Abstract
New Zealand coastal sea temperature, predicted to warm by ~1°C and ~2°C in middle and end- century, respectively, as well an increase in future marine heat waves, will severely impact coastal benthic habitats. Serpulid tube worm communities play an important role in benthic ecosystems, including detrimental economic impacts. However, the ability of marine worms to survive under projected warming scenarios remains poorly investigated, due to the difficulty in studying their responses under realistic conditions, and to difficulties in identifying tubeworm species. Predicting responses of serpulids’ tube worm species to future warming temperature remains thus a challenge. Here, using novel heated settlement panel technologies deployed at the Portobello Marine Science Laboratory (PML), Otago Harbour, New Zealand, 11 local serpulid marine tube worm species were identified over three seasons (winter 2021, spring 2021, and summer 2021/2022) using morphological characteristics of the calcareous tubes, and were further characterised by comparison of their 18S genotypes. Warming responses of size and growth rate through time of this tube worms’ community were also investigated. This novel technology, developed by the British Antarctic Survey (BAS), can finely control environmental temperatures in situ, in the benthic boundary layer above the plates surface, to access the effects to warming and heatwave predictions (+1°C and +2°C above ambient temperature) at these important small spatial scales, and over ecologically relevant time scales. This research indicates that the size and growth rate of the tube worm species will overall, be significantly smaller and slower in the middle-century. However, a larger size and a faster rate are expected in the end-century. Under future extreme thermal events occurring in spring, the size and growth of serpulids will be typically larger and faster, while more biological variations will be expected whether a heat wave occur in future summer season. Broader interest about identification and future warming responses of serpulid tube worms at the species level, may therefore allow better predictions of future changes in benthic habitats, and to anticipate local impacts due to migrations of serpulids’ species.