This is definitely a calamity, but don't forget that natural oil seeps have been leaking hydrocarbons into the Santa Barbara Channel for thousands of years. I am just back from a trip to Santa Rosa Island where we observed sediments 80,000 years old that were permeated with oily deposits.
Some of these seeps are marked on nautical charts....
Hikermor is correct that there are many natural oil seeps in that region, both under the water and on land. For example most people will have heard of the
La Brea Tar Pits.The ecosystems have adapted to the slow, chronic, natural release of hydrocarbons over millennium. However, the reason spills like this are a calamity is because it is way too much, way too fast for the environment to deal with. No bird or other critter can easily survive being drenched in oil. And while natural organisms can cope with small amounts of some of the (numerous) toxic compounds in oil, a sudden big dose like this likely just kills them.
Another issue is the oil from the seeps is already partially degraded by the time it reaches the surface (evaporation of volatiles, interaction with groundwater, action of bacteria in the ground,etc). Thus it may be marginally less toxic. My understanding is that the spilled oil apparently came more or less directly from a well into the leaking pipeline. I don't know any specifics about that particular crude, but oil fresh from a deep reservoir could easily be a lot more nasty than oil from a natural seep.