Communicating the Pixel: A Strategy for Guiding the Use of Remotely-Sensed Habitat Data in Coral Reef Management

Over the last decade, coral reef remote sensing research has focused on habitat map development. Advances in field methods, spatial and spectral resolution of remote sensing data, and algorithm development have led to more detailed map categories and to heightened map accuracy. Studies have provided guidance for practitioners in areas such as imagery selection, algorithm application, and class selection methods, but the product has remained relatively unchanged – a habitat map showing the spatial distribution of a range of substrate classes, classified primarily on the basis of their spectral signature. However, the application of such a product in a management context has not been elaborated by the remote sensing community. The research described in this thesis addresses the challenge that the application of remotely-sensed coral reef information in a coral reef management environment elicits. In such an environment, the coral reef manager asks: "What can the map do to help me?", while the remote sensing scientist asks: "What type of information do you need?". The research described here aims to reconcile these two points of view, by answering the research question of this thesis: How can coral reef remotely-sensed information address stakeholder-specific coral reef management objectives? This question was answered through the development of a four-stage strategy. The strategy includes: 1) developing a traditional habitat map, 2) investigating stakeholder receptivity to the habitat map, 3) linking stakeholder interests with habitat data, and 4) illustrating the linked habitat data in what we term a management map. The strategy was applied on Bunaken Island, Indonesia, and involved the collection of both qualitative and quantitative data sets. The research was relevant to the communities on Bunaken Island, as they are directly responsible for the management of the coral reef resources surrounding Bunaken Island, and they are regularly planning and implementing coral reef management projects. The effectiveness of the four-stage strategy was evaluated in a framework that compares potential and actual uses of habitat maps and management maps in coral reef management projects. It was shown that management maps are superior to habitat maps for a wide range of management purposes. This research has provided two main contributions to the field of coral reef remote sensing and management. The first is the four-stage strategy that results in the development of management maps, and the second is the framework for evaluating the effectiveness of the management maps. This research seeks to traverse the gap between producers and users of coral reef remotely-sensed information. The recommendations made from this research addresses coral reef management procedures, action research, and cross-cultural communication. Each recommendation is founded on collaboration between scientist and manager. Such collaboration is crucial for successful application of remotely-sensed information to management

PEMETAAN HABITAT BENTIK PADA EKOSISTEM TERUMBU KARANG DI PERAIRAN PULAU MENJANGAN

Ekosistem pesisir yang meliputi tiga bagian penting yakni mangrove, padang lamun dan terumbu karang merupakan bagian yang tidak terpisahkan dalam proses pemetaan habitat. Penelitian ini bertujuan untuk melakukan pemetaan habitat secara geomorfologi di Pulau Menjangan, Taman Nasional Bali Barat, Bali. Pengumpulan data lapangan dilakukan pada bulan Februari, April dan Agustus 2017.  Total 104 titik sampling telah dikumpulkan, dan dilakukan analisis perbedaan tekstur menggunakan program ENVI v4.7 dari data citra satelit  Worldview 2 dengan resolusi spasial 2 m, tanggal 14 Oktober 2016. Hasil penelitian menunjukkan bahwa secara geomorfologi, kawasan pesisir Pulau Menjangan terbagi dalam 6 tipe habitat yakni mangrove, terumbu depan, lereng terumbu, rataan terumbu, pecahan karang (rubble), pasir dan teras. Berdasarkan hasil foto transek habitat dengan pendekatan skala medium (Medium Scale Approach) khususnya pada daerah rataan terumbu dan terumbu depan (fore reef/crest) dapat diklasifikasikan dalam 12 jenis habitat dengan komposisi bentik dominan karang  adalah 30% yang meliputi beberapa jenis karang keras (Scleractinia) yakni Acropora sp, Montipora sp, Porites lutea dan Porites cylindrica; Rubble & Alga (dari divisi Chlorophyta dan Phaeophyta) masing-masing sebesar 16 %; Pasir  12%; Lamun (diantaranya Syringodium sp, Cymodocea sp dan Thalasia sp) 11% dan sisanya adalah asosiasi karang Heliopora coerulea (non Scleractinia), karang mati dan teras. Daerah rataan terumbu memiliki kategori rugosity berada pada level 1 - 2, sedangkan  terumbu depan dengan rugosity level 3 - 4

Coral Colony-Scale Rugosity Metrics and Applications for Assessing Temporal Trends in the Structural Complexity of Coral Reefs.

Globally, coral reefs are experiencing reductions in structural complexity, primarily due to a loss of key reef building taxa. Monitoring these changes is difficult due to the time-consuming nature of in-situ measurements and lack of data concerning coral genus-specific contributions to reef structure. This research aimed to develop a new technique that uses coral colony level data to quantify reef rugosity (a 3-dimensional measure of reef structure) from three sources of coral survey data: 2D video imagery, line intercept data and UAV imagery. A database of coral colony rugosity data, comparing coral colony planar and contour length for 40 coral genera, 14 morphotypes and 9 abiotic reef substrates, was created using measurements from the Great Barrier Reef and Natural History Museum. Mean genus rugosity was identified as a key trait related to coral life history strategy. Linear regression analyses (y = mx) revealed statistically significant (p < 0.05) relationships between coral colony size and rugosity for every coral genus, morphotype and substrate. The gradient governing these relationships was unique for each coral taxa, ranging from mean = 1.23, for (encrusting) Acanthastrea, to m = 3.84, for (vase-shape) Merulina. These gradients were used as conversion factors to calculate reef rugosity from linear distances measured in video transects of both artificial reefs, used as a control test, and in-situ natural coral reefs, using Kinovea software. This calculated, ‘virtual’ rugosity had a strong, positive relationship with in-situ microscale rugosity (r2 = 0.96) measured from the control transects, but not with that measured at the meso-scale in natural, highly heterogeneous reef environments (r2 < 0.2). This showed that the technique can provide accurate rugosity information when considered at the coral colony level. The conversion factors were also applied to historic line intercept data from the Seychelles, where temporal changes in calculated rugosity were consistent with changes in coral cover between 2008 and 2017. Finally, on application to 2,283 corals digitised from UAV imagery of the Maldives, the conversion factors enabled calculation of rugosity for three 100 m2 reef areas and prediction of how this rugosity will decrease during two future scenarios of coral reef degradation and community change. The study highlights that the application of genera-specific coral rugosity data to both new and existing coral reef survey datasets could be a valuable tool for monitoring reef structural complexity over large spatial scales

The Future of Coral Reefs

This volume contains a series of papers prepared for presentation at the 14th International Coral Reef Symposium, originally planned for July 2020 in Bremen, Germany, but postponed until 2021 (online) and 2022 (in person) because of the COVID-19 pandemic. It contains a series of papers illustrating the breadth of modern studies on coral reefs and the response of the reef science community to the threats that coral reefs now face, above all from climate change. The first group of papers focus on the biology of a selection of reef organisms, ranging from sea fans to coral dwelling crabs. The next group describe studies of coral communities and ecological interactions in regions as diverse as Florida, Kenya, Colombia, and Norway. Further papers describe investigations into the effects of global warming (in the Maldives and in Timor-Leste) and of other impacts (UV blockers, ocean acidification). The final two papers describe the latest applications of satellite and camera technology to the challenge of mapping and monitoring reefs

11th International Coral Reef Symposium Proceedings

A defining theme of the 11th International Coral Reef Symposium was that the news for coral reef ecosystems are far from encouraging. Climate change happens now much faster than in an ice-age transition, and coral reefs continue to suffer fever-high temperatures as well as sour ocean conditions. Corals may be falling behind, and there appears to be no special silver bullet remedy. Nevertheless, there are hopeful signs that we should not despair. Reef ecosystems respond vigorously to protective measures and alleviation of stress. For concerned scientists, managers, conservationists, stakeholders, students, and citizens, there is a great role to play in continuing to report on the extreme threat that climate change represents to earth’s natural systems. Urgent action is needed to reduce CO2 emissions. In the interim, we can and must buy time for coral reefs through increased protection from sewage, sediment, pollutants, overfishing, development, and other stressors, all of which we know can damage coral health. The time to act is now. The canary in the coral-coal mine is dead, but we still have time to save the miners. We need effective management rooted in solid interdisciplinary science and coupled with stakeholder buy in, working at local, regional, and international scales alongside global efforts to give reefs a chance.https://nsuworks.nova.edu/occ_icrs/1000/thumbnail.jp

Reef fish associations with benthic habitats at a remote protected coral reef ecosystem in the Western Indian Ocean-Aldabra Atoll, Seychelles

The aim of the thesis is to develop an understanding of the associations between reef fish and benthic habitats and assess the modifying effects of environmental processes on these relationships at Aldabra, a pristine atoll in the Western Indian Ocean (WIO). Conducting research in pristine, or reference coral reef ecosystem, removes the impact of direct anthropogenic disturbances and provides essential information on natural ecosystem structure and functioning. Three primary hypotheses were tested: 1) Environmental drivers such as depth and exposure to wave energy determine the spatial distribution of benthic habitats; 2) The reef fish assemblage structure is explained by habitat at multiple scales and modified by the effects of environmental drivers such as depth, wave energy and cyclical temporal drivers such as time and tides; 3) The reef fish assemblage at Aldabra represents a pristine reef fish assemblage, comprising high levels of herbivores and predators. The research focussed on the benthic habitat on the seaward reefs between the shoreline and 50 m depth. The first objective was to characterise the benthic habitats on Aldabra Atoll’s seaward reefs and map their spatial distributions using remotely sensed imagery and ground truthing data. The second was to assess the influence of depth and exposure to wave energy on the distribution of benthic habitats. The third was to identify the most suitable standardised method to survey the reef fish assemblage structure on Aldabra’s, and fourth to determine the effect of tide and time of day on the reef fish assemblage. The fifth objective was to establish the association between reef fish assemblage structure and benthic habitats and to test how species-size influenced the scale of habitat at which the associations were most apparent. Four categories of geomorphic reef zones (reef flats (19.2 km2), top of the forereef slope (7.8 km2), deep forereef slope (11.6 km2), and reef platform (14.3 km2)) were manually delineated following the visual outlines of reef features from satellite imagery. The six broad-scale and twelve fine-scale benthic habitats were mapped using a supervised maximum likelihood classification and the spatial coverage of each determined. The broad-scale habitats were 1) Epilithic algal matrix, 2) Hard and soft (coral, 3) Rubble, 4) Macroalgae, 5) Seagrass and 6) Sand. Similarly, twelve fine-scale benthic habitats were characterised and mapped, for example, Hard coral (19 %) including massive and submassive forms with Millepora and Rhytisma. The broad-scale benthic habitat map had an overall producer accuracy of 54 % and fine-scale habitat map 29 %, which was consistent with studies using similar habitat classification methods. The prevailing wave energy, depth and the directional orientation of coral reefs (aspect) significantly influenced the probability of occurrence of each of the broad-scale benthic habitats, and there was a shift in peak probability of occurrence of all habitat categories to a greater depth with an increase in wave energy. The strong relationship of benthic habitats with depth and wave energy suggests that the distributions of benthic habitats are likely to change with sea-level rise and increased intensity and frequency of storms in future. Overall, 338 fish species from 51 families, including 14 species of elasmobranch were recorded using Baited Remote Underwater Video systems (BRUVs) and unbaited Remote Underwater Video systems (RUVS) from 231 samples. Fish were significantly more abundant when observed using BRUVs (119 ± 7) relative to RUVs (92 ± 7), and the assemblage structures were significantly different between the two sampling methods. Abundance and species richness of generalist carnivores and piscivores were significantly greater in BRUVs, while RUVs recorded significantly greater numbers of herbivores and more species of herbivore and corallivore. The results suggest that BRUVs are better suited when studying predatory fish which may not be detected without bait. However, when surveying a taxonomically and functionally diverse assemblage of fishes at a pristine reef, RUVs may provide a more accurate estimate of natural reef fish assemblage structure. Reef fish assemblages observed using RUVs were significantly different between morning-high-tide, midday-low-tide and evening-high-tide for all trophic groups. However, the reef fish assemblage structure observed using BRUVs was insensitive to change in tide and time of day, which may be explained by the attraction effect of bait dampening the effect of tide and time of day. While RUVs appear better to detect more subtle variations in fish assemblage structure, care needs to be taken when designing research programmes that use RUVs, as the sampling design should account for tide and time of day to avoid misinterpreting the cyclical variation, which may confound results. Reef fish assemblages were significantly different among habitats within geomorphic reef zones, broad-scale and fine-scale habitats. Species turnover rates were significantly different for all Actinopterygii size-class categories between the three scales of habitat. No marked differences in species turnover rates among habitats were detected for the majority of Elasmobranch size-class categories. The strong habitat dependency over various spatial scales indicates that effective conservation of Actinopterygii fish at Aldabra, and elsewhere in similar ecosystems requires protection of representative sets of benthic habitats. However, Elasmobranch conservation requires sufficiently large areas as these species utilise multiple habitats, over multiple scales, which are likely to exceed the confines of Aldabra’s reef

Reef fish associations with benthic habitats at a remote protected coral reef ecosystem in the Western Indian Ocean-Aldabra Atoll, Seychelles

The aim of the thesis is to develop an understanding of the associations between reef fish and benthic habitats and assess the modifying effects of environmental processes on these relationships at Aldabra, a pristine atoll in the Western Indian Ocean (WIO). Conducting research in pristine, or reference coral reef ecosystem, removes the impact of direct anthropogenic disturbances and provides essential information on natural ecosystem structure and functioning. Three primary hypotheses were tested: 1) Environmental drivers such as depth and exposure to wave energy determine the spatial distribution of benthic habitats; 2) The reef fish assemblage structure is explained by habitat at multiple scales and modified by the effects of environmental drivers such as depth, wave energy and cyclical temporal drivers such as time and tides; 3) The reef fish assemblage at Aldabra represents a pristine reef fish assemblage, comprising high levels of herbivores and predators. The research focussed on the benthic habitat on the seaward reefs between the shoreline and 50 m depth. The first objective was to characterise the benthic habitats on Aldabra Atoll’s seaward reefs and map their spatial distributions using remotely sensed imagery and ground truthing data. The second was to assess the influence of depth and exposure to wave energy on the distribution of benthic habitats. The third was to identify the most suitable standardised method to survey the reef fish assemblage structure on Aldabra’s, and fourth to determine the effect of tide and time of day on the reef fish assemblage. The fifth objective was to establish the association between reef fish assemblage structure and benthic habitats and to test how species-size influenced the scale of habitat at which the associations were most apparent. Four categories of geomorphic reef zones (reef flats (19.2 km2), top of the forereef slope (7.8 km2), deep forereef slope (11.6 km2), and reef platform (14.3 km2)) were manually delineated following the visual outlines of reef features from satellite imagery. The six broad-scale and twelve fine-scale benthic habitats were mapped using a supervised maximum likelihood classification and the spatial coverage of each determined. The broad-scale habitats were 1) Epilithic algal matrix, 2) Hard and soft (coral, 3) Rubble, 4) Macroalgae, 5) Seagrass and 6) Sand. Similarly, twelve fine-scale benthic habitats were characterised and mapped, for example, Hard coral (19 %) including massive and submassive forms with Millepora and Rhytisma. The broad-scale benthic habitat map had an overall producer accuracy of 54 % and fine-scale habitat map 29 %, which was consistent with studies using similar habitat classification methods. The prevailing wave energy, depth and the directional orientation of coral reefs (aspect) significantly influenced the probability of occurrence of each of the broad-scale benthic habitats, and there was a shift in peak probability of occurrence of all habitat categories to a greater depth with an increase in wave energy. The strong relationship of benthic habitats with depth and wave energy suggests that the distributions of benthic habitats are likely to change with sea-level rise and increased intensity and frequency of storms in future. Overall, 338 fish species from 51 families, including 14 species of elasmobranch were recorded using Baited Remote Underwater Video systems (BRUVs) and unbaited Remote Underwater Video systems (RUVS) from 231 samples. Fish were significantly more abundant when observed using BRUVs (119 ± 7) relative to RUVs (92 ± 7), and the assemblage structures were significantly different between the two sampling methods. Abundance and species richness of generalist carnivores and piscivores were significantly greater in BRUVs, while RUVs recorded significantly greater numbers of herbivores and more species of herbivore and corallivore. The results suggest that BRUVs are better suited when studying predatory fish which may not be detected without bait. However, when surveying a taxonomically and functionally diverse assemblage of fishes at a pristine reef, RUVs may provide a more accurate estimate of natural reef fish assemblage structure. Reef fish assemblages observed using RUVs were significantly different between morning-high-tide, midday-low-tide and evening-high-tide for all trophic groups. However, the reef fish assemblage structure observed using BRUVs was insensitive to change in tide and time of day, which may be explained by the attraction effect of bait dampening the effect of tide and time of day. While RUVs appear better to detect more subtle variations in fish assemblage structure, care needs to be taken when designing research programmes that use RUVs, as the sampling design should account for tide and time of day to avoid misinterpreting the cyclical variation, which may confound results. Reef fish assemblages were significantly different among habitats within geomorphic reef zones, broad-scale and fine-scale habitats. Species turnover rates were significantly different for all Actinopterygii size-class categories between the three scales of habitat. No marked differences in species turnover rates among habitats were detected for the majority of Elasmobranch size-class categories. The strong habitat dependency over various spatial scales indicates that effective conservation of Actinopterygii fish at Aldabra, and elsewhere in similar ecosystems requires protection of representative sets of benthic habitats. However, Elasmobranch conservation requires sufficiently large areas as these species utilise multiple habitats, over multiple scales, which are likely to exceed the confines of Aldabra’s reef

11th International Coral Reef Symposium Abstracts

https://nsuworks.nova.edu/occ_icrs/1001/thumbnail.jp

Hyperspectral Remote Sensing Applied to Shallow Coastal Waters

A shallow water reflectance model was developed for application to optical remote sensing in highly diverse and complex coastal environments. A numerical inversion scheme, based on analytical parameterisation, was applied to airborne hyperspectral imagery collected over two regions of the Western Australian coastline; Jurien Bay and the Ningaloo Marine Park. Detailed maps of water quality, water depth and benthic cover classification were derived with a high degree of accuracy as compared to ground truth data

Oceanography and Marine Biology

Oceanography and Marine Biology: An Annual Review remains one of the most cited sources in marine science and oceanography. The ever-increasing interest in work in oceanography and marine biology and its relevance to global environmental issues, especially global climate change and its impacts, creates a demand for authoritative refereed reviews summarizing and synthesizing the results of both historical and recent research. This Volume celebrates 60 years of OMBAR, over which time it has been an essential reference for research workers and students in all fields of marine science. The peer-reviewed contributions in Volume 60 are available to read Open Access via this webpage and on OAPEN. If you are interested in submitting a review for consideration for publication in OMBAR, please email the Editor-in-Chief, Stephen Hawkins ([email protected]) for Volume 61. For Volume 62 onwards, please email the new co-Editors in Chief, Dr Peter Todd ([email protected]) and Dr Bayden Russell ([email protected]). Volume 60 features an editorial on the UN Decade of Ocean Science and goes on to consider such diverse topics as Cenozoic tropical marine biodiversity, blue carbon ecosystems in Sri Lanka, marine litter and microplastics in the Western Indian Ocean, and the ecology and conservation status of the family Syngnathidae in southern and western Africa. This volume also contains a retrospective Prologue on the evolution of OMBAR and pays tribute to one of its early Editors in Chief, Margaret Barnes, by providing an update on her review in OMBAR of the stalked barnacle Pollicipes. Supplementary online videos as well as additional Tables and Appendices are available on the Support Tab of the book's Routledge webpage. An international Editorial Board ensures global relevance and expert peer review, with editors from Australia, Canada, Hong Kong, Ireland, Singapore and the UK. The series volumes find a place in the libraries of not only marine laboratories and oceanographic institutes, but also universities worldwide