MEPS 624:131-141 (2019)  -  DOI: https://doi.org/10.3354/meps13027

ABSTRACT: Intraspecific niche shifts occur in nature and can be measured from different ecological views, including distributional, dietary and behavioral aspects. While the ecological niche concept is widely known and adopted, it has been applied to very different approaches in ecological investigations. In this study, we addressed 4 niche-based analyses (spatial, dietary, isotopic and functional) to investigate whether the ecological niche of the intertidal predatory fish Labrisomus nuchipinnis varies ontogenetically between juvenile and adult stages. L. nuchipinnis adults inhabited more complex intertidal tidepools dominated by calcareous algae, rocky rubbles and macroalgae, whereas juveniles occurred in pools with a predominantly sandy substrate. Also, dietary and isotopic niches indicated a trophic niche partitioning between juveniles and adults, with the latter foraging on more diverse (8 vs. 2 dominant prey types) and large-sized food resources (e.g. grapsid crabs). The ecological functional niche based on 10 morphological traits corroborated that juveniles and adults did not overlap their niches in functional space, which may facilitate juvenile survival and adult growth in a semi-confined intertidal ecosystem. Our study revealed that L. nuchipinnis exhibits a marked niche change during its life cycle, thus acting as distinct ecological species along its ontogenetic development. This evidence suggests that niche variations within coastal marine ecosystems may be a strategy to increase fitness in a highly competitive environment.

KEY WORDS: Ontogeny · Tidepool · Rockpool · Atlantic · Tropical · Niche