Resilience Of Invasive Tubeworm (Hydroides Dirampha) To Warming And Salinity Stress And Its Implications For Biofouling Community Dynamics

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Marine Biology


Anthropogenic activities have accelerated the movement of non-indigenous species throughout the world. One approach to predict the spread of non-indigenous species is to employ bioclimatic envelope models which often assume niche conservation among sympatric, closely related species. Here, we test this assumption by comparing early developmental progress of two non-indigenous calcareous biofouling tubeworms Hydroides elegans and H. dirampha. In the subtropical Hong Kong monsoon climate, H. dirampha and H. elegans experience dramatic seasonal fluctuations in temperature (from 17 to 30 °C) and salinity (from 15 to 34 psu). Hydroides elegans was previously shown to be sensitive to lower salinity and warmer temperature while H. dirampha persisted in the field under these seasonal conditions. Thus, we hypothesize that the observed shift in abundance is due to the resilience of early stages of H. dirampha to the interactive stress of warming and lower salinity. Larval survival, growth, clearance, and settlement rate of H. dirampha were quantified in a 2 × 3 factorial experiment (24 and 28 °C; 20, 26, 32 psu). Stage-dependent tolerance was observed: cleavage was hindered by low salinity. However, larval growth and clearance did not follow this trend and instead peaked at 26 psu. Similarly, settlement rate did not decrease with freshening; rather, it peaked at 26 psu under warming. The salinity tolerance of H. dirampha is compared with that determined by Qiu and Qian (Mar Ecol Prog Ser 168: 127–134, 1998) for H. elegans. Differences in larval physiological tolerances could shape abundance and distribution of a single species as well as broader community structure.