Climate change,human impacts,and the resilience of coral reefs

The diversity, frequency, and scale of human impacts on coral reefs are increasing to the extent that reefs are threatened globally. Projected increases in carbon dioxide and temperature over the next 50 years exceed the conditions under which coral reefs have flourished over the past half-million years. However, reefs will change rather than disappear entirely, with some species already showing far greater tolerance to climate change and coral bleaching than others. International integration of management strategies that support reef resilience need to be vigorously implemented, and complemented by strong policy decisions to reduce the rate of global warming.     

Zonation of uplifted pleistocene coral reefs on barbados, west indies

The coral species composition of uplifted Pleistocene reefs on Barbados is very similar to Recent West Indian reefs. Acropora palmata, Acropora cervicornis, and Montastrea annularis are qtuantitatively the most important of the coral species.     

Connectivity and management of caribbean coral reefs

Surface current patterns were used to map dispersal routes of pelagic larvae from 18 coral reef sites in the Caribbean. The sites varied, both as sources and recipients of larvae, by an order of magnitude. It is likely that sites supplied copiously from "upstream" reef areas will be more resilient to recruitment overfishing, less susceptible to species loss, and less reliant on local management than places with little upstream reef. The mapping of connectivity patterns will enable the identification of beneficial management partnerships among nations and the design of networks of interdependent reserves.     

Paleoceanography of coral reefs in the hawaiian-emperor chain

The fossil record of shallow marine organisms in the Hawaiian Archipelago and Emperor seamount chain indicates that reef corals were absent during the first half of the Tertiary. Their appearance during the early Oligocene, 34 million years ago, is associated with several paleoceanographic events that appear to have combined to intensify gradually gyral surface currents in the north Pacific. This association suggests that corals were absent in the early Tertiary because of isolation of the Hawaiian Archipelago from the Indo-West Pacific (IWP), the center of reef coral abundance and diversity in the Pacific. Today, the number of species of reef corals in Hawaii is less than 10 percent of the number of species in the IWP. Since their initial colonization, reef corals have been present continuously in the Hawaiian Archipelago, although not without taxonomic change. Episodes of extinction and recolonization are the most likely cause of change in species composition. Recolonization from the IWP may also explain the low rate of endemism (about 20 percent) in the present-day coral fauna.     

Regional-scale assembly rules and biodiversity of coral reefs

Tropical reef fishes and corals exhibit highly predictable patterns of taxonomic composition across the Indian and Pacific Oceans. Despite steep longitudinal and latitudinal gradients in total species richness, the composition of these key taxa is constrained within a remarkably narrow range of values. Regional-scale variation in reef biodiversity is best explained by large-scale patterns in the availability of shallow-water habitat. Once habitat area is accounted for, there is surprisingly little residual effect of latitude or longitude. Low-diversity regions are most vulnerable to human impacts such as global warming, underscoring the urgent need for integrated management at multinational scales.     

Diversity in tropical rain forests and coral reefs

The commonly observed high diversity of trees in tropical rain forests and corals on tropical reefs is a nonequilibrium state which, if not disturbed further, will progress toward a low-diversity equilibrium community. This may not happen if gradual changes in climate favor different species. If equilibrium is reached, a lesser degree of diversity may be sustained by niche diversification or by a compensatory mortality that favors inferior competitors. However, tropical forests and reefs are subject to severe disturbances often enough that equilibrium may never be attained.     

Geochemical consequences of increased atmospheric carbon dioxide on coral reefs

A coral reef represents the net accumulation of calcium carbonate (CaCO3) produced by corals and other calcifying organisms. If calcification declines, then reef-building capacity also declines. Coral reef calcification depends on the saturation state of the carbonate mineral aragonite of surface waters. By the middle of the next century, an increased concentration of carbon dioxide will decrease the aragonite saturation state in the tropics by 30 percent and biogenic aragonite precipitation by 14 to 30 percent. Coral reefs are particularly threatened, because reef-building organisms secrete metastable forms of CaCO3, but the biogeochemical consequences on other calcifying marine ecosystems may be equally severe.     

三亚礁区普哥滨珊瑚对海水悬浮物的生理适应

为了了解海水悬浮物质量浓度的升高对造礁石珊瑚的生存影响,于2020年5-9月期间,调查了三亚3个礁区（崖州湾、凤凰岛和西岛）的海水悬浮物质量浓度,测定了礁区中普哥滨珊瑚(Porites pukoensis)及其共生虫黄藻的生理指标,并筛选了敏感生物标志物,用以评价悬浮物对普哥滨珊瑚的影响程度。结果表明,崖州湾礁区的海水悬浮物月均质量浓度为13.7～19.4 mg·L-1,其含量显著高于凤凰岛（1.9～8.8 mg·L-1）和西岛（0.7～5.3 mg·L-1）。相关性分析表明,海水悬浮物浓度与共生虫黄藻的密度（R=0.27,P<0.05）和一氧化氮合成酶活力（R=0.27,P<0.05）均呈显著正相关,而与共生虫黄藻的谷胱甘肽S-转移酶活力呈显著负相关。因此,普哥滨珊瑚可能通过共生虫黄藻密度和NOS活力的诱导及其GST活力的抑制来适应悬浮物浓度较高的礁区环境。此外,本研究构建的综合生物标志物响应（IBR）指数具有崖州湾>凤凰岛>西岛的特征,与礁区悬浮物含量趋势相一致,提示IBR指数能够为珊瑚礁生态风险评估提供理论基础。     

Community structure of coral reefs on opposite sides of the isthmus of panama

Competition for space amon reef corals includes interspecific destruction by extracoelenteric digestion., rapid growth. and Overtopping. No Caribbean species excela in all strategies, and on western Caribbean coral reefs there is a positive correlation between coral abudance and diversity. On eastern Pacific coral reefs, however. Pocillopora damicornis excludes other corals, and on these reefs there is an inverse relation between coral abundance and diversity, except in areas where distrubances, such as Acanthaster predation offset space monopolization.     

Pleistocene sea levels from raised coral reefs of haiti

The elevations and ages of a sequence of three uplifted Pleistocene coral reefs on the Northwest Peninsula of Haiti have been determined. With the assignment of a sea level of +6 meters (relative to the present day) at 130,000 years before present and constant uplift of the reefs, the data indicate that sea level stood -10 and -13 meters at 108,000 and 81,000 years before present, respectively. These results are in substantial agreement with those reported for Barbados and New Guinea and support the hypothesis of constant uplift for each area. Sea level data from raised reefs indicate that the interglacial marine oxygen isotope oscillations during oxygen isotope stage 5 are a result of 30 percent ice volume effects and 70 percent temperature effects.     

ENSO drove 2500-year collapse of eastern Pacific coral reefs

Cores of coral reef frameworks along an upwelling gradient in Panamá show that reef ecosystems in the tropical eastern Pacific collapsed for 2500 years, representing as much as 40% of their history, beginning about 4000 years ago. The principal cause of this millennial-scale hiatus in reef growth was increased variability of the El Ni?o-Southern Oscillation (ENSO) and its coupling with the Intertropical Convergence Zone. The hiatus was a Pacific-wide phenomenon with an underlying climatology similar to probable scenarios for the next century. Global climate change is probably driving eastern Pacific reefs toward another regional collapse.     

Milankovitch hypothesis supported by precise dating of coral reefs and deep-sea sediments

Barbados provides a possibly unique opportunity for reconstruction of the times and elevations of late-Pleistocene high stands of the sea. The island appears to be rising from the sea at a uniform rate that is fast enough to separate in elevation coral-reef tracts formed at successive high stands of the sea. Unaltered coral found in the lower terraces enables high-precision Th(230): U(234) and Pa(231): U(235) dating. Three distinct high stands of the sea are found about 122,000, 103,000, and 82,000 years ago. New Pa(231) and Th(230) dates from a deep-sea core also indicate that Ericson's W-X cold-to-warm climatic change occurred close to 126,000 years ago. These data show a parallelism over the last 150,000 years between changes in Earth's climate and changes in the summer insolation predicted from cycles in the tilt and precession of Earth's axis.