Temperate Kelp Forest Collapse by Fish Herbivory: A Detailed Demographic Study

Kelps dominate rocky shores in temperate latitudes, acting as important foundation species. Recently, kelp forests have received growing attention for their decline around the world. Climate change is one of main drivers deforestation, both through abiotic stress and/or distortion biotic interactions. In NW Spain, golden ( Laminaria ochroleuca ) recently declined some areas due to excessive grazing. To further investigate mechanisms behind this decline, a thorough 1-year seasonal demographic study was carried out on eight reefs: four healthy and degraded by herbivory. covered full range size classes throughout year reefs. By contrast, only small, newly recruited kelps were found reefs spring-summer, because herbivory autumn-winter caused total collapse populations reef-scale (i.e., all reduced inviable stubs with no blade growth meristem). Bite marks covering showed that fishes, instead invertebrates, culprits Recent studies, mostly conducted Indo-Pacific, also fish herbivory, alone or combination stressors, can maintain canopy-free state best our knowledge, first time shown cause entire reef scale Atlantic. The implications finding management potential recovery are discussed.