Sodwana Bay Research Articles

New Ladybirds from Southern Africa (Coleoptera, Coccinellidae)

Two new coccinellid species from Southern Africa are described, Hyperaspis kochi sp. n. (type locality: South Africa: Northern Province: Lekgalameetse Nature Reserve) and Scotoscymnus punctatissimus sp. n. (type locality: South Africa: KwaZulu-Natal: Sodwana Bay National Park), and compared with the closely related species. A key to the South African Hyperaspis species is provided. Mainly body outlines and the morphology of genitalia are used as distinctive characters.

Coral community structure and risk assessment of high-latitude reefs at Sodwana Bay, South Africa

The importance of studying coral communities at different spatial scales is acknowledged in a growing volume of scientific literature, and principles of landscape ecology were thus used to elucidate the patterns in coral community structure on the high-latitude reefs in South Africa. These reefs are at the southernmost distribution of this fauna in Africa, are surprisingly species rich, and represent a biodiversity peak in this fauna south of the equator, regardless of the marginal nature of the environment. Coral community patterns were identified on and between the reefs at Sodwana Bay, justifying the grouping of reef areas in distinct zones. A number of landscape components were identified, ranging from the entire reef complex (10 km scale), individual reefs (1 km scales) and reef zones, to components that were separated using multivariate statistical analysis of transect data. These components transcended spatial similarities, e.g. the fore-reef on Five-mile Reef was not similar to the fore-reef on Seven-mile Reef, but was rather grouped with the reef flat on Two-mile Reef. This information was “translated” into an index of management intervention, based on risk assessment, and was generated using parameters that measure susceptibility to crown-of-thorns feeding, bleaching, diver-related damage and swell-induced breakage. We also assessed was the time elapsed since the last major disturbance and the proximity to the only boat launch site, a proxy measure of continuous disturbance. The risk assessment suggested that conservation management is most needed in the stable and “climax” coral communities that are usually characterised by a near-equal mix of hard and soft corals at maximal coral species diversity.

Maximising the Local Pro-Poor Impacts of Dive Tourism: Sodwana Bay, South Africa

This article examines the local impacts of dive tourism in a South African case study, namely Sodwana Bay in Maputaland, KwaZulu-Natal province. Using extensive primary research interviews with key tourism stakeholders and local product owners, dive tourism at Sodwana Bay is considered an example of niche tourism in small-town South Africa. It is argued that opportunities exist for extending local pro-poor impacts if several challenges are addressed concerning improved skill levels, the institutional environment and extending local small business opportunities.

Use of space by the four-toed elephant-shrew Petrodromus tetradactylus (Macroscelidae) in Kwazulu-Natal (South Africa)

Four four-toed elephant-shrews Petrodromus tetradactylus were radio-tracked at Sodwana Bay National Park in the dune forest situated on sand-hills above the high water mark along the east coast of KwaZulu-Natal, South Africa. Tracking was conducted over 5 months during summer and the results were used to explore the use of space by the elephant-shrews. None of the topographical or vegetational features of the study area had any great influence on the distribution of the elephant-shrews. Both sexes occupied highly symmetrical (circular) home ranges that were similar in area. The elephant-shrews showed considerable fidelity to their home ranges, which had long-term permanence, but were not obviously defended as territories. Activity of the elephant-shrews, monitored for the first time during 24 h in the wild, was strongly crepuscular, with intense activity around dusk and dawn, much reduced during the day, with complete cessation of activity at night. There was considerable overlap between individual home ranges, suggesting a high population density. This may be related to the mild climate and ample food supply of the dune forest of northern KwaZulu-Natal or to the season of observation.

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.

Patterns in subtidal seaweed communities on coral-dominated reefs at Sodwana Bay on the KwaZulu-Natal coast, South Africa

Subtidal seaweed communities of the northern coast of KwaZulu-Natal (KZN) have not been studied before. At Sodwana Bay, we tested the hypotheses that the seaweed communities would (1) differ floristically with depth, (2) be more species-rich in shallower water, (3) show similar biomasses within the depth range sampled and (4) be affected (biomass and/or species composition) by sand. Samples were collected (using SCUBA) from reefs ('sites') at depths of about 1m, 7m, 10m, 15m and 26m. Each sample comprised all macroscopic (non-crustose) seaweeds within a 25cm × 25cm quadrat (five quadrats per depth). Environmental factors, including percentage sand cover and depth, were recorded. The seaweed communities were mainly compact turfs; a total of 82 Rhodophyta, 14 Chlorophyta and eight Phaeophyta were recorded. Ordination (canonical correspondence analysis) and classification (Twinspan) of the data showed clear differences in the floristic composition (either as species biomass or presence/absence) with depth, mainly between shallow subtidal communities (0.5–1.0m depth) and those at intermediate depths (5.5–15.0m), followed by the deepest communities (25.7–29.0m) and those at intermediate depths. The shallow samples showed the greatest species diversity. Total seaweed biomass decreased significantly with depth and percentage bare (seaweed-free) substratum increased significantly with depth, possibly because of lower wave action, light penetration, or different grazing patterns. Sand (as percentage sand cover) also affected seaweed community composition, but this showed no pattern with depth. The algal communities on these reefs at Sodwana Bay showed exceptional α-diversity, with 104 taxa (>20% of the recorded KZN flora) occurring in the total sample area of only 1.56m2. The seaweed communities of northern KZN are structurally and floristically similar to those of other tropical coral reefs around the world.

Coral reef mantis shrimps from the vicinity of Sodwana Bay, South Africa (Crustacea: Stomatopoda)

Coral reef stomatopods from the vicinity of Sodwana Bay, South Africa, are reported. Ten species of Gonodactyloidea from seven genera and four families are represented. All species are new records for Sodwana Bay. Eight species represent new records for South Africa of which one, Pseudosquillisma kensleyi, is new to science. Pseudosquillisma kensleyi is the fourth species in the genus to be recognised, differing from all known congeners in having an inflated and globular, instead of a flattened and subtrapezoid cornea.

Polychaete (Spirobranchus giganteus) loading on South African corals

Abstract Spirobranchus giganteus is a ubiquitous serpulid polychaete that is an obligate associate of living coral. At Sodwana Bay, South Africa, it is a conspicuous associate of Acropora clathrata plates. This study explores the relationship between S. giganteus abundance and factors hypothesized to represent stress to the corals, in particular coral bleaching, diving intensity and exposure to destructive wave action as a function of depth. In addition, plate size was investigated to increase understanding of habitat selection by S. giganteus. There was no significant correlation between diving intensity and S. giganteus abundance on the three reefs studied, suggesting either that the current level of diving intensity causes no stress or that S. giganteus does not indicate stress. Depth influenced the size distribution of A. clathrata plates, with the larger plates being at greatest depths (>0.4 m2 at depths >14 m). Extremely high S. giganteus densities (most plates with number of individuals >50 m−2; maximum number of individuals 413.63 m−2 at 9 m depth on one reef) were recorded at depths >14 m, with density increasing overall with depth. The high densities of S. giganteus on A. clathrata plates are possibly because the plates are a physically elevated platform above the reef, where factors such as predation, competition and smothering by sand are far less important than on the reef surface. In turn, upwelling of nutrients and dependent plankton may encourage S. giganteus to maintain high population levels. Climatic or other stresses are not considered currently to be responsible for these high S. giganteus densities. Rather, the worm data reflect a healthy upwelling, which may change as the coral reef becomes stressed with global climate change. Copyright © 2005 John Wiley & Sons, Ltd.

Identity and distribution of southern African sciaenid fish species of the genus Umbrina

Two Umbrina species, U. canariensis Valenciennes 1843 and U. robinsoni Gilchrist and Thompson 1908, are recognised from southern Africa. The latter species was hitherto believed to be a synonym of Umbrina ronchus Valenciennes 1843 (type locality Canary Islands). U. canariensis is distributed along the South Africa eastern seaboard from Cape Point to Sodwana Bay and U. robinsoni is known from False Bay to Madagascar and Oman. African Umbrina taxonomy has, however, been hindered by geographic samples that were either too few or consisted of specimens of disparate length; and as a result the identification and distribution of South African Umbrina species was confused. Morphological comparison of a large number of South African Umbrina with specimens from the type locality (Canary Islands) confirmed the identity of South African U. canariensis and allowed for an expanded description of the species. However, differences between specimens of U. ronchus and those of the second South African species (n = 251) led us to resurrect U. robinsoni (Gilchrist and Thompson 1908) as a valid name for this species. U. robinsoni differs from U. ronchus in having a smaller supraoccipital crest and thus a less steep pre-dorsal profile; a shallower preorbital bone (13–21% head length [HL] vs 21% HL); and a shorter nostril-orbit distance (2.4–6.9% HL vs 7.8–8.5% HL). Colour patterns also differ between the two species, with U. ronchus lacking the oblique, wavy, white stripes evident on the flanks of U. robinsoni. U. ronchus does not occur in South African waters, and is an eastern Atlantic species occurring from Gibraltar to Angola. Specimens from the east coast of Africa (Moçambique to Gulf of Oman) that were previously identified as U. ronchus are U. robinsoni. Differences between U. robinsoni and U. canariensis include: a lower modal number of soft dorsal fin rays, (22–27 vs 24–30); less deep body depth, (26–36% standard length [SL] vs 33–39% SL); shorter pectoral fin length (15–21% SL vs 20–25% SL); longer caudal peduncle length (26–34% SL vs 21–28% SL) and snout length (27–38% HL vs 23–32% HL); and smaller orbit diameter (14–33% HL vs 23–34% HL). Otoliths of U. robinsoni differ from those of U. canariensis in being smaller, less elongate, lacking a massive post-central umbo and having a post-dorsal spine remnant. The body colour and nature of the striping pattern on the flanks differs markedly between the species: in U. robinsoni the oblique stripes are thin, wavy, white lines; in U. canariensis the oblique stripes are thicker, nearly straight and brown; U. robinsoni also lacks the triangle-shaped mark on the outer operculum and the dark pigmentation of the inner operculum that is found on U. canariensis. Spatial analysis of South African specimens collected with a variety of gear revealed U. robinsoni to be a shallow-water species found from the surf-zone to 40m, whereas U. canariensis occurs predominantly from 40 to 100m depth. Although both species occur throughout the South African eastern seaboard, U. canariensis is most common west of the Kei River, where the shelf is wider. Examination of three specimens of U. steindachneri Cadenat 1950 confirmed the presence of a fourth sub-Saharan Umbrina species that is limited to tropical West African waters from Senegal to Angola. U. steindachneri differs from the other African Umbrina in having a high number of soft dorsal rays (28–29), a greater 3rd dorsal spine length (25–27% SL) and a very pronounced and convoluted striping pattern on the flanks.

Taxonomy of the monotypic genus Koehleria Cherbonnier, 1988 (Echinodermata: Holothuroidea: Cucumariidae)

Voucher material recently collected from the 2-Mile Reef at Sodwana Bay (Republic of South Africa), allows the evaluation of the monotypic genus Koehleria Cherbonnier, 1988 and its species K. unica Cherbonnier, 1988 collected from Tul ar (Madagascar). Cherbonnier s (1988) conclusion, that Koehleria is most related to the also monotypic genus Pseudocolochirus Pearson, 1910 is correct, but the differences between Koehleria and Pseudocolochirus are too small to justify the retention of Koehleria. Koehleria is relegated herein to the synonymy of Pseudocolochirus. Such a step decreases the velocity with which monotypic genera are currently described within the Dendrochirotida.

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.

Possible refugia for reefs in times of environmental stress

This paper investigates the refuge potential of (1) upwelling areas, (2) coral areas at medium depth, and (3) offshore bank and island reefs in a scenario of increased global warming, and thus increased sea surface temperature (SST) and increased solar UV radiation. (1) Observations on coral health and water temperature in the subtropical Atlantic (Eleuthera and Cat Island, Bahamas) and Indian Ocean (Sodwana Bay, South Africa) suggest a link between cool water delivered by upwelling and coral health. After the 1998 bleaching event, caused by strong SST anomalies, coral health and recovery from the previous year's bleaching was significantly better on the narrow southern Cat Island shelf (70% of corals healthy) where the presence of cold water was observed, which was attributed to small-scale upwelling, than on the wide northern Eleuthera shelf (44% of corals healthy), where downwelling of hot bank waters was believed to have damaged corals. In South Africa, regular, short-term upwelling events in five summers reduced SST to well below bleaching level. (2) In the northern Red Sea (Safaga Bay) and in South Africa (Sodwana Bay), wide areas with either coral frameworks or non-framework communities exist. Calculations show that if the top 10 m (20 m) of the ocean became inhospitable to corals, still 50.4% (17.5%) of the coral area would remain intact in the Red Sea and 99% (40%) in South Africa. (3) Offshore bank and island reefs investigated in the Turks, Caicos, and Mouchoir Banks and Grand and Little Cayman showed high rates of mortality and coral diseases. The most remote sites (Mouchoir Bank) were not the healthiest. Refuge areas appear to exist in (1) and (2), but in (3) only if vigorous water-circulation is encountered.

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

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.

Coral bleaching on high-latitude marginal reefs at Sodwana Bay, South Africa

Coral bleaching, involving the expulsion of symbiotic zooxanthellae from the host cells, poses a major threat to coral reefs throughout their distributional range. The role of temperature in coral bleaching has been extensively investigated and is widely accepted. A bleaching event was observed on the marginal high-latitude reefs of South Africa located at Sodwana Bay during the summer months of 2000. This was associated with increased sea temperatures with high seasonal peaks in summer and increased radiation in exceptionally clear water. The bleaching was limited to Two-mile Reef and Nine-mile Reef at Sodwana Bay and affected <12% of the total living cover on Two-mile Reef. Montipora spp., Alveopora spongiosa and Acropora spp. were bleached, as well as some Alcyoniidae ( Sinularia dura, Lobophytum depressum, L. patulum). A cyclical increase in sea temperature (with a period of 5–6 years) was recorded during 1998–2000 in addition to the regional temperature increase caused by the El Niño Southern Oscillation phenomenon. The mean sea temperature increased at a rate of 0.27 °C year −1 from May 1994 to April 2000. High maximum temperatures were measured (>29 °C). The lowest mean monthly and the mean maximum monthly temperatures at which coral bleaching occurred were 27.5 and 28.8 °C, respectively, while the duration for which high temperatures occurred in 2000 was 67 days at ⩾27.5 °C (4 days at ⩾28.8 °C). Increased water clarity and radiation appeared to be a synergistic cause in the coral bleaching encountered at Sodwana Bay.

Sustainable dive ecotourism on a South African coral reef

SCUBA ecotourism provides economic support for local human communities and for conservation. Such support should be sustainable and as ecologically non-destructive as possible to its coral reef foundation. In recent years, the major increase in SCUBA activity has become a significant consideration at some locations. Among these are the South African coral reefs at Sodwana Bay, which receive 80 000 dives per year. Between May 1998 and January 1999, assessments using line-intercept and belt transects showed that 5.9% of hard corals and 4.0% of soft corals were damaged from various causes, while only 0.02% of the hard corals were dead. Of the 222 diver contacts observed, only 1.63% produced instant and visually-clear damage, with no measurable decline in overall coral reef health. Direct observations on 89 recreational divers showed that photographers made damaging contacts on nine out of ten dives, while novice divers made one such contact per six dives, moderately experienced divers about once every 14 dives, and very experienced divers about once every 123 dives. Increased time lapsed since the last dive increased diver damage by novices. We calculated that the 80 000 dives were equivalent to 1 m2 of reef receiving 2.3 diver contacts per year. Acropora austera was by far the most significantly damaged coral, with one out of four branches broken per year. But as this species accounted for only 0.2% of reef benthos cover, this impact was not representative of overall reef health. This heavy species-specific impact makes A. austera a good bio-monitor.

Clathculins A and B, two novel nitrogen-containing metabolites from the sponge Clathrina aff. reticulum.

Two novel acyclic diaza alkenynes, clathculins A and B (1 and 2), were isolated from the Indo-Pacific sponge Clathrina aff. reticulum collected in Sodwana Bay, South Africa. The structure of the mixture of the two unstable inseparable compounds was established by spectroscopic analysis, mainly 1D and 2D NMR measurements and two chemical transformations. Clathculins A and B are the first reported linear marine metabolites containing a 1,2-diaminoethane moiety.

Parasitism and introduced species: epidemiology of trematodes in the intertidal mussels Perna perna and Mytilus galloprovincialis

The Mediterranean mussel Mytilus galloprovincialis was accidentally introduced onto the South African west coast in the late 1970s and has since become invasive. It is spreading onto the south and east coasts where it has the potential to outcompete the indigenous mussel Perna perna. One possible explanation for this phenomenon is that it is not affected by the natural parasites of the area where it was introduced. A survey of trematodes was done at different spatial scales for populations of the indigenous mussel Perna perna and the invasive Mytilus galloprovincialis in South Africa, as well as for indigenous populations of M. galloprovincialis in Spain. Both South African and Spanish populations of M. galloprovincialis were found to be free of trematodes, whilst P. perna was commonly infected by trematodes. The most important trematodes found in this mussel were metacercariae of Proctoeces and bucephalid sporocysts, with infection rates up to 62 and 49%, respectively. Both Proctoeces and the bucephalid sporocysts were randomly distributed within a mussel bed. Bucephalid sporocysts were found in very low prevalences at most sites along the South African coast. Prevalences were highly dependent on the size of the mussel, and there were no seasonal variations in infection rates with this parasite. Proctoeces was only found between Cape Agulhas on the south coast and Sodwana Bay on the east coast, and infected significantly more females than males. Prevalence of infection was highly dependent on the size of the mussel in the case of females but not in the case of males. There were no seasonal variations in prevalence of infection with Proctoeces in either females or males. Mytilus galloprovincialis has proved to be a competitively superior species which has replaced the indigenous Aulacomya ater as the dominant mussel on the west coast. The fact that it is free of trematodes, whilst Perna perna on the south and east coasts is commonly infected by trematodes, may be one of the reasons for its success in South Africa as a whole and its incipient invasive behaviour on the south coast.

Oriamide, a new cytotoxic cyclic peptide containing a novel amino acid from the marine sponge Theonella sp

A novel cyclic peptide, oriamide ( 1) containing the new 4-propenoyl-2-tyrosylthiazole amino acid (PTT), was isolated from the marine sponge Theonella sp. collected in Sodwana Bay. The structure of oriamide, including the absolute configuration of all amino acids, was elucidated by spectroscopic analysis and degradation experiments.

Durbinal A, B and C: Three new cytotoxic sponge metabolites

Three cytotoxic alkylated sacculatane diterpenoids have been isolated from the Sodwana Bay, Durban, South Africa, sponge Psammoclema sp. The structure of the three compounds, durbinal A, B and C ( 1–3), was elucidated primarily by NMR spectroscopy.

Marine geology of the Sodwana Bay shelf, southeast Africa

The geostrophic current-controlled northern Zululand shelf displays a unique assemblage of interesting physical, sedimentological and biological phenomena. The shelf in this area is extremely narrow (3 km) and is characterised by submarine canyons, coral reefs, and steep gradients on the continental slope. Three submarine canyons occur in the study area and are classified as mature- or youthful-phase canyons depending on the degree to which they breach the shelf. These canyons originated as mass-wasting features which were exploited by palaeo-drainage during sea-level regressions. Shelf lithology is dominated by a series of coast-parallel patch coral reefs which have colonised beachrock and aeolianite sequences that extend semi-continuously from −5 to −95 m, and delineate late Pleistocene palaeocoastline events. The unconsolidated sediment on the shelf is either shelf sand (mainly terrigenous quartz grains) or bioclastic sediment. Large-scale subaqueous dunes commonly form in the unconsolidated sediment on the outer-shelf due to the Agulhas Current flow. These dunes occur as two distinct fields at depths of −35 to −70 m; the major sediment transport direction is towards the south, but occasional bedload parting zones exist where the bedform migration direction changes from south to north.