Corals

Review of the State Party Report on the State of Conservation of the Great Barrier Reef World Heritage Area (Australia)

Tarte D, Hughes T. Review of the State Party Report on the State of Conservation of the Great Barrier Reef World Heritage Area (Australia). Australian Marine Conservation Society; 2020. Available from: https://independent.academia.edu/DiTarte
Freely available?: 
Yes
Summary available?: 
No
Type: Report

In response to the 2015 and 2017 decisions of the World Heritage Committee, the Australian government submitted to the World Heritage Centre in December 2019 the State Party Report on the state of conservation of the Great Barrier Reef (GBR) World Heritage Area (WHA). The 2017 decision of the World Heritage Committee (WHC) focussed on two areas in particular, namely:

4. .... accelerate efforts to ensure meeting the intermediate and long-term targets of the [Reef 2050 Long-Term Sustainability] plan ... in particular regarding water quality;

6. .... demonstrating the effective and sustained protection of the property’s Outstanding Universal Value and effective performance in meeting the targets established under the 2050 LTSP [Reef 2050 Long-Term Sustainability Plan], linked to the findings of the 2014 and 2019 Great Barrier Reef Outlook Reports.

This review also focusses on these two areas, as well as the implications of Australia’s current climate change polices and the existing funding arrangements for management of the GBR.

Relative to previous GBR State Party Reports (2013, 2014, 2015) the 2019 Report provides more detail on funding arrangements and progress to achieving management targets. Overall, it is a more informative document. However, it still overstates the efficacy of existing management arrangements and understates the critical importance of effectively and immediately addressing the causes of climate change. We are concerned particularly by the present Australian government’s inadequate national climate change and energy policies and programs, and the implications these have for the future of the Great Barrier Reef.

Megacity development and the demise of coastal coral communities: Evidence from coral skeleton δ15N records in the Pearl River estuary

Duprey NN, Wang TX, Kim T, Cybulski JD, Vonhof HB, Crutzen PJ, Haug GH, Sigman DM, Martínez‐García A, Baker DM. Megacity development and the demise of coastal coral communities: Evidence from coral skeleton δ15N records in the Pearl River estuary. Global Change Biology [Internet]. 2019 . Available from: https://onlinelibrary.wiley.com/doi/full/10.1111/gcb.14923
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Historical coral skeleton (CS) δ18O and δ15N records were produced from samples recovered from sedimentary deposits, held in natural history museum collections, and cored into modern coral heads. These records were used to assess the influence of global warming and regional eutrophication, respectively, on the decline of coastal coral communities following the development of the Pearl River Delta (PRD) megacity, China. We find that, until 2007, ocean warming was not a major threat to coral communities in the Pearl River estuary; instead, nitrogen (N) inputs dominated impacts. The high but stable CS‐δ15N values (9‰–12‰ vs. air) observed from the mid‐Holocene until 1980 indicate that soil and stream denitrification reduced and modulated the hydrologic inputs of N, blunting the rise in coastal N sources during the early phase of the Pearl River estuary urbanization. However, an unprecedented CS‐δ15N peak was observed from 1987 to 1993 (>13‰ vs. air), concomitant to an increase of NH4+ concentration, consistent with the rapid Pearl River estuary urbanization as the main cause for this eutrophication event. We suggest that widespread discharge of domestic sewage entered directly into the estuary, preventing removal by natural denitrification hotspots. We argue that this event caused the dramatic decline of the Pearl River estuary coral communities reported from 1980 to 2000. Subsequently, the coral record shows that the implementation of improved wastewater management policies succeeded in bringing down both CS‐δ15N and NH4+ concentrations in the early 2000s. This study points to the potential importance of eutrophication over ocean warming in coral decline along urbanized coastlines and in particular in the vicinity of megacities.

New insights into the ecology and conservation of bryozoans: from global diversity patterns to the responses to anthropogenic stressors in the Mediterranean Sea

Escolà MPagès. New insights into the ecology and conservation of bryozoans: from global diversity patterns to the responses to anthropogenic stressors in the Mediterranean Sea. University of Barcelona; 2018.
Freely available?: 
Yes
Summary available?: 
No
Type: Thesis

Marine ecosystems are directly threatened by multiple and interactive human stressors at global and local scales. Hence, it is vital to study biodiversity and ecological patterns through a multi-disciplinary approach, from understanding global diversity patterns to evaluating the ecological responses of species to different impacts in order to protect marine ecosystems. Until this moment most of related ecological studies have focused on charismatic and popular groups, such as gorgonians, corals, macroalgae or seagrasses. In this thesis, we focused on bryozoans, an abundant group of sessile marine invertebrates distributed worldwide, but generally understudied. Moreover, large bryozoans are considered habitat-forming species that can create bioconstructions enhancing the associated biodiversity and providing different ecological benefits. Bearing this in mind, the main aim of this thesis was to provide different approaches to understand discovery and macroecological patterns at global scales, and the response of species to different stressors at local scales, combining the use of open databases, the in situ monitoring of natural populations, experiments in aquaria and the development of restoration techniques. Furthermore, the present thesis aims to contribute to provide a general framework to identify and protect vulnerable populations in the context of increasing human threats.

In the first chapter, the discovery patterns of fossil and extant bryozoans revealed the highest number of fossil species described, highlighting that the current biodiversity represents only a small proportion of Earth’s past biodiversity. Beyond these differences, both groups showed an increase in the taxonomic effort during the past century, reflecting the increase in the interest in the exploration of the marine environment, and the improvement of technological developments. Despite this progress, future projections of discovery patterns of both groups showed a large proportion of species remaining to be discovered by the end of this century, which corroborate the need to increase the effort to name and quantify marine biodiversity before hundreds of species become extinct due to human impacts.

In chapter 2, a comparative approach between marine sessile and bryozoan biodiversity patterns reported that the most of sessile groups presented higher diversity in the Southern ocean, displaying a non-unimodal latitudinal pattern with a dip in the number of species at the equator, contrary to the most traditionally accepted pattern in diversity studies. Moreover, this region will represent the less affected by global warming at the final of this century, suggesting that the high species richness recorded in this region may be explained by it has suffered lower temperature stress over evolutionary time. Related to biases in sampling effort, our analyses showed that the most sampled region for both marine sessile species and bryozoans was North Temperate Atlantic. To identify and quantify environmental drivers for both groups, we tested the effect of using the popular method of rarefaction to correct sampling effort biases vs the incorporation of a frequency index of sampling effort as co-variate in quantitative models. Despite we obtained the same best predictors for both approches (depth, nitrate, and SST), the models using the correction of sampling biases through frequency index showed better fitting, encouraging to incorporate this methodology in future studies.

Focusing on the Mediterranean Sea, in Chapter 3 we studied the responses of bryozoans to different stressors. First, we showed that two abundant and common bryozoans, Pentapora fascialis and Myriapora truncata, displayed different tolerances to warming. Through the combination of in situ monitoring and experiments in aquaria, we revealed that mass mortality event recorded of Pentapora fascialis populations during summer 2015 may be explained by its lower thermal tolerance ranks. Moreover, in Chapter 4 we take the advantage of the in situ monitoring of Pentapora fascialis natural populations increasing the spatial and temporal effort, revealing that the bryozoan Pentapora fascialis is characterized by fast population dynamics, with high recruitment and growth rates, and a high capacity of recovery. Accordingly, we observed an increase in the density of its populations in the Marine Reserve of Medes Island since the 1990s. However, we evidenced that in this Marine Protected Area, diving can impact on the density, recruitment, survival, and the size of the colonies, registering lower values in frequented localities. Our results highlight that although Marine Protected Areas have been recognized as effective management and conservation tools to protect coastal ecosystems, the over frequentation of divers compromises the future viability of populations, highlighting the need to explore other management strategies.

In this context, for the first time in Chapter 5, different restoration techniques for bryozoans were developed and tested, focusing on the recruitment enhancement through the installation of recruitment surfaces and the transplantation of adult colonies of Pentapora fascialis. Plastic grids represented the best substrate in terms of facilitating the recruitment of our model species. The most successful technique to transplant adult colonies was to fix the colonies to the substrate with a nylon thread attached to the colony ex situ. The successful results and the affordable and economic cost of tested techniques aim to encourage the managers of Marine Protected Areas to apply similar methodologies to restore and conserve bryozoan temperate bioconstructions and the ecological services that they provide.

The results presented in this thesis show the importance to combine different approaches to understand the global and local ecological patterns of understudied but abundant groups, such as bryozoans. Our findings enlarge the current ecological knowledge of bryozoans at different scales, and highlight that more effort is needed to protect vulnerable populations. Accordingly, adaptive management formal plans and restoration actions are required to promote the conservation of marine communities in the context of increasing local and global stressors.

Building resilience in practice to support coral communities in the Western Indian Ocean

Hattam C, Evans L, Morrissey K, Hooper T, Young K, Khalid F, Bryant M, Thani A, Slade L, Perry C, et al. Building resilience in practice to support coral communities in the Western Indian Ocean. Environmental Science & Policy [Internet]. 2020 ;106:182 - 190. Available from: https://www.sciencedirect.com/science/article/pii/S1462901119308044
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Global environmental change and other site specific pressures (e.g. over fishing and pollution) are threating coral reefs and the livelihoods of dependent coastal communities. Multiple strategies are used to build the resilience of both coral reefs and reef dependent communities but the effectiveness of these strategies is largely unknown. Using the Western Indian Ocean (WIO) as a case study, this paper combines published literature and expert opinion elicited through a multi-stakeholder workshop to assess the intended and realised social and ecological implications of strategies commonly applied in the region. Findings suggest that all strategies can contribute to building social and ecological resilience, but this varies with context and the overall strategy objectives. The ability of strategies to be successful in the future is questioned. To support effective resilience policy development more nuanced lesson learning requires effective monitoring and evaluation as well as a disaggregated understanding of resilience in terms of gender, agency and the interaction between ecological and social resilience. Opportunities for further lesson sharing between experts in the region are needed.

Sexual production of corals for reef restoration in the Anthropocene

Randall CJ, Negri AP, Quigley KM, Foster T, Ricardo GF, Webster NS, Bay LK, Harrison PL, Babcock RC, Heyward AJ. Sexual production of corals for reef restoration in the Anthropocene. Marine Ecology Progress Series [Internet]. 2020 ;v635:203 - 232. Available from: https://www.int-res.com/abstracts/meps/v635/p203-232
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Coral-reef ecosystems are experiencing frequent and severe disturbance events that are reducing global coral abundance and potentially overwhelming the natural capacity for reefs to recover. While mitigation strategies for climate warming and other anthropogenic disturbances are implemented, coral restoration programmes are being established worldwide as an additional conservation measure to minimise coral loss and enhance coral recovery. Current restoration efforts predominantly rely on asexually produced coral fragments—a process with inherent practical constraints on the genetic diversity conserved and the spatial scale achieved. Because the resilience of coral communities has hitherto relied on regular renewal with natural recruits, the scaling-up of restoration programmes would benefit from greater use of sexually produced corals, which is an approach that is gaining momentum. Here we review the present state of knowledge of scleractinian coral sexual reproduction in the context of reef restoration, with a focus on broadcast-spawning corals. We identify key knowledge gaps and bottlenecks that currently constrain the sexual production of corals and consider the feasibility of using sexually produced corals for scaling-up restoration to the reef- and reef-system scales.

Monitoring of Coral Reefs Using Artificial Intelligence: A Feasible and Cost-Effective Approach

González-Rivero M, Beijbom O, Rodriguez-Ramirez A, Bryant DEP, Ganase A, Gonzalez-Marrero Y, Herrera-Reveles A, Kennedy EV, Kim CJS, Lopez-Marcano S, et al. Monitoring of Coral Reefs Using Artificial Intelligence: A Feasible and Cost-Effective Approach. Remote Sensing [Internet]. 2020 ;12(3):489. Available from: https://www.mdpi.com/2072-4292/12/3/489
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Ecosystem monitoring is central to effective management, where rapid reporting is essential to provide timely advice. While digital imagery has greatly improved the speed of underwater data collection for monitoring benthic communities, image analysis remains a bottleneck in reporting observations. In recent years, a rapid evolution of artificial intelligence in image recognition has been evident in its broad applications in modern society, offering new opportunities for increasing the capabilities of coral reef monitoring. Here, we evaluated the performance of Deep Learning Convolutional Neural Networks for automated image analysis, using a global coral reef monitoring dataset. The study demonstrates the advantages of automated image analysis for coral reef monitoring in terms of error and repeatability of benthic abundance estimations, as well as cost and benefit. We found unbiased and high agreement between expert and automated observations (97%). Repeated surveys and comparisons against existing monitoring programs also show that automated estimation of benthic composition is equally robust in detecting change and ensuring the continuity of existing monitoring data. Using this automated approach, data analysis and reporting can be accelerated by at least 200x and at a fraction of the cost (1%). Combining commonly used underwater imagery in monitoring with automated image annotation can dramatically improve how we measure and monitor coral reefs worldwide, particularly in terms of allocating limited resources, rapid reporting and data integration within and across management areas.

Coral restoration – A systematic review of current methods, successes, failures and future directions

Boström-Einarsson L, Babcock RC, Bayraktarov E, Ceccarelli D, Cook N, Ferse SCA, Hancock B, Harrison P, Hein M, Shaver E, et al. Coral restoration – A systematic review of current methods, successes, failures and future directions. PLOS ONE [Internet]. 2020 ;15(1):e0226631. Available from: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0226631
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Coral reef ecosystems have suffered an unprecedented loss of habitat-forming hard corals in recent decades. While marine conservation has historically focused on passive habitat protection, demand for and interest in active restoration has been growing in recent decades. However, a disconnect between coral restoration practitioners, coral reef managers and scientists has resulted in a disjointed field where it is difficult to gain an overview of existing knowledge. To address this, we aimed to synthesise the available knowledge in a comprehensive global review of coral restoration methods, incorporating data from the peer-reviewed scientific literature, complemented with grey literature and through a survey of coral restoration practitioners. We found that coral restoration case studies are dominated by short-term projects, with 60% of all projects reporting less than 18 months of monitoring of the restored sites. Similarly, most projects are relatively small in spatial scale, with a median size of restored area of 100 m2. A diverse range of species are represented in the dataset, with 229 different species from 72 coral genera. Overall, coral restoration projects focused primarily on fast-growing branching corals (59% of studies), and report survival between 60 and 70%. To date, the relatively young field of coral restoration has been plagued by similar ‘growing pains’ as ecological restoration in other ecosystems. These include 1) a lack of clear and achievable objectives, 2) a lack of appropriate and standardised monitoring and reporting and, 3) poorly designed projects in relation to stated objectives. Mitigating these will be crucial to successfully scale up projects, and to retain public trust in restoration as a tool for resilience based management. Finally, while it is clear that practitioners have developed effective methods to successfully grow corals at small scales, it is critical not to view restoration as a replacement for meaningful action on climate change.

Abundance, size, and survival of recruits of the reef coral Pocillopora acuta under ocean warming and acidification

Bahr KD, Tran T, Jury CP, Toonen RJ. Abundance, size, and survival of recruits of the reef coral Pocillopora acuta under ocean warming and acidification. PLOS ONE [Internet]. 2020 ;15(2):e0228168. Available from: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0228168
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Ocean warming and acidification are among the greatest threats to coral reefs. Massive coral bleaching events are becoming increasingly common and are predicted to be more severe and frequent in the near future, putting corals reefs in danger of ecological collapse. This study quantified the abundance, size, and survival of the coral Pocillopora acuta under future projections of ocean warming and acidification. Flow-through mesocosms were exposed to current and future projections of ocean warming and acidification in a factorial design for 22 months. Neither ocean warming or acidification, nor their combination, influenced the size or abundance of P. acuta recruits, but heating impacted subsequent health and survival of the recruits. During annual maximum temperatures, coral recruits in heated tanks experienced higher levels of bleaching and subsequent mortality. Results of this study indicate that P. acutais able to recruit under projected levels of ocean warming and acidification but are susceptible to bleaching and mortality during the warmest months.

Differential recovery from mass coral bleaching on naturally extreme reef environments in NW Australia

Schoepf V, E. Jung MU, McCulloch M, White NE, Stat M, Thomas L. Differential recovery from mass coral bleaching on naturally extreme reef environments in NW Australia. [Internet]. 2020 . Available from: https://marxiv.org/s9xha/
Freely available?: 
Yes
Summary available?: 
No
Type: Manuscript

Coral reefs are severely threatened by climate change and recurrent mass bleaching events, highlighting the need for a better understanding of the factors driving recovery and resilience both at the community and species level. While temperature variability has been shown to promote coral heat tolerance, it remains poorly understood how this influences coral recovery capacity. Similarly, few studies have investigated how the presence of cryptic species influences bleaching and recovery responses. Using an integrated ecological, physiological and genomic approach, we examined the recovery of both coral communities and their dominant species from the 2016 mass bleaching event in the macrotidal Kimberley region, NW Australia. We show that recovery of coral communities inhabiting adjacent but environmentally contrasting reef habitats differed dramatically following unprecedented bleaching in 2016. Both intertidal (thermally extreme) and subtidal (thermally moderate) habitats experienced extensive bleaching (72-81%), but subtidal coral communities had a greater percentage of severely bleached corals than the intertidal community (76% versus 53%). Similarly, subtidal Acropora aspera corals suffered much greater losses of chlorophyll a than intertidal conspecifics (96% versus 46%). The intertidal coral community fully recovered to its pre-bleaching configuration within six months, whereas the adjacent subtidal suffered extensive mortality (68% loss of live coral cover). Despite the presence of three cryptic genetic lineages in the dominant coral species, the physiological response of A. aspera was independent of host cryptic genetic diversity. Furthermore, both intertidal and subtidal A. aspera harbored symbionts in the genus Cladocopium (previously clade C). Our findings highlight the important role of tidally-controlled temperature variability in promoting coral recovery capacity, and we propose that shallow reef environments characterized by strong environmental gradients may generally promote coral resilience to extreme climatic events. Thermally variable reef environments may therefore provide important spatial refugia for coral reefs under rapid climate change.

Coral Reefs in the Gulf of Mexico Large Marine Ecosystem: Conservation Status, Challenges, and Opportunities

Gil-Agudelo DL, Cintra-Buenrostro CE, Brenner J, González-Díaz P, Kiene W, Lustic C, Pérez-España H. Coral Reefs in the Gulf of Mexico Large Marine Ecosystem: Conservation Status, Challenges, and Opportunities. Frontiers in Marine Science [Internet]. 2020 ;6. Available from: https://www.frontiersin.org/articles/10.3389/fmars.2019.00807/full
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

The importance of coral reefs (CR) within marine ecosystems has become widely recognized. Although shallow CR are not as abundant in the Gulf of Mexico (GoM) as in other areas such as the Caribbean, their uniqueness, singularity, isolation, and conservation status make their conservation highly important. Corals and CR, both shallow and deep, are more widely distributed throughout the GoM than previously thought, providing new venues of research but also new challenges for their sustainable management. They are widely present in the three countries circumscribing the GoM (Cuba, Mexico, and the United States). Corals are also distributed throughout different depths, from the keys of Florida and Cuba, to the mesophotic reefs in Flower Garden Banks, Pulley Ridge, and submerged banks in the southern GoM; additional coral presence occurs even beyond mesophotic depths (∼30–150 m). Like reefs around the world, they are subject to an increased threat from anthropogenic causes, including overfishing, pollution, and climate change. But there is also hope. Some reefs in the area, such as those in Flower Garden Banks National Marine Sanctuary are probably the best-preserved reefs in the region, with coral cover greater than 50%, which is unusual in the Wider Caribbean. Others are experiencing new protections through the work of government and local communities. The objectives of this manuscript are to summarize the overall status of corals and CR in the GoM, analyze some of the current and future threats, and explore opportunities for their conservation in the region. Aside from the above mentioned anthropogenic threats bleaching, coral diseases, and hurricanes have been identified as main contributors for CR declines not only in the GoM but abroad; some nowadays present but likely to increase threats are invasion by alien species or by Sargassum spp. Among some of the opportunities identified are to capitalize on existing and emerging multilateral agreements and initiatives (e.g., GoM Large Marine Ecosystem, trinational sanctuaries agreement); increase financial support for conservation through international initiatives and the private sector; and a need to comprehend the inherent interconnection among corals, CR, and deeper bank ecosystems as they do not function in isolation.

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