The East Australian Current is among the fastest-warming ocean systems globally, driving documented poleward range shifts across marine taxa. Yet for Syngnathids (seahorses, pipefish, seadragons, and pipehorses) no systematic distributional analysis exists for Australian waters. These highly habitat-dependent, low-mobility species are flagship indicators of estuarine health, nonetheless, an estimated 39% face conservation risk.
We compiled over 10,500 georeferenced occurrence records for 38 east coast syngnathid species spanning from 1859 to 2025, sourced from the Atlas of Living Australia, iNaturalist, Wilderlab eDNA, and unpublished NSW and Queensland Fisheries data. Occupancy modelling and latitudinal centroid analysis revealed statistically significant distributional shifts in 12 species, with tropical taxa showing the largest poleward displacement, patterns that align temporally with regional sea surface temperature trends and suggest accelerating redistribution at range boundaries.
The cost of inaction is well documented. The 2025 South Australian harmful algal bloom caused the largest recorded mass mortality of leafy and weedy seadragons - a tragic loss that remains difficult to fully quantify without pre-event distributional baselines. We discuss implications for marine protected area design under the 30×30 framework and identify priority monitoring gaps along the east coast.