Understanding the consequences of fragmentation of coastal habitats is an important topic
of discussion in marine ecology. Research on the effects of fragmentation has revealed
complex and context-dependent biotic responses, which prevent generalizations across different
habitats or study organisms. The effects of fragmentation in marine environments
have been rarely investigated across heterogeneous habitats, since most studies have
focused on a single type of habitat or patch. In this study, we assessed the effects of different
levels of fragmentation (i.e. decreasing size of patches without overall habitat loss). We
measured these effects using assemblages of macro-invertebrates colonizing representative
morphological groups of intertidal macroalgae (e.g. encrusting, turf and canopy-forming
algae). For this purpose, we constructed artificial assemblages with different combinations
of morphological groups and increasing levels of fragmentation by manipulating the amount
of bare rock or the spatial arrangement of different species in mixed assemblages. In general,
our results showed that 1) fragmentation did not significantly affect the assemblages of
macroinvertebrates; 2) at greater levels of fragmentation, there were greater numbers of
species in mixed algal assemblages, suggesting that higher habitat complexity promotes
species colonization. Our results suggest that predicting the consequences of fragmentation
in heterogeneous habitats is dependent on the type and diversity of morphological
groups making up those habitats.