Rapid Recovery of a Coral Reef at Darwin Island, Galapagos Islands

Surveys at Darwin Island in 2006 and 2007 have demonstrated that this northernmost Galapagos Islands coral reef has recovered significantly since the 1982–3 El Niño event. When first surveyed in 1975, this structural reef exhibited actively accreting frameworks of pocilloporid and poritid corals. The coral suffered severe mortality in 1983, resulting in the near total loss of pocilloporids and extensive partial mortality of poritid corals. Large sections of the reef had not recovered by 1992 and dead frameworks were subject to bio-erosion, although small numbers of sexual recruits of pocilloporid corals and numerous recruits plus regenerating patches of Porites lobata were present in some areas. An increase in live coral cover and recruitment was apparent through 2000 and 2002. Recent sampling at three sites along the reef has demonstrated mean (± 1 SD) live coral cover of 21.9 ± 1.7 % with P. lobata as the predominant species. Pocillopora spp. were present, but not so abundant as in earlier surveys. In spite of moderate erosion by echinoid and fish grazers, much of the original coral framework remained intact, providing a substrate for coral regeneration and recruitment. Recovery can be attributed to the original reef structure remaining intact, asexual regrowth of surviving tissues and sexual recruitment of poritid corals from surviving source populations

Water column productivity and temperature predict coral reef regeneration across the Indo-Pacific

Predicted increases in seawater temperatures accelerate coral reef decline due to mortality by heat-driven coral bleaching. Alteration of the natural nutrient environment of reef corals reduces tolerance of corals to heat and light stress and thus will exacerbate impacts of global warming on reefs. Still, many reefs demonstrate remarkable regeneration from past stress events. This paper investigates the effects of sea surface temperature (SST) and water column productivity on recovery of coral reefs. In 71 Indo-Pacific sites, coral cover changes over the past 1-3 decades correlated negative-exponentially with mean SST, chlorophyll a, and SST rise. At six monitoring sites (Persian/Arabian Gulf, Red Sea, northern and southern Galápagos, Easter Island, Panama), over half of all corals were <31 years, implying that measured environmental variables indeed shaped populations and community. An Indo-Pacific-wide model suggests reefs in the northwest and central Indian Ocean, as well as the central west Pacific, are at highest risk of degradation, and those at high latitudes the least. The model pinpoints regions where coral reefs presently have the best chances for survival. However, reefs best buffered against temperature and nutrient effects are those that current studies suggest to be most at peril from future ocean acidification

7700-Year Persistence of an Isolated, Free-Living Coral Assemblage in the Galapagos Islands: A Model for Coral Refugia?

In an eastern-Pacific coral assemblage at Devil’s Crown, Galápagos Islands, Ecuador, two coral species, Psammocora stellata and Cycloseris (Diaseris) distorta, form dense populations of unattached colonies on sand and rubble substrata. In the Galápagos, living C. (D.) distorta is found only at this single site, whereas populations of P. stellata are found throughout the Archipelago. Six cores dating to ~ 7700 yBP showed P. stellata to be dominant throughout the history of this isolated community, but C. (D.) distorta increased in abundance from ~ 2200 yBP and reached peak abundance between 1471 yBP and the present. The relative frequency of the two coral species may be linked to millennial-scale climatic variability, and this site may represent a refuge for C. (D.) distorta from unfavorable climatic fluctuations on millennial timescales. Our results demonstrate that some corals can persist in isolated populations for millennia

Insights from extreme coral reefs in a changing world

© 2020, Springer-Verlag GmbH Germany, part of Springer Nature. Coral reefs are one of the most biodiverse and economically important ecosystems in the world, but they are rapidly degrading due to the effects of global climate change and local anthropogenic stressors. Reef scientists are increasingly studying coral reefs that occur in marginal and extreme environments to understand how organisms respond to, and cope with, environmental stress, and to gain insight into how reef organisms may acclimate or adapt to future environmental change. To date, there have been more than 860 publications describing the biology and/or abiotic conditions of marginal and extreme reef environments, most of which were published within the past decade. These include systems characterized by unusually high, low, and/or variable temperatures (intertidal, lagoonal, high-latitude areas, and shallow seas), turbid or urban environments, acidified habitats, and mesophotic depth, and focus on reefs geographically spread throughout most of the tropics. The papers in this special issue of Coral Reefs, entitled Coral Reefs in a Changing World: Insights from Extremes, build on the growing body of literature on these unique and important ecosystems, providing a deeper understanding of the patterns and processes governing life in marginal reef systems, and the implications that these insights may have for the future of tropical coral reefs in our rapidly changing world

Palaeobiology, ecology, and distribution of stromatoporoid faunas in biostromes of the mid-Ludlow of Gotland

Six well exposed mid−Ludlow stromatoporoid−dominated reef biostromes in four localities from the Hemse Group in southeastern Gotland, Sweden comprise a stromatoporoid assemblage dominated by four species; Clathrodictyon mohicanum, “Stromatopora” bekkeri, Plectostroma scaniense, and Lophiostroma schmidtii. All biostromes investigated in this area (of approximately 30 km2) are interpreted to belong to a single faunal assemblage forming a dense accumulation of fossils that is probably the best exposed stromatoporoid−rich deposit of the Silurian. The results from this comprehensive study strengthen earlier interpretations of a combination of genetic and environmental control on growth−forms of the stromatoporoids. Growth styles are similar for stromatoporoids in all six biostromes. Differences in biostrome fabric are due to variations in the degree of disturbance by storms. The uniformity of facies and the widespread low−diversity fauna support the view that palaeoenvironmental conditions were similar across the area where these biostromes crop out, and promoted the extraordinary growth of stromatoporoids in this shallow shelf area

Modern rhodolith-dominated carbonates at Punta Chivato, Mexico

Rhodolith-dominated carbonate environments, characterized by high abundances of free-living coralline algae, have been described globally from a wide range of Recent and fossil shallow marine settings. In the present-day warm-temperate Gulf of California, Mexico, rhodolith-dominated systems are important contributors to carbonate production. One of the most prolific rhodolith factories is located on the Punta Chivato shelf, in the central Gulf of California, where due to a lack of input of terrigenous material from the arid hinterland, carbonate content averages 79%. Punta Chivato rhodoliths thrive above the shallow euphotic zone under normal saline, warm-temperate and meso- to eutrophic conditions. A detailed sedimentologic study combined with acoustic seafloor mapping indicates the presence of extensive rhodolith-dominated facies at subtidal water depth covering an area of \u3e17 km2. Additional facies, surrounding the rhodolith-dominated facies include a fine-grained molluscan, a transitional bivalve-rhodolith and a bivalve facies. While the Punta Chivato shelf yields average abundances of 38% rhodolith-derived coralline algal components in the gravel-sized sediment fraction, the rhodolith facies itself is characterized by more than 60% coralline algal components. Other important carbonate producers at Punta Chivato include bivalves (35%), bryozoa (11%) and gastropods (8%). The present study shows that acoustic sediment mapping yields highly resolved continuous coverage of the seafloor and can distinguish modern rhodolith facies from surrounding sediment. This has important implications for quantifying rhodolith-dominated settings globally, as well as for ecological and conservation studies. © Publications Scientifiques du Muséum national d\u27Histoire naturelle, Paris

Present Limits to Heat-Adaptability in Corals and Population-Level Responses to Climate Extremes

Climate change scenarios suggest an increase in tropical ocean temperature by 1–3°C by 2099, potentially killing many coral reefs. But Arabian/Persian Gulf corals already exist in this future thermal environment predicted for most tropical reefs and survived severe bleaching in 2010, one of the hottest years on record. Exposure to 33–35°C was on average twice as long as in non-bleaching years. Gulf corals bleached after exposure to temperatures above 34°C for a total of 8 weeks of which 3 weeks were above 35°C. This is more heat than any other corals can survive, providing an insight into the present limits of holobiont adaptation. We show that average temperatures as well as heat-waves in the Gulf have been increasing, that coral population levels will fluctuate strongly, and reef-building capability will be compromised. This, in combination with ocean acidification and significant local threats posed by rampant coastal development puts even these most heat-adapted corals at risk. WWF considers the Gulf ecoregion as “critically endangered”. We argue here that Gulf corals should be considered for assisted migration to the tropical Indo-Pacific. This would have the double benefit of avoiding local extinction of the world's most heat-adapted holobionts while at the same time introducing their genetic information to populations naïve to such extremes, potentially assisting their survival. Thus, the heat-adaptation acquired by Gulf corals over 6 k, could benefit tropical Indo-Pacific corals who have <100 y until they will experience a similarly harsh climate. Population models suggest that the heat-adapted corals could become dominant on tropical reefs within ∼20 years

Integrated Conceptual Ecosystem Model Development for the Southeast Florida Coastal Marine Ecosystem

The overall goal of the MARES (MARine and Estuarine goal Setting) project for South Florida is “to reach a science-based consensus about the defining characteristics and fundamental regulating processes of a South Florida coastal marine ecosystem that is both sustainable and capable of providing the diverse ecosystem services upon which our society depends.” Through participation in a systematic process of reaching such a consensus, science can contribute more directly and effectively to the critical decisions being made both by policy makers and by natural resource and environmental management agencies. The document that follows briefly describes MARES overall and this systematic process. It then describes in considerable detail the resulting output from the first step in the process, the development of an Integrated Conceptual Ecosystem Model (ICEM) for the third subregion to be addressed by MARES, the Southeast Florida Coast (SEFC). What follows with regard to the SEFC relies upon the input received from more than 60 scientists, agency resource managers, and representatives of environmental organizations during workshops held throughout 2009–2012 in South Florida

Heritage buildings as a contribution to the contemporary city: the relocation of Braga’s District Archive

This paper reflects on the ability to adapt buildings with relevant heritage and historical value to different uses and functions. A case study is presented: The relocation of Braga?s District Archive from the former Archbishop?s Palace in Largo do Paço, a building dating back to the XIVth century confined within the Historical Center?s buffer zone, into a modernist building located in Abade Loureira street, North of the original complex and outside the medieval walled city. The methodological approach and the processes associated with the intervention are presented according to the analysis of the proposed program, rather than by the formal and symbolic features of the building itself. Extensive in-situ surveys took place at the two buildings, comparing both the present and the proposed solution. Based on this analysis, the Program?s adequacy is discussed, displaying the advantages and disadvantages of this change and how it may affect the mission of the District Archive