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151.
152.
Declining coral calcification in massive Porites in two nearshore regions of the northern Great Barrier Reef 总被引:1,自引:0,他引:1
TIMOTHY F. COOPER † GLENN DE'ATH KATHARINA E. FABRICIUS JANICE M. LOUGH 《Global Change Biology》2008,14(3):529-538
Temporal and spatial variation in the growth parameters skeletal density, linear extension and calcification rate in massive Porites from two nearshore regions of the northern Great Barrier Reef (GBR) were examined over a 16‐year study period. Calcification rates in massive Porites have declined by approximately 21% in two regions on the GBR ~450 km apart. This is a function primarily of a decrease in linear extension (~16%) with a smaller decline in skeletal density (~6%) and contrasts with previous studies on the environmental controls on growth of massive Porites on the GBR. Changes in the growth parameters were linear over time. Averaged across colonies, skeletal density declined over time from 1.32 g cm?3 (SE = 0.017) in 1988 to 1.25 g cm?3 (0.013) in 2003, equivalent to 0.36% yr?1 (0.13). Annual extension declined from 1.52 cm yr?1 (0.035) to 1.28 cm yr?1 (0.026), equivalent to 1.02% yr?1 (0.39). Calcification rates (the product of skeletal density and annual extension) declined from 1.96 g cm?2 yr?1 (0.049) to 1.59 g cm?2 yr?1 (0.041), equivalent to 1.29% yr?1 (0.30). Mean annual seawater temperatures had no effect on skeletal density, but a modal effect on annual extension and calcification with maxima at ~26.7 °C. There were minor differences in the growth parameters between regions. A decline in coral calcification of this magnitude with increasing seawater temperatures is unprecedented in recent centuries based on analysis of growth records from long cores of massive Porites. We discuss the decline in calcification within the context of known environmental controls on coral growth. Although our findings are consistent with studies of the synergistic effect of elevated seawater temperatures and pCO2 on coral calcification, we conclude that further data on seawater chemistry of the GBR are required to better understand the links between environmental change and effects on coral growth. 相似文献
153.
The spiny damselfish, Acanthochromis polyacanthus, is widely distributed throughout the Indo‐Australian archipelago. However, this species lacks a larval dispersal stage and shows genetic differentiation between populations from closely spaced reefs. To investigate the dispersal strategy of this unique species, we used microsatellite markers to determine genetic relatedness at five dispersal scales: within broods of juveniles, between adults within a collection site (~30 m2), between sites on single reefs, between nearby reefs in a reef cluster, and between reef clusters. We sampled broods of juveniles and adults from seven reefs in the Capricorn‐Bunker and Swain groups of the Great Barrier Reef. We found that extra‐pair mating is rare and juveniles remain with their parents until fledged. Adults from single sites are less related than broods but more related than expected by chance. However, there is no evidence of inbreeding suggesting the existence of assortative mating and/or adult migration. Genetic differences were found between all of the reefs tested except between Heron and Sykes reefs, which are separated only by a 2‐km area of shallow water (less than 10 m). There was a strong correlation between genetic distance, geographical distance and water depth. Apparently, under present‐day conditions spiny damselfish populations are connected only between sites of shallow water, through dispersal of adults over short distances. Assuming that dispersal behaviour has not changed, the broad distribution of A. polyacanthus as a species is likely based on historical colonization patterns when reefs were connected by shallow water at times of lower sea levels. 相似文献
154.
Epidemiology of skeletal eroding band on the Great Barrier Reef and the role of injury in the initiation of this widespread coral disease 总被引:1,自引:0,他引:1
Skeletal eroding band (SEB), which manifests as dense aggregations of the ciliate Halofolliculina corallasia, was the first coral disease described from the Indo-Pacific. Little is known about its etiology or impact. This study describes
the distribution, prevalence and host range of SEB on a 500 km extent of the Great Barrier Reef (GBR), together with in situ
rates of progression and infection following experimental injury. SEB occurred on 90–100% of reefs surveyed (n=18) in each of 3 years, demonstrating that SEB is widely distributed and persistent. SEB had the highest prevalence of any
disease, affecting approximately 2% of 283,486 scleractinians and hydrocorals surveyed. Its host range was large, affecting
12 families and at least 82 scleractinian species, as well as the hydrocoral, Millepora. Corals in the families Pocilloporidae and Acroporidae were most susceptible, the former being up to five times more susceptible
than other families. Progressive tissue loss was recorded on 95% of Acropora muricata colonies monitored (n = 18), with rates of SEB progression averaging ∼2 mm/day. Injury experiments demonstrated that H. corallasia, the putative pathogen of SEB, readily colonised recently exposed coral skeleton in the absence of a vector, but did not
colonise intact coral tissue. Invading ciliates failed to form band-like aggregations associated with progressive tissue loss
on any of three coral species tested experimentally, suggesting that, while H. corallasia readily colonises recently exposed coral skeleton, it may not be sufficient in itself to cause tissue mortality. Interactions
with additional agents or factors, increasing ciliate virulence or lowering disease resistance of coral hosts may be required
before halofolliculinid infections become associated with tissue loss. 相似文献
155.
C. Dang X. de Montaudouin J. Bald F. Jude N. Raymond L. Lanceleur I. Paul-Pont N. Caill-Milly 《Hydrobiologia》2009,630(1):139-148
Knowledge of temporal variation in nearshore Laurentian Great Lakes fish assemblages is important for understanding species–habitat
associations, how abiotic and biotic influences vary temporally, and when sampling should occur. Using spring and fall seining
data from Lake Erie beaches, we compared day and night fish assemblages and tested for differences among sampling periods.
Beaches were utilized by a diverse collection of Lake Erie basin fishes (one-third of known species). During all sampling
periods, catches were dominated by cyprinid species (53–91%), and by invertivores and planktivorous fishes. Diel differences
were detected in abundance, species richness and assemblage structure. Multivariate analyses (canonical analysis of principal
coordinates) indicated that season had a larger influence on fish assemblage structure than diel period. Given observed temporal
variation in assemblage structure, studies of Laurentian Great Lakes beach fishes should be restricted to a single time period
(e.g. day-time spring sampling), or adopt sampling designs that permit diel period and season to be included as factors in
analyses. Second, the large seasonal variation in assemblage composition combined with higher night species richness indicates
that night sampling during both spring and fall would be the most efficient and comprehensive approach for beach fish inventory.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Handling editor: J. Trexler 相似文献
156.
Short-term experiments were used to isolate the detrimental effects of grazer disturbance on young corals, and determine the
stage of development at which recruits are no longer susceptible to this disturbance. Artificial substrata containing an algal
matrix and coral recruits of different life stages were exposed to grazing by epilithic algal matrix (EAM) feeding combtoothed
blennies, Salarias fasciatus. Single polyp recruits were vulnerable to grazer disturbance, while multi-polyp recruits (ca. 6–8 polyps) survived with evidence of minor damage in the form of tissue and polyp loss. The result indicates that blennies,
although small and possessing weak dentition, can negatively influence the survival of young coral recruits. The protruding
structure of micro-nubbins, representing juvenile corals were not damaged, suggesting that coral achieving that size and form
can escape such damage.
Communicated by Ecology Editor Prof. Peter Mumby 相似文献
157.
Serge A. Wich Karyl B. Swartz Madeleine E. Hardus Adriano R. Lameira Erin Stromberg Robert W. Shumaker 《Primates; journal of primatology》2009,50(1):56-64
The capacity of nonhuman primates to actively modify the acoustic structure of existing sounds or vocalizations in their repertoire
appears limited. Several studies have reported population or community differences in the acoustical structure of nonhuman
primate long distance calls and have suggested vocal learning as a mechanism for explaining such variation. In addition, recent
studies on great apes have indicated that there are repertoire differences between populations. Some populations have sounds
in their repertoire that others have not. These differences have also been suggested to be the result of vocal learning. On
yet another level great apes can, after extensive human training, also learn some species atypical vocalizations. Here we
show a new aspect of great ape vocal learning by providing data that an orangutan has spontaneously (without any training)
acquired a human whistle and can modulate the duration and number of whistles to copy a human model. This might indicate that
the learning capacities of great apes in the auditory domain might be more flexible than hitherto assumed.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
158.
Question: Can a new cost‐distance model help us to evaluate the potential for accessibility bias in ecological observations? How much accessibility bias is present in the vegetation monitoring plots accumulated over the last three decades in Great Smoky Mountains National Park? Location: Great Smoky Mountains National Park, North Carolina and Tennessee, USA. Methods: Distance, slope, stream crossings, and vegetation density were incorporated into a least‐cost model of energetic expenditure for human access to locations. Results: Estimated round‐trip energy costs for the park ranged from 0 to 1.62 × 105 J kg?1. The estimated round‐trip energetic expenditure for the surveys ranged from 53 to 1.51 × 105 J kg?1. Their distribution was more accessible than the random expectation. Ten (17%) of the vegetation types in the park are significantly under‐sampled relative to their area, and 16 (29%) are over‐sampled. Plots in 18 of the 40 vegetation types exhibited a significant positive correlation with accessibility. Conclusions: The least‐cost model is an improvement over previous attempts to quantify accessibility. The bias in plot locations suggests using a least‐cost model to test for bias in cases in which human accessibility is confounded with other sources of ecosystem variation. 相似文献
159.
160.
Leela J. Chakravarti Victor H. Beltran Madeleine J. H. van Oppen 《Global Change Biology》2017,23(11):4675-4688
Climate warming is occurring at a rate not experienced by life on Earth for 10 s of millions of years, and it is unknown whether the coral‐dinoflagellate (Symbiodinium spp.) symbiosis can evolve fast enough to ensure coral reef persistence. Coral thermal tolerance is partly dependent on the Symbiodinium hosted. Therefore, directed laboratory evolution in Symbiodinium has been proposed as a strategy to enhance coral holobiont thermal tolerance. Using a reciprocal transplant design, we show that the upper temperature tolerance and temperature tolerance range of Symbiodinium C1 increased after ~80 asexual generations (2.5 years) of laboratory thermal selection. Relative to wild‐type cells, selected cells showed superior photophysiological performance and growth rate at 31°C in vitro, and performed no worse at 27°C; they also had lower levels of extracellular reactive oxygen species (exROS). In contrast, wild‐type cells were unable to photosynthesise or grow at 31°C and produced up to 17 times more exROS. In symbiosis, the increased thermal tolerance acquired ex hospite was less apparent. In recruits of two of three species tested, those harbouring selected cells showed no difference in growth between the 27 and 31°C treatments, and a trend of positive growth at both temperatures. Recruits that were inoculated with wild‐type cells, however, showed a significant difference in growth rates between the 27 and 31°C treatments, with a negative growth trend at 31°C. There were no significant differences in the rate and severity of bleaching in coral recruits harbouring wild‐type or selected cells. Our findings highlight the need for additional Symbiodinium genotypes to be tested with this assisted evolution approach. Deciphering the genetic basis of enhanced thermal tolerance in Symbiodinium and the cause behind its limited transference to the coral holobiont in this genotype of Symbiodinium C1 are important next steps for developing methods that aim to increase coral bleaching tolerance. 相似文献