About This Project

The importance of reef structural complexity for small organisms, such as cryptobenthic reef fish (CRFs), is poorly resolved. This project's objectives are to examine how variations in reef structure affect CRF communities using underwater photogrammetry and to use aerial imagery to scale-up the resolved relationship to the area of entire reefs. This will allow us to unveil how many hidden, but critically important, fishes a reef can hold solely by mapping the reef from the air.

Ask the Scientists

What is the context of this research?

Coral reefs are one of the most complex marine ecosystems. However, human impacts have flattened reefs worldwide, dramatically changing the environment for thousands of species living on reefs. Tiny, benthic-associated (‘cryptobenthic’) fishes (CRFs) are critical for feeding larger reef animals, but rely on nooks and crannies that complex reefs provide. Yet, the relationship between reef complexity and CRFs, and how that relationship scales across entire reefs, are unknown. By combining cutting-edge high-resolution technologies (structure-from-motion photogrammetry and remote sensing) with collections of CRFs, we can 1) examine how reef structure shapes CRFs and 2) potentially characterize structural complexity and CRF communities on an entire reef system from a single drone flight.

What is the significance of this project?

This study will advance the understanding of reef function by revealing how reef structures affect CRFs, which are often overlooked in survey methods. Specifically, the project may help us develop a broader theory regarding how the nature of space provided by corals affects small, mobile fishes. What shapes these communities affects the larger fishes that support human populations throughout the Indo-Pacific. Remote sensing is a powerful tool, yet by combining it with workflow of structure-from-motion (SfM) photogrammetry, it may be possible to characterize reef structural complexity of an entire reef system by diving on a fraction of the reef. This not only allows for the ease of monitoring reef health over large areas but also for predicting spatial distribution of reef fish communities.

What are the goals of the project?

Funds will be used on equipment and materials needed for fieldwork on Lizard Island reefs which will occur Jan-Feb 2025. With a scientific dive team, my objectives are to: 1) analyze spatial variation in reef complexity (rugosity, surface height, fractal dimension) using SfM photogrammetry for small 5m² reef patches using Agisoft Metashape and HABtools (R Package); 2) determine CRF abundance and diversity from enclosed-clove oil stations on the same patches; 3) obtain fine-scale aerial imagery to create high-resolution reconstructions of the entire reef using a DJI drone. Using a quantitative color analysis and structural complexity metrics, I will characterize the benthic microhabitats, quantify CRFs to a subset of small reef patches, and then test the predictions to in situ measurements.