Linking fishes to multiple metrics of coral reef structural complexity using three-dimensional technology

González‐Rivero, Manuel; Harborne, Alastair R.; Herrera-Reveles, Ana Teresa; Bozec, Yves‐Marie; Rogers, Alice; Friedman, Ariell; Ganase, Anjani; Høegh-Guldberg, Ove

doi:10.1038/s41598-017-14272-5

Cited by 55 publications

(64 citation statements)

References 99 publications

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“…Elevated points are likely to receive the highest herbivory rates because they are less likely to accumulate sediments, have relatively high detrital levels, and are likely to be zones of high algal turf productivity (Figure ). Furthermore, these elevated points allow a greater field of view over the landscape when fishes feed, lowering predation risk (Bellwood et al, ; Brandl & Bellwood, ; González‐Rivero et al, ). Therefore, elevated surfaces are likely to offer appealing feeding locations for herbivorous fishes, and this feeding activity could in‐turn act to maintain low sediment loads in a positive feedback.…”

Section: Discussionmentioning

confidence: 99%

A 3D perspective on sediment accumulation in algal turfs: Implications of coral reef flattening

2019

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Globally, coral reefs are being transformed by a suite of stressors, the foremost being climate change. Increasingly, it is expected that these reconfigured reef systems will emerge with lower‐complexity and will be dominated by algal turfs. Understanding this new operating space is vital if we are to maintain the services, such as fishable biomass production, that reefs provide. However, the functionality of these systems appears to depend on the nature of the algal turfs themselves, which is in‐turn, intimately linked to the sediments they contain. As reefs are losing complexity, we need to understand if, and to what extent, algal turf condition and complex reef structure are connected. To address this issue we took advantage of recent developments in 3D structure‐from‐motion technology to examine how complexity metrics (elevation and surface angle) related to the nature of algal turfs on a heavily climate‐impacted coral reef. This represents a novel application of this technology in the context of coral reef ecosystems. We found that as both elevation and surface angle decreased, the nutritional value of the epilithic algal matrix also decreased while sediment accumulation increased. Furthermore, we showed that elevated surfaces were characterized by far shorter algal turfs, and are potentially herbivory hotspots, offering fertile grounds for further exploration of herbivory dynamics at sub‐metre spatial scales. Synthesis. This study yields new insights into the operating‐space of future reefs, and suggests that as reefs flatten, sediment accumulation is likely to increase even if sediment inputs remain unchanged, altering algal turfs fundamentally. Maintaining key services provided by climate‐transformed, low‐complexity algal turf‐dominated reefs of the future, will depend on managing the complex interactions between herbivory, sediments, algal turfs and reef structural complexity.

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Section: Discussionmentioning

confidence: 99%

A 3D perspective on sediment accumulation in algal turfs: Implications of coral reef flattening

2019

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“…380 m 2 is suggested in order to facilitate the use of digital photogrammetry techniques to characterise coral reefs in the Caribbean. Underwater digital photogrammetry techniques, have recently been applied to map and assess several attributes of coral assemblages, such as cover, condition, growth and structure (Lirman et al, 2007;Westoby et al, 2012;Gintert et al, 2012;Burns et al, 2015b;Edwards et al, 2017;González-Rivero et al, 2017;Gintert et al, 2018). Here, the high resolution of the obtained ortho-mosaics allowed a high number of colonies to be quantified, and the real area covered by live coral in colonies from 3 cm 2 to be estimated.…”

Section: Discussionmentioning

confidence: 99%

Size-frequency distribution of coral assemblages in insular shallow reefs of the Mexican Caribbean using underwater photogrammetry

Hernández-Landa

Barrera-Falcón

Rioja-Nieto

2020

PeerJ

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The characterisation of changes in coral communities depends heavily on systematic monitoring programs and the collection of necessary metrics to assess reef health. Coral cover is the most used metric to determine reef health. The current organizational shift in coral requires the evaluation of complementary metrics, such as colony size and frequency distributions, which help to infer the responses of the coral populations to local stress or larger scale environmental changes. In this study, underwater digital photogrammetry techniques were used to assess the live cover of all coral colonies ≥3 cm2 and determine the size-frequency distribution of the dominant species in the shallow reefs of the Cozumel Reefs National Park (CRNP). In addition, the minimum sampling area (m2) needed to obtain a representative sample of the local species pool was estimated. Areas between 550 and 825 m2 per reef were photographed to generate high-resolution digital ortho-mosaics. The live area of the colonies was digitised to generate community matrices of species and abundance. EstimateS software was used to generate accumulation curves and diversity (Shannon H′) at increasing area intervals. Chi-Square tests (χ2, p = 0.05) were used to compare the observed vs estimated species richness. Spearman’s coefficients (rs), were calculated to correlate the increase in sampling area (m2) vs H′, and the Clench’s function was used to validate the observed richness (R2 = 1 and R > 90%). SIMPER analysis was performed to identify dominant species. Comparisons in terms of abundance, coral cover and size-frequencies were performed with Kruskal-Wallis (H test, p = 0.05), and paired Mann-Whitney (U test, p = 0.05). In order to obtain 90% of the species richness, a minimum sampling area of 374 m2is needed. This sampling area could be used in shallow Caribbean reefs with similar characteristics. Twelve (mainly non-massive) species: Agaricia agaricites, A humilis, A. tenuifolia, Eusmilia fastigiata, Meandrina meandrites, Montastrea cavernosa, Orbicella annularis, Porites astreoides, P. porites, Pseudodiploria strigosa, Siderastrea radians andS. siderea, were dominant in terms of abundance and coral cover. A significant increase (p < 0.05) in the number of colonies and live coral (m2) was observed from north to south of the study area. Furthermore, a wide intraspecific variation of size-frequency, even between adjacent reefs, was also observed. The size-frequency distributions presented positive skewness and negative kurtosis, which are related to stable populations, with a greater number of young colonies and a constant input of recruits. Considering the increase in disturbances in the Caribbean and the appearance of a new coral disease, digital photogrammetry techniques allow coral community characteristics to be assessed at high spatial resolutions and over large scales, which would be complementary to conventional monitoring programs.

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“…Biodiversity is strongly related to habitat structural complexity in both marine and freshwater environments [28][29][30][31][32][33][34]. While several definitions of habitat complexity have been used interchangeably with heterogeneity and diversity [35], in this study, we refer to habitat diversity as the variety of substrate types (e.g., sand, pebbles, boulders, bedrock) and heterogeneity as the magnitude of substrate diversity within a study site such as patches of sand interspersed with rocks versus homogenous sand.…”

Section: Introductionmentioning

confidence: 99%

Freshwater Fish Habitat Complexity Mapping Using Above and Underwater Structure-From-Motion Photogrammetry

et al. 2018

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Substrate complexity is strongly related to biodiversity in aquatic habitats. We illustrate a novel framework, based on Structure-from-Motion photogrammetry (SfM) and Multi-View Stereo (MVS) photogrammetry, to quantify habitat complexity in freshwater ecosystems from Unmanned Aerial Vehicle (UAV) and underwater photography. We analysed sites in the Xingu river basin, Brazil, to reconstruct the 3D structure of the substrate and identify and map habitat classes important for maintaining fish assemblage biodiversity. From the digital models we calculated habitat complexity metrics including rugosity, slope and 3D fractal dimension. The UAV based SfM-MVS products were generated at a ground sampling distance (GSD) of 1.20–2.38 cm while the underwater photography produced a GSD of 1 mm. Our results show how these products provide spatially explicit complexity metrics, which are more comprehensive than conventional arbitrary cross sections. Shallow neural network classification of SfM-MVS products of substrate exposed in the dry season resulted in high accuracies across classes. UAV and underwater SfM-MVS is robust for quantifying freshwater habitat classes and complexity and should be chosen whenever possible over conventional methods (e.g., chain-and-tape) because of the repeatability, scalability and multi-dimensional nature of the products. The SfM-MVS products can be used to identify high priority freshwater sectors for conservation, species occurrences and diversity studies to provide a broader indication for overall fish species diversity and provide repeatability for monitoring change over time.

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Linking fishes to multiple metrics of coral reef structural complexity using three-dimensional technology

Cited by 55 publications

References 99 publications

A 3D perspective on sediment accumulation in algal turfs: Implications of coral reef flattening

A 3D perspective on sediment accumulation in algal turfs: Implications of coral reef flattening

Size-frequency distribution of coral assemblages in insular shallow reefs of the Mexican Caribbean using underwater photogrammetry

Freshwater Fish Habitat Complexity Mapping Using Above and Underwater Structure-From-Motion Photogrammetry

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