Ecological benchmarks in the Santa Cruz County kelp forests before the re-establishment of sea otters

Surveys of the subtidal kelp forest communities were conducted between Point Santa Cruz and Año Nuevo Island. Relative abundancies of major macroinvertebrates and algae, as well as depth and profile, were recorded. The Macrocystis forests along protected regions of this coast are composed of very large plants with few juveniles. Sea urchins occur in high densities (~50/10m2) bordering the outer edges of these forests and extending seaward. Inside the kelp forest, densities of urchins approach zero; crabs are common but abalones are rarely found. The Nereocystis forests along unprotected parts of the coast consist of many adult and juvenile plants. Urchin densities inside the forest are high (~40/10m2) and decrease (15/10m2) seaward of the kelp forest. The highest densities of abalones are found in this area at depths less than 6 meters. Sites for long term study were selected in kelp forests where potential interactions between sea otters and the kelp forest communities might be followed. A Nereocystis and a Macrocystis forest were each sampled quantitatively at sites inside and adjacent to the seaward edges of the kelp forests. The densities of the major macroinvertebrates and algae were counted at each site.

CCMS/UCSC Technical Report Number 6. Final Report to the U.S. Marine Mammal Commission in fulfillment of Contract MM6AC029; Report No. MMC-76/04