Recent changes in coral assemblages of a South African coral reef, with recommendations for long-term monitoring

Two-mile reef, Sodwana, South Africa is an unusual coral reef, being situated on a submerged fossilized sand dune and being very southerly (27°54). It is a popular Scuba diving venue receiving about 100000 dives year^–1. The line-intercept transect method, as recommended by the global coral reef monitoring network (GCRMN), was used to determine soft coral, hard coral and other benthos percentage cover. Physical coral damage, disease and bleaching were also recorded. Results were compared with those of B. Riegl (1993 – unpublished PhD thesis) 5 to 7 years earlier. The reef appears to be ecologically and highly dynamic. In the interim, there has been an increase in living benthos cover of 22.3% but also an increase in coral bleaching from 0% in 1993 to 1% in 1998. Physical damage, despite the large number of dives on the reef was minimal (1.52%), although it appears as if coral diseases may be increasing. The 20-m transects recommended by GCRMN are too long for this highly rugose reef with its distinct ridges and gullies. It is recommended that benthos cover, coral damage, bleaching and disease should be monitored annually using 40 5-m transects on the reef ridges and 40 5-m transects on the reef slopes.     

Taxonomic patterns of bleaching within a South African coral assemblage

In 1998, the Indian Ocean coral reefs suffered a severe and extensive mass bleaching event. The thermal tolerances of corals were exceeded and their photosynthetic symbionts (zooxanthellae) lost. Mortalities of up to 90% were recorded on the reefs of Seychelles, Maldives, Kenya and Tanzania. South African coral reefs were among the few that largely escaped the 1998 mass bleaching event, but may be threatened in the future if global warming increases. This study assessed the extent of coral bleaching and partial recovery at Sodwana Bay, South Africa during 2000 and 2001. Bleaching levels in this study varied over the course of a year, which suggested that seasonally varying parameters such as sea temperature were the most likely cause of bleaching. Bleaching levels were highest at the shallowest site. However, these bleaching levels were very low in comparison with those of reefs elsewhere in the Indian Ocean. The greater volume of water over the relatively deeper reefs of Sodwana Bay may have protected the reefs from severe bleaching. Field measurements on the three reefs indicated that, although the reefs at Sodwana Bay are still healthy, bleaching increased from <1% in 1998 to 5–10% in 2002. Bleaching occurred in 26 coral genera. The Alcyonacea were highly susceptible to bleaching, especially Sarcophyton sp. Among the hard corals, Montipora spp. were the species most susceptible to bleaching. The sensitivity of these genera to early and slight increases in temperature suggests that they can forewarn of a possible greater bleaching event. In contrast, the coral genera Turbinaria and Stylophora were most resistant to bleaching.     

Vertical zonation of coral reef fishes in the Sudanese Red Sea

The vertical zonation of 38 species of fish inhabiting coral reefs in the Sudanese Red Sea is described. A marked degree of vertical zonation of the fishes is shown to exist. The usefulness of a depth oriented survey method for studying reef fish is discussed in relation to these results.General relationships between vertical zonation and species diversity are noted.     

Habitat utilization by coral reef fish: implications for specialists vs. generalists in a changing environment

1. The impact of environmental disturbance and habitat loss on associated species is expected to be dependent on a species' level of specialization. We examined habitat use and specialization of coral reef fish from the diverse and ecologically important family Pomacentridae, and determined which species are susceptible to declines in coral cover due to disturbance induced by crown-of-thorns seastar (COTS, Acanthaster planci L.). 2. A high proportion of pomacentrid species live in association with live coral as adults (40%) or juveniles (53%). Adults of many species had strong affiliations with branching corals, while juveniles favoured plating growth forms, reflecting the sizes of refuge provided by coral types. 3. Juveniles of species that associated with coral had narrower niche breadths than adult conspecifics, due to associations with specific coral types. The especially high coral association and narrower niche breadth of juveniles suggest that the presence of live coral is crucial for many species during early life history, and that disturbance-induced coral loss may have serious flow-on effects on adult abundance. 4. Microhabitat availability was a poor predictor of fish species abundance. Significant correlations between coverage of coral types and abundance of five adults and two juvenile species were detected; however, these relationships explained <35% and <10% of the variation in abundance of adult and juvenile species, respectively. 5. Niche breadth explained 74% of the variation in species' mean response to coral decline and it is clear that disturbance has a greater impact on resource specialists, suggesting that increasing frequency and intensity of coral loss will cause reef fish communities to become dominated by habitat generalists at the expense of coral-dwelling specialists.     

Sustainable ecotourism in Costa Rica: the Monteverde Cloud Forest Preserve

The paper discusses the sustainability of the Monteverde Cloud Forest Preserve in the context of Costa Rican ecotourism. While the history of the Preserve is somewhat unique, the analysis of visitation, financial, ecological and economic factors provides a convincing case that tourism at the Preserve is sustainable. The experience of the Preserve is also put in the context of Costa Rican ecotourism, particularly to the national parks. The paper concludes that the Preserve has played a very important role in the development of Costa Rica as an ecotourism destination. Nonetheless, the failure of experience at the Preserve to inform recent changes in national park pricing policy reveal that Costa Rica has yet to fully capitalize on the experience gained and lessons learned at the Preserve.     

The ontogeny of home ranges: evidence from coral reef fishes

The concept of home ranges is fundamental to ecology. Numerous studies have quantified how home ranges scale with body size across taxa. However, these relationships are not always applicable intraspecifically. Here, we describe how the home range of an important group of reef fish, the parrotfishes, scales with body mass. With masses spanning five orders of magnitude, from the early postsettlement stage through to adulthood, we find no evidence of a response to predation risk, dietary shifts or sex change on home range expansion rates. Instead, we document a distinct ontogenetic shift in home range expansion with sexual maturity. Juvenile parrotfishes displayed rapid home range growth until reaching approximately 100–150 mm length. Thereafter, the relationship between home range and mass broke down. This shift reflected changes in colour patterns, social status and reproductive behaviour associated with the transition to adult stages. While there is a clear relationship between body mass and home ranges among adult individuals of different species, it does not appear to be applicable to size changes within species. Ontogenetic changes in parrotfishes do not follow expected mass–area scaling relationships.     

An introduction to the biogeochemical cycling of calcium and substitutive strontium in living coral reef mesocosms

The coral reef mesocosms designed by the Smithsonian Institution's Dr. Walter Adey, his Marine System Laboratory personnel, and staff members of the Pittsburgh Aqua-Zoo simulate most of the physical, chemical, and biological parameters found in natural Caribbean coral reefs. After developing the mesocosm in Pittsburgh, an evaluation and comparison between natural reef seawater sources and closed mesocosm seawater conditions indicated that an additional parameter should be investigated. It was hypothesized that, given time, the aragonite- and calcite (CaCO₃ crystal forms)-producing organisms in the closed mesocosms could deplete the seawater of available Ca²⁺ and substitutive Sr²⁺. Atomic absorption spectrophotometry was utilized to determine concentrations in the seawater over time. Results showed a substantial reduction in dissolved Ca and Sr in the mesocosm after approximately two years. Dissolved aragonitic Halimeda algae parts were put into the system for replacive purposes. In terms of the biogeochemical cycling of Ca²⁺ and Sr²⁺, the coral reef mesocosm organisms behaved similarly to natural reefs, which have a constant supply of dissolved Ca²⁺ and Sr²⁺. Further research utilizing radiolabeled sources of Ca²⁺, Sr²⁺, and Mg²⁺, in conjunction with in vivo scanning electron microscopy (SEM) and growth increment studies, are recommended for determining the exact biogeochemical pathways for these elements in coral reefs, and to quantify growth parameters. © 1993 Wiley-Liss, Inc.     

A new genus of soft coral of the family Alcyoniidae (Cnidaria, Octocorallia) with re-description of a new combination and description of a new species

A new genus, Aldersladum (family Alcyoniidae), is established to accommodate a previously described species, Efflatounaria sodwanae Benayahu, 1993 (family Xeniidae) from Sodwana Bay, South Africa that was wrongly assigned to the latter genus. This species is redescribed and a second new species, Aldersladum jengi from Penghu Is., Taiwan, is described. The diagnostic features of the new genus include the presence of only figure-eight shaped platelets in all parts of the colony, thus differentiating it from all known genera of the Alcyoniidae. Based on examination of additional material from other localities, the zoogeographical distribution of the genus is confirmed to include the coral reefs of South Africa, Kenya, Gulf of Oman, Taiwan and Japan. Phylogenetic analyses of two mitochondrial genes strongly support its placement in the family Alcyoniidae.     

Farming behaviour of reef fishes increases the prevalence of coral disease associated microbes and black band disease

Microbial community structure on coral reefs is strongly influenced by coral–algae interactions; however, the extent to which this influence is mediated by fishes is unknown. By excluding fleshy macroalgae, cultivating palatable filamentous algae and engaging in frequent aggression to protect resources, territorial damselfish (f. Pomacentridae), such as Stegastes, mediate macro-benthic dynamics on coral reefs and may significantly influence microbial communities. To elucidate how Stegastes apicalis and Stegastes nigricans may alter benthic microbial assemblages and coral health, we determined the benthic community composition (epilithic algal matrix and prokaryotes) and coral disease prevalence inside and outside of damselfish territories in the Great Barrier Reef, Australia. 16S rDNA sequencing revealed distinct bacterial communities associated with turf algae and a two to three times greater relative abundance of phylotypes with high sequence similarity to potential coral pathogens inside Stegastes''s territories. These potentially pathogenic phylotypes (totalling 30.04% of the community) were found to have high sequence similarity to those amplified from black band disease (BBD) and disease affected corals worldwide. Disease surveys further revealed a significantly higher occurrence of BBD inside S. nigricans''s territories. These findings demonstrate the first link between fish behaviour, reservoirs of potential coral disease pathogens and the prevalence of coral disease.     

CO2 partial pressure controls the calcification rate of a coral community

Previous studies have demonstrated that coral and algal calcification is tightly regulated by the calcium carbonate saturation state of seawater. This parameter is likely to decrease in response to the increase of dissolved CO₂ resulting from the global increase of the partial pressure of atmospheric CO₂. We have investigated the response of a coral reef community dominated by scleractinian corals, but also including other calcifying organisms such as calcareous algae, crustaceans, gastropods and echinoderms, and kept in an open‐top mesocosm. Seawater pCO₂ was modified by manipulating the pCO₂ of air used to bubble the mesocosm. The aragonite saturation state (Ω_arag) of the seawater in the mesocosm varied between 1.3 and 5.4. Community calcification decreased as a function of increasing pCO₂ and decreasing Ω_arag. This result is in agreement with previous data collected on scleractinian corals, coralline algae and in a reef mesocosm, even though some of these studies did not manipulate CO₂ directly. Our data suggest that the rate of calcification during the last glacial maximum might have been 114% of the preindustrial rate. Moreover, using the average emission scenario (IS92a) of the Intergovernmental Panel on Climate Change, we predict that the calcification rate of scleractinian‐dominated communities may decrease by 21% between the pre‐industrial period (year 1880) and the time at which pCO₂ will double (year 2065).     

Microbial utilization of coral mucus in long term in situ incubation over a coral reef

The purpose of this study was to assess degradation and utilization of the mucus produced by 3 coral reef Anthozoa (Sarcophyton, Fungia and Acropora) by microorganisms. This was achieved by carrying out long term in situ incubations at Nouméa lagoon (New Caledonia).The microbial population including bacterial and eukaryotic cells was monitored by cell counts, cultures of mucus degraders, and by estimation of microbial activity from the pool of adenylates and enzymatic activity. In addition the chemical composition (C and N) of the mucus was monitored and its morphological features were observed by scanning electron microscope (SEM).Only slight differences were found between the 3 types of mucus studied. On the whole, they follow the same pattern of change. After a short bacterial growth phase (4 days), a bloom of eukaryotes (Flagellates, Ciliates and Diatoms) was observed. This eukaryote population remained constant for at least 10 days. A similar pattern has been described in the breakdown of detritus of plant origin.Several observations suggest that bacteria utilize only certain components of mucus, the most widely used being proteins, triglycerides and wax esters; these latter two compounds are known to be the dissolved photosynthetic products released by zooxanthellae during mucus secretion. Neither bacteria nor eukaryotes completely degrade the mucus web even after 21 days of incubation. The likelihood that mucus excretion is a defensive reaction against physical and chemical stresses might explain why mucus is a poor, or even inhibiting medium for the bacterial degraders isolated from the mucus itself.     

Coral bleaching, reef fish community phase shifts and the resilience of coral reefs

The 1998 global coral bleaching event was the largest recorded historical disturbance of coral reefs and resulted in extensive habitat loss. Annual censuses of reef fish community structure over a 12-year period spanning the bleaching event revealed a marked phase shift from a prebleach to postbleach assemblage. Surprisingly, we found that the bleaching event had no detectable effect on the abundance, diversity or species richness of a local cryptobenthic reef fish community. Furthermore, there is no evidence of regeneration even after 5–35 generations of these short-lived species. These results have significant implications for our understanding of the response of coral reef ecosystems to global warming and highlight the importance of selecting appropriate criteria for evaluating reef resilience.     

Photoinhibition of photosynthesis on a coral reef

Photoinhibition of macroalgae in the epilithic algal community (KAC) of coral reefs was studied using chlorophyll fluorescence techniques at One Tree Island, Great Barrier Reef, Australia. F_v/F_m (variable to maximum fluorescence, darkened samples) of shallow macroalgae declined by 50% on fine summer and winter days, recovering in late afternoon. Within a species, thalli from low-light habitats were more photoinhibited (2h at 1400μimol m^?2 s^?1) than those from high-light habitats. The sensitivity of Lobophora variegata (Phacophyta) and Chlorodesmis fastigiata (Chlorophyta) increased with depth (1 versus 20 m). However, shallow Halimeda tuna (Chlorophyta) plants growing between corals were more photoinhibited than those from deep, open areas. Photoinhibition and recovery were depth- and species-specific. Shallow Lobophora and Chlorodesmis maintained a greater degree of Q _A oxidation during photoinhibition. In deep thalli, reduced effective quantum yield of open photosystem II centres reflected lower proportions and excitation capture efficiencies of open centres. In Lobophora, zeaxanthin formation accompanied non-photochemical fluorescence quenching (NPQ), but in Chlorodesmis NPQ was limited and no zeaxanthin or antherxanthin formed. Higher photosynthetic efficiency in the lower storey of the EAC may compensate for photoinhibition in the upper storey, thereby reconciling photoinhibition of individual thalli with previous observations of no net inhibition of community productivity.     

Identifying multiple coral reef regimes and their drivers across the Hawaiian archipelago

Loss of coral reef resilience can lead to dramatic changes in benthic structure, often called regime shifts, which significantly alter ecosystem processes and functioning. In the face of global change and increasing direct human impacts, there is an urgent need to anticipate and prevent undesirable regime shifts and, conversely, to reverse shifts in already degraded reef systems. Such challenges require a better understanding of the human and natural drivers that support or undermine different reef regimes. The Hawaiian archipelago extends across a wide gradient of natural and anthropogenic conditions and provides us a unique opportunity to investigate the relationships between multiple reef regimes, their dynamics and potential drivers. We applied a combination of exploratory ordination methods and inferential statistics to one of the most comprehensive coral reef datasets available in order to detect, visualize and define potential multiple ecosystem regimes. This study demonstrates the existence of three distinct reef regimes dominated by hard corals, turf algae or macroalgae. Results from boosted regression trees show nonlinear patterns among predictors that help to explain the occurrence of these regimes, and highlight herbivore biomass as the key driver in addition to effluent, latitude and depth.     

A low-cost procedure for automatic seafloor mapping, with particular reference to coral reef conservation in developing nations

Loss of marine biodiversity through benthic habitat destruction has created urgent needs for low-cost, high-performance seafloor survey methods. However, accurate seafloor mapping and classification is usually an expensive undertaking requiring sophisticated equipment, which excludes important low-budget user groups in developing nations. In this paper, we introduce a low-cost procedure for seafloor mapping based on free-of-charge data acquisition software that can be downloaded from the Internet. Using a Malaysian coral-reef case-study, we show how comprehensive bathymetric mapping can be implemented with such software using inexpensive eccosounder and GPS, and describe principles for integration of environmental data, either by connecting additional instruments to the computer (up to 32 instruments with up to eight channels each can be handled simultaneously), or by using simple synchronisation techniques with equipment that records to separate media, such as video cameras. We mapped a Malaysian coral-reef area of 114 hectares in 6 hours of video mapping, achieving reef mapping rates that matches rates currently achieved only with air-borne imaging devices. However, the present methodology results in completely ground-truthed data that can be classified according to many schemes by direct observation of the habitat, and provides detailed bathymetric data that satellite imagery or air-borne spectrographic sensors do not provide. The method can be used as a stand-alone reef mapping and classification tool on the scale of tens to hundreds of square kilometres. On larger scales (thousands of square kilometres), airborne survey methods are likely to remain more cost-effective than boat-based methods, yet also in such settings this simple method offer unprecedented capacity for ground truthing and thereby increased capacity for habitat classification.     

Spatial patterns and ecology of benthic communities on a high-latitude South Florida (Broward County,USA) reef system

High-latitude reef communities consisting of typical Caribbean fauna of variable composition and density exist on four parallel ridges at varying depths along the Broward County (Florida, USA) coast. Two of these ridges, at 7–13 and 15–30 m in depth, are drowned early Holocene coral reefs of 5 and 7 ky uncorrected radiocarbon age. In this study, community data were collected on each reef using 50-m, line-intercept transects. Using multivariate non-metric statistics, the data show distinct differences in benthic community structure across several spatial gradients. Diversity indices revealed that while all values were low, species diversity (H) was consistent throughout the county, and species richness (d) and evenness (J) increased along a north-south gradient. Scleractinian coral (27 species) cover was low (<6%) in all areas, and Montastrea cavernosa dominated as the major hermatypic scleractinian. Notably absent was the major Caribbean reef-builder Acropora palmata. A rich alcyonacean fauna was present on all studied reefs, and these were typically the most important faunal group determining community structure. Although during the 2-year period 2000–2002 mean water temperatures never fell below 20 °C, scleractinia were small in size.     

Coral recruitment patterns at Sodwana Bay, South Africa

Recruitment is widely acknowledged as one of the most important processes in the maintenance of coral reef systems, particularly in their recovery and replenishment following disturbances. In this study variation in coral recruitment was monitored for 3 years at Sodwana Bay, South Africa, located in the Greater St Lucia Wetland Park (GSLWP), a world heritage site. Due to the latitude (27–28°S) and physical conditions, this area is considered marginal for coral reef growth. Recruitment of corals to ceramic tiles peaked between March and May each year, with broadcast spawners dominating plates in March and brooders more abundant in May. Pocilloporid corals were the most abundant during all periods except March 2001, when acroporids comprised 72% of the total number of spat. Total recruitment was the highest during this period, with a mean of 13.2 ± 15.73 (mean ± SD) corals tile⁻¹. Recruitment rates varied widely between and within different reefs monitored. Patterns of variation were inconsistent between seasons, but some reefs had persistently low rates of settlement.     

South African Museums and the Creation of a New National Identity

Museums are important sites of national cultural production, collective memory making, and the construction of national narratives. Contemporary South Africa is a particularly interesting place to study these processes. With the demise of apartheid, South Africa faces the difficult challenge of creating a new national identity that incorporates an examination of past oppression yet leaves the way open for building a national identity that incorporates all its diverse groups. The museums reviewed below, the Robben Island Prison Museum, the District Six Museum in Capetown, and the Kwa Muhle local history museum in Durban all make important contributions to this process.     

Local responses to conservation in the Richtersveld National Park, South Africa

Local notions of conservation deserve closer scrutiny. We cannot assume that they naturally coincide with those of the tourist core; nor that they are automatically given higher priority when local populations are induced to participate in practices which conserve flora and fauna. A case study of the establishment of the Richtersveld National Park in Namaqualand, a remote arid region of South Africa, is used to argue that local attitudes to conservation and development (associated with tourism) can become increasingly cynical and ambivalent in the context of ecotourism. Furthermore, such attitudes are shaped less by economic inducements than by the often contradictory messages about conservation that are being communicated daily.