The effect of dispersal and temperature on the early life history of a temperate marine fish

Understanding the mechanisms that influence the successful recruitment of marine species is one of the great challenges in marine science, particularly for species that undergo a protracted larval phase. Here we apply a bio-physical individual-based model (IBM) which couples data from a high-resolution oceanographic model with temperature-related survival characteristics for the early life stage of a temperate marine fish. The IBM was run retrospectively for the years 1993–2007 with spawning locations occurring around Tasmania, Australia. Meso-scale oceanographic features led to individuals spawned on the west coast, and to a lesser extent the south coast, being washed ashore prior to achieving a competent size to actively influence their migratory paths. Individuals spawned on the east coast had significantly higher survival rates. Temperature-induced mortality was relatively consistent across years. This indicates that the dispersal envelopes, of pre-flexion larvae, across all years are predominately within the thermal niche of this species. To further understand the effect of temperature on survival we integrated global climate model warming scenarios into the model. The results indicated that around the year 2050 the predicted warming would have a minor positive effect on the survival of individuals but by 2100 the pejus temperature will frequently be exceeded leading to a significant decline in survival, particularly towards the northern end of the dispersal range.