Small-scale variation in tropical tidepoolfish assemblages

Abstract

Habitat heterogeneity is known to promote species diversity and othereffects in communities by increasing structural complexity, access to foodresources and to refuge spaces. However, the influence of environmentalheterogeneity at small spatial scale settings is challenging to detect andto measure. In tropical intertidal rocky shores, the low tidal zones aresometimes encrusted by reef-building organisms forming complex biogenicflat reefs below rocky outcrops that appear at mid-to-upper intertidallevel. Here, we investigated a tidepool community situated on an intertidalshore with marked variation in structure and texture within metres to testwhether tidepool fauna would differ between biogenic and rocky reefs inregard to their composition, diversity and trophic structure. Our findingsrevealed that tidepool fish assemblages differed significantly between reeftypes. Trophic structure exhibited variations in resource use, food webhierarchy and trophic roles of species occurring in both biogenic and rockytidepools. Our results imply that tropical intertidal reefs show pronouncedtaxonomic and trophic distinctiveness at small spatial scales.