Examining the effect of reef structural complexity on cryptobenthic fish assemblages

Coral reefs are one of the most diverse and valuable ecosystems on Earth. Rapid environmental change is shifting coral communities toward reefs dominated by stress-resistant, often less structurally complex species, which may influence the ability of reefs to support biodiversity and provide ecosystem services. However, detailed links between environmental conditions, three-dimensional structural complexity, and small reef-associated species are not fully resolved and may vary among regions. One group of reef fishes that are tightly associated with the benthos and occur in high densities are ‘cryptobenthic’ fishes, which are defined by small body size. Cryptobenthic fish are central to energy and nutrient fluxes that support reef fish biomass and, by virtue of their tight association with the benthos, perhaps highly responsive to changes in reef geometry. To test this, we examined the relationship between structural complexity, environmental conditions, and cryptobenthic fish community composition from Long Reef, Belize. Specifically, using underwater surveys and 3D-photogrammetry, we determined the rugosity, fractal dimension, and surface height of sites along the forereef and obtained fine-scale wave acceleration. Using enclosed clove oil stations, we collected cryptobenthic fish to quantify fish community composition. Our major overall finding was that structural complexity in the form of rugosity corresponds to the diversity of cryptobenthic reef fishes. Additionally, we showed that community composition may be driven by reef structure and environmental conditions. Our study demonstrates how fine scale structural complexity helps disentangle reef characteristics that make habitats suitable for small yet important reef fishes.

Presentation Preference: Oral

Primary Presenter: Kyra Jean Cipolla, University of Texas at Austin (kyrajean.cipolla@utexas.edu)

Authors:

Mariana Rivera-Higueras, University of Texas at Austin  (m.rivera-higueras@utexas.edu)

Philip Souza, University of Texas at Austin  (philip.souza@utexas.edu)

Douglas Rasher, Bigelow Laboratory for Ocean Sciences  (drasher@bigelow.org)

Karen Joyce, James Cook University  (karen.joyce@jcu.edu.au)

Simon Brandl, University of Texas at Austin  (simon.brandl@austin.utexas.edu)