Beyond the tide: pool type as a key driver of intertidal fish assemblages in a subtropical island

Abstract

Tide pools are dynamic intertidal habitats that host specialized fish communities adapted to extreme and fluctuating environmental conditions. This study investigates how tidal cycles influence the diversity and abundance of ichthyofauna in natural and artificial tide pools along the coast of Gran Canaria, Canary Islands. Ten pools (five of each type) were sampled during both high and low tides over a two- month period. Fish species were identified and quantified using visual census techniques, and data were analyzed using multivariate statistics. Results revealed that while species richness remained relatively stable across tidal stages, fish abundance was generally higher during low tide (largely due to the increased presence of juvenile individuals). Furthermore, clear differences in community structure were found between natural and artificial pools: artificial pools supported greater fish abundance, whereas natural pools hosted a higher proportion of native, specialized species such as gobies and blennies. These findings highlight the ecological role of tide pools as both nursery and refuge areas and emphasize the importance of considering habitat type and tidal dynamics when assessing coastal biodiversity in subtropical marine ecosystems.