Soft-Bottom Intertidal and Beach Ecosystems

SOFT SAND AND WAVES

For MPA monitoring, soft-bottom intertidal and beach ecosystems are wave-dominated areas of sand and gravel substrate occurring below mean high water and above mean lower low water. There are two main types of beaches occurring across California’s coastline, long beaches and pocket beaches. Long beaches consist of at least 1km of contiguous sandy shoreline, while pocket beaches consist of less than 1km of sandy shoreline bounded by rocky shoreline.

 

AN ECOSYSTEM DEFINED BY EXTERNAL INPUTS

Species inhabiting sandy beaches are often almost entirely supported by external nutrient input. Beach wrack, or coarse brown kelp that grows on the shoreline, are especially important sources of food and nutrients in these habitats. Pocket beaches typically have more abundant kelp wrack and wrack-associated invertebrates including beach hoppers and terrestrial birds. Long beaches, on the other hand, have more abundant sand crabs and shorebirds, such as Western snowy plover.

Natural increases or decreases in the extent of wrack are partly driven by the changes occurring offshore in kelp-dominated habitats. As a result, connectivity between beach and kelp forest ecosystems is especially important for the health of beach habitats.

 

LET’S ALL GO TO THE BEACH

Soft-bottom intertidal and beach ecosystems are a hallmark destination for people and draw in visitors. By in large, they are culturally important and contribute economic benefits as people enjoy both consumptive and non-consumptive activities associated with beach environments.

Like the rocky intertidal and estuarine ecosystems, beach ecosystems occur at the interface between marine and terrestrial habitats. As a result, they are often strongly influenced by a variety of different natural and human factors that include indirect influences (e.g., coastal development and freshwater or polluted run-off) and direct influences of human visitation (e.g., disturbance or extraction of organisms). As such, to inform MPA design and management, it is essential to combine ecological monitoring data with information on human use.