Coral reefs as ocean-connected ecosystems: Impacts on food webs and reef futures under climate change.

Global decline in capacity of coral reefs to provide ecosystem services

Nanobiotech engineering for future coral reefs

Coral reefs are iconic examples of biological hotspots, highly appreciated because of their ecosystem services. Yet, they are threatened by human impact and climate change, highlighting the need to develop tools and strategies to curtail changes in these ecosystems. Remarkably, ever since Darwin’s descriptions of coral reefs, it has been a mystery how one of Earth’s most productive and diverse ecosystems thrives in oligotrophic seas, as an oasis in a marine desert. Sponges are now increasingly recognized as key ecosystem engineers, efficiently retaining and transferring energy and nutrients on the reef. As a result, current reef food web models, lacking sponge-driven resource cycling, are incomplete and need to be redeveloped. However, mechanisms that determine the capacity of sponge “engines,” how they are fueled, and drive communities are unknown. Here we will discuss how sponges integrate within the novel reef food web framework. To this end, sponges will be evaluated on functional traits (morphology, associated microbes, pumping rate) in the processing of dissolved and particulate food. At the community level, we discuss to what extent these different traits are a driving force in structuring shallow- to deep-sea reef ecosystems, from fuel input (primary producers) to engine output (driving and modulating the consumer food web). Finally, as climate change causes the onset of alterations in the community structure and food web of reef ecosystems, there is evidence accumulating that certain biological pathways are triggered, such as the sponge loop and the microbial loop, that may shift reef ecosystems faster than their original stressors (e.g., warming oceans and ocean acidification). Unfortunately, these biological pathways receive much less attention at present, which seriously hampers our ability to predict future changes within reef ecosystems.

<p>Climate change, in particular the rise in tropical sea surface temperatures, is the greatest threat to coral reef ecosystems today and causes climatic extremes affecting the livelihood of tropical societies. The combination of long-term global warming and interannual El Niño-related warm events has severely affected corals and coral reefs throughout the tropical ocean basins. Mass coral bleaching, a result of large-scale temperature stress, was first observed during the 1982/83 El Niño, and was followed by much more severe, global scale bleaching events during the El Niño years of 1997/98 and 2010, culminating in the most wide-spread and most destructive global bleaching episode to date, which lasted from 2014-2017. The interval between recurrent mass coral bleaching events driven by anomalously high sea surface temperatures is becoming too short for a full recovery of mature coral reef assemblages and will have dramatic effects on future coral reef growth. Assessing how future warming will change coral reef ecosystems and tropical climate variability is therefore of extreme urgency.</p><p>The recently established Priority Programme „Tropical Climate Variability and Coral Reefs – A Past to Future Perspective on Current Rates of Change at Ultra-High Resolution“ (SPP 2299; https://www.spp2299.tropicalclimatecorals.de/) of the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) aims to enhance our current understanding of tropical marine climate variability and its impact on coral reef ecosystems in a warming world, by quantifying climatic and environmental changes during both the ongoing warming and past warm periods on timescales relevant for society. Ultra-high resolution coral geochemistry provides a tool to understand the temporal response of corals and coral reefs to ongoing climate and environmental change, to reconstruct past tropical climate and environmental variability and to use these data in conjunction with advanced statistical methods, earth system modelling and observed ecosystem responses for improved projections of future changes in tropical climate and coral reef ecosystems.</p><p>The Priority Programme is organised around three major research topics in order to fuel interdisciplinary collaboration among various disciplines: (a) Large-scale ocean, climate & environment reconstructions, (b) Coral & reef-scale response to current environmental stress, and (c) Climate, reef & proxy modelling – Climate & proxy advanced statistics. The strongly interdisciplinary Priority Programme will bring together expertise in the fields of climate, environmental and ecosytem research in a sustainable manner, and aims to provide an ultra-high resolution past to future perspective on current rates of change to project how tropical marine climate variability and coral reef ecosystems will change in a warming world.</p>

Coral reef ecosystems are being altered by rising ocean temperatures and increasing nutrient inputs, yet their combined influence on food-web structure is not well understood. Here we analyzed 130 coral reef food webs across the South China Sea, constructed from environmental DNA surveys integrated with trophic interactions. We grouped the food webs into surface-water, bottom-water and sediment habitats. Our analyses reveal pronounced structural differences among habitats: surface- and bottom-water webs exhibit significantly higher connectance and nestedness, whereas sediment webs are more compartmentalized. Using linear mixed-effects models, we find that temperature and productivity interact in nonlinear ways to shape food-web properties. In surface waters, higher temperature together with higher productivity tends to increase connectance, whereas in deeper waters the same conditions tend to lengthen trophic pathways and reduce stability. These results suggest that future environmental change may influence pelagic and benthic reef food webs in contrasting ways.

Coral reef ecosystems are beautiful and vibrant underwater communities inhabited by a spectacularly diverse and abundant array of organisms essential to human needs. Reefs are severely threatened worldwide—estimates are that one-fifth of coral reefs have already been lost or severely damaged, and the rest are expected to disappear before the end of this century. The intrinsic value of coral reefs is incalculable and immense, and this technical note seeks to educate students about that value, as well as the threats—global and local—to coral reefs. Excerpt UVA-ENT-0201 Mar. 12, 2014 CORAL REEF ECOSYSTEMS: VALUABLE AND CRITICALLY THREATENED The Value of Coral Reefs Coral reef ecosystems are beautiful and vibrant underwater communities inhabited by a spectacularly diverse and abundant array of organisms essential to human needs. Reefs are severely threatened worldwide—estimates are that one-fifth of coral reefs have already been lost or severely damaged, and the rest are expected to disappear before the end of this century. The intrinsic value of coral reefs is incalculable and immense. Figure 1 shows the distribution of coral reefs worldwide. Each red dot represents an image taken by the Landsat 7 spacecraft for the Millennium Coral Reef Mapping Project. Red dots located over smaller reefs may over-represent the area covered by those reefs. Figure 1. Worldwide coral reef distribution. Source: “NASA Coral Reef Images Key to New Global Survey,” http://www.nasa.gov/vision/earth/lookingatearth/coral_assessment.html (accessed March 29, 2013). . . .

基于文献计量分析的珊瑚礁研究现状与热点

Climate change, in particular the rise in tropical sea surface temperatures, is the greatest threat to coral reef ecosystems today and causes climatic extremes affecting the livelihood of tropical societies. Assessing how future warming will change coral reef ecosystems and tropical climate variability is therefore of extreme urgency. Ultra-high resolution (monthly, weekly) coral geochemistry provides a tool to understand the temporal response of corals and coral reefs to ongoing climate and environmental change, to reconstruct past tropical climate and environmental variability, and to use these data in conjunction with advanced statistical methods, earth system modelling and observed ecosystem responses for improved projections of future changes in tropical climate and coral reef ecosystems. The recently established Priority Programme “Tropical Climate Variability and Coral Reefs - A Past to Future Perspective on Current Rates of Change at Ultra-High Resolution” (SPP 2299, https://www.spp2299.tropicalclimatecorals.de/) of the German Research Foundation (DFG) aims to enhance our current understanding of tropical marine climate variability and its impact on coral reef ecosystems in a warming world, by quantifying climatic and environmental changes during both the ongoing warming and past warm periods on timescales relevant for society. The programme aims to provide an ultra-high resolution past to future perspective on current rates of change to project how tropical marine climate variability and coral reef ecosystems will change in a warming world. Information on the organisational structure and research topics of this collaborative programme, which involves ten universities and five research centres from all over Germany, will be provided.

A Hybrid Modelling Framework for Ecosystem-Based Climate Change Adaptation Using System Dynamics and Bayesian Networks

Chapter 20 - Changes in coral reef ecosystems as an indication of climate and global change

Coral reef ecosystems are important fishing grounds in tropical and subtropical areas and have been widely contaminated by chemicals. However, the current understanding of the pollution status and trophic transfer of exogenous chemicals in coral reef ecosystems is still limited. This study aims to characterize the occurrence of 16 priority polycyclic aromatic hydrocarbons (PAHs) in sediments, corals, and other biotas in the trophic-complex coral reef ecosystems in the Xisha and Nansha Islands of the South China Sea. PAH transfer characteristics in the highly diverse coral reef food webs were analyzed through stable isotope ratios and trophic magnification factors (TMFs). PAHs were observed in sediment and biota samples of both Xisha and Nansha coral reef ecosystems. The TMFs ranging from 0.46 to 2.18 for the Xisha food web indicate limited trophic transfer of PAHs, while those ranging from 1.07 to 5.25 for the Nansha food web indicate trophic magnification of PAHs. The octanol-water partition coefficient (Kow) of PAHs may positively influence the PAH biomagnification via accumulation along the trophic levels. This study provides new insights into PAH contamination patterns and their trophodynamic behaviour in highly diverse coral reef ecosystems, which can serve as a scientific basis for ecological risk assessment, biodiversity conservation, and coastal function management in global coral reef systems.

Refining the ecological role of stingrays in coral reef ecosystems

珊瑚礁生态系统病毒研究进展

Coral reefs are one of the ecosystems that provide economic and environmental benefits to coastal communities in Indonesia. However, coral reef ecosystems are also one of the ecosystems threatened by climate change at the local scale. The waters of North Sekotong, West Lombok, Indonesia, are a tropical coastal system with beautiful coral reefs and marine ecosystems. Coral reef damage has been widespread in this area due to increased water temperatures. Increased water temperature results in coral reef degradation. Field surveys were conducted on May 23-28, 2016, in collaboration with the Marine and Coastal Resources Research and Development Center, Ministry of Marine Affairs and Fisheries, and coral reef mapping using Landsat 7 and Landsat 8 during 2002 - 2016 as well as processing monthly sea surface temperature (SST) data from the AquaModis and Oi SST V2 satellites and daily SST data from the NOAA Coral Reef Watch satellite. Changes in coral cover area were compared with temperature changes due to climate change. The increase in temperature creates a hotspot phenomenon in the coral reef ecosystem, resulting in coral reef degradation. The results showed that coral reefs in this area have degraded by 17.55% or 78.21 Ha from 455.68 Ha (2002) to 367.46 Ha (2016), with a degradation rate of 2.8 Ha/year in 2002 - 2014; 8.1 Ha/year (2014 - 2014) and 36 Ha/year (2015 - 2016) caused by an increase in SST which caused a hotspot phenomenon with a high enough intensity that there was an increase in temperature in 2016 which reached 9.77oC.

Coral reefs are found in a wide range of environments, where they provide food and habitat to a large range of organisms as well as other ecological goods and services. Warm-water coral reefs, for example, occupy shallow sunlit, warm and alkaline waters in order to grow and calcify at the high rates necessary to build and maintain their calcium carbonate structures. At deeper locations (40 – 150 m), “mesophotic” (low light) coral reefs accumulate calcium carbonate at much lower rates (if at all in some cases) yet remain important as habitat for a wide range of organisms, including those important for fisheries. Finally, even deeper, down to 2000 m or more, the so-called ‘cold-water’ coral reefs are found in the dark depths. Despite their importance, coral reefs are facing significant challenges from human activities including pollution, over-harvesting, physical destruction, and climate change. In the latter case, even lower greenhouse gas emission scenarios (such as Representative Concentration Pathway RCP 4.5) are likely drive the elimination of most warm-water coral reefs by 2040-2050. Cold-water corals are also threatened by warming temperatures and ocean acidification although evidence of the direct effect of climate change is less clear. Evidence that coral reefs can adapt at rates which are sufficient for them to keep up with rapid ocean warming and acidification is minimal, especially given that corals are long-lived and hence have slow rates of evolution. Conclusions that coral reefs will migrate to higher latitudes as they warm are equally unfounded, with the observations of tropical species appearing at high latitudes ‘necessary but not sufficient’ evidence that entire coral reef ecosystems are shifting. On the contrary, coral reefs are likely to degrade rapidly over the next 20 years, presenting fundamental challenges for the 500 million people who derive food, income, coastal protection, and a range of other services from coral reefs. Unless rapid advances to the goals of the Paris Climate Change Agreement occur over the next decade, hundreds of millions of people are likely to face increasing amounts of poverty and social disruption, and, in some cases, regional insecurity.