Susceptibility of Tidal Pool Fish Assemblages to Climate Change

There is a need for improved understanding of how climate-change driven rises in sea level and increased ocean temperatures will affect fish assemblages in rocky shore tidal pools. Rising sea levels are predicted to alter habitat availability and increasing ocean temperatures will drive tropicalisation, both of which are likely to alter tidal pool fish assemblages. Consequently, we examined changes in fish assemblages in tidal pools at four sites in Coffs Harbour, Australia, using baited video sampling. Data were collected seasonally at each site, in pools at differing tidal elevations. We identified significant differences in tidal pool fish assemblages among elevations and found that assemblages exhibited cyclic seasonal patterns. Modelling identified that ocean temperature was the most powerful factor for explaining variations in assemblages, followed by pool area and pool elevation. Results highlight that distinct fish assemblages occur in tidal pools at different elevations and indicate that assemblages at higher elevations could be squeezed out by rising sea levels and by increased competition from tropical fish species. Future conservation assessments are needed to determine whether latitudinal and vertical range shifts for tidal pool fishes are possible, with facilitation of these range shifts needed to address displacement of tidal pool fishes by rising sea levels and ocean temperatures.