Taxonomy and ecology of South African reef corals

Bibliography: p. 492-494.This thesis provides a complete taxonomic review of South African hermatypic Scleractinian reef corals, a description of coral communities on northern Natal coral reefs, experiments isolating the influence of the most important abiotic factors forcing these communities and finally management suggestions for the marine reserves within which these reefs are situated, based on the results of the ecological investigation. The taxonomic part reviews the entire hermatypic scleractinian coral fauna of South Africa and Southern Mozambique, including also material from the Atoll Bassas da India in the Mozambique channel. The study of coral communities on Northern Natal coral reefs revealed major differences in the nature of the reefs and the community structure of the reef corals from typical coral reefs in the Inda-Pacific. The study lead to the assumption that wave-action and sedimentation are the most important abiotic factors influencing these coral communities. These hypotheses were experimentally tested in the field and in the laboratory, using indicator species for specific community types, as identified in the community study. Testing fragment survival of the hard coral Acropora austera confirmed the assumption that wave action is an important factor shaping coral communities by only allowing this species to dominate in depths greater than 18m. Four hard- and five soft coral species were used to quantify the effects of sedimentation on the coral communities. It was demonstrated that long-term sedimentation had greater influence on soft corals than on hard corals, leading to tissue necroses and local bleaching. These experiments confirmed the assumption that sedimentation is a major forcing factor on South African coral communities. The final part of thesis provides management options for the St. Lucia and Maputaland Marine Reserves focussing on conservation of the coral communities. The findings obtained in the ecological investigation allowed to identify which activities in the reserves have to be controlled in order to minimize damage to the coral communities by park visitors

Degradation of Reef Structure, Coral and Fish Communities in the Red Sea by Ship Groundings and Dynamite Fisheries

Reef degradation was investigated on 66 Egyptian Red Sea reefs—60 reefs for dynamite damage (using line transects) and six ship grounding sites (using 1 m sample squares). Ship groundings and dynamite fishing caused similar damage, reduction of the reef to rubble (65% of reefs were dynamited, mostly leeward, 58%). Changes in coral (line transect study) and fish communities (point count study) in impacted sites were documented. On impacted reefs, coral cover decreased, bare substratum and rubble increased, and fish dominance shifted away from Pomacentridae. Oceanographic conditions result in a stable pattern of coral communities (windward Acropora, leeward Porites). Most dynamite damage was on leeward, near-climax Porites reef slopes or Porites carpets. Most ship groundings were on windward Acropora reefs with regeneration periods calculated to be between 100 and 160 yrs. Regeneration time of dynamite damage is expected to be similar because of similar damage. Rehabilitation could speed up recovery but has to be consistent with natural community patterns. Coral transplants should mimic previously existing community structure in order to avoid space preemption by introduced superior competitors. Particularly if Acropora were introduced on a large scale into normally Porites dominated reef areas, re-establishment of the original community within the desired time-frame could be delayed

Corals in a Non-Reef Setting in the Southern Arabian Gulf (Dubai, UAE): Fauna and Community Structure in Response to Recurring Mass Mortality

Reef coral communities in a non-reef setting on shallow, flat hardgrounds were quantitatively sampled in Dubai Emirate (UAE, Southern Arabian Gulf) before and after a coral mass mortality in 1996. The coral fauna consisted of 34 scleractinian species before and 27 after the event, which removed virtually all Acropora. No alcyonacea were recorded. Five community types were identified and characterized by the dominant species: (A) a sparse Porites lutea community in sandy areas, (B) a dense Acropora clathrata community in areas with little sand, (C) a faviid community in muddy areas, (D) a Siderastrea savignyana community in sandy areas, and (E) a Porites compressacommunity, which built a framework in sandy areas. These communities are comparable to those described from other areas of the Gulf, where a stable pattern of community differentiation appears to exist. The spatial distribution and dynamics of the coral communities appears to be strongly influenced by mass mortality events recurring every 15 to 20 y. A combination of extreme water temperatures and high sedimentation/turbidity appear to be the major cause of mortality

A Discrete Mathematical Extension of Conceptual Ecological Models - Application for the SE Florida Shelf

Conceptual ecological models (CEM) respond to the need for improved management of natural resources due to increasing scale and severity of human impacts. CEMs, like the EBM-DPSER framework, serve as non-quantitative planning tools identifying stressors and drivers on natural systems, effects and biological indicators best suited to show these effects. A disadvantage of CEMs is their non-quantitative nature restraining users from performing sensitivity and quantitative scenario analysis. Here we develop a quantitative extension of a EBM-DPSER model of the SE Florida shelf based on the assumption that the CEM flow diagrams express as digraphs. It was quantified with transition weights from literature research and local data, turning the digraph into a network. The usefulness of the network extension and its underlying weighted adjacency matrix were verified using monitoring data from the Florida Keys Reef Tract. The network extension was then used to explore outcomes of two different management scenarios. Model results suggest that advanced waste water treatment in SE Florida would increase reef diversity and framework growth and could reduce macroalgae cover while increasing coral cover, fish and shellfish abundance and eliminating phytoplankton blooms. Climate change is projected to have an effect on sea level rise, acidification and bleaching but probably with a minor influence on coral cover, reef framework and diversity – which are already low. Tested scenarios show that the modeled impact of regulation processes can vary profoundly even if the number of arcs and vertices in their largest possible out-tree are comparable. Such a tool extends the power of the conceptual model by adding significant new information and the ability to quantifiably test of hypotheses

Remote Sensing: A Key Tool for Interdisciplinary Assessment of Coral Reef Processes

Without Abstract

Biostromal Coral Facies—A Miocene Example from the Leitha Limestone (Austria) and its Actualistic Interpretation

Coral-rich strata of the Leitha Limestone of Badenian age (Middle Miocene) at the type-locality in Grosshoeflein (Burgenland province, Austria) were re-interpreted from an actualistic viewpoint in comparison with Recent Bahamian and Arabian Gulf coral communities. The investigated outcrop (quarry “Fenk”) is interpreted as a sequence of framebuilding coral carpets and non-framebuilding biostromal coral communities, alternating with bryozoan and corallinacean calcarenites and bivalve beds. No indication for the presence of a reef was found. In total, a sequence of 10 coral intervals was observed, which can be grouped into 2 coral carpet types (high carpet framework, low bushy framework), four non-framework communities, and one bivalve/coral community. Within this sequence, no unequivocal indication for sea-level changes at the time of deposition was apparent. The different coral facies are interpreted as having been deposited within roughly the same water depth as Recent coral systems observed in the Bahamas (Andros, Exuma Cays) and the Arabian Gulf (Dubai, UAE). According to the model presented, the facies merely represent different lateral positions within the same spatially highly complex environment. A distribution map of benthic biota in the Arabian Gulf (Jebel Ali, Dubai, UAE) was used to illustrate the likely lateral distribution of the Miocene facies

From Coral Framework to Rhodolith Bed: Sedimentary Footprint of the 1982/1983 ENSO in the Galápagos

Without Abstract

Soft Coral Mimesis by an Aeolidiid Nudibranch

Without Abstract

Is Coral Community Structure Linked to Damage Susceptibility? A Case Study from South Africa

Africa\u27s southernmost coral communities are situated in northern Natal, South Africa (27°50\u27 S), within the Maputaland and St. Lucia Marine Reserves. Growing concern about the possible impact of recreational acti vities on the health of the coral ecosystem prompted the present study on the structure and health of the reefs. Coral community studies by means of line transects identified three basic coral community types, which correlated with the geomorphology of the sandstone outcrops on which corals grew. 1) Fossil dunes were dominated by alcyonacea in depths between 8 and 24 m. 2) Flat outcrops between 18 and 24 m depth were dominated by scleractinia (mainly Acropora). Within these community types, a further small-scale differentiation into sub-communities inside and outside of gullies occurred. 3) Deep hard substrata between 25 and 34 m depth were dominated by sponges, ascidians and sea-fans. Quantitative damage assessment was used to correllate community structure to damage susceptibility. The flat-outcrop Acropora community was considered most fragile, while the other community types (dominated by leathery alcyonaceans or by sponges) were considered more robust. Such quantitative assessments can be of value to the development of zoning schemes for marine reserves