Critical intertidal habitat

The tidelands along the beach near Shark Reef National Wildlife Refuge are rich with seaweeds, eelgrass, crabs, sea cucumbers, and multitudes of tiny creatures such as snails and tube worms. These low tide areas are teeming with life and serve as a critical habitat for the nearshore food web. Diving ducks feed on the seaweeds and snails; snails and forage fish lay their eggs on the eelgrass and seaweeds; tiny invertebrates feed small fish and crabs, which in turn feed larger fish, which in turn feed seals and otters. When the sea covers the intertidal zone they are protected from the feet of human visitors. However, at low tide—which is usually during the day in summertime—these gardens of eelgrass and seaweeds are not only vulnerable to the drying effects of the sun (a stressor to which they have been evolutionarily exposed), but are also extremely vulnerable to trampling by human feet (a new stressor to which they do not have adaptations).

The Clure proposal will facilitate greatly increased human presence on these designated Critical habitats.

Ecologist Judy Meyer notes the impact that human feet have on the intertidal zone: “Increasing human traffic on the beach will be detrimental to the plants and animals.  Numerous scientific studies in the peer-reviewed literature have demonstrated the negative impacts of human trampling on intertidal organisms around the world and as close to home as San Juan County Park (citations can be found at  I am attaching a photo of the intertidal area on this beach.  What appear to the human eye as little black dots on the rocks are snails that look like dinner to shore birds; human feet can easily crush those snails.”

According to Lopez scientist Russel Barsh of Kwiáht: “Our feet compress gravels and cobbles beneath which inter-tidal invertebrates and fish are taking shelter from the sun. People appear to find turning over rocks irresistible, and this exposes inter-tidal animals to heat, desiccation, and predators such as gulls and crows. The ‘crunch’ when people climb on inter-tidal rocks is the sound of barnacles, mussels, limpets and other small animals being crushed underfoot.”

See the Beach Map.

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