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California State Waters Map Series—Benthic Habitat Characterization in the Region Offshore Humboldt Bay, California

Open-File Report 2024-1047
Prepared in cooperation with California State University, Monterey Bay, and the California Ocean Protection Council
By:
https://doi.org/10.3133/ofr20241047

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  • Document: Report (2 MB pdf)
  • Data Releases:
    • USGS Data Release - Bathymetry, backscatter intensity, and benthic habitat offshore of Cape Mendocino, California
    • USGS Data Release - Bathymetry, backscatter intensity, and benthic habitat offshore of the Eel River, California
    • USGS Data Release - Bathymetry, backscatter intensity, seismic reflection, and benthic habitat offshore of Arcata, California
    • USGS Data Release - Bathymetry, backscatter intensity, seismic reflection, and benthic habitat data offshore of Eureka, California
  • Download citation as: RIS | Dublin Core

Abstract

Coastal and Marine Ecological Classification Standard (CMECS) geoform, substrate, and biotic component geographic information system (GIS) products were developed for the California State Waters of northern California in the region offshore of Humboldt Bay. The study was motivated by interest in development of offshore wind-energy capacity and infrastructure in Federal waters offshore. This project, carried out by the U.S. Geological Survey (USGS), resulted in four data releases for individual map blocks that are part of the “California State Waters Map Series”: (1) Offshore of Arcata, (2) Offshore of Eureka, (3) Offshore of the Eel River, and (4) Offshore of Cape Mendocino. The study area consists of 436 square kilometers of multibeam echo sounder (MBES) data acquired by Fugro Pelagos, Inc., in 2007. Towed camera-sled video was acquired in 2009 and 2010 to supervise the classification of the MBES data into habitats, and single channel sparker data were collected to calculate sediment thickness above the transgressive unconformity. Using video observations of habitat as ground truth, derivatives of the MBES data were classified into 3 seafloor character types (hard-rugose, hard-flat, and soft-flat), 26 induration-slope-depth groups, and 15 geoforms. The study area substrate is predominantly soft-flat sediment (mud and fine sand) covering 73.6 percent of the area. Hard-flat substrate areas, predominantly coarse sediment in scour depressions, cover 5.4 percent of the study area. The hard-rugose substrate areas are primarily outcrops of layered sedimentary bedrock and constitute 20.9 percent of the study area. Fifteen geoforms were identified in the analysis. The predominant geoforms mirror the seafloor character results, shelf geoforms, rock outcrop geoforms, and scour depression geoforms. Rock and scour areas are restricted to the southern portion of the study area off Cape Mendocino where uplift has exposed bedrock. On the flat shelf area post-transgressive sediment varies in thickness from 1.7 meters (m) nearshore to 28.1 m offshore.

Suggested Citation

Cochrane, G.R., 2024, California State Waters Map Series—Benthic habitat characterization in the region offshore Humboldt Bay, California: U.S. Geological Survey Open-File Report 2024–1047, 16 p., https://doi.org/10.3133/ofr20241047.

ISSN: 2331-1258 (online)

Study Area

Table of Contents


  • Acknowledgments
  • Abstract
  • Introduction
  • Purpose and Scope
  • Methods
  • Results
  • Summary
  • References Cited
Publication type Report
Publication Subtype USGS Numbered Series
Title California State Waters Map Series—Benthic habitat characterization in the region offshore Humboldt Bay, California
Series title Open-File Report
Series number 2024-1047
DOI 10.3133/ofr20241047
Publication Date November 26, 2024
Year Published 2024
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Pacific Coastal and Marine Science Center
Description Report: vi, 16 p.; 4 Data Releases
Country United States
State California
Other Geospatial Humboldt Bay
Online Only (Y/N) Y
Additional publication details