Mill Creek at Big Sur

Macrocystis pyrifera (giant kelp) growing in a shallow pool in the intertidal.

Big Sur is one of my favorite places along the northeastern Pacific coast. Here the Santa Lucia Range presses against the Pacific coast, forming rugged rocky shoreline next to steeply cut valleys filled with redwoods and hillside slopes of chaparral and grassland.  

Much of the area is designated as California State Parks or National Forest (including wilderness) land. Big Sur has the usual California problems of invasive species, but the area has historically endured relatively little development. Tourists stream in along Highway 1 (in seemingly greater volume), particularly from the Monterey Peninsula, but much of the shoreline and coast range is too rugged for heavy human use.

I have a few favorite intertidal locations in Big Sur that I’ve visited intermittently over the years to tidepool, photograph marine life, or just collect seaweeds. Actually, quite a bit of the coastline is relatively inaccessible because of its steep topography, or for other reasons. For this month’s early morning spring tides, I visited Mill Creek on the southern Big Sur coast. Because of the early morning tide, I camped Sunday night at Plaskett Creek, and then Monday morning was lucky to have Mill Creek’s rocky stretch of coastline to myself.

Sea stars at Mill Creek, including Henricia leviuscula (center) and two examples of what may be
Leptasterias, a species complex of 6-armed Pacific coast stars. 

Desmarestia munda, acid (!) "kelp".

Excellent low tides notwithstanding, large swells offshore can keep the low intertidal relatively inaccessible for those wishing to stay relatively dry, but one solution to this is to don a wetsuit, at least up to one’s stomach, and make way into the low intertidal and the deeper intertidal pools. With some decent off-shore waves, this trip benefited from that method and I was able to access the deeper pools and photograph quite a few marine treasures with my underwater camera.

Mill Creek has a good mix of seaweeds (large brown seaweeds, foliose and finely-branched red algae, and some green algal species), seagrass (Phyllospadix) and invertebrates (anemones, seastars, mussels, etc.) – an example of a high diversity, less disturbed stretch of central California coastline. The substrate here is a field of large boulders, a cobble beach, and larger bedrocks with areas of coarse sand. The boulders tend to be rather large and are covered generously with algae and invertebrates.

Small seastars were common this month. Many were the whitish Leptasterias spp. (a six armed star typically a few cm across), but some were also juveniles of larger species. These new recruits perhaps represent local evidence of the reported rebound in sea star populations after the wasting disease phenomenon that led to a crash in west coast sea star populations in the last couple years.

Brightly-colored nudibranchs were also abundant and I spent some time photographing these beautiful animals underwater in the shallow pools. I observed at least 5 to 6 species including Okenia rosacea, which has seemed pretty abundant across the central to northern California coast over the last year. Yellow dorids were the most common on this trip ato Mill Creek. 

Two Mill Creek nudibranchs. Left: Triopha catalinae. Right: Dendrodoris fulva or Doriopsilla albopunctata.

Hermissenda crassicornis on articulated red coralline algae.

References

Behrens DW. 1991. Pacific Coast Nudibranchs. Sea Challengers, Monterey, CA.

Morris RH, Abbott DP, Haderlie EC. 1980. Intertidal Invertebrates of California. Stanford University Press, Standford, CA.