Part I: Carpinteria Salt Marsh: Background and Natural History
B. ENVIRONMENTAL SETTING
Carpinteria Salt Marsh is located at latitude 34'0 24' N and longitude 119'0 31' 30" W, about 12 miles (19.4 km) east of Santa Barbara and immediately west of the City of Carpinteria, along the South Coast of Santa Barbara County, California (Fig. 1). This estuary is characterized by a series of natural and artificial channels and adjacent estuarine emergent wetlands that occur at the base of the watersheds of Franklin and Santa Monica creeks (Fig. 5). These streams and several smaller channels drain portions of the southern slope of the Santa Ynez Mountains and the Carpinteria Valley. The latter is a part of the coastal plain of the South Coast, and is bounded on the north by the foothills of the Santa Ynez Mountains, on the south by the Pacific Ocean, on the east by Rincon Mountain, and on the west by Toro Canyon. The Santa Ynez Mountains north of the Valley reach a height of about 3900 feet (1189 m) and are the westernmost portion of the Transverse Ranges.
The Carpinteria Valley is characterized by a Mediterranean climate with mild, moist winters and moderately warm, generally rainless summers. Point Conception, which approximates the western-most extension of the Santa Ynez Mountains nearly 56 miles (90.1 km) west of Carpinteria Salt Marsh, has been identified as a major climatic boundary in the region, separating the relatively cool and moist conditions to the north from the warmer and drier conditions to the east and south. In the Santa Barbara County area, the Santa Ynez Mountains separate northern and southern California biogeographic regions. Thus, Carpinteria Salt Marsh is located in the northwestern portion of the southern California Mediterranean climatic and biogeographic regions (Ferren 1985).
The climate of the Carpinteria Valley is influenced directly by the prevailing westerly transoceanic air currents. However, during winter months the regional trend is for night and early morning offshore air movement driven by continental cooling. By afternoon, the prevailing westerly winds and interior convection give rise to regional onshore winds, or occasionally winds that blow parallel to the coast. During spring months the daytime wind patterns are similar to those of winter, but they are stronger. Summer months are characterized by stabilized weather, having calm morning conditions and light to moderate onshore air movement in the afternoon. During fall months continental cooling generates offshore breezes at night that can be strong in large canyons such as that of Santa Monica Creek, which drains directly into the estuary.
Fog is an important characteristic of the Carpinteria Valley. The coastline of southern California is subjected to an inversion layer that traps cool, moist air at low elevations, producing fog or low clouds during the night and early morning hours. As the inversion layer rises slowly during the day, the fog evaporates. Fog develops more frequently during the late spring and early summer when warmer air comes in contact with cool ocean water. Fog is then drawn over land, a process usually associated with seasonal warming of the interior land. As ocean temperatures increase during the summer, the occurrence of fog decreases.
Temperature data for Santa Barbara reveal that the region is characterized by a low seasonal range in temperature. This low range is illustrated by an average temperature in the warmest month (August) that is approximately 140F higher than in the coolest month (December) (Ferren 1985). Although temperatures below freezing are recorded for the coastal plain, the average minimum temperature in the coldest month is above freezing. Similarly, although there are temperatures recorded over 1000F, the average maximum temperature approximates 750F and occurs in August. These moderate temperature conditions are due in large part to the maritime location of the region.
Precipitation in the Santa Barbara region has a Mediterranean pattern of winter rain and summer drought. Rainfall records for the region reveal that nearly 90% of the average monthly precipitation falls during the six-month period of November through April. The average annual precipitation at Santa Barbara for the period 1967 to 1979 was 17.8 inches (45.6 cm); however, fluctuations in annual precipitation are considerable as illustrated by 7.83 inches (19.9 cm) in 1975-76, and 36.67 inches (93.1 cm) in 1982-83 (Ferren 1985). Most rain-bearing storm systems come from the northwest in winter. Infrequent summer rains may occur from tropical air masses but are generally of little consequence to plant growth.
In summary, the Mediterranean climate of the coastal, southern California biogeographic region in which Carpinteria Salt Marsh occurs is characterized by coastal winds and morning fog, consistently mild air temperatures that rarely dip below freezing, and variable, largely winter rainfall.
6.0 Geomorphology, Geology, and Drainage
The Carpinteria Valley or basin is an east-trending, northward verging, faulted syncline (Fig. 6) containing shallow marine and non-marine, Pleistocene sediments from several hundred to several thousand feet thick that are deposited on older, folded rocks (Jackson and Yeats 1982). Approximately one million years ago the Carpinteria area was the northern margin of the offshore Ventura basin. Uplift north of the Red Mountain Fault separated the Carpinteria basin, structurally and topographically, during middle to late Pleistocene time. Today the basin is located along the northeastern coast of the Santa Barbara Channel between the Santa Ynez Mountains to the north and the Ventura basin to the south. With sedimentation from the emergent landscape to the north, the Carpinteria basin became quite shallow and portions of it were eventually covered by a large alluvial fan complex. The Carpinteria basin eventually filled with sediment and formed the Carpinteria Valley. Movement along the red Mountain Fault has caused the structural isolation of the Carpinteria basin, although various faults within the basin control its shape (Jackson and Yeats 1982). Carpinteria Salt Marsh is what remains of a larger historic bay or estuary that formed in the basin.
Varying erosional and depositional processes occurred along the South Coast depending on local geological phenomena. For example, in the Goleta basin west of Carpinteria, streams excavated valleys that were graded to sea level more than 200 feet (61 m) lower than today (Upson 1949). However, in the Carpinteria basin deposition may have continued through Pleistocene times, perhaps as a result of intermittent subsidence of the area along the Rincon, Carpinteria, or Red Mountain faults and the continued access of the basin to the ocean (Ferren 1985). In discussing the history of infilling in Goleta Slough, Lohmar et al. (1980) concluded that many of the small estuaries and lagoons along the coast of southern California were probably created approximately 5-7,000 years ago when post-glacial rising sea level flooded the incised drainages cut during the Wisconsin glacial period (10-60,000 years ago). This rise is sea level averaged approximately 40 feet (12 m) each 1000 years until about 5000 years ago when sea level approached that of today (Zedler 1982). Based on the evidence available for the Carpinteria Valley, it appears that a marine basin or estuarine lagoon may have characterized the region long before this gradual flooding event. Robert Norris (pers. comm., UCSB Dept. Geol. Sci., 1985) suggests, however, that the present estuary at Carpinteria is the result of the deposition of a sandbar caused by a rocky reef. The reef, apparently part of the southern limb of the syncline, occurs just beyond the mouth of the estuary and provides enough of a wave barrier to cause deposition of the sandbar behind it and a realignment of the coast.
The Carpinteria Valley (basin) includes the lowest parts of a major drainage system. This system contains the watersheds of Rincon, Gobernador, Carpinteria, Franklin, and Santa Monica creeks, and streams in Arroyo Paridon and Toro Canyon. These streams are relatively short; however, all but two have separate drainage basins. They generally have perennial flows in the headwater areas, but rarely have natural perennial surface flows across the coastal plain. The groundwater basin of this system occurs adjacent to the area of consolidated rocks (the principal area of surface water runoff) and consists of two parts. The marginal parts of the basin cover about 7 sq. mi., extend along the base of the mountains, and are underlain by unconsolidated deposits. These deposits contain a significant amount of water and are the only ones that absorb large amounts of surface water runoff from rain and streams. The groundwater basin recharge area was covered historically by mostly grassland or coastal sage scrub, but today is characterized by agriculture or other forms of development. The lower portion of the groundwater basin covers about 5 sq. mi. and also is underlain by unconsolidated deposits. Impermeable beds occur near the surface and prevent the downward movement of rain, irrigation, and stream water into the deeper groundwater-bearing beds. This water is discharged directly from the shallow groundwater body. Carpinteria Salt Marsh occurs in the area of impermeable beds and receives discharges from the shallow groundwater body into lower stream channels and at seeps along the northwestern margin of the estuary. This discharge is one source of nutrient enriched water that can pollute the estuary.
The watershed of Carpinteria Salt Marsh is confined to the drainages of Franklin and Santa Monica Creeks, and a smaller unnamed drainage to the west of Santa Monica Creek (Fig. 5). The Franklin Creek sub-watershed drains approximately 2,732 acres (1107 hectares) and reaches an elevation of 1,746 feet (533 m). The Santa Monica Creek sub-watershed drains approximately 3,853 acres (1561 hectares) and reaches an elevation of 3,853 feet (1175 m). Santa Monica Creek extends about 5 miles (8 km) southward from the crest of the watershed to Carpinteria Salt Marsh, where it joins Franklin Creek to form the "Main Channel", extending to the mouth of the estuary. Franklin Creek extends about 4 miles (6.5 km) southward from the foothills of the Santa Ynez Mountains to the confluence of the tidal portion of the creeks. Historically, Carpinteria Creek to the east and Arroyo Paridon to the west also flowed into this estuary, but this situation occurred prior to extensive infilling due to the deposition of alluvial fans, and their corresponding wetland deltas, and prior to urbanization of the Carpinteria Valley (Fig. 5).
7.0 Biological Resources
The rich, often narrowly-restricted (e.g., estuarine emergent wetland), and even rare and endangered (e.g., Salt Marsh Bird's-beak and Light-footed Clapper Rail) biological resources of Carpinteria Salt Marsh are reflective of the geologic context (structural basin), geographic position (transition between northern and southern California), and climatic conditions (Mediterranean) that influence the formation of this ecosystem. Carpinteria Salt Marsh and Goleta Slough, located west of Santa Barbara, are the north-westernmost large estuaries in the southern California biogeographic region. Because of the geographic position of these estuaries, the northwestern geographic limits for many species (e.g., Estero Seepweed [Goleta Slough], Shoregrass, Belding's Savannah Sparrow, and Light-footed Clapper Rail [Carpinteria Salt Marsh]), which are characteristic of southern California estuaries, occur at Carpinteria or Goleta. Furthermore, because both estuaries are geologic structural basins along the coastal plains adjacent to the Santa Ynez Mountains, they have similar features such as large deltaic deposits and hyperhaline or euryhaline soils. Such features of Goleta Slough and Carpinteria Salt Marsh are different from other types of estuaries including many bay and lagoon types and the mouths of rivers, canyons, and dune streams. Thus, the special biological and physical characteristics of Carpinteria Salt Marsh must be taken into account when management programs are proposed for the estuary and the CSMR.
The flora, vegetation, and habitats of Carpinteria Salt Marsh (Fig. 7) have been evaluated by Ferren (1985) and others (e.g., Callaway et al. 1990, Callaway and Sabraw 1994, Pennings and Callaway 1992). Carpinteria Salt Marsh Reserve and vicinity contains both upland habitats (e.g., dunes, alluvial fans/deltas, berms, roadside, and dredge spoil) and wetland habitats (e.g., intertidal and non-tidal vegetated and non-vegetated flats, ditches, banks, slopes, and depressions), and deepwater habitats (e.g., estuarine, shallow subtidal-channels and marine, offshore subtidal-rocky-reef). The predominant vegetation/habitat form is estuarine emergent wetland dominated by Pickleweed (Salicornia virginica).
The flora of Carpinteria Salt Marsh has been of interest to many scientists (see Appendix A, CSMR Bibliography) for at least 90 years. Historical records and collections have made possible a reconstruction of the floristic diversity of the estuary and vicinity before many impacts of urbanization occurred. A synopsis of the findings (Ferren 1985) has shown that at least 55 vascular plants families containing 153 genera and 252 species are know to occur or have occurred at Carpinteria Salt Marsh (see Appendix B, Checklist of Vascular Plants), including the estuary's historical limits and adjacent sand dunes. Of those plants, 104 species (45%) are native. Eleven species listed for Carpinteria Salt Marsh and vicinity are possibly extirpated, representing 17% of the 64 native wetland species. Eleven species growing presently at the estuary are regionally rare plants, and two species (Salt Marsh Bird's-beak and Salt Marsh Goldfields) are considered endangered.
The fauna of Carpinteria Salt Marsh also has been studied by many researchers from UCSB and other institutions (see Appendix A, CSMR Bibliography). At least 190 bird species, 37 fish species, 11 mammal species, 5 herpetofauna species, and over 100 invertebrate species have been observed, collected, or reported from Carpinteria Salt Marsh (see Appendix C, Checklist of Invertebrate and Vertebrate Animals). The estuary is important for resident species including (1) birds such as many shorebirds (e.g., Marbled Godwits), wading birds (e.g., Great Blue Herons), gulls and terns, and passerines (e.g., Belding's Savannah Sparrows); (2) fish such as Arrow Gobies, and California Killifish (Fig. 8); and estuarine-restricted crustaceans (e.g., Fiddler Crabs and Ghost Shrimp) and molluscs (e.g., California Oysters) (see Fig. 9). The estuary also provides important habitat for migratory birds and habitat for seasonal use by species of special interest such as regionally-declining and threatened or endangered bird species including Long-billed Curlews, Least Terns, and Snowy Plovers (see Part II, 3.0 Endangered and Special Interest Species Protection and Recovery Program). Carpinteria Salt Marsh also provides important nursery functions for various marine fish including Diamond Turbot, Stary Flounder, and the economically-important California Halibut (Fig. 8).
Thus, Carpinteria Salt Marsh is an estuary that is characteristic of the southern California region as well as unique in its environmental setting. Its high level of ecosystem functions illustrates the estuary's importance among the remaining examples of such ecosystems in the urbanized coast of southern California. A comprehensive management plan for the entire estuary, as proposed by Macdonald (1976), Doerner (1979), and Ferren (1985, 1987d&e), would provide a mechanism to protect and when possible restore the natural resources and ecosystem functions, and provide a framework for their use in research, education, and public service.
8.0 Ecosystem Functions and Socio-Economic Values
Carpinteria Salt Marsh provides many important ecosystem functions that can be categorized into several major groups: hydrology, water quality and nutrient cycling, food chain support, and habitat. The hydrology function at Carpinteria includes shoreline protection from major winter storms, storm runoff capacity during flooding, and protection of groundwater resources as a transition between saline and freshwater resources (e.g., USDA Soil Conservation District 1976a&b, 1978, 1981, 1983, 1984). The water quality and nutrient cycling function includes improvement in water quality through conversion or assimilation of pollutants in watershed runoff and ground water seepage and the cycling of nutrients among watershed, estuarine, and marine sources (e.g., Page in press, 1990b, 1993a, 1995c).
The food chain support function at Carpinteria is complex and wide-reaching (e.g., Page 1996a, Page et al. 1990a). It includes the assimilation of nutrients and detritus by primary producers such as micro-organisms and plants through the growth and reproduction of various macro-invertebrates such as molluscs and arthropods. It also includes the predation on marsh organisms by estuarine-restricted vertebrate animals as well as estuarine visitors such as marine fish, migratory birds, and local mammals. Thus, as with the nutrient cycling function, the food chain function extends beyond the estuary and into the surrounding region and beyond.
The habitat function includes both extant and historic types. Existing habitat functions are perhaps highest for endangered species including nesting habitats for resident endangered birds (e.g., Light-footed Clapper Rails and Belding's Savannah Sparrows) and endangered plants (e.g., Salt Marsh Bird's-beak and Salt Marsh Goldfields). Other existing habitat functions at Carpinteria Salt Marsh include: habitat for preservation of native biodiversity such as endemic, estuarine-restricted organisms; nursery functions for marine fish such as California Halibut and Diamond Turbot; and habitats for migratory birds such as various shore birds and ducks. Historically, Carpinteria Salt Marsh also provided habitat for anadromous fish including Steelhead Trout that once spawned in Santa Monica Creek and for an endangered brackish-water fish, the Tidewater Goby (see Appendix C, Checklist of Invertebrate and Vertebrate Animals). Steelhead Trout can enter the estuary, but because of stream alterations can no longer reach watershed sites to spawn; and Tidewater Gobies have not been collect for approximately 70 years, apparently because brackish-water habitats are no longer sustained in the estuary.
Socio-economic values of Carpinteria Salt Marsh can be grouped into two major categories: consumptive and non-consumptive types. Consumptive values include the current important role of the estuary in the local sports fishery for California Halibut, because of the growth of young-of-the-year individuals in estuarine channels. Consumptive values also include the historic local role in production of salt and oysters and the growth of culturally important plants (e.g., Anemopsis californica [Yerba Mansa]) used by Chumash and perhaps earlier cultures.
Non-consumptive values include research and educational activities (see Part II, 6.0 Research Program, 7.0 Education Program, and 8.0 Public Service Program) conducted by the UC Natural Reserve System and other public interest groups, and passive recreational activities such as painting (e.g., the Oak Group, Plein Air Artists, and Painters of California Reserves), bird watching (e.g., Santa Barbara Audubon and Lompoc Audubon), and guided tours (e.g., Santa Barbara Botanic Garden and Santa Barbara Museum of Natural History). Another important socio-economic value that is less tangible is the aesthetic value of the estuary and its contribution to the overall quality of life in the Carpinteria Valley for residents as well as visitors. This value is clearly demonstrated by the enormous public support and decade-long investment in effort and money to purchase, restore, and provide interpretive access to the Ash Avenue Wetlands along the eastern margin of Carpinteria Salt Marsh (see Part II, 12.0 Restoration and Enhancement Program).
The broad-based desire to protect and when necessary restore overall high-quality ecosystem functions, socio-economic values, and aesthetic importance of Carpinteria Salt Marsh is confirmation of the rationale for developing an ecosystem-based management plan.