Holocene reef accretion of the inshore Kimberley Bioregion and response to sea-level changes

The Kimberley Bioregion of Northwest Australia is one of the world’s last great pristine marine environments and is broadly recognised as a “biodiversity hostspot” but is poorly known and studied. This project completed a comprehensive description of reef geomorphology and associated habitats, stratigraphy, palaeoecology, geochronology, accretion history along with shallow seismic profile. A combination of the data collected and interpreted provides the foundation for a scientifically based management plan of the Bioregion

Morphodynamic controls for growth and evolution of a rubble coral island

Rubble islands are dynamic sedimentary features present on reef platforms that evolve under a variety of morphodynamic processes and controlling mechanisms. They provide valuable inhabitable land for small island nations, critical habitat for numerous species, and are threatened by climate change. Aiming to investigate the controlling mechanisms dictating the evolution of One Tree Island (OTI), a rubble island in the Southern Great Barrier Reef, we combined different remotely-sensed data across varying timescales with wave data extracted from satellite altimetry and cyclone activity. Our findings show that (1) OTI had expanded by 7% between 1978 and 2019, (2) significant gross planform decadal adjustments were governed by the amount, intensity, proximity, and relative position of cyclones as well as El Niño Southern Oscillation (ENSO) phases, and (3) the mechanisms of island growth involve rubble spits delivering and redistributing rubble to the island through alongshore sediment transport and wave overtopping. Frequent short-term monitoring of the island and further research coupling variations in the different factors driving island change (i.e., sediment availability, reef-wave interactions, and extreme events) are needed to shed light on the future trajectory of OTI and other rubble islands under a climate change scenario

Late Quaternary Evolution of Western Australian Continental Shelf Sediment Systems

This thesis shows how Western Australian coast and continental shelf evolved into their present form, in response to changes in sea-level and climate, during the last Glacial Age. I have focused on four contrasting marine environments: the Kimberley coast and offshore islands, Shark Bay, the Swan River estuary and Geographe Bay. In each area, I took a multidisciplinary approach to my data collection and analysis utilising remote sensing, marine geophysics, sedimentological and geochronological methodologies

Variable Patterns in Spur and Groove Reef Morphology Explained by Physical Controls and their Relevance for Platform-Top Sedimentology

Spur and groove (SaG) morphology is a common ornamentation of reef-armored Holocene carbonate platform margins. Composed of margin-normal promontories constructed of coral framestone, termed “spurs”, interleaved with similarly orientated gullies, “grooves”, this morphology varies based on a host of physical controls. Primarily, the surrounding oceanographic conditions as well as the size and shape of the platform the SaG is encompassing, directly influence the development and organization of SaG. Since grooves act as conduits for carbonate sediment transport, this study seeks to examine the relationship between SaG organization dictated by platform size and shape and how that in turn influences platform-top sedimentation. The analysis reveals trends that suggest platform shape plays a larger role than platform size in allowing highly organized SaG to develop on multiple margins around the platform. In turn, those trends would suggest these sites to have more stable platform top sediment deposits. However, many variables go in to the creation and maintenance of platform top cays. While this study enhanced the current understanding of how oceanographic conditions influence SaG development and organization, expanding on the concepts and results found in this study coupled with coring data of SaG and platform-top cays, could further link the connection between SaG and sediment transport

Diversity and drivers of coral reef cryptofauna communities

Tropical coral reefs are exceptionally biodiverse ecosystems, and many species within reefs remain undiscovered, undescribed or under-studied. This is especially true of organisms living hidden within the cavities and crevices of the reef matrix, the cryptofauna. Cryptofauna, and the cryptobenthic communities they form, make up a significant portion of animal diversity within coral reefs and play functional roles vital for reef productivity and trophodynamics. Globally, coral reefs are experiencing degradation due to climate-change and direct human impacts, and face mass biodiversity loss by the end of the 21st century. To predict the impacts of projected climate change on coral reefs, we must have a comprehensive understanding of the baseline diversity and composition of the communities they harbour. This thesis explores the diversity and drivers of cryptobenthic communities across the remote and protected Chagos Archipelago Marine Protected Area (MPA)(Central Indian Ocean), an important scientific reference site for the wider Indian Ocean due to its near-pristine status and minimal local human impacts. Standardised artificial substrates named Autonomous Reef Monitoring Structures (ARMS) were deployed across three reefs in 2018 and retrieved in 2019 and 2021 to collect image and genetic data on cryptobenthic communities. Little research has been conducted on cryptobenthic communities in the Chagos Archipelago, and we have a poor understanding of their biodiversity across the MPA in comparison to other reefs of the Indo-Pacific. Here, a rich and highly diverse community of coral reef organisms is recovered using multi-marker (COI, 18S) metabarcoding, and significant spatial and temporal variability in the metazoan community composition of three reefs is observed. However, only 3-4% of the 18,436 COI sequence variants identified are assigned to species level. With high confidence I identify 168 fully described species, but 95% of these are not represented in online museum records which hold specimen collected from the archipelago. This indicates that the archipelago’s reef biodiversity is likely far higher than presently understood. However, less than half of the species known to inhabit the archipelago have representative sequences in this study’s classifier, which is used to assign taxonomy to sequences , highlighting how the current paucity of references databases hinders metabarcoding studies of cryptofauna. Studies integrating biological and physical components of reef habitats are needed to understand how cryptobenthic communities may respond to shifts in environmental conditions. I show how ocean-facing and lagoonal reefs differ in environmental conditions, using seven in-situ environmental variables, and how this is reflected in the community composition of sessile cryptobenthic organisms. Internal waves are detected across ocean-facing reefs and found to maintain lower temperature conditions, and findings demonstrate the importance of using in-situ data, rather than ex-situ satellite-based data. Calcifying organism abundance significantly correlates with lower temperature profiles of ocean-facing reefs, but fleshy macroalgal abundance is associated with more variable profiles of pH and dissolved oxygen in a lagoonal habitat. Overall, results highlight habitat preferences of sessile invertebrate and algal groups within year-old communities and suggest which may be more resilient to climate-change induced increases in temperature and pH conditions. All artificial substrates used to study coral reefs have inherent biases, and it is important to determine what those biases are when using them to study natural reefs. I compare sessile communities recovered on ARMS against those on dead tabular Acropora sp. coral, a common species in the archipelago, to help understand these biases. I find similar abundances of sponges, soft-tube worms and ascidians on both substrates, but that ARMS may significantly overestimate natural abundances of calcifying invertebrates and under-estimate those of hard corals, turf and crustose coralline algae. I also compare communities recovered, using metabarcoding, on ARMS versus those from filtered water samples (environmental DNA) collected in the vicinity. I find eDNA sampling may be a poor proxy for studying motile invertebrates, but valuable for studying sponges, as it detects 17 out of 20 most abundant sponge species as well as an additional 9 species not detected on ARMS. Finally, I explore the use of fluorescence imaging to study ARMS sessile communities, and record 35 hard coral colonies on average per m2 across study sites. I find overall coral abundance is equal between lagoonal and ocean- facing reefs, but that coral abundance in the lagoonal reef is higher on the undersides of ARMS plates than on top of them, a pattern not observed across ocean-facing reefs and potentially driven by higher sedimentation occurring in the lagoon. This study highlights how fluorescence imaging may be a valuable additional method for the study of cryptobenthic assemblages on ARMS and I recommend its integration within the ARMS toolkit. In summary, this thesis significantly advances the knowledge of cryptobenthic communities of the Chagos Archipelago MPA, highlights its importance as a biodiverse scientific reference site, and furthers our understanding of the ARMS methodology. Whilst further work will be needed to fully characterise cryptofauna biodiversity across these reefs, findings presented in this thesis provide a baseline for future studies of these complex communities across the Indian Ocean region

Assessing the impacts of shoreline hardening on beach response to hurricanes: Saint-Barthélemy, Lesser Antilles

International audienc

The Use of Remote Sensing for Coral Reef Mapping in Support of Integrated Coastal Zone Management: A Case Study in the NW Red Sea - Volume I

Worldwide, coral reefs are rapidly degrading due to the combined negative effects of human activities and global change. Even though the Red Sea is a very suitable natural environment for coral reef growth, their status also has rapidly deteriorated since the 1970s. Coral reefs are especially affected in the NW Red Sea, primarily due to coastal development projects supporting the booming tourism industry. Integrated coastal zone management (ICZM), therefore, is urgently needed to protect the coral reefs and conserve these valuable natural resources for future generations. Effective ICZM necessitates sound baseline information concerning the current status of the coral reefs and the actual human activities taking place, as well as a tool to monitor changes in both elements. Fulfilling these requirements using in situ observations alone is both time- and labour-intensive and, therefore, often financially too demanding, especially for developing countries. Here, remote sensing may bring the solution as it synoptically collects data over large areas in a cost-efficient way. This work has proven the usefulness of passive, optical remote sensing from spaceborne platforms to collect and monitor the required data and support an effective ICZM. Based on Landsat 7 ETM+ and QuickBird data, accurate information has been collected on the bathymetric structure of the coral reef seabed, its geomorphological zonation, and the distribution of the main marine coastal habitats. The possibility to monitor changes in these elements as well as in the coastal development has also been confirmed. These remote sensing derived products have subsequently been analysed and integrated with auxiliary datasets in a GIS to develop valuable decision-support products such as a risk assessment map and a multi-use marine protected area zoning plan. To support ICZM, remote sensing is best integrated in a multi-level sampling approach in which detailed in situ observations are complemented with more broad-scale, regional information derived from remote sensing data analysis. As such, information-based decisions can be made, augmenting the success of the ICZM. This not only counts for the specific study area but is likely necessary for the sustainable development of coral reef coastal zones worldwide

BENTHIC HABITAT MAPPING OF MOUNTAIN TOP BANK WITHIN THE NORTHERN GULF OF MEXICO THROUGH INTEGRATED GEOPHYSICAL AND VISUAL DATA ANALYSIS

Mesophotic coral ecosystems (MCEs) are among the seafloor ecosystems that have been poorly studied throughout the world’s oceans, but they are a vital and diverse ecosystem that should be prioritized for future mapping and ecological studies. Priority should be given to them because they possess natural, social, and economic values, and face a variety of threats, all of which, if not better understood will result in the loss of this unique ecosystem. Insights into these ecosystems, among other deep-sea environments, are lacking due to difficulty accessing them, inherent lag between data collection by an autonomous system and observation by a scientific team, and the vastness of the seafloor. The Gulf of Mexico, a geologically complex environment, has demonstrated the characteristics needed to support MCEs, with reefs such as the Pinnacle Reefs, Flower Garden Banks National Marine Sanctuary (FGBNMS), the Florida Middle Ground reef system, and Pulley Ridge already identified. Mountain Top Bank (MTB), a hardground feature 60-150 m below the sea surface, is a mesophotic reef site off the coast of Mississippi, USA. As it is poorly understood, it is the focus of this study. Bathymetry, backscatter, and photographic ground truthing data were collected by autonomous surface and underwater vehicles (ASV, AUV) and compiled into ArcGIS software to produce a benthic habitat map (BHM) and geodatabase of this site. These data were used to correlate fish and macroinvertebrate presence and abundance with habitat features within a transect atop MTB. This analysis illustrated that the site is characterized by a network of outcrops and boulders interspersed within a predominately sandy environment, with a diverse array of biota including Cnidaria, Porifera, Mollusca, Chordata, Echinodermata, and Rhodophyta. Compiling these data into a BHM and geographic information system (GIS) geodatabase is a powerful way to assess ecosystems and support conservation efforts

Vulnerable Islands: Climate Change, Tectonic Change, and Changing Livelihoods in the Western Pacific

Small Pacific islands, especially atolls, have been widely argued to be in the forefront of climate change. Recent degradation of island environments has primarily been attributed to the impact of sea-level rise. However, physical changes to several small islands can be linked to a range of physical influences and to human modification. La Niña events, cyclones, and wind waves have caused localized flooding and storm damage. Most atoll islands have not significantly changed in size, as deposition balances erosion. Many islands have experienced broadly similar environmental problems in earlier times, at different scales, and over different time periods, now accentuated by human pressures on scarce land areas and resources. Local human factors (including construction and mining), tectonic subsidence, and La Niña events have created some iconic sites that have become symbols of sea-level rise, sometimes erroneously attributed solely to global warming. Limited economic prospects in most small islands, rising expectations, and growing populations have contributed to a culture of migration, marked by international migration and urbanization, that has diversified impoverished livelihoods, extended island geographies, and resulted in accentuated population concentrations. Contemporary climate change exacerbates present environmental changes, stimulates further migration, and points to diasporic futures

HERMIONE news

18 páginasIn summer 2010, the German research vessel POSEIDON started its 400th cruise to the Porcupine Seabight off Ireland. Led by the HERMIONE scientist Claudia Wienberg, a team of 9 scientists and technicians from MARUM, SaM (Senckenberg Institute Wilhelmshaven) and UCC (University College Cork) was exploring the unique cold-water coral ecosystems of this area. The focus of expedition POS400 was set on the investigation of cold-water coral mounds of the Belgica Mound Province, where coral mounds are aligned as chains stretching from north to south, parallel to the slope.The HERMIONE project is funded by the European Commission's Framework 7 Programme, under the theme "Environment (including climate change)". EC contract no. 226354.Peer reviewe