The cave complex on the UCSC Campus Reserves supports the rarest suite of fauna on all of the UCSC Campus lands. Yet, there is relatively little known about the cave fauna and their distribution and abundance. Human impacts through trespass and potential groundwater contamination pose potential threats to the unique organisms that live in the caves. As such, caves on the Campus Reserves are not to be used for recreational opportunities. In 2001 Darrell Ubick authored a white paper on the invertebrate fauna found in the Cave Gulch cave system. Below, is the introduction to the paper (a complete copy can be downloaded as a PDF by clicking here).
The importance of the cavernicole fauna of the Santa Cruz region has long been recognized. The isolation of this karst, being the only sizable exposure in the Coast Ranges, as well as its proximity to spreading urbanization, has certainly contributed to the attention it has received. The first systematic study of this biota, conducted over 4 decades ago, was by Graham, who later published a series of papers on the general biology of several species (Graham, 1963, 1966, 1967, 1968a, 1968b). Starting in the late 1960’s, Briggs and his students, including myself, began exploring these caves and focused on the opilionids and other arachnids, which contributed to some taxonomic studies (Briggs, 1968, 1971, Ubick & Briggs, 1989). In 1979, Rudolph and his team surveyed the caves and incorporated the results into an unpublished manuscript on the cave fauna of California (Rudolph et al, MS). As plans developed to deforest the Cave Gulch area, in the late 1980’s, Briggs and I conducted additional surveys and updated the species list (Briggs & Ubick, 1988). The present work includes data from all of the above studies along with two recent surveys conducted during July and December 2001.
The Cave Gulch caves occur in metamorphosed limestone which lies on the Salinian Block, west of the San Andreas Fault. As they are located at relatively low elevations, between 100-170 m, they were subjected to periodic inundation during the late Tertiary and early Quaternary. These inundations were caused by changes in sea levels which resulted in a series of marine terraces. The caves are located on one of these, the Blackrock Terrace, which is believed to be about 1 million years old. Thus, it is only after this date, as the sea level dropped, that the caves would have been formed, dissolved out of the limestone, and subsequently populated by organisms (Tinsley, 1985). The relative ages of the caves have been estimated by their elevations from the canyon floor. As both IXL and Bat Caves are located highest on the canyon walls, they are believed to be the oldest. Similarly, Dolloff and Empire Caves, located closest to the stream channel, are considered the youngest, with Stump and Stearns Caves being of intermediate age (Rogers, 1983). Human interaction with these caves has been poorly recorded. The best known is Empire Cave, which was first mentioned in 1872. Little has been recorded of the others except that IXL and Dolloff were both discovered in the 1950’s (Halliday, 1962).