Intertidal Ecosystems Blog Posts

Every beachgoer has probably noticed plastic trash littering their favorite beaches, however remote. A new study of microplastic distribution on national park beaches indicates that whichever one you visit, there is probably also some amount of plastic that is harder to see, mixed in with the sand between your toes.

For decades, San Francisco Bay Area Network biologists have used on-the-ground monitoring techniques to gather data on how small rocky intertidal areas along the central California coast are responding to changing environmental conditions. Now, they are exploring aerial mapping as a new method to create a comprehensive record of these important ecosystems and how they are shifting.

Standing on what would soon be the ocean floor again, it felt like I’d stumbled upon a secret no one had ever told me. Across rocky intertidal sites at Golden Gate and Point Reyes National Seashore, I saw colorful claws from a few crabs, who seemed to be happy to be getting some sun. I knew the intertidal stole my heart when I saw a baby ochre star nestled beside a much larger purple ochre star. There were also anemones smaller than quarters, and some larger than my hand!

Black abalone are endangered marine snails. When I told people that I was making a podcast about them, I was often met with the question, “Why black abalone?” If you are curious too, you’re in the right place. I hope to elucidate why black abalone represent an interesting case study in delicate balances: between marine and terrestrial, ancient and Anthropocene, and vulnerability and resiliency in the context of roles they play in their communities and in ours.

Ocean acidification (OA) is a huge threat to marine life. But for now, it is harder to track remotely on a large scale. So this summer, seven West Coast national parks are teaming up with the 2021 NOAA West Coast Ocean Acidification Cruise. They’re collecting water samples in-person to check several OA indicators. Their data will help paint the most detailed picture yet of OA conditions up and down the coast, from parks’ rocky intertidal zones to dozens of miles offshore.

Every year, National Park Service biologists conduct intertidal surveys at sites along the San Francisco Bay Area coast, contributing to growing long-term data sets. Typically, they survey fixed plots, focusing on small areas of the reef and specific communities like mussels, barnacles, and algae. This year, they have also adapted an approach of sampling large areas of the reef at once and documenting all observed species along a set of transect lines.

This summer as park biologists conducted rocky intertidal surveys, they also surveyed for black abalone, the only federally endangered marine invertebrate that resides in Bay Area National Parks. Black abalone were once common in California before threats like commercial fishing, poaching, and disease drove major declines in the species across the California coast. They are rare North of the Golden Gate bridge, and their numbers do not appear to be recovering on their own.

Since 2013, sea stars from Alaska to Mexico have been dying in droves of a mysterious disease referred to as sea star wasting syndrome. Symptoms typically include the appearance of white lesions followed by tissue decay, body fragmentation and death, often within only a few days. Sea star die-offs are not necessarily unusual, but this one is unprecedented in terms of the numbers affected and the extensive area impacted.

Sea stars like ochre stars used to be abundant in Bay Area National Parks, but in 2013 park biologists saw a sharp decline in both the size and number of sea stars along park shorelines. Scientists are still looking for the cause of the mysterious “sea star wasting syndrome” behind this population crash. The disease has persisted along much of the Pacific coast, including in the Golden Gate National Recreation Area and Point Reyes National Seashore.

A new study has revealed no one cause of the disease, which hit populations of the keystone predator ochre sea star particularly hard in 2014 and 2015. The authors used data from 90 sites ranging from Alaska to southern California to try to determine what caused the outbreak.