Thermal exposure risks to mobile tropical marine snails: are eco-engineered rock pools on seawalls scale-specific enough for comprehensive biodiversity outcomes?

To test the model that eco-engineering plant boxes on seawalls sustain water temperatures within thermal tolerance to maximize tropical marine biodiversity, we conducted acute thermal effects (AET) experiments using intertidal gastropods (Nerita albicilla and Littoraria articulata). The AET50 (50th percentile) for N. albicilla (39.6 °C) was higher than L. articulata (32.8 °C). Loggers (Hobo) in boxes on a seawall positioned for full exposure to air temperature at mean sea level (< 1.1 m) recorded temperature every 20 min during summer months. Temperature frequency distribution plots were generated for day and night, above and below 1.1 m (which is proximal to mean tide level for the region). Using the AET50, N. albicilla would need to thermoregulate for a lower percentage of time compared to L. articulata regardless of day and night. It is likely that designing eco-engineering improvements to include microclimate refugia are particularly relevant in tropical areas, where extreme environmental conditions mean that scale-specific actions are important components for climate adaptation