg maturation, brood and cohort survival, growth, sexual differentiation, habitat use, and escape responses. Reduced pH disrupted early developmental processes, leading to incomplete egg maturation, brood failure, and the absence of post-breeding moults. Broods and cohorts exhibited low survival, limited growth, and irregular sexual differentiation, and no ovigerous females were detected. Behavioural responses were also altered, with sex-specific shifts in substrate use and slower escape reactions. Together, these multilevel responses indicate that decreased pH induce physiological and behavioural constraints that propagate into demographic instability. Such response at both individual and population levels suggests that reduced pH conditions could limit the capacity of M. palmata to sustain populations and may influence its future invasion dynamics, although field-level consequences remain to be determined. These findings highlight how early acting individual responses can scale up to shape population persistence under projected coastal acidification scenarios.
Bazterrica M. C., Rumbold C., Méndez Casariego A., Hidalgo F., de Marco S. & Obenat S., 2026. Developmental and behavioural responses of the non-indigenous amphipod Melita palmata (Montagu, 1804) at individual and population under reduced pH scenarios. Estuarine, Coastal and Shelf Science 343: 110264. doi: 10.1016/j.ecss.2026.110264. Article (subscription required).
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