Collecting Benthic Data
When you're ready to enter your benthic observations from your dive sheets, navigate to your project's Collecting page and click + Add Sample Unit. Choose one of the benthic methods (i.e., Benthic PIT, Benthic LIT, or Benthic Photo Quadrat) to open a sample unit form organized into four main sections: Sample Event, Transect, Observers, Observations.
MERMAID Collect supports three widely used benthic methods, i.e., point intercept transect (PIT), line intercept transect (LIT), and photo quadrat transect (PQT). Read more about our benthic methods in Supported Survey Methods.
Completing a Benthic Sample Unit Form
Note: Required fields are marked with a red asterisk (*). These include site, management regime, observers, and key transect attributes. Optional fields include time, visibility, current, tide, and notes. Helper text is available for every field—just click the info icon next to a label to view tips, definitions, and example entries. |
1. Sample Event
Defines where and when the benthic survey data was conducted. You'll select:
Site – From the list of sites added to the project. Learn more about adding sites here.
Management Regime – From the list of management regimes added to the project. Learn more about adding regimes here.
Date of Survey – The date the sample unit was collected.
Each sample event (site, management regime, and date) is used to group your benthic sample units for the benthic % cover calculations in MERMAID. Read more in Learning about Our Reef Health Metrics.
Each sample event (site, management regime, and date) is used to group your sample units for the calculation of sample event summary for benthic % cover. Learn more in Learning about Our Reef Health Metrics.
2. Transect
Protocol-specific fields for the benthic survey:
Survey Method | Protocol-Specific Fields |
All benthic methods | Transect number Depth (m) Transect length surveyed (m) Optional fields: Reef Slope Visibility Current Relative Depth Tide Notes |
Benthic PIT only | Interval Size (m) Interval Start (m) |
Benthic Photo Quadrat only | Quadrat number start Quadrat size (m2) Number of quadrats Number of points per quadrat |
Some fields use standardized dropdowns (e.g., reef slope, visibility) while others accept numeric or text-free entries (e.g., depth, transect number, transect length surveyed).
3. Observers
In this section, assign the person(s) who collected the observations underwater:
Select from the list of project users
Click to add or remove names
At least one observer is required per sample unit
Accurate attribution helps with training, reporting, and quality assurance.
4. Observations
Here’s where you enter your actual data (observations):
Survey Method | Protocol-Specific Fields |
All benthic methods | Benthic Attribute Growth Form |
Benthic LIT only | Length (cm) |
Benthic Photo Quadrat only | Quadrat number Number of points |
Suggesting a New Benthic Attribute
If a benthic attribute isn’t yet listed in the dropdown:
Type its name in the Observations table.
Select Propose New Benthic Attribute...
Enter the coral genus/family/top-level category in Parent and the species/genus in Name
Click Next to review.
Click Send to MERMAID to submit it for review.
If the parent (genus/family/top-level category) is missing, select Contact us for help to notify the MERMAID team.
The benthic taxonomy in MERMAID is standardized using the World Register of Marine Species (WoRMS) to ensure consistent species classification.
Note: Check the benthic attribute in WoRMS to ensure the species name is accepted before submitting. Your entry will be provisionally included but becomes official only after being reviewed and approved by the MERMAID Team. |
You can download the full list of available benthic attributes using the Reference icon in MERMAID Collect.
Tips for Data Entry: Keyboard Shortcuts and Predictive Text
Use these keyboard shortcuts and the predictive text to move quickly through the Observations table in a sample unit form:
Use the Tab key to move across fields in a row.
Use the Up and Down arrow keys to scroll through benthic attribute suggestions.
Under the column Benthic Attribute, type a few letters of your observation (e.g., Acropal for Acropora palmata), then use the arrow keys and Enter/Return/Tab to select it from the matching dropdown options. Or type until there’s only one option and press Enter/Return.
Press Tab at the end of a row to duplicate the observation in the next row—useful for entering multiple observations of the same benthic attribute in a transect.
Press Enter/Return to start a new row and begin typing the next observation.
This helps ensure consistent naming and speeds up your workflow—especially when entering lots of observations.
Metric Summaries in a Benthic Sample Unit
MERMAID automatically calculates and displays key benthic metrics as you enter observations, providing immediate feedback for data validation and quality control—even while offline.
For all benthic methods, percent cover is automatically calculated for each top-level benthic category (e.g., hard coral, soft coral, macroalgae) based on the observations you enter. These percentages are displayed beneath the Observations table. Each benthic attribute entered is hierarchically grouped into these broader categories commonly used in global reef monitoring.
Read more about these calculations in Learning About Our Taxonomic Reference.
