Ecology, evolution and conservation of tidepool fishes of the Americas

Intertidal ecology has been considered the cradle of modern marine ecology with insightful investigations on the biological and ecological mechanisms allowing "life between the tides". Most of the early investigations focused on macrophytes (seagrasses and macroalgae) and benthic invertebrates inhabiting emerged intertidal substrata. However, tidepools also shelter a rich fauna, including fishes, which display a wide diversity and a variety of ecological interactions and functions. Here, we review the diversity, ecology, evolution and conservation of the American tidepool fishes, from definition to trophic roles, ecological vulnerabilities and societal importance that reveal an extraordinary biodiversity and the important roles fishes play in the coastal ecosystems. Tidepool fish studies increased sharply from the mid twentieth century onwards, but many geographic gaps still exist. Tidepool fishes connect marine and terrestrial communities via substantial predation upon insects and exporting energy to land as prey for terrestrial fauna. Sea-level rise driven by climate change will reduce or eliminate current intertidal habitats, where little or no space is available for landward accommodation in the supralittoral zone. Concurrently, tidepool habitat would be 'squeezed' to a narrow intertidal stripe by 'coastal squeeze' process. Endemic, habitat-restricted, and specialist species could be particularly affected by human-induced habitat loss on the coastal stripe. Tidepool fishes provide many ecological services, such as well-being, environmental awareness, outdoor recreation, and bioinspiration for ancient and current societies. The level of intertidal rocky shore protection varies among American countries, but in most cases rocky shores are included in the least effective protection categories allowing extractive activities.