Marine biodiversity hotspots and conservation priorities for tropical reefs

Coral reefs are the most biologically diverse of shallow water marine ecosystems but are being degraded worldwide by human activities and climate warming. Analyses of the geographic ranges of 3235 species of reef fish, corals, snails, and lobsters revealed that between 7.2% and 53.6% of each taxon have highly restricted ranges, rendering them vulnerable to extinction. Restricted-range species are clustered into centers of endemism, like those described for terrestrial taxa. The 10 richest centers of endemism cover 15.8% of the world's coral reefs (0.012% of the oceans) but include between 44.8 and 54.2% of the restricted-range species. Many occur in regions where reefs are being severely affected by people, potentially leading to numerous extinctions. Threatened centers of endemism are major biodiversity hotspots, and conservation efforts targeted toward them could help avert the loss of tropical reef biodiversity.     

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.     

Comparative species richness in fluctuating and constant environments: coral-associated decapod crustaceans

The number of decapod species associated with the coral Pocillopora damicornis is compared between two regions on the Pacific coast of Panama which are of the same geologic age but differ in environmental characteristics. The relationship between number of species and coral head size does not differ between the two regions but species composition among coral heads is more variable in the fluctuating environment. Thus there are more species (55 compared to 37) associated with corals in the fluctuating environment than in the constant environment. These data impugn the concept that environmental constancy increases species richness. They support the hypothesis that species equilibrium within habitats is maintained by measurable ecological factors-in this case, the effects of a natural physical disturbance.     

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.     

回头岸礁区4 种造礁珊瑚中可培养细菌的多样性

采用稀释涂布平板法,分离三亚鹿回头岸礁区4种造礁珊瑚及其周围海水中的细菌,并基于16S r RNA基因序列进行了系统发育分析,从而探讨造礁珊瑚中可培养细菌的物种多样性。从澄黄滨珊瑚(Porites lutea)、鹿角珊瑚(Acropora sp.)、盔形珊瑚(Galaxea sp.)、扁脑珊瑚(Platygyra sp.)样品中分别分离获得细菌60、61、54、20株,从珊瑚周边海水中分离获得细菌31株。16S r RNA基因序列分析表明,珊瑚来源的细菌分布于放线菌门(Actinobacteria)、α-变形菌纲(Alphaproteobacteria)、γ-变形菌纲(Gammaproteobacteria)、厚壁菌门(Firmicutes)和拟杆菌门(Bacteroidetes)。在属级水平上对4种珊瑚及海水来源细菌群落组成分析,发现在4种珊瑚中均有分布的属有3个,为Brachybacterium、Microbacterium和Ruegeria,珊瑚来源细菌类群有一定差异。同时发现4种珊瑚来源细菌与海水来源细菌类群差异较大。在分离的菌株中,有7株菌与已有效描述的细菌物种典型菌株的全长16S r RNA基因相似性低于97%,代表着潜在新属或新种。试验结果表明,三亚鹿回头岸礁区珊瑚中存在较为丰富的细菌多样性,并潜藏较多的新物种资源。     

Long-term region-wide declines in Caribbean corals

We report a massive region-wide decline of corals across the entire Caribbean basin, with the average hard coral cover on reefs being reduced by 80%, from about 50% to 10% cover, in three decades. Our meta-analysis shows that patterns of change in coral cover are variable across time periods but largely consistent across subregions, suggesting that local causes have operated with some degree of synchrony on a region-wide scale. Although the rate of coral loss has slowed in the past decade compared to the 1980s, significant declines are persisting. The ability of Caribbean coral reefs to cope with future local and global environmental change may be irretrievably compromised.     

Coral community reproductive patterns: red sea versus the great barrier reef

In contrast to many corals of the Great Barrier Reef, Australia, which are synchronous multispecific spawners, the abundant coral species in the northern Red Sea, Israel, exhibit temporal reproductive isolation. Spawning dates of 12 of the 13 Red Sea species followed lunar periodicity and were consistent throughout 3 years of study. Spawning periods of all species occurred in different seasons, different months, or different lunar phases within the same month. The high abundance of the corals studied at Eilat may be due in part to the advantages gained through not having overlapping spawning periods and settlement times.     

Flexibility in algal endosymbioses shapes growth in reef corals

The relation between corals and their algal endosymbionts has been a key to the success of scleractinian (stony) corals as modern reef-builders, but little is known about early stages in the establishment of the symbiosis. Here, we show that initial uptake of zooxanthellae by juvenile corals during natural infection is nonspecific (a potentially adaptive trait); the association is flexible and characterized by a change in (dominant) zooxanthella strains over time; and growth rates of experimentally infected coral holobionts are partly contingent on the zooxanthella strain harbored, with clade C-infected juveniles growing two to three times as fast as those infected with clade D.     

Caribbean reef development was independent of coral diversity over 28 million years

The relationship between natural variations in coral species diversity, reef development, and ecosystem function on coral reefs is poorly understood. Recent coral diversity varies 10-fold among geographic regions, but rates of reef growth are broadly similar, suggesting that diversity is unimportant for reef development. Differences in diversity may reflect regional differences in long-term biotic history in addition to environmental conditions. Using a combination of new and published fossil and stratigraphic data, we compared changes in coral diversity and reef development within the tropical western Atlantic over the past 28 million years. Reef development was unrelated to coral diversity, and the largest reef tracts formed after extinction had reduced diversity by 50%. High diversity is thus not essential for the growth and persistence of coral reefs.     

Mass spawning in tropical reef corals

Synchronous multispecific spawning by a total of 32 coral species occurred a few nights after late spring full moons in 1981 and 1982 at three locations on the Great Barrier Reef, Australia. The data invalidate the generalization that most corals have internally fertilized, brooded planula larvae. In every species observed, gametes were released; external fertilization and development then followed. The developmental rates of externally fertilized eggs and longevities of planulae indicate that planulae may be dispersed between reefs.     

Coral reef growth in the galapagos: limitation by sea urchins

The regular echinoid Eucidaris thouarsii is a conspicuous omnivore on coral bottoms in the Galápagos. Unlike Eucidaris in Panama and mainland Ecuador, Galápagos Eucidaris are large and abundant and graze heavily in the open on live corals day and night. These differences are probably due in large part to more intense predation by fishes on mainland compared with island urchin populations. An assessment of coral growth versus coral attrition from grazing shows that Eucidaris interferes with the establishment of pocilloporid reef frame and therefore reduces reef growth in the Galápagos.     

西沙群岛海域砗磲资源的调查

砗磲是珊瑚岛礁的构成物种,对维护珊瑚礁生态系统平衡起着重要作用。近年来,由于非法捕捞和海洋生态环境影响,对我国西沙砗磲资源造成严重威胁。为掌握西沙海域砗磲资源现状,笔者于2017年6—7月采用截线样带法,对西沙主要岛礁海域砗磲的种类、分布及其与环境相关性进行了分析。结果显示,调查海域共发现4种砗磲：鳞砗磲(Tridacna squamosa)、长砗磲(T.maxima)、番红砗磲(T.crocea)和砗蚝(Hippopus hippopus),分别占总数的71.9%、15.6%、9.4%和3.1%。西沙不同岛礁海域砗磲密度、物种多样性指数存在显著差异,砗磲平均密度为0.026个·m^-2。砗磲密度与珊瑚覆盖率呈显著正相关(P<0.05,R²=0.706 5),表明珊瑚覆盖率是影响砗磲分布的重要因素。     

Hybridization and the evolution of reef coral diversity

Hundreds of coral species coexist sympatrically on reefs, reproducing in mass-spawning events where hybridization appears common. In the Caribbean, DNA sequence data from all three sympatric Acropora corals show that mass spawning does not erode species barriers. Species A. cervicornis and A. palmata are distinct at two nuclear loci or share ancestral alleles. Morphotypes historically given the name Acropora prolifera are entirely F(1) hybrids of these two species, showing morphologies that depend on which species provides the egg for hybridization. Although selection limits the evolutionary potential of hybrids, F(1) individuals can reproduce asexually and form long-lived, potentially immortal hybrids with unique morphologies.     

Coherence and conservation

A principal aim of current conservation policy is to reduce the impact of habitat fragmentation. Conservation corridors may achieve this goal by facilitating movement among isolated patches, but there is a risk that increased connectivity could synchronize local population fluctuations (causing coherent oscillations) and thereby increase the danger of global extinction. We identify general conditions under which populations can or cannot undergo coherent oscillations, and we relate these conditions to local and global extinction probabilities. We suggest a simple method to explore the potential success of conservation corridors and, more generally, any manipulations of dispersal patterns that aim to protect threatened species or control pests.     

Discovery of symbiotic nitrogen-fixing cyanobacteria in corals

Colonies of the Caribbean coral Montastraea cavernosa exhibit a solar-stimulated orange-red fluorescence that is spectrally similar to a variety of fluorescent proteins expressed by corals. The source of this fluorescence is phycoerythrin in unicellular, nonheterocystis, symbiotic cyanobacteria within the host cells of the coral. The cyanobacteria coexist with the symbiotic dinoflagellates (zooxanthellae) of the coral and express the nitrogen-fixing enzyme nitrogenase. The presence of this prokaryotic symbiont in a nitrogen-limited zooxanthellate coral suggests that nitrogen fixation may be an important source of this limiting element for the symbiotic association.     

Tropical reef corals: tolerance of low temperatures on the north carolin

Individual heads of two species of reef or herinatypic coral, Solenastrea hyades (Dana) and Siderastrea siderea (Ellis and Solander), occur on rock outcrops on the inner continental shelf off North Carolina in waters where winter bottom temperatures are as low as 10.6 degrees C. These temperatures are significantly lower than previously assumed minimum temperatures for the survival of tropical reef corals in their natural environment.     

Deep-Sea coral evidence for rapid change in ventilation of the deep north atlantic 15,400 years Ago

Coupled radiocarbon and thorium-230 dates from benthic coral species reveal that the ventilation rate of the North Atlantic upper deep water varied greatly during the last deglaciation. Radiocarbon ages in several corals of the same age, 15.41 +/- 0.17 thousand years, and nearly the same depth, 1800 meters, in the western North Atlantic Ocean increased by as much as 670 years during the 30- to 160-year life spans of the samples. Cadmium/calcium ratios in one coral imply that the nutrient content of these deep waters also increased. Our data show that the deep ocean changed on decadal-centennial time scales during rapid changes in the surface ocean and the atmosphere.     

The impact of conservation on the status of the world's vertebrates

Using data for 25,780 species categorized on the International Union for Conservation of Nature Red List, we present an assessment of the status of the world's vertebrates. One-fifth of species are classified as Threatened, and we show that this figure is increasing: On average, 52 species of mammals, birds, and amphibians move one category closer to extinction each year. However, this overall pattern conceals the impact of conservation successes, and we show that the rate of deterioration would have been at least one-fifth again as much in the absence of these. Nonetheless, current conservation efforts remain insufficient to offset the main drivers of biodiversity loss in these groups: agricultural expansion, logging, overexploitation, and invasive alien species.     

京北山区水源保护林的现状与发展策略

该文在野外调查工作和对“八五”二类调查资料统计分析的基础上,通过对京北山区(包括密云、怀柔、延庆、昌平四县)水源保护林现状的总体分析和对密云县北庄乡的典型分析,指出林种比例不当及树种资源单一是该区水源保护林发展中存在的比较突出的问题.该文从多林种、多树种配置,造林树种选择和林分结构的优化与调整方面提出现有林的发展策略,并提供了现有林的经营类型和对应各种立地类型的造林树种.     

潜水旅游对珊瑚礁生态系统影响研究的进展

早期潜水活动曾被认为是一种经济价值高且对珊瑚礁影响较小的生态旅游项目,但随着潜水旅游逐渐盛行,诸多研究结果表明,全世界潜水区的珊瑚礁均出现了不同程度的退化,一些热门潜水旅游区每年接纳的游客数量甚至远超出珊瑚礁的生态承受极限.笔者对与珊瑚礁生态系统与潜水旅游承载能力相关的研究结果进行了统计分析,总结了潜水活动影响珊瑚礁的...