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MEPS prepress abstract   -  DOI: https://doi.org/10.3354/meps13984

Resident lobsters dominate food competition with range-shifting lobsters in an ocean warming hotspot

Samantha Twiname*, Quinn P. Fitzgibbon, Alistair J. Hobday, Chris G. Carter, Michael Oellermann, Gretta T. Pecl

*Corresponding author:

ABSTRACT: Species redistributions are one of the most prevalent changes observed in oceans worldwide due to climate change. One of the major challenges is being able to predict temperature-driven changes to species interactions, and the outcome of these changes for marine communities due to the complex nature of indirect effects. In the ocean warming hotspot of south-east Australia, many species have been observed shifting their ranges poleward. The eastern rock lobster Sagmariasus verreauxi has extended its range into warming Tasmanian waters inhabited by the resident southern rock lobster Jasus edwardsii, which may lead to increased competitive interactions between both species. Using video monitoring, we investigated how the 2 species compete for food at current (18°C), future (21°C), and future heatwave (24°C) summer temperatures. Behavioural competition between both species occurred in 80% of experiments during which J. edwardsii won 84% of competitive interactions and showed more aggressive behaviour at all temperatures. This indicates that resident J. edwardsii is not only more dominant in direct food competition than the range-shifting S. verreauxi, but surprisingly also sustains competitive dominance beyond its physiological thermal optimum under predicted future ocean warming and heatwave scenarios.