Impacts of stratospheric aerosol geoengineering strategy on Caribbean coral reefs

Purpose: Currently, negotiation on global carbon emissions reduction is very difficult due to lack of international willingness. In response, geoengineering (climate engineering) strategy is proposed to artificially cool the planet. Meanwhile, as the harbor around one-third of all described marine species, coral reefs are the most sensitive ecosystem on the planet to climate change. However, until now, there is no any quantitative assessment on impacts of geoengineering on coral reefs. In this study, we model impacts of stratospheric aerosol geoengineering on coral reefs. Design/methodology/approach: We will use the HadGEM2-ES climate model to model and evaluate impacts of stratospheric aerosol geoengineering on coral reefs. Findings: This study shows that a) stratospheric aerosol geoengineering could significantly mitigate future coral bleaching throughout the Caribbean Sea; b) Changes in downward solar irradiation, sea level rise and sea surface temperature caused by geoengineering implementation should have very little impacts on coral reefs; c) although geoengineering would prolong the return period of future hurricanes, this may still be too short to ensure coral recruitment and survival after hurricane damage

Corals, fishermen and tourists

Two major anthropogenic activities that disturb coral reefs are fishing and tourism, even though coral reefs are important for both fishing and tourism. Already more than 60 per cent of all reefs worldwide are endangered. The use of explosives and poison by small-scale fishers, to supply the market for live fish for aquariums and for human consumption, cause irreversible damages to reefs. Similarly, rapid and unmanaged coastal development for marine tourism negatively affects coral reefs in many ways. Though marine parks and marine protected areas are being promoted all over the world, developing countries need assistance in establishing and assessing such reserves and for taking appropriate actions for rehabilitation of reefs. These can be accomplished through partnership projects

Borneo coral reefs subject to high sediment loads show evidence of resilience to various environmental stressors

For reefs in South East Asia the synergistic effects of rapid land development, insufficient environmental policies and a lack of enforcement has led to poor water quality and compromised coral health from increased sediment and pollution. Those inshore turbid coral reefs, subject to significant sediment inputs, may also inherit some resilience to the effects of thermal stress and coral bleaching. We studied the inshore turbid reefs near Miri, in northwest Borneo through a comprehensive assessment of coral cover and health in addition to quantifying sediment-related parameters. Although Miri’s Reefs had comparatively low coral species diversity, dominated by massive and encrusting forms of Diploastrea, Porites, Montipora, Favites, Dipsastrea and Pachyseris, they were characterized by a healthy cover ranging from 22 to 39%. We found a strong inshore to offshore gradient in hard coral cover, diversity and community composition as a direct result of spatial differences in sediment at distances <10 km. As well as distance to shore, we included other environmental variables like reef depth and sediment trap accumulation and particle size that explained 62.5% of variation in benthic composition among sites. Miri’s reefs showed little evidence of coral disease and relatively low prevalence of compromised health signs including bleaching (6.7%), bioerosion (6.6%), pigmentation response (2.2%), scars (1.1%) and excessive mucus production (0.5%). Tagged colonies of Diploastrea and Pachyseris suffering partial bleaching in 2016 had fully (90–100%) recovered the following year. There were, however, seasonal differences in bioerosion rates, which increased five-fold after the 2017 wet season. Differences in measures of coral physiology, like that of symbiont density and chlorophyll a for Montipora, Pachyseris and Acropora, were not detected among sites. We conclude that Miri’s reefs may be in a temporally stable state given minimal recently dead coral and a limited decline in coral cover over the last two decades. This study provides further evidence that turbid coral reefs exposed to seasonally elevated sediment loads can exhibit relatively high coral cover and be resilient to disease and elevated sea surface temperatures

Region-wide temporal and spatial variation in Caribbean reef architecture: is coral cover the whole story?

The architectural complexity of coral reefs is largely generated by reef-building corals, yet the effects of current regional-scale declines in coral cover on reef complexity are poorly understood. In particular, both the extent to which declines in coral cover lead to declines in complexity and the length of time it takes for reefs to collapse following coral mortality are unknown. Here we assess the extent of temporal and spatial covariation between coral cover and reef architectural complexity using a Caribbean-wide dataset of temporally replicated estimates spanning four decades. Both coral cover and architectural complexity have declined rapidly over time, with little evidence of a time-lag. However, annual rates of change in coral cover and complexity do not covary, and levels of complexity vary greatly among reefs with similar coral cover. These findings suggest that the stressors influencing Caribbean reefs are sufficiently severe and widespread to produce similar regional-scale declines in coral cover and reef complexity, even though reef architectural complexity is not a direct function of coral cover at local scales. Given that architectural complexity is not a simple function of coral cover, it is important that conservation monitoring and restoration give due consideration to both architecture and coral cover. This will help ensure that the ecosystem services supported by architectural complexity, such as nutrient recycling, dissipation of wave energy, fish production and diversity, are maintained and enhanced

Corals, fishermen and tourists

Two major anthropogenic activities that disturb coral reefs are fishing and tourism, even though coral reefs are important for both fishing and tourism. Already more than 60 per cent of all reefs worldwide are endangered. The use of explosives and poison by small-scale fishers, to supply the market for live fish for aquariums and for human consumption, cause irreversible damages to reefs. Similarly, rapid and unmanaged coastal development for marine tourism negatively affects coral reefs in many ways. Though marine parks and marine protected areas are being promoted all over the world, developing countries need assistance in establishing and assessing such reserves and for taking appropriate actions for rehabilitation of reefs. These can be accomplished through partnership projects.Coral reefs, Marine parks, Tourism, Fishing

Caution: Do Not Bleach!

In this lesson, students will investigate the importance of coral reefs to the Earth as a whole and learn some possible explanations for the phenomenon known as "coral bleaching". They should be able to identify ways that coral reefs benefit human beings, identify major threats to reefs and discuss how they might be reduced or eliminated, describe the Coral Reef Early Warning System, and discuss why corals might expel their zooxanthellae (symbiotic algae) when under stress. Educational levels: High school, Middle school, Undergraduate lower division

Identification of Coral Reefs in Mamburit Waters, Sumenep Regency

This research was conducted in September to October 2013 in Mamburit Waters, Sumenep Regency. This study was aimed to assess the percentage of coral reefs and acknowkedge the type of the coral reefs. Coral reefs was observed with the Line Intercept (LIT) method laid parallel to the coastline in the depth of 3 m and 10 m in windward and leeward area. Total of 59.88% coral reefs lived in leeward area in 3 m depth includes in good category and the percentage of dead coral reefs and other fauna for 40.12%. In the 10 m depth, 69.19% live coral reefs include as medium category with percentage of dead coral reefs and other fauna for 30.81%. Winward location of 3 m depth has 68.38% live coral reefs in good category and percentage of dead coral reefs and other fauna for 31.62%. Whereas for 10 m depth, 40.86% of live coral reefs include as medium category with percentage of dead coral reefs and other fauna for 59.14 %

Reefs at Risk: A Map-Based Indicator of Threats to the Worlds Coral Reefs

This report presents the first-ever detailed, map-based assessment of potential threats to coral reef ecosystems around the world. "Reefs at Risk" draws on 14 data sets (including maps of land cover, ports, settle-ments, and shipping lanes), information on 800 sites known to be degraded by people, and scientific expertise to model areas where reef degradation is predicted to occur, given existing human pressures on these areas. Results are an indicator of potential threat (risk), not a measure of actual condition. In some places, particularly where good management is practiced, reefs may be at risk but remain relatively healthy. In others, this indicator underestimates the degree to which reefs are threatened and degraded.Our results indicate that:Fifty-eight percent of the world's reefs are poten-tially threatened by human activity -- ranging from coastal development and destructive fishing practices to overexploitation of resources, marine pollution, and runoff from inland deforestation and farming.Coral reefs of Asia (Southeastern); the most species-rich on earth, are the most threatened of any region. More than 80 percent are at risk (undermedium and high potential threat), and over half are at high risk, primarily from coastal development and fishing-related pressures.Overexploitation and coastal development pose the greatest potential threat of the four risk categories considered in this study. Each, individually, affects a third of all reefs.The Pacific, which houses more reef area than any other region, is also the least threatened. About 60 percent of reefs here are at low risk.Outside of the Pacific, 70 percent of all reefs are at risk.At least 11 percent of the world's coral reefs contain high levels of reef fish biodiversity and are under high threat from human activities. These "hot spot" areas include almost all Philippine reefs, and coral communities off the coasts of Asia, the Comoros, and the Lesser Antilles in the Caribbean.Almost half a billion people -- 8 percent of the total global population -- live within 100 kilometers of a coral reef.Globally, more than 400 marine parks, sanctuaries, and reserves (marine protected areas) contain coral reefs. Most of these sites are very small -- more than 150 are under one square kilometer in size. At least 40 countries lack any marine protected areas for conserving their coral reef systems