Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
  • BCO-DMO Curation Notes
• Related Publications
• Parameters
• Instruments
• Project Information
• Funding

Rock Strength 
We quantified the strength (friability) of intertidal rock substrates using a mechanical sclerometer configured as a scratch tester. This approach resembles Mohs hardness testing, however instead of switching between materials of varying hardness, we used a constant scratching tool—a 1 mm diameter tungsten carbide tip—and increased the applied force until the tip produced a visible scratch. For each trial, we aimed to create a scratch approximately 2 cm in length, although surface conditions sometimes required shorter passes. We repeated each test at progressively higher forces to identify the minimum force necessary to initiate a scratch.

We measured friability at 38 sites along the Pacific coastline of California and Washington (see map). Sites were selected based on three criteria: accessibility, presence on geologic maps, and prior sampling of marine community composition, which allowed us to link our measurements with regional monitoring programs (aka MARINe). At each site, we targeted mid-intertidal bench habitats with low to moderate slopes and sampled during low tide to maximize surface dryness. For general surveys, we performed at least three scratch tests per rock type. For more detailed surveys, we increased sampling effort to a minimum of twelve measurements per rock type.

In the field, we assigned each surface to a broad rock categories. Although we consulted geologic maps when available, these maps typically describe formations above the high-tide line and often fail to resolve intertidal substrates, which can differ substantially and are frequently labeled as undifferentiated “bedrock.” To maintain consistency, we classified rocks into the following categories: black, striated black, grey, green, striated green, conglomerate, metamorphic, sandstone, granodiorite, mudstone, siltstone, embedded cobblestone, and rounded cobble. Rocks were then described in more detail in the notes. 

No pre-processing beyond data cleaning was performed on these data. 

This section documents curation actions performed prior to publication review with the submitter, and additional information relevant to understanding and reusing this dataset. It distinguishes changes made to the submitted (meta)data from unresolved issues and/or enhancements that improve future reuse and interoperability.

CURATION ACTIONS PERFORMED ON DATA

- Loaded BroadScale_SubstrateData.csv, setting empty string and "nd" as missing values
- Converted sampling_date column from M/D/YYYY string format to ISO 8601 date format (YYYY-MM-DD)
- Converted data_entry_date column from M/D/YYYY string format to ISO 8601 date format (YYYY-MM-DD)
- Renamed resource broadscale_substratedata to 1008814_v1_broadscale

CURATION ACTIONS PERFORMED ON METADATA

- BCO-DMO's standard metadata entry and text formatting steps were performed. See: https://www.bco-dmo.org/how-to/standard-curation-edits

ISSUES POTENTIALLY IMPACTING REUSE

NA

NSF Award Abstract

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).

Human actions impact marine ecosystems in a variety of ways, including shifting wave and current dynamics through global warming and altering the composition of the ocean floor. These changes, in turn, affect the location and distribution of marine communities. For soft-sediment communities, such as sandy beaches, the interaction between fluid forces and sediment disturbance is well understood. This allows scientists to measure sediment mobility and to create detailed predictions of the impact of human activities on these ecosystems. To date there are no measurements analogous to sediment mobility available for marine hard rock ecosystems. This research will investigate a potential measurement system which connects the forces of waves and currents to the resulting erosion of hard rock substrates and will test and evaluate how these disturbance patterns govern the distribution of communities themselves. By developing and testing this substrate mobility metric, this research will open new avenues of investigation for core ecological hypotheses. In addition, this work will allow managers, conservationists, and engineers to better predict the impact of human-generated change on hard rock marine communities. This project will also support the training and education of groups underrepresented in the geosciences through (1) field and data analysis experience via Research Experiences for Undergraduates summer programs, (2) professional development via mentoring relationships between the fellow and undergraduate trainees, and (3) the expansion of their professional network via cross-institutional coordination.

Disturbance, including fluid forces via waves on rocky shores, is well understood as a community organizing and structuring force. Foundational concepts within ecology, such as Connell’s Intermediate Disturbance Hypothesis and Menge and Sutherland’s Competition/Predation/Disturbance model, recognize that communities exist within a complex mosaic of physical and biological disturbance. This mosaic presents challenges when measuring disturbance regimes since the scales, causes, and consequences of disturbance vary between systems. However, in the marine environment, substrate mobility represents an explicit measure of disturbance impact present across marine ecosystems. This project will determine how to measure substrate mobility on hard substrates through collaboration with USGS geologists. In addition, this research will investigate a mechanism for disturbance via substrate mobility on benthic organisms through lab experiments and use field surveys to compare patterns of substrate mobility with the distribution of benthic communities and species functional groups. Explicitly quantifying the realized movement of hard substrate in response to fluid forcing integrates hard substrates into the already well understood sediment disturbance paradigm. This results in a universal framework of marine disturbance that is potentially revolutionary as it allows for comparative questions spanning a huge diversity of marine ecosystems, from coral reefs to the abyssal plain. This mechanistic framework provides a new connection between the disciplines of geomorphology and marine ecology.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.