November brings the first winter storms and the end of the "Oceanic Season" and the beginning of the "Davidson Current" season on the Central California Coast. The southerly-flowing California Current weakens and moves offshore, to be replaced by the northerly-flowing Davidson Current.
Strong southerly winds during storms augment the Davidson Current to create northerly currents during the winter months, which tend to keep drifting algae and animals close to shore. These same southerly winds cause surface waters to be mixed down below the surface. This strong vertical mixing, along with low concentrations of nutrients, make it hard to for phytoplankton (and the animals that feed on them) to survive. Those algal blooms that do occur tend to take place relatively close to shore.
On the deeper parts of the continental shelf, however, the water is warmer during winter than at other times of year. A number of seafloor fishes and other animals move from the inner shelf into deeper water, where they spawn during the winter months.
Whales, porpoises, and seabirds that prefer warm water and feed on krill leave the Central Coast around November. Dolphins and seabirds that remain in the area often congregate relatively close to shore, where food such as schools of anchovies is still available.
Winter storms and sand movement wreck havoc in the kelp beds and intertidal areas. Some animals move into deeper water to avoid the effects of storms. Some algae take advantage of increased light from a thinner kelp canopy to put on new growth. Others rapidly colonize newly exposed rock surfaces in the intertidal zone. Other animals and algae release spores or larvae in winter with the hope that these microscopic life forms will survive the winter storms and recolonize intertidal areas in spring.
