Harvesting Ascophyllum nodosum (Phaeophyceae) reduces the abundance of its host-specific epiphyte Vertebrata lanosa (Rhodophyta)

Ascophyllum nodosum is commercially harvested in the southwestern parts of Nova Scotia. Here the hypothesis is evaluated that harvesting results in a reduction in the abundance of Vertebrata lanosa, an obligate epiphyte of A. nodosum. Sampling at 10 harvested and 16 non-harvested sites showed that percent cover and frequency were significantly lower at harvested sites (i.e. 5.4 +/- 4.0 and 0.6 +/- 0.7% cover, and 61 +/- 24 and 21 +/- 18% frequency for non-harvested and harvested sites, respectively). Vertebrata lanosa is suggested as a useful indicator of ecological integrity at harvesting sites.