Chapter 4: California's Ocean Ecosystem

CHAPTER 4: CALIFORNIA'S OCEAN ECOSYSTEM

Habitats within California's ocean ecosystem contain some of the most biologically diverse natural communities in the world. The abundance of species and habitats located offshore California can be attributed to the inter-relationship of the identified resource zones located both onshore and offshore. Onshore, an extensive system of inland waterways provide habitat for various marine species, as well as freshwater and nutrient flows. Offshore, several major oceanic factors, such as the California and Davidson Currents and a hydrological phenomenon known as upwelling, contribute essential nutrients to nearshore and deep ocean waters. It is beyond the scope of this analysis to fully identify the many factors affecting the diversity of biological resources off the California coast. However, the analysis does describe the major interactions between different ocean resource zones, how these interactions affect diversity, and the fact that modifications in one zone may strongly influence biological processes in other zones located miles away.

OCEAN RESOURCE ZONES

For descriptive purposes, the habitats which make up California's ocean ecosystem have been grouped into four zones (see Figure 4-1):

inland watershed zone, extending from the watersheds of the Sierra Nevada to the California shoreline;
enclosed waters zone, including waters and habitats of bays, estuaries, and subtidal areas;
nearshore ocean zone, including nearshore open coastal waters out to a depth of 100 meters; and
offshore ocean zone, extending from a depth of 100 meters to the edge of the Exclusive Economic Zone (200 miles offshore).

The following sections summarize the habitat types, flora and fauna, and current issues that relate to each ocean resource zone. More detailed descriptions and analyses of the current issues are provided in Chapter 5.

THE INLAND WATERSHED ZONE

California's extensive inland watershed zone consists of approximately 7,800 miles of rivers, creeks and drainages, traversing a rich variety of climatic, geographic, sedimentary and topographic conditions as they meander towards the Pacific Ocean. These waterways play a critical role in providing freshwater flows which support anadromous fish and dependent habitats, such as coastal wetlands and nearshore coastal waters.

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Habitat Types

The health and productivity within California's inland watershed zone depends on the appropriate distribution of sediments, adequate vegetation along waterways, and sufficient flows of freshwater to the system. Coniferous forests, common along northern streams and in the upper reaches of most watersheds, function to retain topsoil and prevent sediment loading in rivers. When sediment loads increase, stream channels and associated wetlands may lose their effectiveness for flood control and wildlife habitat. Riverside forests and riparian woodlands provide nutrients, shade, and channel stability, permitting river waters to support spawning and the survival of young fish, such as salmon. Freshwater wetlands, also common to the inland watershed zone and often associated with rivers, are important for controlling and reducing the effects of peak flood flows, breaking down pollutants from contaminated waters, providing fish and wildlife habitat, and settling sediments before they reach coastal or urbanized areas. Adequate stream flow and water quality are required for anadromous fish to reach their spawning grounds, successfully spawn, rear to emigration size, and safely reach the ocean.

Flora and Fauna

Numerous fish species spend most of their lives in the ocean, but are seasonally dependent upon rivers and streams for reproduction. Known as anadromous fish, these species include the coho and chinook salmon, steelhead trout, American shad, striped bass and white sturgeon. Anadromous fish require rivers and associated tributaries for migratory routes, as well as for spawning and nursery grounds. Although these species historically used rivers and streams along the entire coast of California, the strongest remaining populations of anadromous fish typically occur in the rivers near and north of the San Francisco Bay. Some anadromous fishes, such as the striped bass and white sturgeon, mainly spawn in the Sacramento-San Joaquin Delta.

Striped bass (an introduced species), as well as many native anadromous fish, have shown significant population declines in the last decade. For instance, the winter-run chinook salmon in the Sacramento River has decreased in recent years from a high run of 117,808 fish in 1969 to a run of only a few hundred individuals in 1989-1991 (Department of Fish and Game, 1993). At least sixteen marine anadromous fish species depend on the inland watershed zone for survival at some point during their life cycles (Moyle, pers. comm.).

Current Issues

Land reclamation activities, including agriculture and urbanization, have resulted in the loss of more than 90% of the state's historic distribution of riparian and freshwater wetlands. In addition, dam construction, river channelization and water diversions have altered the natural flow of many rivers which, in combination with increased sediment loads from logging and cattle grazing, has diminished recreational and environmental values. Pollution also has become a problem with nearly 75% of the pollutants entering marine waters originating from land-based activities. These pollutants ultimately find their way to coastal wetlands or nearshore ocean waters. Overall, habitat alteration, including modifications in water management regimes and increased pollutant loads, has adversely affected many fish and wildlife populations dependent upon the waters of the inland watershed zone.

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Figure 4 - 1

Looking Forward

A variety of efforts have been initiated to reverse this trend. For example, the California Department of Fish and Game, California Department of Water Resources, and U.S. Bureau of Reclamation, have ongoing habitat restoration and fishery protection programs within the Central Valley. These projects include stream bank protection, stabilization, and revegetation, as well as installation of structures to provide cover, scour holding and rearing pools, and removal of barriers to upstream migration. A variety of other planning processes are in progress such as the development of a water quality protection plan for the Monterey Bay National Marine Sanctuary which is developing strategies for watershed management reaching far into the Salinas Valley.

THE ENCLOSED WATERS ZONE

The enclosed waters zone, consisting primarily of the State's bays and estuaries, is ecologically, economically, and recreationally important to California. Bays and estuaries are the places where the land meets the sea. Freshwater originating from as far away as the Sierra Nevada mixes with saltwater from the Pacific Ocean and, in the process, creates some of the State's most unique and delicate habitats. While estuaries and bays support an abundant and diverse assemblage of plants and animals, they are largely dependent upon nutrient inputs from the inland watershed, nearshore ocean and offshore ocean zones for maintenance of these organisms.

Habitat Types

Emergent coastal wetlands, mudflats, and seagrass meadows are the major habitat types present within the enclosed waters zone. These three habitats, although distinct in many ways, are strongly dependent upon one another. Transitions among these habitats are often gradual, with the same nutrients, plants and animals sometimes found in more than one habitat. For example, young fish and invertebrate species migrate between emergent wetlands and submergent seagrass meadows as tidal fluctuations submerge and expose different areas of an estuary.

Emergent coastal wetlands usually occur in intertidal marine, brackish, and freshwater areas of the enclosed waters zone. Vegetation produced in wetlands supports an extensive food chain, largely based on the consumption of decaying plant material by organisms known as detritivores. Although the production of vegetation in wetlands may be high, the diversity of vegetation species is low due to difficult conditions created by salinity and fluctuating water levels. Ecologically connected to coastal wetlands, upland areas within the inland watershed zone are a refuge for many creatures from rising tides and raging storms.

Mudflats, composed of soft, fine sediments, are another common habitat in the enclosed waters zone, occurring in intertidal areas. Mudflats form in areas where impacts from ocean wave activity is low and water movement is minimal. These conditions create a gentle slope that is much flatter than that observed for sandy beaches. These gentle slopes coupled with fine sediment particles result in long water retention, in turn allowing organic material to accumulate and serve as an abundant food source for the creatures residing in mudflats.

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Submerged seagrass meadows are another prominent habitat in the enclosed waters zone and often occur in the shallow subtidal areas. Dense seagrass beds, in conjunction with emergent wetlands, perform many important functions, such as providing fish and wildlife habitat, reducing coastal erosion, and filtering pollutants from the water column before they can flow into the Pacific Ocean. Soft bottom channels and submerged seagrass beds often provide a transition between the enclosed waters and nearshore ocean zones. These habitats are less conspicuous than others in this zone because they are always covered by water and, therefore, not seen by the casual observer. Tidal scour and freshwater flushing create highly changing sediment and salinity conditions, and are the driving force in the formation of seagrass beds and soft bottom channels. Currents in the channels can reach velocities of up to several knots, creating soft bottom areas where organisms must be highly adapted for survival. Tidal conditions in submerged seagrass beds are diminished, allowing sediment to settle and seagrasses and other organisms to flourish. Although conditions in the subtidal habitat can be severe, anadromous fish and other organisms have adapted to and use the habitat as migratory channels and feeding grounds.

Flora and Fauna

The high productivity of plants and algae in the enclosed waters zone attracts large numbers of animals. For instance, habitat provided by the stems and roots of emergent wetland and submerged seagrass vegetation provides spawning, nursery, and feeding grounds for important fishery species, such as the striped bass, California halibut, white sea bass, herring, and various salmonids. Taller wetland plants, such as the cordgrasses and bulrushes, provide cover and nesting sites for the endangered light-footed clapper rail, while shorter vegetation provides habitat for the endangered Belding's savannah sparrow. Other prominent coastal birds, such as the least tern, snowy egret and the great blue heron, are common to wetland and seagrass habitats, while eelgrass (the dominant seagrass species in the enclosed waters zone) is the primary food source for the black brant, a migratory goose.

The apparently barren appearance of mudflats is deceiving. Organic material carried into mudflats via tidal action is decomposed by microscopic bacteria which play a vital role in recycling food for other organisms. Bacteria are very abundant in mudflats, with population estimates as high as 400 million per gram of sediment. Nutrients made available by bacteria support algae, including diatoms and blue-green algae which can form mats up to one centimeter thick. Often hidden under sediments are large populations of commercially valuable invertebrate species, such as clams and oysters, as well as non-harvested species such as other mollusks, crustaceans, and worms. Staghorn sculpin, starry flounder, leopard shark, and California skate are common fish in mudflats. Mudflats also provide foraging areas for many common coastal birds, including the long-billed curlew, marbled godwit, snowy plover, oyster catcher and gulls.

Current Issues

Estuaries and bays are economically, environmentally and recreationally important, yet more than two-thirds of these areas have been eliminated in California. Historically, ninety percent of emergent wetland habitats and more than half the mudflats in the enclosed waters zone have disappeared, while substantial levels of seagrass meadows have been lost. Most of this loss is the

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result of physical displacement from coastal developments, or the result of modifications to other resource zones which eliminate the supply of fresh and salt water to these areas.

For instance, hydrological changes in a watershed drainage may reduce the supply of water or nutrients to distant coastal wetlands and seagrass meadows. In addition, polluted runoff generated within inland watersheds is deposited in these coastal water bodies. Events that sometimes occur offshore, such as oil spills, can also have devastating impacts on California's bay, estuarine, and wetland habitats in the enclosed waters zone. Also, increasing instances are being documented of non-native species being introduced into the enclosed waters zone through ships arriving from foreign waters and discharging bilge wastes. These species may reproduce in large numbers and compete with native species for food and habitat.

Looking Forward

Although some losses continue in small wetland systems, the conversion of major wetlands, bays, and estuaries has largely been abated, and properly designed and monitored mitigation projects may even begin to increase habitat in the enclosed waters zone. Habitat restoration projects, either planned or ongoing, are being pursued for many of the coastal wetlands throughout the State, consistent with the State's policy of no net loss of wetland habitat adopted in 1993. For example, the Sonoma Baylands, Cargill Baylands, Ballona Wetlands, and Batiquitos Wetlands projects may substantially increase habitat values in those areas.

THE NEARSHORE OCEAN ZONE

The nearshore ocean zone, comprised of over 1,100 miles of coastline, extends from such onshore areas as sandy beaches, boulder fields and rocky outcroppings to an ocean floor depth of about 100 meters and the associated kelp beds and sandy and muddy bottoms. Waters of this zone are rich in nutrients from freshwater inflows and upwelling currents, supporting an abundance of habitats and organisms which also offer many economic and recreational opportunities.

Habitat Types

Wave action exerts a strong influence on habitat distribution within the nearshore ocean zone. Fine, sandy beaches often occur in areas where wave action is light, while beaches with more coarse sand are found where wave activity is stronger. Sandy beaches are dynamic habitats in which sediments are constantly shifted down the coast and between deeper and shallower waters. Boulder fields occur in areas of greater wave activity, and rocky outcroppings occur where wave action is the greatest. The pounding surf within boulder fields and rocky shores often creates small habitats known as tidepools, which support creatures uniquely adapted for survival under such extreme physical conditions as temperature variation, salinity, and wave action. Although shoreline habitats may appear distinct from those offshore, they are dependent upon each other, with the exchange of nutrients and organisms among them being common.

Kelp forests, shale, and sandy and muddy bottoms are the dominant habitat types occurring just offshore. Kelp forests are common in areas with rocky substrates and may extend for miles along

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the coast, forming habitats that, in some ways, function similarly to terrestrial forests. Species may be found at different depths within kelp forests, which grow in water depths up to 100 feet. Some organisms prefer the anchor-like holdfasts near bottom sediments, others prefer the stem-like stipes in the mid-water column, and still others mostly inhabit upper canopy areas near the ocean's surface. Shale, also known as hard bottom, occurs in the nearshore ocean zone as a substrate for burrowing organisms.

Sandy and muddy bottoms are common along the entire coast of California. Sandy bottoms are located intermittently along the coast, while muddy bottoms are most common at the mouths of rivers and estuaries, where sediment loads of silt and clay settle out as the water moves further offshore.

Flora and Fauna

California's nearshore ocean zone is rich in biodiversity and commercially important species. Giant kelp, common to many coastal regions, is the largest and fastest growing algae in the ocean. While kelp forests provide refuge and forage areas for many sea creatures, they are also harvested regularly for use in manufactured products, such as cosmetics and ice cream. Commercial and recreational fishing have a long history in California's nearshore ocean zone. Species with current commercial value include the sea urchin, squid, abalone, spiny lobster, California halibut, Pacific mackeral, rockfish, and several species of crab. Commercial importance can vary over time; for example, in just over 20 years, the red sea urchin has risen from virtual obscurity to become California's largest single-species fishery.

Many vertebrates, including fish, birds and mammals, also are common in the nearshore ocean zone. The sandy beaches of Southern California serve as the major spawning grounds for grunion, which wriggle onto beaches during certain full moons to mate and lay eggs. Rockfish, white seabass, lingcod and various perch species are common to kelp forests, while white croaker, halibut and other flatfishes often inhabit muddy and sandy bottoms. Shorebirds, such as sandpipers, godwits and curlews frequent sandy and muddy shores, where they feed on tiny invertebrates buried beneath the sand. Other bird species, including many gulls and the endangered brown pelican, also feed in shallow, nearshore waters.

Several mammal species depend on nearshore ocean habitats for forage and breeding grounds. Harbor seals, sea lions and elephant seals are among the pinnipeds commonly seen along the coast of California. San Miguel Island, located in the Santa Barbara Channel Islands National Marine Sanctuary, is estimated to support the largest concentration of pinnipeds in the world. The California sea otter, a threatened species, occurs locally along the central coast of California, usually in association with kelp forests and sea urchin colonies. Once numbering less than 100, the sea otter population in California is now roughly 2300 individuals. Whales and dolphins swim into nearshore waters, but these species are more common in deeper, offshore waters.

Current Issues

Throughout the world, coastal areas tend to support large human populations. A problem associated with increasing populations is coastal development and increased pollution. Discharge of pollutants from point sources, such as sewage and industrial wastes, is monitored closely in California,

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although the appropriate level of treatment continues to be controversial. Another problem of an international nature is that Mexico's discharge regulations are less strict, which has resulted in some increased pollution levels in the waters offshore San Diego. Waters of the nearshore ocean zone also receive pollution from such sources as agriculture and urban run-off from watersheds in the inland watershed zone. In addition to increased pollution, dredging and filling that accompany coastal construction and development have significantly affected the ecological functioning of many nearshore areas.

In the 1800's, many species of marine mammals which live in the nearshore ocean zone were hunted to near extinction for their fur, meat, and oil. However, enactment of the federal Marine Mammal Protection Act of 1972 now protects these creatures, and many populations have grown significantly in recent years. The population of northern elephant seals, for instance, was once reduced to less than 100 individuals by hunting and now numbers approximately 80,000 in California. Also, California sea lions now number approximately 160,000 along the California coast, with an average annual population increase of about 8 percent (Schultze, pers. comm.).

Some coastal fishery stocks have declined, resulting from a combination of factors such as habitat disruption, changing ocean conditions, and overfishing. Unfortunately, funding limitations have significantly reduced the ability of most State and federal agencies to implement necessary resource assessment and habitat restoration efforts or to fully enforce existing fishery management laws and regulations to help identify changes and, where necessary, reduce the decline of fishery stocks.

Looking Forward

While management guidelines have been formulated for most important fisheries in California, comprehensive management is conducted for only a few, such as northern anchovy, Pacific sardine, and Pacific herring. The State is currently preparing a pilot management plan for the white sea bass and, if successful, similar plans may be developed for other species. A major factor in the success of these plans is adequate funding. Additionally, a variety of efforts are ongoing to address the problems associated with nonpoint sources of pollution. Efforts to identify sources and obtain control of nonpoint pollution are underway by several departments within the Resources Agency, as well as through efforts by departments within the California Environmental Protection Agency.

THE OFFSHORE OCEAN ZONE

The offshore ocean zone of California begins at a depth of about 100 meters and extends to the edge of the Exclusive Economic Zone (200 miles offshore). Most of California's offshore ocean zone lies beyond the continental shelf, although deep submarine canyons split the shelf in some areas and bring the deep ocean environment in close proximity to shore. For example, the Monterey Submarine Canyon in Central California reaches a depth of nearly two miles and approaches within 300 feet of the beach. This diversity of depths, combined with a strong connection to the ecology of both upland habitats and deep ocean waters, creates an environment vital for supporting a diverse biological community and significant economic, recreational, and educational opportunities.

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Productive oceanographic factors, such as major ocean currents, stimulate biological productivity in both nearshore and offshore ocean waters. The California Current is a cold water current that originates north of California and moves southward along the coast, whereas the Davidson Current is a periodic, nearshore current that flows in a northerly direction, carrying warm waters from semitropical seas to southern California. Interactions between the flows of these currents create two distinct marine biological regions along the coast of California. The southern region, extending from the Mexican border to Point Conception near the City of Santa Barbara, is composed of warmer waters and primarily supports temperate and warm water fish and invertebrate species. The central and northern coast region of California, extending from Point Conception to Oregon, contains colder waters and organisms adapted to such conditions. Another oceanographic factor influencing abundance and diversity of biological resources along California's coast is upwelling, the movement of deep ocean waters into shallower, nearshore areas. Upwelling provides essential nutrients needed to support vast populations of microscopic organisms collectively known as plankton. Plankton are a vital component of numerous foodwebs that support important fish, mammal and bird populations.

Habitat Types

The shallower waters of the offshore ocean zone (to a depth of about 600 feet) are relatively warm, receiving an abundant supply of sunlight. These waters are usually high in oxygen content and receive plentiful nutrients from upland runoff and deeper ocean regions on upwelling currents, creating what are generally the most nutrient rich waters in the ocean. In general, as water depth increases, temperature, oxygen concentrations and sunlight decrease. Although nutrients may be plentiful in deeper waters, changes in atmospheric pressure, temperature, and food resources restrict species distributions to specific depths. For instance, many species spend most of their lives within several meters of the water's surface, such as the Pacific sardine, while others live in complete darkness at depths of hundreds of meters, such as the splitnose rockfish and California flashlightfish.

Flora and Fauna

In the relatively shallow waters of the offshore ocean zone, there is an abundance of plankton. Phytoplankton directly harness the power of the sun through photosynthesis, while zooplankton feed upon the phytoplankton. Small and abundant, plankton form the base of many food chains and support such commercial fisheries as herring, mackerel and sardine. In addition to being consumed by small fish, plankton also support shrimp-like crustaceans known as krill, the major source of nutrition for the largest creatures on earth, including blue and fin whales. The offshore ocean zone also supports other important fishery stocks typically restricted to deeper waters, including tuna, swordfish, rockfish, sablefish, Pacific hake and flatfishes.

The abundant food sources in the offshore ocean zone also support other vertebrate populations, including numerous bird and marine mammal species. Several large birds, such as albatrosses, frigatebirds and various gulls, travel many miles from shore into the offshore ocean zone to feed on crustaceans and small fishes. California sea lions and northern elephant seals also travel far out to sea in search of fish and other food sources. Although blue and fin whales are now relatively uncommon in the offshore zone, other marine mammals are commonly found in California's offshore waters, including gray and humpback whales and several species of dolphins and porpoises.

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Current Issues

Similar to other natural areas in California, the offshore ocean zone and its inhabitants are facing increasing pressures from human activities. Dredge disposal, oil and gas operations, shipping operations and military exercises can disturb or harm marine life within this zone. For instance, change in the historical migratory patterns of gray whales along California's coast has been associated with shipping activity and increased noise pollution, while overfishing and nearshore habitat degradation may be adversely affecting populations of several important fishery species. Unfortunately, assessing the health of marine populations is difficult due to the costs associated with assessment and insufficient knowledge about the marine environment and its inhabitants. The data bases and vital statistics regarding many marine species are often limited or non-existent.

The well-being of marine mammals continues to be a major public policy concern. For example, the recent proposal by the Scripps Institution of Oceanography to locate the Acoustic Thermometry of Ocean Climate (ATOC) project within the Monterey Bay National Marine Sanctuary resulted in major opposition from interest groups and the general public. The ATOC project is designed to transmit sound signals to reception sites located in Kauai, Hawaii in an attempt to learn more about global warming. Specifically, the speed of sound through water is measured to determine water temperatures between the California coastline and Hawaii. Opposition resulted in a revised proposal which now includes plans for initial studies to determine if the sound is harmful to marine mammals, and a new preferred alternative with a location outside sanctuary boundaries. The revised proposal has been analyzed through an environmental impact statement prepared pursuant to the requirements of the National Environmental Policy Act.

Looking Forward

There are indications of improving conditions in some aspects of the offshore ocean zone, and ecosystem degradation in others. The most current biological surveys indicate that blue, fin, and humpback whale populations have grown markedly in recent years. The number of gray whales migrating between Mexico and the Bering Sea along the California coast appears to represent those estimated to have existed prior to the onset of commercial whaling activities in the Pacific Ocean. Consequently, the grey whale has recently been taken off the federal endangered species list. Associated with this resurgence of marine mammal populations has been a corresponding growth in the west coast "whale-watching" industry.

Unfortunately, a study released by Dr. Dean Roemmich and Dr. John McGowan of Scripps Institution of Oceanography indicates that warming trends in Southern California waters are resulting in substantial zooplankton kills off the west coast. These water temperature increases may be robbing surface water of valuable nutrients needed to sustain the zooplankton populations. The phenemenon, which is cited as occurring over the last 10-30 years, is having a detrimental impact on higher level marine resources, such as fishery and seabird populations, that previously existed off the coast. (Roemmich, 1995).

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CONCLUSION

California's four resource zones are dynamic, interdependent, and delicately balanced, forming one of the biologically richest ecosystems in the world. Management of the ocean's resources must take into consideration this interdependence and address any impacts generated in one resource zone which may ultimately affect resources in another zone.

The ocean ecosystem also contributes substantially to the economic health of the State. However, numerous human activities are exerting increasing pressures on the marine environment, which can negatively impact commercially valuable ocean industries. Although coastal areas have supported human activities for years, environmental impacts have grown significantly with increased urban and rural pressures for land, resources and recreational areas. As a result, it has become increasingly important that California's ocean ecosystem be managed in an environmentally and economically sound fashion.

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