Comparison of three methods for quantifying topographic complexity on rocky shores

Area of Science:

• Ecological studies
• Aquatic habitat assessment
• Geomorphological analysis

Background:

• Topographic complexity (TC) significantly influences aquatic community structure.
• Accurate estimation of TC is crucial for ecological research.
• Existing methods for TC measurement vary in efficiency and reliability.

Purpose of the Study:

• To compare the accuracy, efficiency, and variability of three methods for estimating topographic complexity: chain, divider, and distance-wheel.
• To evaluate these methods across different substrata and spatial scales (78-1030 mm).
• To recommend the most suitable method for TC estimation in aquatic environments.

Main Methods:

• Three distinct methods (chain, divider, distance-wheel) were employed to measure TC.
• Measurements were conducted by multiple users across various substrata.
• Data were analyzed to compare time efficiency, estimate variability, and accuracy across different scales.

Main Results:

• All methods indicated a similar trend in TC across substrata.
• The chain method was time-consuming (>1.5x longer at scales >271 mm) and produced highly variable TC estimates.
• The distance-wheel method yielded higher TC values (1.8x divider method), was significantly less variable than the chain method, and proved rapid and easy to use, especially on complex topographies.

Conclusions:

• The distance-wheel method is recommended for estimating TC on rock surfaces at scales >50 mm.
• This method offers advantages in speed, ease of use, and reliability compared to chain and divider techniques.
• The distance-wheel method has potential for further refinement and application in aquatic habitat assessments.