Effects of habitat fragmentation and patch size on recruitment and the abundance of kelp forest fishes (funded by National Undersea Research Program -- West Coast and Polar Region Center; National Science Foundation; SDSU Master's Program in Ecology)

Andres Deza's thesis project --

The relationship between habitats and the density or abundance of fishes has been explored extensively, and experimental manipulations have demonstrated how the presence of habitat and its structural complexity influence the distribution and abundance of temperate and tropical reef fishes. However, although patch dynamics and the effects of habitat fragmentation on invertebrates have been studied in seagrass beds and on coral reefs, few studies have investigated the response of reef fishes to fragmentation and patch size. The various sources of disturbance that impact kelp forests (both natural and anthropogenic) requires that we understand the effects of disturbance-mediated habitat fragmentation and loss on associated fauna. The responses of fishes to habitat fragmentation and variation in patch size may provide valuable information to resource managers charged with protecting essential fish habitat.

The overall objective of Andres' research was to determine, at large and small spatial scales, the importance of habitat fragmentation and patch size of giant kelp (Macrocystis pyrifera) on the recruitment and abundance of kelp-associated fishes. Manipulations within kelp forests resulted in fragments from 100m²to 1600 m². Kelp patches of the same density but different area (0.6 m² to 9 m²) were constructed to determine recruitment as a function of patch size. At the scale of a kelp forest, numerical and biomass abundance generally increased linearly with fragment size. For kelp patches, recruitment was not related to the size of a patch. These data suggest that habitat loss is more important than fragmenatation in reducing the abundance of kelp forest fishes. However, surveys of larger delineated kelp forests separated by unsuitable habitat suggests that recruitment and the abundance of older fishes may increase exponentially. These results may be useful to resource managers who may be interested in the configuration and area of kelp-forested rocky reefs in siting marine protected areas.

This page was last modified on May 10, 2012.

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