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Monterey Bay Studies

Monterey Bay Studies


Monterey Bay National Marine Sanctuary Project, 1999

Characteristics of Surface Sediment on the Monterey Bay National Marine Sanctuary Shelf - Carmel to the Golden Gate

by Brian D. Edwards, James V. Gardner, and Jamie L. Stocking


This on-going study is part of a larger multi-disciplinary and multi-agency effort to map characteristics of biohabitats on the Monterey Bay National Marine Sanctuary continental shelf. We collected sediment samples at approximately 400 station locations from Carmel to the Golden Gate using a sampling design based on the EPA/EMAP grid. The design allows us to statistically evaluate the distribution of many attributes including textural variables (e.g., mean grain size, sorting) and physical properties (e.g., wet bulk density) of shelf sediment. Correlation of these variables combined with interpretations from high-resolution seismic-reflection profiles, bottom photographs collected simultaneously with sampling, and available swath-mapping coverage allow us to map facies distributions and draw inferences as to areas of erosion, deposition, and sediment bypass.

As an example of this data set, preliminary mapping based on more than 100 surface samples shows a nearshore modern sand belt, a mid-shelf mud-rich belt, and an outer shelf (relict?) sand belt. First order trend-surface analysis of mean grain size throughout the study area reveals regional coarsening toward the Golden Gate. Residuals on the trend (differences between observed values and trend values) identify concentrations of coarse-grained sediment offshore Half Moon Bay and Monterey and concentrations of fine-grained sediment offshore Pigeon Point and the mid-shelf region west of the Salinas River mouth that are not predicted by the trend.

This abstract is from Monterey Bay National Marine Sanctuary Symposium, Sanctuary Currents '98, Human Influences on the Coastal Ocean, Poster Session, 1998.

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