Boundaries

This coastal ecoregion begins just south of Monterey, California and encompasses southwestern California and the entire Baja Peninsula in Mexico. The Channel Islands and Isla Cedros are also part of this ecoregion.

Topography

The Peninsular Ranges extend down the center of the ecoregion from southern California through the length of the Baja California Peninsula. Elevations reach over 3300 m asl. Some of the ranges within this chain include the Laguna Mountains, Santa Rosa Mountains, Sierra de la Giganta, Sierra San Pedro Màrtir, and Sierra de Juariz.

Freshwater habitats

There are almost no permanent watercourses in Baja California. Yet, in spite of the arid conditions, the ecoregion contains high grade mountain creeks, coastal plain creeks, springs, and coastal lagoons.

Terrestrial habitats

In the northern part of the ecoregion, coastal sage scrub, chamise chaparral, and oak woodlands predominate over much of the landscape. Other habitats include montane conifer forests, Torrey pine (Pinus torreyana) woodlands, cypress (Cupressu spp.) woodlands, riparian woodlands, and grasslands. Western Baja is dominated by xeric scrubs, including Ambrosia camphorata, Erodium cicutarium, Astragalus prorifer, and many species of cacti. A majority of the perennial vegetation are epiphytes like Tillandsia recurvata and Rocella tinctoria that grow in low, humid areas. The eastern side of the Peninsular Ranges is part of the Sonoran Desert, and includes species like ironwood (Palo fierro), cardón (Pachycereus pringlei), and saguaro (Carnegiea gigantea spp.).

Description of endemic fishes

Most of the endemism of the region is found in the Los Angeles basin, in California. There are four known endemic fish species in the ecoregion. Endemic fish that occur in the Los Angeles basin include the Santa Ana sucker (Catostomus santaanae) and California killifish (Fundulus parvipinnis). Peninsular clingfish (Gobiesox juniperoserrai), killifish (F. lima), threespine stickleback (Gasterosteus aculeatus microcephalus), and San Pedro Mártir rainbow trout (Onchorhynchus nelsoni) are also endemic to the ecoregion.

Ecological phenomena

The freshwater fish fauna include genetically important populations as well as species with marginal distributional records.

Justification for delineation

Ecoregion delineations were based on qualitative similarity/dissimilarity assessments of major basins, using the standard administrative hydrographical regions of the Mexican federal government.

Level of taxonomic exploration

Excellent