Abstract
<jats:p>Patchy habitat biodiversity studies predominantly focus on fragmented spaces regardless of the causes. They report mostly, but not always, negative impacts, without a general explanation of inconsistencies. We suggest that the explanation may depend on the patch system age and development time. Species in recently fragmented landscapes may have limited ability to cope with habitat discontinuities (a major natural or anthropogenic disturbance), whereas slowly formed patch arrays, such as reef patches starting as coral colonies, may lack this limitation or even perform better. To explore this idea, we propose that many small naturally developing patches are more likely to exhibit greater species richness than a few large habitat patches of equivalent area. To test this, we used coral reef fishes on 30 naturally formed, distinct reef patches of varying sizes in Discovery Bay, Jamaica. We found cumulative species richness to be higher on small patches (38 species) and lower on large patches (35 species). Surprisingly, while mean abundance was higher on large patches, the total abundance was higher on small patches. The small patches were, on average, associated with lower compositional interpatch dissimilarity relative to large patches, but not when abundance was included in the metric. These characteristics suggest possible scenarios for why small patches support lower density but higher species richness than larger patches. Several mechanisms may contribute to the observed diversity pattern, but further research is necessary. The findings of this study emphasize the overlooked importance of preserving numerous small patches, as they can support species diversity and more individuals in naturally fragmented habitats with a long history and broad distribution. However, we caution that small patches may benefit only a subset of the coral reef species pool, whereas large patches or continuous areas may be equally critical for other species.</jats:p>