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The seaweed industry of temperate Southern Africa was last reviewed in 2003. Since then there have been considerable changes. There are three main uses of kelp (mostly Ecklonia maxima, with some Laminaria pallida) in South Africa. The collection of wash-up for drying and exporting for alginate extraction has drastically reduced to very small amounts in recent years. The boat harvest of fresh kelp for abalone feed in land-based farms has reached a plateau of between 4000 and 5000 t fresh per annum. The diver harvest of E. maxima for agricultural liquid plant growth enhancer shows a constant increase over several years, is still growing, and is currently over 3000 t fresh per annum. The small intertidal collection of Gelidium pristoides as export for agar production has maintained a small, sustainable production of around 100 t dry for many years. Former Gracilaria industries in sheltered bays in both South Africa and Namibia have collapsed, and there is currently no commercial collection. There was commercial raft aquaculture production of Gracilaria in Lüderitz Bay, Namibia for a number of years, but this is no longer practised. Currently, the only commercial seaweed use in Namibia is of L. pallida. Annually, ca. 150 t of fresh wash-up is collected, in Lüderitz, to be used as feed in land-based abalone aquaculture. There are a number of small start-up companies experimenting with seaweed products for cosmetics and nutritional products in both countries, some involving species of Ulva and Porphyra. The former species is a major aquaculture product, with around 2000 t fresh yr–1 being produced in integrated land-based systems with abalone. [ABSTRACT FROM AUTHOR]

The Mediterranean mussel Mytilus galloprovincialis is the most significant invasive alien marine species in South Africa and, although not normally found subtidally, has recently been observed colonising heads and stipes of the kelp species Ecklonia maxima in False Bay. We quantified this invasion and explored its ecological implications. Transects laid across kelp beds revealed that 10.34% of kelp individuals surveyed bore canopy mussels, with kelp heads (10.07%) being far more commonly infected than stipes (0.27%). Twenty kelp individuals with infected heads and 20 with infected stipes were separately collected for more-detailed examination. Wet mass of mussels on these kelp heads ranged from 2.5 to 2 462 g (median 86.4 g, interquartile range 14.8–353.8 g) and that of mussels on the stipes from 7.6 to 3 492 g (median 595.5 g, interquartile range 194.0–955.0 g). Mussel clumps consisted mostly of individuals <40 mm in length. Mussel clumps supported a rich biota of 80 invertebrate and 13 algal species. Larger clumps supported more epibiotic species, and those on stipes more species than those of comparable mass on kelp heads. The mussels and their associated epibiotic species negatively affected kelp buoyancy, but rarely enough to overcome natural buoyancy. Some kelp individuals that had been toppled by the weight of mussels and their epibiotic species, however, were encountered in situ. Implications of this invasion include large increases in animal biomass and species richness in the kelp canopy, plus reductions in kelp buoyancy and increased hydrodynamic drag on infected kelps, increasing their probability of being uprooted. Uprooted kelp individuals can raft long distances, potentially transporting both native and alien species to distant sites. [ABSTRACT FROM AUTHOR]

The herbivorous amphipod Sunamphitoe roberta n. sp. is described from the canopy of kelp beds in False Bay, South Africa. The new species has unusual habits, small family groups burrowing directly into the margins of the swollen primary fronds of the kelp Ecklonia maxima (Osbeck) Papenfuss, 1940. Morphologically, the new species is best distinguished from other species of Sunamphitoe by strong rows of dorsal spines on the outer rami of uropods 1 and 2. These spine rows appear to be employed as 'drill-bits' to excavate kelp tissue and create the burrows. Damage to hosts does not appear to be fatal, but requires further investigation. [ABSTRACT FROM AUTHOR]

Objective To compare complication rates, efficacy and acceptability of buccal misoprostol to laminaria for cervical preparation before dilation and evacuation (D&E) in South Africa. Study design We performed a randomized, single-blind trial comparing buccal misoprostol 400 mcg (1–2 doses, administered at least 3 h before D&E) to laminaria inserted the day before D&E among women at 13–19 weeks gestation. The primary outcome was expulsion of the fetus prior to surgery; secondary outcomes included other complications, need for mechanical dilation, procedure duration, side effects and satisfaction. Required sample size was 176 to detect a difference in expulsion of 20% to 5%, with a two-sided alpha of 0.05 and 80% power. Results Due to slow enrollment and low incidence of primary outcome, the study was stopped early. One hundred fifty-nine women were randomized, and 156 received treatment (78 in each group). Mean gestational age was 14.8 weeks (range, 13.0–18.6 weeks). Complications were rare and did not differ by group [three in each group; odds ratio (OR), 1; 95% confidence interval (CI), 0.20–5.11]; this included two expulsions in the misoprostol group (2.6%). Misoprostol participants were more likely to require mechanical dilation compared to those receiving laminaria (35% vs. 8%; OR, 6.4; 95% CI, 2.4–16.5). The proportion of women reporting each side effect was similar except for diarrhea (21.3% in misoprostol group vs. 5.2% in laminaria group, p=0.004). Procedure time and satisfaction did not differ between groups. Conclusions Both misoprostol and laminaria are associated with a low complication rate in this setting, although misoprostol requires more mechanical dilation and causes more diarrhea. Implications Cervical preparation using either laminaria or misoprostol can be safely used before D&E up to at least 19 weeks. Physicians using misoprostol must be skilled at mechanical dilation, since this is commonly required. [ABSTRACT FROM AUTHOR]

In South Africa two species of kelp, Ecklonia maxima and Laminaria pallida, occur in quantities sufficient for commercial use. Currently, the former species is harvested in large quantities (about 5 000 tonnes wet weight per year) as abalone feed. In order to set limits to the amount of kelp that may be harvested, it is necessary to obtain reasonably accurate measurements of kelp biomass. Biomass estimates are traditionally obtained by destructive sampling of kelp sporophytes from quadrats placed on the bottom. Scuba divers harvest the plants and weigh them ashore. This method is slow and labour-intensive, and severely limits the area of kelp bed that can be sampled. This study investigates several alternative methods to determine an easier, quicker method of estimating kelp biomass. First, morphometric data on both species of kelp were collected to investigate if there were easily measurable characters that correlate with the weights of individual sporophytes, which then could be used as proxies for destructive sampling. Second, floating quadrats were used to establish correlations between the density of kelp heads at the water surface during low spring tides and kelp biomass. Good correlations were found between (1) individual sporophyte weight and stipe weight for E. maxima (p = 0.0000; r2 = 0.5693) and L. pallida (p = 0.0000; r2 = 0.6175), and (2) individual sporophyte weight and stipe length for E. maxima (p = 0.0000; r2 = 0.5828) and L. pallida (p = 0.0000; r2 = 0.4817). Such measurements are time consuming and labour intensive, and require scuba and destructive sampling. However, using floating 1 m2 surface quadrats, good correlations were found between the density of kelp heads at the surface and the biomass of kelp (E. maxima, p = 0.0000, r2 = 0. 3469; L. pallida, p = 0.0000, r2 = 0.4785). Surface density measurements are more than eight times quicker than the traditional biomass determination method, are non-destructive, require fewer personnel, can be done by snorkelling and are unaffected by water clarity. Furthermore, harvesting for abalone feed is boat-based and targets only surface-reaching kelp. Sporophytes of E. maxima that reach the surface at low water spring tide comprise on average 62% of the total biomass of kelp in these beds, so scuba should still be used where observations and measurements of subcanopy biota are required. [ABSTRACT FROM AUTHOR]

Understanding of urban residents' preferences and dislikes for tree species and attributes is necessary to provide them with the species they most favour. Yet there is relatively little understanding of local species preferences, the reasons underlying them and how they vary with context and scale. We interviewed 1100 urban residents in eleven towns (four in Zimbabwe, four in Limpopo Province and three in the Eastern Cape of South Africa) to determine what were their favourite and least favourite tree species and the reasons for such. Fifty-nine species were listed amongst the preferred species (the four most common being Jacaranda mimosifolia (10% or respondents), Mangifera indica (10%), Adonsonia digitata (7%) and Colophospermum mopane (7%)), and 29 as disliked (the four most common being Vachellia spp , J. mimosifolia , Euphorbia spp. and Melia azedarach), with 16 in common between the two. Across the entire sample, the most common reason for preferring a particular species was that it had tasty fruits (19%), closely followed by the species evoking memories of where the respondent grew up (19%), and that it attained a large size (15%). The main reasons for disliking a species were because it was thorny (26% of responses), messy (16%), allergenic (15%), or poisonous (14%). There were no clear associations between preferences and respondent attributes, other than females being more likely to mention a disliked species than were males. There were clear intra- and inter-regional differences in the species preferred, and some of the reasons provided. There was some indication that preferred species are ones that are most apparent in the local environment but requires further investigation. The regional and inter-town differences emphasise that planting programmes should be informed by local preferences and needs, and that planting a diversity of species is likely to help match the diversity of preferences and needs. [ABSTRACT FROM AUTHOR]

Large-scale and small-scale natural barriers have the ability to mediate the ecological dynamics within a region. In some instances, these barriers greatly influence the presence of predators and prey on spatio-temporal scales. For this study, we aimed to assess how varying densities of sea bamboo (Ecklonia maxima), a kelp species found within South African waters, could influence the presence of C. carcharias. Using baited remote underwater video systems (BRUVS), thirty-one different C. carcharias were identified and a total of 135 h of video were collected in high, moderate, and low kelp densities to create an organismal sighting index. Generalized linear models illustrated that the best fit model included the main effect of kelp density, with a clear inverse relationship between kelp density and C. carcharias sightings. However, although zero sharks were sighted within the high kelp density regions, ten different C. carcharias were sighted within the moderate kelp density regions, illustrating that the broad notion that C. carcharias do not navigate through kelp ecosystems is false and requires more specificity (e.g. high density kelp areas may result in decrease C. carcharias presence). In contrast, kelp density had no significant influence on the presence of five other elasmobranch species detected by the BRUVS. This study demonstrated that highly dense kelp forests (i.e. ≥1 stalk of kelp per 1 m2) serve as a local natural barrier for large C. carcharias ; however, the need for a more inclusive analysis (e.g. routine inclusion of current speed and multi-location assessment) is warranted. • Kelp density had an inverse relationship with white shark sightings. • White sharks were routinely sighted in kelp forests of moderate density. • Zero white sharks were sighted in high density kelp forests. • High density kelp forests may serve as a natural barrier for large white sharks. [ABSTRACT FROM AUTHOR]