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Pacific Coastal & Marine Science Center

Monterey Bay Studies

Monterey Bay Studies


Monterey Bay National Marine Sanctuary Project, 1999

Accomplishments (up to 1999)

Mapping by sidescan sonar and multibeam bathymetry has revealed the major rock units that outcrop on the Sanctuary's seafloor. Young sand bodies are marked by high acoustic-backscatter regions that change shape with time and that overprint the rock outcrops. Faults, some that may be active earthquake faults, can be seen in the imagery as well as in vertical acoustic-reflection profiles that are collected concurrently with side-scan sonar data.

Samples of seafloor sediments have been collected by box-coring at over 400 sampling sites on the continental shelf in the greater Monterey Bay area. Analysis has revealed the partitioning of sediment types into patterns that are influenced by water depth, nearby sediment sources, and wave-energy climate. Various analyses, including isotope sedimentation-rate studies, micropaleontologic studies, and natural and anthropogenic hydrocarbon signatures, are underway.

A transect of environmental-monitoring moorings have operated since August, 1996. They measure prevailing currents, temperature, salinity, waves, water clarity, and they collect sediment fallout in sediment traps. To record similar information in the nearshore zone, solid-mounted instruments were installed in October, 1997. These moorings collect information from near-surface, mid-water, and near-bottom depths at four locations south and west of Santa Cruz and have revealed an extraodinarily high rate of sediment transport in suspension. The first 8 months of recording suffered from anomalously high barnacle growth rates that impeded some of the instrument recording.

Another similar mooring in the axis of Monterey Canyon at 3200 meters depth is now in its fourth year of recording. It is believed to have produced the longest record of environmental conditions in a canyon axis.

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