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

The Most Temperature-Adapted Corals Have an Achilles\u27 Heel

The corals of the Persian/Arabian Gulf are better adapted to temperature fluctuations than elsewhere in the Indo-Pacific. The Gulf is an extreme marine environment displaying the highest known summer water temperatures for any reef area. The small and shallow sea can be considered a good analogue to future conditions for the rest of the world’s oceans under global warming. The fact that corals can persist in such a demanding environment indicates that they have been able to acclimatize and selectively adapt to elevated temperature. The implication being that colonies elsewhere may be able to follow suit. This in turn provides hope that corals may, given sufficient time, similarly adapt to survive even in an impoverished form, under conditions of acidification-driven lowering of CaCO3 saturation state, a further consequence of raised atmospheric CO2. This paper demonstrates, however, that the uniquely adapted corals of the Gulf may, within the next three centuries, be threatened by a chronic habitat shortage brought about by the dissolution of the lithified seabed on which they rely for colonisation. This will occur due to modifications in the chemical composition of the Gulf waters due to climate change

Coral Reefs of the Gulf: Past, Present and the Future of a Unique Ecosystem

This issue of Marine Pollution Bulletin was guest edited by John Burt, David Feary, and Bernhard Riegl

Habitat Mapping in the Farasan Islands (Saudi Arabia) Using CASI and QuickBird Imagery

Map products derived from remote sensing technology increase our understanding and ability to manage tropical marine environments. The enhanced mapping capabilities of hyperspectral sensors are well understood; yet technology uptake, particularly for large scale tasks, has been slow. The study presented represents one of the largest hyperspectral projects to date, and paves the way towards increased use of this technology. Hyperspectral CASI-550 imagery and multispectral QuickBird imagery, was acquired over 3,168 km2 of the Farasan Islands. In addition to the typical image processing steps, inopportune water condensation in the CASI sensors lens necessitated further processing to remove an across-track artifact. We present a simple protocol for correcting this abnormality, utilizing an abundance of optically deep water to model and correct the error. Investment in optical, bathymetric, and other supporting field data, along with the acquisition of the QuickBird imagery was vital. Data pre-processing facilitated thematic mapping with accuracy comparable to other studies, while allowing the use of spectral unmixing to discriminate coral from within algae dominated patches in shallow water (0-5 m) environments. The unmixing model proved robust, was readily adaptable to the CASI sensor and provides additional habitat information beyond the level of thematic mapping alone

A Coral Damage Index and its Application to Diving Sites in the Egyptian Red Sea

A coral damage index (CDI) is provided, to screen sites to obtain a perspective on the extent and severity of physical damage to coral. Sites are listed as “hot spots” if in any transect the percent of broken coral colonies (BCC) is greater than or equal to 4% or if the percent cover of coral rubble (CR) is greater than or equal to 3%. To demonstrate its utility, the CDI is applied to a real-life management situation off Hurghada and Safaga, Egypt in the Red Sea. The extent of coral damage covered all four diving sites. Forty percent of all the transects were “hot spots” that required management action. Thirty-one percent of the 16 “hot spot” transects were identified by both broken coral and rubble criteria, 25% by only broken coral criterion and 44% by only coral rubble criterion of the CDI, suggesting that past breakage was responsible for most of the observed damage. Sixty-three percent of the “hot spot” transects were at 4 m depth versus 37% at 8 m depth, suggesting that most of the damage was caused by anchors dragging across the reef in shallow water. The severity of coral damage, reflected by CR, was the greatest at Small Giftun in transect 5 at 4 m depth (333% above the CDI). EI Fanous experienced the most severe degree of broken coral damage (325% above the CDI) at 8 m depth along transect 2. Estimates of the number of dives per year show diving carrying capacities for El Fanous, Gotta Abu Ramada, Ras Abu Soma and Small Giftun being exceeded by large amounts. The CDI can be used globally to; gauge the severity and extent of damage, focus managers on areas that need mooring buoys and associated dive site management programs, and provide a starting point from which to focus more detailed coral reef assessments and restoration programs

A Quantitative Ecological Assessment of Diving Sites in the Egyptian Red Sea During a Period of Severe Anchor Damage: A Baseline for Restoration and Sustainable Tourism Management

This paper assesses damage to diving sites off Hurghada and Safaga, Egypt, and examines management responses and options. Data were obtained using the line-intercept-transect method. Using general field observations, a control site comparison and a historical comparison, it was found that the four diving sites studied suffered varying degrees of physical damage and needed management attention. Some transect locations had experienced severe physical damage while others had escaped damage. The most obvious difference between the control site and the four damaged sites (at both 4 and 8 m depths) was the consistently high percentage cover of hard coral (especially Acropora coral) and low percentage cover of soft corals among all transects at the Giftun Canal control site. Total algae percentages were also consistently higher at impacted transect sites versus the control site. From a historical perspective, at the Small Giftun site from 1987 to 1996, percentage hard coral cover decreased by 43% and algal cover increased over fourfold. If the diving tourism industry is to sustain itself in the Egyptian Red Sea, every management effort must be made to minimise controllable sources of stress on the coral reef system. Dive site management programme options, based on peer-reviewed carrying capacity research and stakeholder involvement, are reviewed

Acute and Sub-Acute Toxicity of the Polycyclic Aromatic Hydrocarbon 1-Methylnaphthalene to the Shallow-Water Coral Porites divaricata: Application of a Novel Exposure Protocol

Previous research evaluating hydrocarbon toxicity to corals and coral reefs has generally focused on community-level effects, and results often are not comparable between studies because of variability in hydrocarbon exposure characterization and evaluation of coral health and mortality during exposure. Toxicity of the polycyclic aromatic hydrocarbon 1-methylnaphthalene to the coral Porites divaricata was assessed in a constant exposure toxicity test utilizing a novel toxicity testing protocol uniquely applicable to shallow-water corals, which considered multiple assessment metrics and evaluated the potential for post-exposure mortality and/or recovery. Acute and subacute effects (gross morphological changes, photosynthetic efficiency, mortality, and histologic cellular changes) were evaluated during pre-exposure (4 wk), exposure (48 h), and post-exposure recovery (4 wk) periods. Coral condition scores were used to determine a 48-h median effective concentration of 7442 μg/L. Significant physical and histological changes resulted from exposure to 640 μg/L and 5427 μg/L 1-methylnaphthalene, with a 1-d to 3-d delay in photosynthetic efficiency effects (ΔF/Fm). Pigmented granular amoebocyte area was found to be a potentially useful sublethal endpoint for this species. Coral mortality was used to estimate a 48-h median lethal concentration of 12 123 μg/L

Short-Term Toxicity of 1-Methylnaphthalene to Americamysis bahia and 5 Deep-Sea Crustaceans

There are few studies that have evaluated hydrocarbon toxicity to vertically migrating deep-sea micronekton. Crustaceans were collected alive using a 9-m2 Tucker trawl with a thermally insulated cod end and returned to the laboratory in 10 °C seawater. Toxicity of the polycyclic aromatic hydrocarbon 1-methylnaphthalene to Americamysis bahia, Janicella spinacauda, Systellaspis debilis, Sergestes sp., Sergia sp., and a euphausiid species was assessed in a constant exposure toxicity test utilizing a novel passive dosing toxicity testing protocol. The endpoint of the median lethal concentration tests was mortality, and the results revealed high sensitivity of the deep-sea micronekton compared with other species for which these data are available. Threshold concentrations were also used to calculate critical target lipid body burdens using the target lipid model

Atlas of Saudi Arabian Red Sea Marine Habitats

The Red Sea is a narrow, but relatively deep, oceanic trough that extends for over 1900 km, between 13º and 28º N latitude. It has a total surface area of roughly 438,000 km², with a width of approximately 180 km in the north, and 354 km at its widest point in the south. The Red Sea narrows to about 29 km in the Strait of Bab el Mandab, where it joins the Gulf of Aden and the Indian Ocean. The maximum depth is over 2200 m, with an average depth of 490 m. The Red Sea is shallowest at the southern end, with depths of only 130 m in the Strait of Bab el Mandab. It is the world’s northernmost tropical sea, with extensive shallow shelves that support complex coral reefs and associated ecosystems. The Red Sea is part of the tropical Indo-Pacific Ocean, which encompasses the largest marine ecosystem on earth and also the most diverse. Much of the Saudi Arabian Red Sea coastline is characterized by coastal fringing reefs that are narrow, extending tens of meters from shore before plummeting to deep water. However, several regions in Saudi Arabia contain extensive seagrass beds, offshore reef habitats, mangroves, and algal flats. These areas support a wide range of reef morphologies, such as barrier reefs, patch reefs, ridge reefs, atolls, tower reefs, pinnacles, pillars, and spur and groove structures, as well as diverse coral communities growing on algalderived limestone structures (Sheppard et al. 1992). Over a four year period, the Living Oceans Foundation has been involved in a massive scale marine habitat research project in the Red Sea. The results are now published in this first ever atlas of the Red Sea marine habitats of offshore coral reefs. It is available for download in both English and Arabic.https://nsuworks.nova.edu/occ_facbooks/1042/thumbnail.jp

Palaeobiology, ecology, and distribution of stromatoporoid faunas in biostromes of the mid-Ludlow of Gotland

Six well exposed mid−Ludlow stromatoporoid−dominated reef biostromes in four localities from the Hemse Group in southeastern Gotland, Sweden comprise a stromatoporoid assemblage dominated by four species; Clathrodictyon mohicanum, “Stromatopora” bekkeri, Plectostroma scaniense, and Lophiostroma schmidtii. All biostromes investigated in this area (of approximately 30 km2) are interpreted to belong to a single faunal assemblage forming a dense accumulation of fossils that is probably the best exposed stromatoporoid−rich deposit of the Silurian. The results from this comprehensive study strengthen earlier interpretations of a combination of genetic and environmental control on growth−forms of the stromatoporoids. Growth styles are similar for stromatoporoids in all six biostromes. Differences in biostrome fabric are due to variations in the degree of disturbance by storms. The uniformity of facies and the widespread low−diversity fauna support the view that palaeoenvironmental conditions were similar across the area where these biostromes crop out, and promoted the extraordinary growth of stromatoporoids in this shallow shelf area