Human Impacts on Mussel Beds:
By Ishbel Kerkez    Awards: Myers

There is growing interest in the potential application of de facto reserves as a tool for marine conservation. De facto reserves are areas of the marine environment where access is restricted for reasons other than conservation such as military bases, power-plants, private homes that restrict access to the coast and areas where topography, conditions or remoteness make access difficult are some examples of de facto reserves. They represent an opportunity to expand on the current extent of habitat and natural resources in marine reserves and to complement reserves. They have the benefit of already being implemented and, in addition, disturbances associated with visitation do not occur in de facto reserves, as opposed to marine reserves where visitation can increase because of protection. Consideration of de facto reserves and their inclusion as a potentially significant tool for marine conservation becomes increasingly relevant as incentives to sell private land become more apparent. Conversion of coastal lands that are currently protected de facto to areas with public access may lead to unintended impacts on populations and communities if these areas are opened to the public without first implementing protective legislation.

To determine whether there are benefits of restricted access and thus potential for de facto reserves as a conservation management tool, I assessed and compared the characteristics of mussel beds in areas that are highly visited, moderately visited, reserves and de facto reserves. Abundance (percent cover), size of individual mussels as well as thickness of the beds were measured and samples were taken so that species richness of the associated invertebrate assemblage can be determined and compared between sites. Mussel beds are an important biogenic habitat that supports an extraordinarily high diversity of invertebrates that depend on them for shelter, space and a microclimate that assists living in the harsh intertidal environment. They are vulnerable to the impacts of trampling which crushes them as well as weakening the abyssal threads that secure them to substrate resulting in dislodgment even some time after the initial disturbance, and they are often collected for food or for fishing bait. They are a suitable habitat therefore, with which to measure the impacts of visitation. Evaluating the conservation value of de facto reserves that are without the disturbance associated with visitation and whether they offer additional benefits of protection compared to marine reserves has implications for coastal management.