Thermal tolerance of two seagrass species at contrasting light levels: Implications for future distribution in the Great Barrier Reef

Future temperature increases may lead to the contraction of Zostera muelleri from the northern Great Barrier Reef (GBR) by over 1000 km, potentially disrupting critical fisheries habitats. This study found that while Halodule uninervis thrives at higher temperatures (33°C), Z. muelleri experiences severe metabolic imbalances and growth reductions under the same conditions. Researchers assessed metabolism, growth, and survival of both species over one month at three temperatures (27°C, 30°C, 33°C) under saturating and limiting light levels. H. uninervis exhibited up to 10× higher carbon production at 33°C with saturating light, while Z. muelleri showed near-zero growth and a 90% reduction in biomass. The decline was more pronounced in low-light conditions, where Z. muelleri's carbon balance shifted into deficit. These findings suggest that Z. muelleri, currently near its thermal threshold, may disappear from northern GBR estuaries, impacting muddy habitat-dependent fisheries.

Collier, C. J., Uthicke, S., & Waycott, M. (2011). Thermal tolerance of two seagrass species at contrasting light levels: Implications for future distribution in the Great Barrier Reef. Limnology and Oceanography, 56(6), 2200–2210. Portico. https://doi.org/10.4319/lo.2011.56.6.2200