Supported Survey Methods
MERMAID Collect supports six widely used coral reef survey methods—each with its own built-in data entry form designed to match how you collect data in the field. Whether you're recording fish biomass, benthic cover, or bleaching severity, MERMAID makes it easy to enter structured, high-quality observations directly into the platform.
Types of Survey Methods Supported for Data Collection
You can enter data for any of the following methods in MERMAID—online or offline—and get automated built-in validation and real-time reef health metrics. Read more in Learning About Our Reef Health Metrics.
Survey Method | Description | Supports | Metric Summaries | Links to Resources |
Fish Belt | Collection of individual fish count per size class by species (or genus, family) along a belt transect with a fixed belt width. | Fish name, count and size data entry and real-time biomass and abundance calculations. | Fish biomass (kg/ha) and abundance (individuals) at three levels—total, by trophic group, and by family—using Bayesian length-weight relationships. | Method described in: Ahmadia et al. 2013 |
Benthic Point-Intercept Transect (PIT) | Collection of benthic attributes at a fixed interval (e.g., every 0.1 m or 0.5 m) along a transect line. | Point-based benthic data entry and real-time percent cover calculations and attribute classification. | Percent cover of top-level benthic groups. | Method described in: Ahmadia et al. 2013 |
Benthic Line-Intercept Transect (LIT) | Collection of continuous benthic attributes and their lengths (cm) as they appear along a transect. | Segment-based benthic data entry and real-time percent cover calculations and attribute classification. | Percent cover of top-level benthic groups. | Method described in: Loya and Slobodkin 1971, Loya 1972 |
Benthic Photo Quadrat | Collection of a set of point-based observations identified per photo quadrat (e.g., 1 m²) taken at a fixed interval (m) along a transect. | Photo upload and storage, point-based benthic data entry and AI-powered Image Classification (Beta). You can choose:
| Percent cover of top-level benthic groups. | Method described in: Preskitt et al. 2004 |
Bleaching (Rapid Survey) | Haphazard quadrat collection to record coral colony counts by genus and bleaching severity category (i.e., normal, pale, 0-20% bleached, 21-50% bleached, 51-80% bleached, 80-100% bleached, and recently dead), and estimate benthic cover of key groups (i.e., hard coral, soft coral, macroalgae). | Entry of colony count per coral genus per bleaching severity category, and benthic percent cover entry. Also real-time average bleaching severity and benthic percent cover calculations. | Bleaching severity by coral genus and percent cover of key benthic groups. | Method described in: Mc Clanahan et al. 2004, Mc Clanahan and Darling Watch video tutorial here |
Habitat Complexity (Visual Scoring) | Collection of individual scores of habitat complexity for each survey area along a transect using a visual scoring from 0 to 5 (i..e, 0 = no vertical relief, 1 = low and sparse relief, 2 = low but widespread relief, 3 = moderately complex, 4 = very complex with numerous fissures and caves, 5 = exceptionally complex with numerous caves and overhangs). | 6-point scoring scale data entry and average habitat complexity calculation.. | Average habitat complexity (rugosity). | Method described in: Wilson et al. 2007, Darling et al. 2017 |
Each method in MERMAID is backed by published protocols and aligns with global coral reef monitoring standards. Built-in helper text and info icons throughout each sample unit form provide guidance and definitions to help you complete each form with accuracy.
Not Seeing a Survey Method You Use?
MERMAID is always evolving. If you use a coral reef survey method that’s not currently supported, let us know! We welcome new method suggestions. Send us a message here.
Need Dive Sheets for the Field?
Download printable dive sheet templates for each survey method on the Dive Sheets for Field Data Collection page. Perfect for underwater use and easy data entry in MERMAID Collect.