Assessment of Storm Impact on Coral Reef Structural Complexity

Abstract

Extreme weather events are increasing in frequency and magnitude. Consequently, it is important to understand their effects and remediation. Resilience reflects the ability of an ecosystem to absorb change, which is important for understanding ecological dynamics and trajectories. To describe the impact of a powerful storm on coral reef structural complexity, we used novel computational tools and detailed 3D reconstructions captured at three time points over three years. Our data-set Reefs4D of 21 co-registered image-based models enabled us to calculate the differences at seven sites over time and is released with the paper. We employed six geometrical metrics, two of which are new algorithms for calculating fractal dimension of reefs in full 3D. We conducted a multivariate analysis to reveal which sites were affected the most and their relative recovery. We also explored the changes in fractal dimension per size category using our cube-counting algorithm. Three metrics showed a signicant difference between time points, i.e., decline and subsequent recovery in structural complexity. The multivariate analysis and the results per size category showed a similar trend. Coral reef resilience has been the subject of seminal studies in ecology. We add important information to the discussion by focusing on 3D structure through image-based modeling. The full picture shows resilience in structural complexity, suggesting that the reef has not gone through a catastrophic phase shift. Our novel analysis framework is widely transferable and useful for research, monitoring, and management. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=107 SRC="FIGDIR/small/519015v3_ufig1.gif" ALT="Figure 1"> View larger version (50K): org.highwire.dtl.DTLVardef@888999org.highwire.dtl.DTLVardef@1c51dorg.highwire.dtl.DTLVardef@340d97org.highwire.dtl.DTLVardef@16865d8_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIThe effect of storms on coral reef 3D structure is poorly understood. C_LIO_LIWe studied the impact of a storm on coral reefs using a novel 3D imaging framework. C_LIO_LIWe used geometrical metrics including new methods for calculating fractal dimension. C_LIO_LIThe reefs recovered in two years with regards to structural complexity. C_LIO_LIBased on 3D analysis the reefs exhibit structural resilience. C_LI