Coral dominance at the reef - sediment interface in marginal coral communities at Sodwana Bay, South Africa

2003 ◽  
Vol 54 (8) ◽  
pp. 967 ◽  
Author(s):  
M. H. Schleyer ◽  
L. Celliers
Keyword(s):  
South Africa ◽  
High Latitude ◽  
Slow Growth ◽  
Coral Community ◽  
Reef Complex ◽  
Tolerant Species ◽  
Coral Communities ◽  
Disturbed Environment ◽  
Sediment Interface

Sedimentation is an important factor that influences the composition of coral communities. The high-latitude, marginal coral community in the central reef complex at Sodwana Bay, South Africa, is subjected to sedimentation at the reef–sediment interface. A lens of bioclastic sediment surrounds the sandstone reefs in the area and acts as a scouring and smothering agent. This affects the composition of the subcommunity on the reef margin at the reef–sediment interface. The interface was studied on two reefs in the complex and their subcommunities did not differ. Alcyoniidae and Scleractinia (34.4% and 34.4% cover, respectively) are the dominant taxa in the reef–sediment subcommunity, which includes genera such as Sinularia, Lobophytum, Sarcophyton, Montipora, Favia and Astreopora (in decreasing order of abundance). Sediment-tolerant species are prevalent, the Alcyoniidae being the most prominent and tolerant by virtue of their morphology. Corals in this environment are generally flat and fairly rigid colonies of Lobophytum and Sinularia spp. (14% and 10% cover, respectively), some with lobes to channel the movement of surge-driven sediment, or are erect, soft and pliable forms such as Sarcophyton spp. (10% cover) that easily shed sediment. Their dominance in this constantly disturbed environment may also be attributable to the low mortality, slow growth and overall persistence of the Alcyoniidae described in the literature.

scholarly journals Environmental Variation and How its Spatial Structure Influences the Cross-Shelf Distribution of High-Latitude Coral Communities in South Africa

Diversity ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 57 ◽  
Author(s):  
Sean N. Porter ◽  
Michael H. Schleyer
Keyword(s):  
South Africa ◽  
Continental Shelf ◽  
High Latitude ◽  
Environmental Variables ◽  
Environmental Gradients ◽  
High Tide ◽  
Environmental Variation ◽  
Shelf Edge ◽  
Spatial Differences ◽  
Coral Communities

Coral communities display spatial patterns. These patterns can manifest along a coastline as well as across the continental shelf due to ecological interactions and environmental gradients. Several abiotic surrogates for environmental variables are hypothesised to structure high-latitude coral communities in South Africa along and across its narrow shelf and were investigated using a correlative approach that considered spatial autocorrelation. Surveys of sessile communities were conducted on 17 reefs and related to depth, distance to high tide, distance to the continental shelf edge and to submarine canyons. All four environmental variables were found to correlate significantly with community composition, even after the effects of space were removed. The environmental variables accounted for 13% of the variation in communities; 77% of this variation was spatially structured. Spatially structured environmental variation unrelated to the environmental variables accounted for 39% of the community variation. The Northern Reef Complex appears to be less affected by oceanic factors and may undergo less temperature variability than the Central and Southern Complexes; the first is mentioned because it had the lowest canyon effect and was furthest from the continental shelf, whilst the latter complexes had the highest canyon effects and were closest to the shelf edge. These characteristics may be responsible for the spatial differences in the coral communities.

scholarly journals Stranger Things: Organismal Traits of Two Octocorals Associated With Singular Symbiodiniaceae in a High-Latitude Coral Community From Northern Taiwan

2020 ◽  
Vol 7 ◽  
Author(s):  
Tsai-Hsuan Tony Hsu ◽  
Lilian Carlu ◽  
Yunli Eric Hsieh ◽  
Tzu-Yu Angel Lai ◽  
Ching-Wei Wang ◽  
...  
Keyword(s):  
Organic Matter ◽  
High Latitude ◽  
Coral Community ◽  
Symbiotic Relationship ◽  
Ecological Strategies ◽  
Significant Difference ◽  
Coral Communities ◽  
Definition Of ◽  
The Individual ◽  
Northern Taiwan

Scrutinizing the traits of octocorals that could affect their physiological performance becomes increasingly important as several of these species are observed to become dominant on reefs pressured by the Anthropocene. In the present study, we compare the organismal traits of two branching octocorals Litophyton sp. and Stereonephthya sp. commonly populating in sympatry the high-latitude coral communities of northern Taiwan. Using 13 traits, we describe and compare performance traits in these two symbiotic species that we discuss in light of the association they maintain with their algal partners. Litophyton sp. and Stereonephthya sp. hosted Durusdinium and Gerakladium, respectively. Both genera represent singular associations, with the latter further establishing the first solid report of Gerakladium in octocorals. Traits distinguished two groups explained by the two partnerships considered. Litophyton sp. associated with Durusdinium had significantly higher organic matter, chlorophyll (chl) a, total lipid and lower chl c/chl a ratio than Stereonephthya sp. associated with Gerakladium. The δ15N in the host and algae, as well as δ13C in the host were also higher in Litophyton species. Although no significant difference was observed in the δ13C of the algae, Litophyton sp. presented a significantly higher variance for this trait and for chl a content than Stereonephthya species. Altogether, the traits examined suggested contrasting performances among the two octocorals. Both octocoral species clearly deviate from an autotrophic diet. Litophyton sp. appears to complement its heterotrophic diet with photosynthetically acquired energy, while Stereonephthya sp. tends to be more specialized and benefits relatively little from its symbiotic relationship. Our study calls for greater consideration of the individual variation in octocoral physiology and in the definition of their ecological strategies.

scholarly journals Sponge and coral communities of potential mineral resources in the deep-sea: An overview

2018 ◽  
Author(s):  
Tina Molodtsova ◽  
Christopher Kelley ◽  
Lénaick Menot ◽  
Les Watling
Keyword(s):  
Deep Sea ◽  
Slow Growth ◽  
Mineral Resources ◽  
Ore Deposits ◽  
Manganese Nodules ◽  
Cumulative Impact ◽  
Mining Sites ◽  
Intensive Exploitation ◽  
Coral Communities ◽  
Hard Substrata

Depletion of commercially valuable minerals on land and increased need of such resources for modern electronics and manufacturing is attracting more and more attention to deep-sea mineral deposits such as cobalt crusts, manganese nodules, phosphorites, polymetallic sulfides and even deep-sea ooze. In a few years we expect intensive exploitation in the deep-sea. Being suspension feeders, corals and sponges associated with hard substrata in potential mining sites would be adversely impacted by deep-sea mining. Deep-sea corals and sponges are characterized by extremely slow growth rates and, as can be seen from fishery impacts, they may take decades to centuries to restore. At the same time, they serve as a substrate, shelter and food for a number of associated deep-sea organisms, thus increasing the cumulative impact of their loss. We summarize here the available data on coral and sponge communities of solid deep-sea ore deposits and possible mechanisms driving their diversity.

Politics and Economic Policymaking in South Africa since 1994

2021 ◽  
pp. 65-90
Author(s):  
Alan Hirsch ◽  
Brian Levy ◽  
Musa Nxele
Keyword(s):  
South Africa ◽  
Black People ◽  
Global Financial Crisis ◽  
Slow Growth ◽  
Economic Transformation ◽  
Policy Uncertainty ◽  
The Poor ◽  
The Global Financial Crisis ◽  
Growth Economic ◽  
Political Settlement

Economic policy in South Africa since 1994 has confronted the imperative to include middle class, working class and poor black people more fully into the economy in circumstances which circumscribe the scope for constructive negotiation and lasting agreement. The new regime of 1994 sought a political settlement which allowed stronger growth, economic transformation of the elite and economic inclusion of the poor. After meeting with some success, the combination of the global financial crisis and new political leadership led to policy uncertainty, increasing corruption and some deterioration of state capacity, which resulted in exceptionally slow growth. The puzzle this chapter engages with is why the struggle over rents has stood in the way of a mutually beneficial deal.

scholarly journals Coverage, Diversity, and Functionality of a High-Latitude Coral Community (Tatsukushi, Shikoku Island, Japan)

PLoS ONE ◽  
2013 ◽  
Vol 8 (1) ◽  
pp. e54330 ◽  
Author(s):  
Vianney Denis ◽  
Takuma Mezaki ◽  
Kouki Tanaka ◽  
Chao-Yang Kuo ◽  
Stéphane De Palmas ◽  
...  
Keyword(s):  
High Latitude ◽  
Coral Community

The Impact of Acanthaster on Corals and Coral Reefs in the Eastern Pacific

1974 ◽  
Vol 1 (4) ◽  
pp. 295-304 ◽  
Author(s):  
Peter W. Glynn
Keyword(s):  
Species Diversity ◽  
Field Work ◽  
Coral Community ◽  
Eastern Pacific ◽  
Live Coral ◽  
Sea Star ◽  
Coral Communities ◽  
Negative Effect ◽  
Population Sizes ◽  
The Impact

The movement of surface currents and the availability of coral prey are probably not responsible for the discontinuities in the distribution of Acanthaster (the Crown-of-thorns Starfish or Sea-star) in American waters. Temperature and salinity conditions are critical in development, and it is possible that these parameters are effective locally, for example in the Gulf of Panamá. There is a strong possibility that continuing field work will show that Acanthaster has a significantly more widespread distribution in the eastern Pacific than is currently known.Adult Acanthaster and several species of coral prey exhibited an unusually high tolerance to varying conditions of temperature and salinity. The possibility of step-wise colonization to new areas, mediated by resistant adult populations that can become established during favourable seasons, should be considered in any plans to alter the existing freshwater canal in Panamá. For introductions can be environmentally dangerous.The highest population densities of Acanthaster so far observed in the eastern Pacific, 1 individual/40 m2 to approximately 1 individual/100 m2, are comparable to population sizes in the Indo-Pacific region that are not considered to have a serious impact on coral communities. Coral destruction by Acanthaster can be significant in certain limited areas, but is usually less than that caused by other corallivores.An analysis of coral community structure in relation to Acanthaster density failed to show a significant correlation with (a) number of species, (b) number of live coral colonies, (c) species diversity (H'), or (d) species evenness (J').Prey preference data indicate that Acanthaster selectively destroys rare corals. Replacement of rare, predated corals by fast-growing species (Pocillopora spp.) has been observed in the field, showing that Acanthaster could have a negative effect on species diversity.

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