Diversity Partitioning of Stony Corals Across Multiple Spatial Scales Around Zanzibar Island, Tanzania

The coral reefs of Zanzibar Island (Unguja, Tanzania) encompass a considerable proportion of the global coral-reef diversity and are representative of the western Indian Ocean region. Unfortunately, these reefs have been recently subjected to local and regional disturbances. The objectives of this study were to determine whether there are potentially non-random processes forcing the observed coral diversity patterns, and highlight where and at which spatial scales these processes might be most influential.A hierarchical (nested) sampling design was employed across three spatial scales, ranging from transects (<or=20 m), stations (<100 m), to sites (<1000 m), to examine coral diversity patterns. Two of the four sites, Chumbe and Mnemba, were located within Marine Protected Areas (MPAs), while the other two sites, Changuu and Bawe, were not protected. Additive partitioning of coral diversity was used to separate regional (total) diversity (gamma) into local alpha diversity and among-sample beta diversity components. Individual-based null models were used to identify deviations from random distribution across the three spatial scales. We found that Chumbe and Mnemba had similar diversity components to those predicted by the null models. However, the diversity at Changuu and Bawe was lower than expected at all three spatial scales tested. Consequently, the relative contribution of the among-site diversity component was significantly greater than expected. Applying partitioning analysis for each site separately revealed that the within-transect diversity component in Changuu was significantly lower than the null expectation.The non-random outcome of the partitioning analyses helped to identify the among-sites scale (i.e., 10's of kilometers) and the within-transects scale (i.e., a few meters; especially at Changuu) as spatial boundaries within which to examine the processes that may interact and disproportionately differentiate coral diversity. In light of coral community compositions and diversity patterns we strongly recommend that Bawe be declared a MPA

Spatio-Temporal Transmission Patterns of Black-Band Disease in a Coral Community

Transmission mechanisms of black-band disease (BBD) in coral reefs are poorly understood, although this disease is considered to be one of the most widespread and destructive coral infectious diseases. The major objective of this study was to assess transmission mechanisms of BBD in the field based on the spatio-temporal patterns of the disease

In the shadow of coral bleaching

Coral reefs are highly susceptible to climate change, as evidenced by extensive mass bleaching events over the past decades. Until solutions to reduce greenhouse gas emissions are implemented, pro-active unconventional approaches to conserve local reefs are required. Here, we demonstrate a management strategy aimed at reducing the magnitude of bleaching events over designated reef sections (thousands of square meters). Since high levels of solar irradiance induce coral bleaching, our goal was to technically test the feasibility of shading a shallow reef at the &quot;Japanese Gardens&quot;, the highest-value reef in the Eilat Coral Nature Reserve (Israel, Red Sea). In practice, a buoyant shade cloth of 400m2 was deployed on the sea surface over the shallow reef (ca. 6m deep) for a 24-hour period and irradiance, as well as water temperature, were continuously monitored in the shaded and the unshaded reef. The deployment was successful and was completed without causing any physical damage to the reef. In addition to decreasing the irradiance by 85.9% in average, the shade cloth eliminated wave lensing, which produces extremely high irradiance levels and is known to contribute to coral bleaching. Surprisingly, we also found that the water temperature on the shaded reef was up to ca. 0.5oC lower than on the unshaded reef. We propose that the reef shading management strategy can be applied to reefs worldwide and may be particularly valuable on spatially isolated locations. These &quot;islands&quot; of survivors may possibly function as source populations and accelerate the recovery of the destroyed region.peerReviewe

Bacterial consortium of millepora dichotoma exhibiting unusual multifocal lesion event in the Gulf of Eilat, Red Sea

Colonies of the hydrocoral Millepora dichotoma along the Gulf of Eilat are exhibiting unusual tissue lesions in the form of white spots. The emergence and rapid establishment of these multifocal tissue lesions was the first of its kind reported in this region. A characterization of this morphological anomaly revealed bleached tissues with a significant presence of bacteria in the tissue lesion area. To ascertain possible differences in microbial biota between the lesion area and non-affected tissues, we characterized the bacterial diversity in the two areas of these hydrocorals. Both culture-independent (molecular) and culture-dependent assays showed a shift in bacterial community structure between the healthy and affected tissues. Several 16S rRNA gene sequences retrieved from the affected tissues matched sequences of bacterial clones belonging to Alphaproteobacteria and Bacteroidetes members previously associated with various diseases in scleractinian corals

Simulated future projections of the local coral community spanning 80 years.

<p>The future projections in panels <b>A</b>, <b>B</b> and <b>C</b> rely on the demographic scenario of constant influx of recruits (64 recruits per year). Panels <b>D</b>, <b>E</b> and <b>F</b> rely on the scenario of free-space regulation of recruitment (see <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1004151#sec016" target="_blank">Material and Methods</a>). Panels <b>A</b> and <b>D</b> are based on the SST time-series measured between June 2006 and May 2007 recurrently from year to year in the corresponding months. Based on this time-series, we generate future projections by adding 0.5°C (panels <b>B</b> and <b>E</b>) and 1°C (panels <b>C</b> and <b>F</b>) to the SST of each month. In these simulations we allow each new recruit to settle randomly anywhere on the 10×10 m plane. <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1004151#pcbi.1004151.s004" target="_blank">S4 Fig</a> demonstrates robustness of these patterns under mild parameter variations.</p

Coral colonies from the genus Favia infected with WPD (white-plague disease).

<p><b>A</b>) Initiation of WPD—a thin zone of bleached tissue grading into exposed coral skeleton. <b>B</b>) A sharp boundary between apparently healthy tissue (‘H’) and freshly exposed skeleton (‘S’), with no build-up of microorganisms or necrotic tissue visible to the eye. With time, the exposed skeleton becomes colonized by algae (‘A’). <b>C</b>) An aggregation of corals infected with WPD.</p

Profile likelihood function <i>M</i>(<i>α</i>).

<p>The function is maximized at </p><p></p><p></p><p><mi>α</mi><mo>^</mo></p><p></p><p></p> = 1.9, giving the estimate of parameter <i>α</i>. The insert shows a close up of the 95% CI of <i>α</i> (represented by the red horizontal line).<p></p

Number of newly-infected corals (NICs).

<p>The red dots represent the number of NICs observed in the field along the studied year. The grey dots represent the median number of NICs as predicted by generating infections according to the SIS epidemic model based on <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1004151#pcbi.1004151.e002" target="_blank">Eq 2</a> (see text), and the grey bars represent their 95% confidence interval.</p