Port Habitats: What makes them diverse?

Encompassing over 15,000 acres of land and water in San Pedro Bay, the current Los Angeles and Long Beach Port Complex is the result of over a century of development prompted by population growth and burgeoning industry, and connects Southern California to the rest of the nation and world.

Compared to other embayments in Southern California, which generally have one narrow connection to the ocean, the Port Complex is a more open coastal feature that is protected from waves by an 8-mile-long constructed breakwater. This barrier has two gates for ships to enter and exit, in addition to an opening to the east.

Background image: Port of Long Beach with Los Angeles River and San Gabriel Mountains visible in distance.

In addition to the breakwater, other development over the past century to accommodate commercial shipping operations include the creation of deep navigation channels and extensive land areas bordered by rock dikes to accommodate marine cargo terminals, and construction of piers and wharves supported by tens of thousands of concrete and wooden pilings.

Background image: Port of Los Angeles with Palos Verdes and Santa Monica Bay visible in distance.

The pilings placed in water create vertical structure that is favorable for animals like mussels, oysters, scallops, and soft corals that filter particles out of the water. Sea stars and crabs crawl along the pilings looking for food, while bass and perch cruise the water column hunting for small invertebrates they can pick off the surface of the pilings.

Background video: Kelp growing on pilings in the outer harbor providing habitat for fish.

Riprap embankments and the breakwaters protect the ports from damage and erosion from waves and storm surge, but also provide complex habitat with crevices and caves for fish and invertebrates to hide in, such as garibaldi, horn sharks, abalone, and lobsters. In the outer harbor, the most recent 2018 Biosurvey found over 100 acres of giant kelp attached to the boulders, with more kelp canopy in the summer than seen in previous surveys. The dense stands of kelp form forests that support many species of fish and invertebrates and provide valuable hunting ground for birds and marine mammals. Above water, the riprap embankments also provide extensive area for birds to roost and marine mammals to haul themselves out of the water to rest in the sun.

Background video: Shallow kelp forest and garibaldi on breakwater.

As mitigation for impacts of their development projects, the ports have created shallow habitat areas, some of which have been enhanced by transplanting eelgrass. These eelgrass beds provide nursery habitat for juvenile fishes and have diverse invertebrate communities that live in the sediment and under the cover of the eelgrass blades, providing food for larger animals such as fish, sea lions, and birds.

Background image: Eelgrass blades with snails in the outer harbor.

The 2018 Biosurvey found over 86 acres of eelgrass throughout the Port Complex, including areas of the inner harbor where eelgrass was observed for the first time, largely due to continuing improvements in water and sediment quality.

While the majority of the Port Complex consists of sandy and muddy bottom habitat, the extensive eelgrass and kelp forest habitat nearby is a critical source of food called “detritus”, or pieces of kelp and eelgrass blades that decay and settle to the bottom. As detritus is transported from the outer harbor to the inner harbor with currents and tides, it fuels food webs throughout the Port Complex and contributes to the nearly 1,000 invertebrate and fish species that are able to thrive in these waters.

Background video: Garibaldi hiding in cave in outer harbor; purple urchins and ochre star on riprap in outer harbor; bat star on riprap in inner harbor; sheep crab on piling in outer harbor; lobster on piling in outer harbor; kelp bass hiding in kelp on piling in outer harbor; round stingray and opaleye on riprap in outer harbor; barred sand bass under pier in inner harbor.