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1.
Experimental evidence for high temperature stress as the cause of El Niño-coincident coral mortality
High temperature tolerance experiments performed on Pocillopora damicornis, a major reef-building coral in the tropical eastern Pacific, resulted in loss of zooxanthellae, histopathological abnormalities, and mortality similar to that observed during the severe 1982–83 El Niño-Southern Oscillation (ENSO) event. Coral vitality declined significantly at 30–32°C during a 10-week period, but remained high at normal temperatures (26–28°C). Laboratory time courses to coral morbidity and death were similar to those observed in the field. Experimental high temperatures had a greater negative effect on corals from the Gulf of Panama, which experiences seasonally cool upwellings, than on corals from the nonupwelling Gulf of Chiriqui. The condition of obligate symbiotic crustaceans (Trapezia, Alpheus) associated with experimental corals declined with their host's declining condition. All Gulf of Panama corals subjected to 32°C were dead after 5 weeks, and all of their associated crustacean symbionts were dead after 9 weeks. Gulf of Chiriqui corals at 30°C survived for 9 weeks and 42% of their crustacean symbionts were still alive after 10 weeks. Coral mortality in the Gulf of Panama was significantly higher (68.5%) after El Niño warming than after subsequent episodes of unusually intense cool upwellings (10.4%). Low temperature stress (cool currents and upwelling) has been generally suggested as the critical limiting condition that prevents extensive coral reef development in the eastern Pacific. Our results suggest that infrequent but severe ENSO sea warming events also may limit reef development in this region. 相似文献
2.
Fisheries catches from Pacific Island coral reefs are rarely recorded in official statistics. Reconstruction of catch estimates with limited hard data requires interpolation and assumptions, justifiable only by the unsatisfactory alternative of continued substitution of zero catches, a common policy interpretation for ‘no data’. Uncertainties associated with reconstructions are high, requiring conservative estimation. American Samoan domestic fisheries consist of an artisanal, small-boat sector, whose commercial catches are reported, and a shore-based subsistence sector, with no regular reporting. Our catch reconstruction (with large pelagic species removed) suggested a 79% decrease in catches between 1950 (752 t) and 2002 (155 t). Accounting for rapid human population growth on the main island, the per capita catch rate may have declined from 36.3 kg·person−1 year−1 in 1950 to 1.3 kg·person−1 year−1 by 2002, while the catch rate for the inhabited outer islands has been independently reported as 58.6 kg·person−1 year−1. Catch per area of coral reef (to 50-m depth) may have declined from 5.5 to 0.7 t km−2 year−1 for the main island, and from 9.1 to 4.9 t km−2 year−1 for the outer islands, for 1950 and 2002, respectively. Summed for 1950–2002, our reconstruction suggested a 17-fold difference between reconstructed estimates and reported statistics. 相似文献
3.
Dr. Georg A. Heiss 《Facies》1995,33(1):19-34
Summary In a fringing reef at Aqaba at the northern end of the Gulf of Aqaba (29°26′N) growth rates, density, and the calcification
rate ofPorites were investigated in order to establish calculations of gross carbonate production for the reefs in this area. Colony accretion
ofPorites decreases with depth as a function of decreasing growth rates. The calcification rate ofPorites is highest in shallow water (0–5 m depth) with 0.9 g·cm−2·yr−1 and falls down to 0.5 g·cm−2·yr−1 below 30 m. Scleractinian coral gross production is calculated from potential productivity and coral coverage. It is mainly
dependent on living coral cover and to a lesser extent on potential productivity. Total carbonate production on the reef ranged
from 0 to 2.7 kg/m2 per year, with a reef-wide average of 1.6 kg/m2 perycar. Maximum gross carbonate production by corals at Aqaba occurs at the reef crest and in the middle fore-reef from
10 to 15 m water depth. Production is low in sandy reef parts. Below 30 m depth values still reach ca. 50% of shallow water
values. Mean potential production of colonies and gross carbonate production of the whole reef community at Aqaba is lower
than in tropical reefs. However, carbonate production is higher than in reef areas at the same latitude in the Pacific, indicating
a northward shift of reef production in the Red Sea. 相似文献
4.
Coral growth in subtropical eastern Australia 总被引:7,自引:0,他引:7
V. J. Harriott 《Coral reefs (Online)》1999,18(3):281-291
Extension rates of corals at two sites in subtropical eastern Australia (Solitary Islands and Lord Howe Island) were measured
to determine whether growth was low relative to tropical locations. Growth was measured using alizarin staining of skeletons
and X-radiographic analysis, and was compared between colonies, species, and sites. Linear extension of individual Pocillopora damicornis colonies averaged 12.4 to 16.1 mm per year at Solitary Islands and Lord Howe Island respectively, which is 50% to 80% of
published values for this species at tropical sites. Similarly, average extension of most massive faviid species examined
at these sites was between 2.6 mm and 4.6 mm per year, considerably lower than most values reported from lower latitudes (generally
6 mm to 10 mm per year). However, growth rates of Acropora yongei, Turbinaria frondens, and Porites heronensis were close to those of closely-related taxa from the tropics. Causal links between latitude, growth rates of coral colonies,
and the potential for reef accretion remain unclear.
Accepted: 22 April 1999 相似文献
5.
P. J. Edmunds 《Coral reefs (Online)》2000,19(1):69-74
To determine what happens to scleractinian corals that have been killed by black band disease (BBD), massive corals with
BBD were monitored for 11 years on a shallow reef (<10 m depth) in St. John, US Virgin Islands. Small quadrats (0.039 m2) were used to compare the rates of scleractinian recruitment to the skeletons of corals killed by either BBD or physical
disturbance (Hurricane Hugo 1989). Coral recruitment was also quantified on the adjacent fringing reef using larger quadrats
(0.25 m2) to detect possible biases associated with using small, permanent quadrats to assess recruitment to BBD-killed corals. Of
28 tagged colonies with BBD in 1988, 43% were lost to Hurricane Hugo in 1989, 7% were lost to unknown causes between 1991
and 1992, and 14 were monitored annually for 11 years; of these, 71% were dead and still in their original growth position
in 1998. Between 1988 and 1997, corals recruited to the BBD-killed surfaces at a rate of 1.1 ± 0.3 recruits · 0.039 m−2 · decade−1 (mean ± SE, n = 14), although mortality reduced the density to 0.3 ± 0.2 recruits · 0.039 m−2 by 1997. The rate of recruitment and the taxonomic composition of the coral recruits to BBD-killed corals were indistinguishable
statistically from those to corals killed by Hurricane Hugo. This demonstrates that BBD creates space that is functionally
the same as other dead coral surfaces in providing a substratum for coral recruitment. However, because coral recruits are
dispersed widely, clumped in distribution and temporally variable in density on the fringing reef as a whole, it is unlikely
that they will be found on monitored coral colonies that have been killed by BBD. While this hypothesis is consistent with
the higher density of recruits on the fringing reef compared with BBD-killed corals, further studies are required to investigate
alternative explanations such as the role of substratum age in favoring recruitment to surfaces other than those killed recently
by BBD.
Accepted: 26 August 1999 相似文献
6.
A reciprocal transplant experiment (RTE) of the reef-building coral Porites lobata between shallow (1.5 m at low tide) back reef and forereef habitats on Ofu and Olosega Islands, American Samoa, resulted
in phenotypic plasticity for skeletal characteristics. Transplants from each source population (back reef and forereef) had
higher skeletal growth rates, lower bulk densities, and higher calcification rates on the back reef than on the forereef.
Mean annual skeletal extension rates, mean bulk densities, and mean annual calcification rates of RTE groups were 2.6–9.8 mm year−1, 1.41–1.44 g cm−3, and 0.37–1.39 g cm−2 year−1 on the back reef, and 1.2–4.2 mm year−1, 1.49–1.53 g cm−3, and 0.19–0.63 g cm−2 year−1 on the forereef, respectively. Bulk densities were especially responsive to habitat type, with densities of transplants increasing
on the high energy forereef, and decreasing on the low energy back reef. Skeletal growth and calcification rates were also
influenced by source population, even though zooxanthella genotype of source colonies did not vary between sites, and there
was a transplant site x source population interaction for upward linear extension. Genetic differentiation may explain the
source population effects, or the experiment may have been too brief for phenotypic plasticity of all skeletal characteristics
to be fully expressed. Phenotypic plasticity for skeletal characteristics likely enables P. lobata colonies to assume the most suitable shape and density for a wide range of coral reef habitats. 相似文献
7.
Nubbins of the coral Acropora aspera were artificially bleached and nitrogen fixation (acetylene reduction) rates were measured on the developing epilithic communities.
Seasonal comparisons were made between corals that died in summer of heat stress and corals that died in winter from natural
cold stress. Rates of acetylene reduction from artificially bleached corals peaked at 26.66 nmol cm−2 h−1 2 weeks after summer mortality, while rates from natural winter mortality peaked at 18.07 nmol cm−2 h−1 12 days after coral death. Comparative rates of acetylene reduction taken from live corals and coral rubble ranged between
0.56 and 1.16 nmol cm−2 h−1, and 0.15 and 12.77 nmol cm−2 h−1, respectively. N2-fixation rates from dead corals were up to 30 times greater than those measured on live corals. The observed increase in
N2-fixation from dead corals may increase the availability of nitrogen for use in trophic processes within the reef for an extended
period following the initial mortality event. If the spatial scale over which coral mortality has occurred in past thermal
bleaching events is considered the ramifications of such an increase may be substantial. 相似文献
8.
P. L. Jokiel K. S. Rodgers I. B. Kuffner A. J. Andersson E. F. Cox F. T. Mackenzie 《Coral reefs (Online)》2008,27(3):473-483
A long-term (10 months) controlled experiment was conducted to test the impact of increased partial pressure of carbon dioxide
(pCO2) on common calcifying coral reef organisms. The experiment was conducted in replicate continuous flow coral reef mesocosms
flushed with unfiltered sea water from Kaneohe Bay, Oahu, Hawaii. Mesocosms were located in full sunlight and experienced
diurnal and seasonal fluctuations in temperature and sea water chemistry characteristic of the adjacent reef flat. Treatment
mesocosms were manipulated to simulate an increase in pCO2 to levels expected in this century [midday pCO2 levels exceeding control mesocosms by 365 ± 130 μatm (mean ± sd)]. Acidification had a profound impact on the development
and growth of crustose coralline algae (CCA) populations. During the experiment, CCA developed 25% cover in the control mesocosms
and only 4% in the acidified mesocosms, representing an 86% relative reduction. Free-living associations of CCA known as rhodoliths
living in the control mesocosms grew at a rate of 0.6 g buoyant weight year−1 while those in the acidified experimental treatment decreased in weight at a rate of 0.9 g buoyant weight year−1, representing a 250% difference. CCA play an important role in the growth and stabilization of carbonate reefs, so future
changes of this magnitude could greatly impact coral reefs throughout the world. Coral calcification decreased between 15%
and 20% under acidified conditions. Linear extension decreased by 14% under acidified conditions in one experiment. Larvae
of the coral Pocillopora damicornis were able to recruit under the acidified conditions. In addition, there was no significant difference in production of gametes
by the coral Montipora capitata after 6 months of exposure to the treatments. 相似文献
9.
The disastrous effects of the intense 198283 El Niño-SouthernOscillation (ENSO) bring new insight into the long-term developmentof eastern Pacific coral reefs. The 198883 ENSO sea surfacewarming event caused extensive reef coral bleaching (loss ofsymbiotic zooxanthellae), resulting in up to 7095% coralmortality on reefs in Costa Rica, Panama, Colombia and Ecuador.In the Galapagos Islands (Ecuador), most coral reefs experienced>95% coral mortality. Also, several coral species experiencedextreme reductions in population size, and local and regionalextinctions. The El Niño event spawned secondary disturbances,such as increased predation and bioerosion, that continue toimpact reef-building corals. The death of Pocillopora colonieswith their crustacean guards eliminated coral barriers now allowingthe corallivore Acanthaster planci access to formerly protectedcoral prey. Sea urchins and other organisms eroded disturbedcorals at rates that exceed carbonate production, potentiallyresulting in the elimination of existing reef buildups. In otherreefbuilding regions following extensive, catastrophic coralmortality, rapid recovery often occurs through the growth ofsurviving corals, recruitment of new corals from nearby sourcepopulations, and survival of consolidated reef surfaces. Inthe eastern Pacific, however, the return of upwelling conditionsand the survival of coral predators and bioeroders hamper coralreef recovery by reducing recruitment success and eroding coralreef substrates. Thus, coral reef growth that occurs betweendisturbance events is not conserved. Repeated El Niñodisturbances, which have occurred throughout the recent geologichistory of the eastern Pacific, prevent coral communities fromincreasing in diversity and limit the development and persistenceof significant reef features. The poor development of easternPacific coral reefs throughout Holocene and perhaps much ofPleistocene time may result from recurrent thermal disturbancesof the intensity of the 198283 El Niño event. 相似文献
10.
A process-based carbonate budget was used to compare carbonate framework production at two reef sites subject to varying degrees
of fluvial influence in Rio Bueno, Jamaica. The turbid, central embayment was subjected to high rates of fluvial sediment
input, framework accretion was restricted to ≤30 m, and net carbonate production was 1,887 g CaCO3 m−2 year−1. Gross carbonate production (GCP) was dominated by scleractinians (97%), particularly by sediment-resistant species, e.g.
Diploria strigosa on the reef flat (<2 m). Calcareous encrusters contributed very little carbonate. Total bioerosion removed 265 g CaCO3 m−2 year−1 and was dominated by microborers. At the clear-water site, net carbonate production was 1,236 g CaCO3 m−2 year−1; the most productive zone was on the fore-reef (10 m). Corals accounted for 82% of GCP, and encrusting organisms 16%. Bioerosion
removed 126 g CaCO3 m−2 year−1 and was dominated by macroborers. Total fish and urchin grazing was limited throughout (≤20 g CaCO3 m−2 year−1). The study demonstrates that: (1) carbonate production and net reef accretion can occur where environmental conditions approach
or exceed perceived threshold levels for coral survival; and (2) although live coral cover (and carbonate production rates)
were reduced on reef-front sites along the North Jamaican coast, low population densities of grazing fish and echinoids to
some extent offset this, thus maintaining positive carbonate budgets. 相似文献
11.
12.
The major reef-building coral genus Acropora has never been recorded, living or fossil, from the Marquesas Islands in the central Pacific Ocean, which are characterized
by limited modern reef formations. During the “Musorstom 9” cruise in 1997, investigations of marine platforms representing
drowned reef systems revealed for the first time the presence of two Acropora species as fossils at seven Marquesas islands. The predominant species was Acropora
valida, which was widespread in the archipelago and dated between 7.4 and 48.6 ka, providing evidence of an earlier Pacific distribution
pattern broader than previously observed. It is proposed that disappearance of Acropora after 7.4 ka was linked to climatic events probably ENSO events controlling the distribution of corals and coral reefs in
the eastern Pacific without excluding alternatively the effects of an increase in sea-level rise. 相似文献
13.
Biological parameters such as age, growth and age (or size) at maturity are vital for stock assessment and management. Aging
is essential in yielding such information. However, limited aging studies have been conducted for large tropical pelagic species
in the eastern and central tropical Pacific Ocean. The objective of this study is to conduct a length frequency analysis for
estimating growth and mortality of bigeye tuna in the eastern and central tropical Pacific Ocean using samples from the Chinese
longline fishery during February to November 2006. The von Bertalanffy growth parameters of asymptotic fork length L
∞
and growth coefficient k were estimated at L
∞
= 207.4 cm fork length, k = 0.23 year-1, and theoretical age at zero length t
0
= −0.40 year. The total mortality rate (Z) was estimated to be 0.60; the fishing mortality rate (F) and the natural mortality rate (M) were 0.25 year-1 and 0.35 year-1, respectively. The exploitation rate (E) was 0.16. This study provides the estimates of growth and mortality rate for bigeye tuna in the eastern and central tropical
Pacific Ocean, which can be used as biological input parameters in further stock evaluations in this region. However, age
analysis, further validation of the age composition and stock structure are needed for future studies. 相似文献
14.
Ocean acidification and warming are expected to threaten the persistence of tropical coral reef ecosystems. As coral reefs face multiple stressors, the distribution and abundance of corals will depend on the successful dispersal and settlement of coral larvae under changing environmental conditions. To explore this scenario, we used metabolic rate, at holobiont and molecular levels, as an index for assessing the physiological plasticity of Pocillopora damicornis larvae from this site to conditions of ocean acidity and warming. Larvae were incubated for 6 hours in seawater containing combinations of CO2 concentration (450 and 950 µatm) and temperature (28 and 30°C). Rates of larval oxygen consumption were higher at elevated temperatures. In contrast, high CO2 levels elicited depressed metabolic rates, especially for larvae released later in the spawning period. Rates of citrate synthase, a rate-limiting enzyme in aerobic metabolism, suggested a biochemical limit for increasing oxidative capacity in coral larvae in a warming, acidifying ocean. Biological responses were also compared between larvae released from adult colonies on the same day (cohorts). The metabolic physiology of Pocillopora damicornis larvae varied significantly by day of release. Additionally, we used environmental data collected on a reef in Moorea, French Polynesia to provide information about what adult corals and larvae may currently experience in the field. An autonomous pH sensor provided a continuous time series of pH on the natal fringing reef. In February/March, 2011, pH values averaged 8.075±0.023. Our results suggest that without adaptation or acclimatization, only a portion of naïve Pocillopora damicornis larvae may have suitable metabolic phenotypes for maintaining function and fitness in an end-of-the century ocean. 相似文献
15.
Prey capture by a benthic coral reef hydrozoan 总被引:1,自引:0,他引:1
The natural diet and prey abundance of the benthic coral reef hydrozoan Nemalecium lighti, a common tropical species, were studied by analysing the gastrovascular contents of polyps. Prey capture was estimated from
10 samples collected at 3-h intervals during a single diel cycle (1–2 September, 1995) in the San Blas Islands (Panamá). Prey
size ranged from 5 to 550 μm, with invertebrate larvae being the main contributor to the diet of the species. Prey items were
found in 56–88% of the polyps over the entire diel cycle. Gastrovascular contents varied between 0.93 and 2.13 prey items
per polyp. These capture incidences are among the highest reported for cnidarian species. Such rates would allow for high
production rates for Nemalecium lighti, consistent with reports of the species’ fast growth and high reproduction rates. The observations suggest that some hydrozoans
may be active heterotrophic components in coral reef ecosystems.
Accepted: 3 January 1999 相似文献
16.
Janja Ceh Matt R. Kilburn John B. Cliff Jean‐Baptiste Raina Mike van Keulen David G. Bourne 《Ecology and evolution》2013,3(8):2393-2400
The waters surrounding coral reef ecosystems are generally poor in nutrients, yet their levels of primary production are comparable with those reported from tropical rain forests. One explanation of this paradox is the efficient cycling of nutrients between the coral host, its endosymbiotic alga Symbiodinium and a wide array of microorganisms. Despite their importance for the animals' fitness, the cycling of nutrients in early coral life stages and the initial establishment of partnerships with the microbes involved in these processes has received little scrutiny to date. Nitrogen is an essential but limited nutrient in coral reef ecosystems. In order to assess the early nutrient exchange between bacteria and corals, coral larvae of the species Pocillopora damicornis were incubated with two coral‐associated bacteria (Alteromonas sp., or Vibrio alginolyticus), prelabeled with the stable nitrogen isotope 15N. The incorporation and translocation of nitrogen from Vibrio‐ and Alteromonas bacteria into P. damicornis coral larvae and specifically into the coral‐symbiotic Symbiodinium were detected by nanoscale secondary ion mass spectrometry (NanoSIMS). A significant increase in the amount of enriched 15N (two to threefold compared to natural abundance) was observed in P. damicornis larvae within 8 h of incubation for both bacterial treatments (one‐way ANOVA, F5,53 = 18.03, P = 0.004 for Alteromonas sp. and F5,53 = 18.03, P = 0.0001 for V. alginolyticus). These findings reveal that coral larvae acquire nutrients previously taken up from the environment by bacteria. The additional nitrogen may increase the survival rate and fitness of the developing coral and therefore contribute to the successful maintenance of coral reefs. 相似文献
17.
Sebastián Rodríguez Adriana Alvizu Alejandro Tagliafico Carolina Bastidas 《Hydrobiologia》2009,624(1):1-11
The study of coral repopulation in marginal communities may provide a useful analog for understanding the dynamics of coral
reefs subjected to deleterious environmental changes. Repopulation of scleractinian reef corals may strongly impact the community
structure on tropical reefs; however, the extent of this process on coral communities influenced by upwelling is unknown,
especially in the Caribbean. In this study, the potential for natural repopulation of coral communities subjected to wind-driven
upwelling was evaluated at three sites on the island of Cubagua, Venezuela. Coral spawning behavior was recorded and both
larval settlement and juvenile abundance were estimated. Upwelling did not appear to affect coral spawning behavior, since
at this locality spawning occurred at dates and times similar to those reported for well-developed reefs in the Caribbean.
Also, juveniles produced by brooding corals were six times more abundant than those of broadcasting species, similar to patterns
on other Caribbean reefs that are not under the influence of upwelling. By contrast, mean larval settlement (4 settlers m−2) and juvenile abundance (0.1 juveniles m−2) in Cubagua were both lower than those elsewhere in the Caribbean and on Pacific reefs. Thus, the potential for repopulation
of these marginal communities seems lower than for well-developed coral reefs in other regions. These results suggest that
more fully developed coral reefs also may have reduced repopulation potential, as they become influenced by suboptimal environmental
conditions.
Handling editor: I. Nagelkerken 相似文献
18.
Visual censuses of coral reef fishes in Nha Trang Bay Marine Protected Area (MPA) were conducted during September–October
2005. Nha Trang Bay MPA is relatively rich in reef fishes compared to other areas in Vietnam and the Pacific Ocean outside
the ‘Coral Triangle,’ consistent with its biogeographic location in the western South China Sea. A total of 266 species of
40 families of coral reef fishes formed five distinct assemblages. Spatial variations in distribution and structure of the
assemblages were associated with eight significant biological and physical variables which were cover of living hard corals,
encrusting corals, branching corals, Acropora, Millepora, Montipora, depth and distance from the coast of the mainland. The six factors in front are likely related to provision of shelter and
nutrition, while the distance factor is likely to represent a gradient in disturbance and impacts from various mainland sources
including sedimentation and pollution discharge from nearby rivers. Local species richness ranged from 35 to 70 species 500 m−2 (mean: 51 ± 2 SE) for reef flat stations and from 23 to 68 species 500 m−2 (mean: 48 ± 4 SE) for reef slope stations. Total species richness at each site averaged 76 species (±4 SE), ranging from
56 to 110 species, dominated by wrasses, damselfishes, butterflyfishes, parrotfishes, surgeonfishes, groupers and goatfishes.
Density of total fishes at each station ranged from 348 to 1,444 individuals 500 m−2 (mean: 722 ± 302 SE) for the reef flat stations and from 252 to 929 individuals 500 m−2 (mean: 536 ± 215.7 SE) for the reef slope stations. Overall mean density at each site averaged 628.9 (±238.4 SE) individuals
500 m−2. The highly protected sites supported higher mean density of fishes per site (ranged: 904.5–1,213 individuals 500 m−2 for Hon Mun and 1,167.5 individuals 500 m−2 for Hon Cau) compared to other sites (<800 individuals 500 m−2). Of the families included in the census, densities were dominated throughout the MPA by damselfishes and wrasses. Many target
species, particularly groupers, snappers and emperors, were rare or absent and the low abundance of big fishes was consistent
with over-harvesting. Similarly a low density of butterfly fishes and angelfishes is likely related to the supply for marine
aquaria in Vietnam and overseas. This study provides an important baseline against which the success of present and future
MPA management initiatives may be assessed. 相似文献
19.
Rising atmospheric CO2 concentrations are placing spatially divergent stresses on the world's tropical coral reefs through increasing ocean surface temperatures and ocean acidification. We show how these two stressors combine to alter the global habitat suitability for shallow coral reef ecosystems, using statistical Bioclimatic Envelope Models rather than basing projections on any a priori assumptions of physiological tolerances or fixed thresholds. We apply two different modeling approaches (Maximum Entropy and Boosted Regression Trees) with two levels of complexity (one a simplified and reduced environmental variable version of the other). Our models project a marked temperature‐driven decline in habitat suitability for many of the most significant and bio‐diverse tropical coral regions, particularly in the central Indo‐Pacific. This is accompanied by a temperature‐driven poleward range expansion of favorable conditions accelerating up to 40–70 km per decade by 2070. We find that ocean acidification is less influential for determining future habitat suitability than warming, and its deleterious effects are centered evenly in both hemispheres between 5° and 20° latitude. Contrary to expectations, the combined impact of ocean surface temperature rise and acidification leads to little, if any, degradation in future habitat suitability across much of the Atlantic and areas currently considered ‘marginal’ for tropical corals, such as the eastern Equatorial Pacific. These results are consistent with fossil evidence of range expansions during past warm periods. In addition, the simplified models are particularly sensitive to short‐term temperature variations and their projections correlate well with reported locations of bleaching events. Our approach offers new insights into the relative impact of two global environmental pressures associated with rising atmospheric CO2 on potential future habitats, but greater understanding of past and current controls on coral reef ecosystems is essential to their conservation and management under a changing climate. 相似文献
20.
T. B. Smith 《Coral reefs (Online)》2008,27(2):397-405
An assumption that a positive relationship exists between temperature and herbivorous fish grazing rates in coral reef environments
has been used to explain seasonal and latitudinal trends in herbivore pressure. However, this assumption has not been systematically
quantified over short-term (hours–days) changes in temperature, avoiding the confounding influences that can occur on seasonal
or latitudinal scales. This study measured grazing activities of the pan Indo-Pacific parrotfish Scarus ghobban over short-term changes in temperature in upwelling and non-upwelling environments on the Pacific coast of Panamá. Individual
juvenile fish were followed over naturally varying temperatures to determine their bite rates (bites min−1), the foray frequency (forays min−1) and bites per foray. In the upwelling environment, there was a significant positive correlation between temperature and
bite rate (R
Partial = 0.63, P < 0.0001) and there was a marked fourfold change in bite rates over the range of temperatures encountered in the study (21.2–29.4°C).
Bites per foray were also positively correlated to temperature (R
partial = 0.27, P < 0.0001), and tide height (R
partial = 0.26, P < 0.001), whilst foray frequency was positively correlated to temperature (R
partial = 0.63, P < 0.0001), but negatively to tide height (R
partial = −0.31, P < 0.0001). The effect of temperature on grazing rates may explain differences in herbivore pressure across different thermal
environments and may be a factor contributing to algal biomass increases in low-temperature coral reef environments. 相似文献