Shallow-water Habitat Change Detection of Kaledupa Island, Wakatobi National Park (Wnp) for 14 Years

Metode penginderaan jauh sangat membantu dalam pemetaan kondisi habitat perairan dangkal secara spasial pada cakupan area yang luas. Penelitian ini bertujuan untuk menganalisis Perubahan habitat perairan dangkal Pulau Kaledupa, Taman Nasional Wakatobi (TNW), selama 14 tahun, dari tahun 2002 hingga 2016. Data citra yang digunakan dalam penelitian ini adalah Landsat 8 OLI (2016), Landsat 5TM (2009), dan Landsat 7ETM+ (2002), yang dikombinasikan dengan data in-situ dan TNW. Klasifikasi Mahalanobis dimanfaatkan untuk memproduksi peta habitat perairan dangkal (karang hidup, karang mati, lamun, dan pasir) dan mendeteksi Perubahannya. Hasil yang diperoleh bahwa Perubahan yang terjadi dari tahun 2002 sampai 2016 adalah tutupan karang hidup menurun dari 2217 ha menjadi 2039 ha, tutupan karang mati juga menurun dari 3327 ha menjadi 2108 ha, luas pasir meningkat dari 1201 ha menjadi 1346 ha, area lamun naik dari 4130 ha menjadi 5294 ha. Metode ini merupakan alat analisis yang baik untuk menilai efektivitas upaya perlindungan ekosistem terumbu karang dan lamun di perairan Pulau Kaledupa, serta dapat diterapkan pada 3 pulau utama lainnya di TNW dan pulau-pulau kecil di Indonesia

SHALLOW-WATER HABITAT CHANGE DETECTION OF KALEDUPA ISLAND, WAKATOBI NATIONAL PARK (WNP) FOR 14 YEARS

Metode penginderaan jauh sangat membantu dalam pemetaan kondisi habitat perairan dangkal secara spasial pada cakupan area yang luas. Penelitian ini bertujuan untuk menganalisis perubahan habitat perairan dangkal Pulau Kaledupa, Taman Nasional Wakatobi (TNW), selama 14 tahun, dari tahun 2002 hingga 2016. Data citra yang digunakan dalam penelitian ini adalah Landsat 8 OLI (2016), Landsat 5TM (2009), dan Landsat 7ETM+ (2002), yang dikombinasikan dengan data in-situ dan TNW. Klasifikasi Mahalanobis dimanfaatkan untuk memproduksi peta habitat perairan dangkal (karang hidup, karang mati, lamun, dan pasir) dan mendeteksi perubahannya. Hasil yang diperoleh bahwa perubahan yang terjadi dari tahun 2002 sampai 2016 adalah tutupan karang hidup menurun dari 2217 ha menjadi 2039 ha, tutupan karang mati juga menurun dari 3327 ha menjadi 2108 ha, luas pasir meningkat dari 1201 ha menjadi 1346 ha, area lamun naik dari 4130 ha menjadi 5294 ha. Metode ini merupakan alat analisis yang baik untuk menilai efektivitas upaya perlindungan ekosistem terumbu karang dan lamun di perairan Pulau Kaledupa, serta dapat diterapkan pada 3 pulau utama lainnya di TNW dan pulau-pulau kecil di Indonesia

Gorgonian Responses to Environmental Change on Coral Reefs in SE Sulawesi, Indonesia

Gorgonian corals (Cnidaria: Anthozoa: Octocorallia) are conspicuous, diverse and often dominant components of benthic marine environments. Intra- & interspecific morphological variability in gorgonians are influenced by environmental factors such as light, sedimentation and flow rates. Yet, little is known about the responses of gorgonian taxa to environmental parameters particularly in Indonesia, despite their high regional abundance and diversity. With a burgeoning human population and subsequent marine resource exploitation, reefs throughout the Indonesian archipelago are under rapid decline and often destroyed. Conservation surveys are however, underway with a tendency to overlook gorgonian taxa primarily due to unresolved taxonomic assignment leading to difficulties in field identification. The aims of this study were to: 1) characterise gorgonian diversity and ecology across a gradient of habitat quality within the Wakatobi Marine National Park (WMNP), SE Sulawesi, Indonesia, 2) assess morphological and genetic variability between morphotypes of the ubiquitous zooxanthellate isidid Isis hippuris Linnaeus 1758 from healthy and degraded reefs, 3) determine if I. hippuris morphotypes are environmentally induced (plastic) or genetically derived through reciprocal transplant experiments (RTEs) between contrasting reefs and thus, 4) identify mechanisms of plasticity capacity or divergence through phenotypic trait integration in response to environmental change. Ecological surveys revealed considerable gorgonian diversity with a total of 197 species and morphotypes from 42 genera, and 12 families within the suborders Calcaxonia and Holaxonia and the group Scleraxonia, with current estimates of over 21 new species and 28 new species records for the region. Gorgonian abundance and diversity increased with reef health and bathymetry. However, a clear loss of gorgonian diversity existed with increased sedimentation and reduced light due to anthropogenic disturbance. In particular, two distinct I. hippuris morphotypes were highly abundant between environmental clines: short-branched multi/planar colonies on healthy reefs, and long-branched bushy colonies on degraded reefs. Comparative morphological and molecular analyses using ITS2 sequence and predicted secondary structure, further corroborated haplotype differences relative to morphotypes between environments. However, unsatisfactory assignment of I. hippuris morphotypes to previously described alternatives (Isis reticulata Nutting 1910, Isis minorbrachyblasta Zou, Huang & Wang 1991) questions the validity to such taxonomic assignments. Phylogenetic analyses also confirm that the polyphyletic nature of the Isididae lies in its type species I. hippuris, being unrelated to the rest of its family members. A one-year RTE revealed three key results, that: 1) reduced survivorship of healthy reef morphotypes on degraded reefs implied the onset of lineage segregation through immigrant inviability, 2) prominent phenotypic traits were at the morphological and bio-optical levels revealing high phenotypic plasticity in healthy clones, and relative insensitivity to environmental change in degraded reef morphotypes, indicative of local adaptation leading to incipient ecological divergence, and 3) photoacclimation at the bio-optical level was not attributed to endosymbiont diversity or shuffling, with all test colonies possessing a novel clade D1a Symbiodinium. While it is clear that gorgonian taxa within the WMNP are of exceptional diversity and abundance, responses to environmental perturbation highlight three pertinent, testable ideas. Firstly, increased species richness specifically with depth in azooxanthellate taxa, invite tests of deep-reef refugia previously established through geological change. Secondly, ecological assessment targets research on informative taxa for focused systematics and mechanisms of phenotypic divergence. Thirdly, exploring intrinsic and extrinsic interactions that define the host-symbiont relationship and differential biological success using physiological and next generation sequencing approaches. These objectives would provide considerable insight into the evolutionary processes to environmental change, accelerated by anthropogenic encroachment. Taken together, this work signifies that gorgonian corals within the WMNP are of foremost diversity and concern, exhibiting informative ecological and mechanistic responses to environmental perturbation. This evidence elicits tests of deep-reef refugia, priority systematics, mechanisms of ecological divergence and physiological assessment. Such tests inevitably expand our understanding of the intrinsic and extrinsic associations of gorgonian taxa to environmental change from an historical and predictive perspective yielding benefits to conservation assessment and management

Impact of the local environmental variability on the patterns of coral recruitment on Indo-Pacific reefs

Coral reefs are threatened by a range of human activities at both local and global scales. The result of these impacts has resulted in a worldwide decline in the coral reef ecosystems. Corals are the principle reef builders and the maintenance of their populations is fundamental for healthy reef ecosystems. Local environmental factors are critically important in shaping coral populations, particularly at the post-settlement phase, when young coral colonies are most vulnerable to disturbances. In this context, understanding the environmental factors that drive coral recruitment and affect coral survivorship in the early life history stages is vital to effectively manage coral reefs. In this thesis I began by investigating the effect of abiotic and biological factors on coral recruitment and juvenile coral life history stages using settlement panels deployed in the Wakatobi Marine National Park (SE Sulawesi, Indonesia). My objectives were to assess the spatio-temporal variability in coral recruitment rates and juvenile abundance. I used a modelling approach to identify the environmental factors that affected the distribution and abundance patterns of corals. Then, I focused on the main environmental factors, identified from previously published research, affecting coral recruitment. I conducted a caging experiment to assess the impact of fish predation on coral juveniles. Finally, I analysed the development of the benthic community and the interactions between corals and benthic organisms in the first two years of colonisation of artificial bare surfaces. I found high spatial and temporal variability in recruitment rates over seven years of data, values were lower than on other Indo-Pacific reefs and ranged from 9.6 (±8.21 SE) to 317.19 (±12.76 SE) rec. m⁻²; while juvenile abundance ranged from 4.2 (±1.49 SE) to 33 (±6.36 SE) juv. m⁻². The local characteristics of the sites, such as coral cover, influenced the distribution of coral colonies in early life history stages; furthermore differences in coral density between the two life history stages (juvenile and recruits) were consistent over time. However, no single or combination of factors adequately explained abundance patterns for either recruits or juveniles. Fish predation did not appear to be the main cause of coral post-settlement mortality in the Wakatobi and it affected only 10.8% of the coral juveniles in the experiment. In contrast, 58.51% of the coral juveniles were found to be overgrown by algae and other invertebrates, however only turf and green encrusting algae affected coral survivorship. Coral colony abundance and the number of interactions with other benthic organisms, especially crustose coralline algae (CCA) and sponges, increased over time on panels and they were different between the front and back side of the panels, which was attributed to differences in light and predation regimes. Coral recruitment was higher on older benthic communities, although none of the known coral recruitment promoters, such as CCA, or competitors, such as turf algae, were correlated with coral abundance. My results show that changes in coral populations between the recruit and juvenile stages are likely driven by small-scale processes. The site characteristics determine the final patterns, which vary over time following temporal fluctuations in environmental factors. The effect of the interactions between algae and sponges with coral recruits and their influence on juvenile survivorship suggests these organisms having a role in coral recruitment success and highlight their importance as a focus for reef management. Furthermore, the use of long term studies allowed a better understanding of the high variability present in coral recruitment and the trends of the recruitment process, which are useful information for conservative purposes

Coral larval recruitment in north-western Australia predicted by regional and local conditions

Understanding ecological processes that shape contemporary and future communities facilitates knowledge-based environmental management. In marine ecosystems, one of the most important processes is the supply of new recruits into a population. Here, we investigated spatiotemporal variability in coral recruitment at 15 reefs throughout the Dampier Archipelago, north-western Australia between 2015 and 2017 and identified the best environmental predictors for coral recruitment patterns over this period. Large differences in recruitment were observed among years with the average density of recruits increasing by 375% from 0.017 recruits cm−2 in 2015 to 0.059 recruits cm−2 in 2017. Despite differences in recruitment among years, the rank order of coral recruit density among reefs remained similar among years, suggesting that spatial variation in recruitment within the Dampier Archipelago is partly deterministic and predictable. The density of coral recruits was best explained by percent cover of live corals at both local (within 5 m) and meso-scales (within 15 km), water turbidity and an oceanographic model that predicted larval dispersal. The highest density of coral recruits (~0.13 recruits cm−2 or 37 recruits per tile) occurred on reefs within sub-regions (15 km) with greater than 35% coral cover, low to moderate turbidity (KD490 < 0.2) and moderate to high modelled predictions of larval dispersal. Our results demonstrate that broad-scale larval dispersal models, when combined with local metrics of percent hard coral cover and water turbidity, can reliably predict the relative abundance of coral recruits over large geographical areas and thus can identify hotspots of recruit abundance and potential recovery following environmental disturbances; information that is essential for effective management of coral reefs

Patterns of Temporal and Spatial Variability of Sponge Assemblages

The primary goals of this thesis were to understand the spatial and temporal pattern of sponge assemblage variation over a variety of scales and investigate suitable monitoring methods for sponge assemblages. Sponges are an ecologically significant group in benthic marine communities, which are often ignored in current monitoring schemes. In chapter two the sponge biodiversity of New Zealand waters to 200m was examined using Taxonomic Distinctness measures initially to test if genera data could be used as a proxy for species level data in New Zealand waters. It was found that over 50% of the variation in genera biodiversity could be explained by location and depth around New Zealand. The study helped pinpoint where there were gaps in the New Zealand dataset, in particular for the West Coast of the South Island and also areas such as the Wellington South Coast, which had higher than expected values for Average and Variation Taxonomic distinctness measures, which as important areas where sponges should be monitored to make sure the high levels of biodiversity are protected. Taxonomic distinctness measures are useful for initially assessing how the biodiversity is distributed, especially when using a data set with uneven sampling effort, as it is robust to spatial and temporal bias in the majority of cases. However, there was an outlier to the genera data correlating well with the variation in species data in the case of a site dominated by Haliclona sp (Lyttelton Harbour). In chapters three and four the spatial and temporal variability of sponge assemblages of the Wellington South Coast were explored creating both a species list for the area and an understanding of how the sponge assemblage varies over time and space. There were significant differences in the sponges assemblages in similar habitat types over a scale of a few hundred metres. In addition, although all the sponge assemblages changed seasonally, the changes at each sampling site responded in a slightly different way most likely due to spatiotemporal variation in environmental conditions. A similar seasonal pattern was also observed in chapter five for sponge assemblages at Skomer Marine Reserve and this pattern was also clear when using morphological monitoring methods. This means that once a site has been mapped for biodiversity it is possible for some habitats to use morphological monitoring to identify if the sponge assemblage is changing significantly saving time and money. The results from Indonesia (chapter six) showed that although the sponge assemblages were changing significantly in the actual species present and their abundances, the proportion of diversity within each spatial level (quadrat, site and region) remained consistent when sampled at the same time each year throughout the five year study. In species rich assemblages there are a variety of life strategies that can respond differently to shifts in environmental conditions and contribute to ecological functioning in various ways. Various monitoring methods have been tested using sponge assemblages over various spatial and temporal scales in this thesis. Spatial, temporal and the interaction of spatial and temporal factors were all important for identifying significant assemblage differences at all of the sites. Further studies integrating the interaction of spatial and temporal factors into understanding monitoring data sets are vital to understand the patterns of assemblage variability and therefore incorporate into habitat management plans

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

Effects of coral-dwelling damselfishes' abundances and diversity on host coral dynamics

Interspecific interactions, particularly positive interactions, between organisms and their physical environment are important forces in shaping ecological diversity and ecosystem structure. In coral reef ecosystems, the associations between habitat-forming corals and coral reef fishes have critical implications for the structure and function of coral reef ecosystems. Coral-dwelling damselfishes rely on branching corals for shelter and confer benefits to their host corals that promote enhanced performance, growth, and colony health. However, there is variability (in strength and symmetry) in both fish-derived and coral responses to abiotic factors and partner ecology. Global environmental change is likely to considerably disrupt fish-coral interactions on reefs through reef degradation, coastal sedimentation, and severe widespread bleaching events. Prior to collapse, however, fish-coral interactions have the potential to act as stabilizing forces on reefs, promoting coexistence, and enhancing the coral holobiont during accelerated environmental change. Thus, the overall focus of this thesis was to understand the relationship between coral-dwelling damselfishes and their small branching coral colony hosts. Specifically, I investigated the prevalence of these fish-coral associations across space, the variations in the intensity of damselfish-coral interactions over time and evaluated the influence of these coral-dwelling damselfishes on the health of their host corals under two types of environmental stress. In Chapter 2, I addressed one of the critical first steps to understanding the magnitude by which coral-dwelling damselfishes impact coral health by establishing the abundance and prevalence of select, fish-coral interaction pairs across different coral colonies, habitats, and seascapes. Through a series of underwater surveys at locations spanning > 1700 km of the Great Barrier Reef, I aimed to: (a) determine if suitable coral habitat governs patterns in damselfishes' distributions and abundances, and (b) quantify variations in damselfish species-specific biomass among coral colonies species. The abundance of fish-coral associations varied with respect to exposure level and habitat with an overall average prevalence of ~30% occupancy, with biomass hotspots confined to sheltered lagoon sand patch and reef slope habitats. Further analysis of colony microstructure traits revealed that isolation from adjacent colonies, branch spacing patterns, and colony orientation governed fine-scale usage. The research presented in Chapter 2 illustrates that coral occupancy (coral-dwelling or sole habitat use) varies significantly by damselfish species, and subsequent fish-derived services are confined to specific reef habitats. While coral-dwelling damselfishes are intimately associated with branching corals, interspecific behavioural variation can alter the nature and strength of these interactions with corals, thereby altering the dynamics of small-scale coral association networks and benefits conferred to host corals. Chapter 3 used in-situ observations to explore interspecific differences in diurnal and nocturnal behaviour among five coral-dwelling damselfish species. Resident damselfishes displayed marked differences in colony interaction and usage, with Dasycllus species exhibiting frequent and sustained interactions with host corals. Pomacentrus species displayed weaker associations and behaviours consistent with commensalistic interactions. Host coral bleaching status altered damselfishes' interactions with colonies, forecasting shifting interchanges between fishes and corals under future stress conditions. Quantifying these focal fishes' behaviours through small-scale observations is relevant to interspecific interactions and coral holobiont persistence, as environmental stressors alter the prevalence of coral-damselfish interactions and the intensity of associated mutualistic services. Global environmental change, particularly in the forms of amplified sedimentation and elevated sea-surface temperatures, could pose to significantly alter how these fish-coral interactions function in isolation and as components of the entire coral holobiont. Many species interactions, mutualistic ones in particular, arise from the ability of species to modify local conditions and diminish stress for their own benefit as well as for their partners, thereby conferring resilience. In Chapters 4 and 5, I evaluated the influence of coral-dwelling fishes (Dascyllus aruanus and Pomacentrus moluccensis, selected due to their abundance and behaviours exhibited in Chapters 2 and 3) on the health of their host corals (Pocillopora damicornis) under two types of environmental stress. When exposing the fish-coral system to daily manipulated severe sedimentation stress in Chapter 4, damselfishes were able to significantly reduce sediment accumulation and sediment-induced partial mortality on coral hosts, 2-10-fold more, compared with fish-vacant colonies. Colonies with Dascyllus aruanus exhibited up to two-fold higher chlorophyll and protein concentrations under sediment conditions compared with other treatments, reinforcing the positive nature and benefits connected with a frequent and sustained (strong) interaction with host colonies. Further linking these results to the behaviour of the damselfish species (Chapter 3), diurnal and nocturnal position of D. aruanus and P. moluccensis in aquaria, helped explain the species-specific services rendered. In Chapter 4, I demonstrated that fish mutualisms may be critical for maintaining coral health and resilience under chronic and severe sediment stress and indicated that some mutualistic or facilitative interactions may become more important for species persistence as stress levels increase. Many studies have independently investigated the effects of increased sea-surface temperatures on fishes and coral bleaching, but little is known about the impacts of coral-dwelling damselfishes on the health of their coral hosts, during and after a thermal-bleaching event. With many services that damselfishes provide to their host colonies, especially those that mimic natural mechanisms mitigating external stress, in Chapter 5, I hypothesized that colonies with symbiont damselfishes would bleach less and recover more quickly during thermal bleaching events, compared to vacant corals, due to key services of enhanced water flow and nutrients. During a natural thermal anomaly, it is evident that P. damicornis with damselfish that are subjected to temperature stress have higher Symbiodinium (+25%), chlorophyll (+30%), and tissue proteins (+57%). These results were reflected in a manipulated thermal bleaching experiment in aquaria, where corals with damselfish subjected to temperature stress again had significantly more Symbiodinium (five-fold), chlorophyll (nine-fold), and tissue biomass (three-fold) compared with vacant colonies during the recovery period. Tissue component differences translated into considerably higher photosynthetic rates in P. damicornis colonies with fish, compared with non-damselfish colonies. However, from the in-situ results from the 2016 bleaching event, it is evident that this fish influence on colony susceptibility/resilience and recovery operates only under moderate level stressors, as severe bleaching events overwhelm the coral holobiont, rendering fish-services insufficient to maintain coral health. This thesis reveals the importance of resident fishes as a fundamental aspect of the dynamic interface between corals and the abiotic environment. Although limited spatially across reef seascapes, and heavily dependent upon the species-specific behaviour of fish partners, these findings suggest that certain coral-dwelling damselfishes have the ability to mediate the impacts of environmental change with regards to coral colony stress susceptibility and survival