CORALS A QUICK REFERENCE GUIDE PDF

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Corals A Quick Reference Guide Pdf

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土, 05 1 GMT corals a quick reference guide pdf - Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. Find the files in zip, txt, site, pdf, word, rar, and also ppt. the corals a quick reference guide that you can take. and when you really need a. Get Free Access To | Corals A Quick Reference Oceanographic Series PDF Now guide oceanographic series, you can download them in pdf format from.

Indeed, lipids are mainly derived from excess carbon fixed by zooxanthellae [43]. Due to its sheltered location and high irradiance, stressful conditions for corals may also be expected to occur frequently here Fig.

Corals: A Quick Reference Guide

Lipids represent important energy at reserves during stressful periods [44] , and integrated symbionts-host lipogenesis is considered as a photoprotective mechanism during periods of excess irradiance [45]. Higher tissue biomass may reflect the opportunities corals have for heterotrophic feeding see review in [46]. The exposed site Kiosque, which receives a regular influx of coastal water, provides this advantage and allows corals to maintain vital processes during periods when photosynthetic function is compromised.

In an earlier study on the lesion regeneration in massive corals at same sites, the potential importance of heterotrophic feeding at Kiosque reef flat during the summer season [22] was already highlighted. Measured photosynthetic efficiencies were higher than those of A.

Differences in the photosynthetic efficiency may also be related to differences in zooxanthellae genotypes [48]. However, while in Chagos Archipelago, A. Homogeneity of lesion sizes avoids an important confounding factor that complicates drawing viable inferences about the regeneration capacity of corals under different environmental conditions [19]. Lesion size in A.

This result is remarkable because it contradicts the general positive relationship found between coral growth and lesion repair ability see review in [21]. Most studies on lesion regeneration in corals have used massive species see review in [21] , and only a few studies on Acropora spp.

In contrast, the very steep slopes obtained for A. Indeed, a previous study suggested the stimulating role of photosynthesis on calcification induced by nutrient enrichment at this site [41].

While a high lesion regeneration rate is generally assumed in fast-growing corals [21] , our observations suggest that environmental conditions that promote fast skeletal growth may compromise rather than boost the lesion regeneration capacity. This observation may help explain the paradox that while fast growing corals such as Acropora spp.

Energetic reserves such as lipids are considered to uphold vital life processes [43]. Despite A.

Tissue biomass of nubbins may be a better predictor of the regenerative capacity, as nubbins from Kiosque showed both high tissue biomass and fast regeneration.

Comparative studies of coral community dynamics in select locations identified several mechanisms that influenced the rate of coral recovery, with patterns of recovery driven by differences in the demographic rates of different coral taxa, including recruitment, post-settlement growth and survival, and the capacity for regrowth of remnant colonies 7 , 9 , These kinds of studies are critical to understanding why coral reefs differ in their ability to recover from disturbances.

However, they are rare in coral reef literature because reefs are often sampled irregularly, and many of the biological and physical variables necessary to test the importance of different mechanisms in determining the rate of population recovery for multiple coral taxa are not measured.

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Additional studies are needed to better understand mechanisms underlying spatial and temporal variation in coral recovery following disturbances 8. Although studies of the effects of disturbances on coral reefs have largely focused on a single benthic state variable i.

A key issue associated with analyzing recovery of a reef community following disturbance is the extent to which the coral assemblage and associated biota e. Understanding the factors determining the similarity of pre- and post- disturbance communities is central to our understanding of community resilience, because coral reefs can recover to pre-disturbance levels of coral cover but shift in the assemblage structure of corals and associated biota 3 , 12 , The fore reef of Moorea, French Polynesia, has undergone repeated disturbances over the past several decades that have resulted in landscape-scale loss of coral followed by return to pre-disturbance cover within about a decade 12 , 20 , 21 , 22 , 23 , 24 , These have included cyclones, coral bleaching events, and outbreaks of predatory crown-of-thorns sea stars.

The most recent major disturbances, a crown-of-thorns sea star outbreak that peaked between and and a cyclone , dramatically reduced cover of live coral on the fore reef 23 , 26 , affording the opportunity to quantify patterns of recovery for two attributes of the coral community coral cover and community re-assembly around the island and to explore the underlying mechanisms driving observed spatial patterns 27 , Here we address three major questions.

First, is there variation in resilience of the fore reef coral community among the three shores of Moorea as measured by the spatial pattern of loss and return rate of live coral? Second, what demographic mechanisms underlie spatial variation in speed of recovery of coral cover?

And third, is the benthic community — defined by cover of scleractinians, Millepora, and the abundance of other sessile benthic taxa — re-assembling to its pre-disturbance community structure?

Results Spatial and temporal variation in the cover of live coral The outbreak of crown-of-thorns sea stars —09 followed by Cyclone Oli in February resulted in nearly complete loss of live coral on the fore reef 23 , 24 , There was variation in the timing and extent of the decline of coral. Most quadrats at sites on the north shore and northern ends of the east and west shores 1, 2, 3, and 6 reached their nadir of coral cover in or , while most quadrats at the southern sites of the east and west shores 4 and 5 reached their nadir of coral cover in or Supplementary Fig.

The most rapid recovery occurred on the north shore, and the least rapid on the east shore Fig. The island wide percent cover of the most abundant genera of macroalgae during the post-disturbance period averaged over all sites and years was as follows: Halimeda — 5. Pocillopora spp. As a result, rates of increase in coral cover were driven by rates of increase in Pocillopora spp.

Thus we focused on Pocillopora spp. Demographic mechanisms underlying recovery of Pocillopora In situ diver surveys of sets of m2 plots and analysis of 0. S4 ; the two estimates of recruitment were strongly positively correlated Supplementary Fig. Despite strong among-year variation, there was a clear pattern of among-shore variation in coral recruitment, with most recruits on the north shore, fewer on the west shore, and the least on the east shore Fig.

During the time period —, a total of 48, recruits were observed in the diver surveys and 1, in the photoquadrats. The magnitude of coral recruitment following varied sharply among sites, and the pattern mirrors the pattern of variation in recovery of live coral cover Fig.

Full size image Figure 3 Relationship between the cumulative number of Pocillopora recruits per m2 from to and the rate of return of coral cover at 6 sites around Moorea.

Line shows fit from least squares linear regression. Full size image In contrast to the among-site variation in Pocillopora recruitment, there was less among-site variation in their growth and survivorship. Variation in survivorship and growth did not match the spatial pattern in return of cover of live coral; these mechanisms appear insufficient to explain the observed variation among sites in return of coral.

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Full size image In addition to the site-level analyses described above, we also tested whether the early demography of Pocillopora could explain variation in recovery at the 0. These analyses confirmed the patterns observed at the site scale. The model that best explained coral recovery on this small spatial scale included site, cumulative recruitment total number of recruits from to , minimum cover of Pocillopora spp.

Average growth rates i. The rates of coral recovery were unrelated to the average survivorship of Pocillopora recruits on a quadrat scale, and survivorship was not included in the final, best-fit model. Patterns of community re-assembly The extent to which the broader benthic community recovered following the two disturbances was addressed using three aspects of benthic community structure: 1 the major benthic substratum categories, 2 taxonomic composition of corals, and 3 taxonomic composition of macroalgae.

NMDS plots revealed a strong response in all three of these aspects to the disturbances, with trajectories indicating that recovery is occurring, as defined by the extent to which initial and final multivariate communities are similar Fig.

From to i. The rate at which sites re-assembled was related to their rates of return of coral cover, with north shore sites e.

Figure 5 Variation in coral reef community structure between and , during which corallivory by COTS and Cyclone Oli depressed coral cover close to zero by Circles are scaled to show mean cover in each year of b scleractinians and Millepora, c Pocillopora spp. Full size image Figure 6 Results of post-hoc multiple contrasts using t-tests, t values plotted between multivariate community structure by functional group see Fig.

Full size image Discussion In the past several decades, there has been increasing interest in quantifying both the responses of coral reefs to disturbances that cause landscape-scale loss of corals, and to understand mechanisms that underlie spatial variation in ecosystem resilience 8 , 9 , 29 , We do not know the mechanisms driving this gradient, but we hypothesize that local physical oceanographic processes involving features such as lagoon-fore reef circulation cells 39 result in locally enhanced densities of pelagic coral larvae along the north shore of Moorea, with these larvae originating from coral parents located either in Moorea or nearby islands.

The mouth divides and new tentacles form. The venom is injected through the hollow filament to immobilise the prey; the tentacles then manoeuvre the prey to the mouth.

The trade-off between growth and lesion regeneration observed in nubbins from Kiosque complement this view. From to i. This synchrony is essential so male and female gametes can meet.

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