African penguins as predators and prey — coping (or not) with change

African penguins Spheniscus demersus live in the Benguela and western Agulhas ecosystems off southern Africa. Their numbers decreased throughout the 20th century from at least 1.5 million to about 0.18 million adults, although different regional trends were apparent. They feed to a large extent on shoaling epipelagic fish, notably anchovy Engraulis capensis and sardine Sardinops sagax, and regional trends in the abundance of penguins are associated with trends in the abundance and distribution of these prey fish. Many first-time breeders emigrate from colonies where feeding or other conditions at the time are unfavourable to more favourable breeding localities. This has led to both the extinction and formation of colonies. Food now may limit colonies at relatively small sizes, a fact attributable to industrial fisheries reducing the densities of forage fish. African penguins share their habitat with several other predators, with which they compete for food and breeding space. One of these, the Cape fur seal Arctocephalus p. pusillus, increased through the 20th century to 1.5–2 million animals at its close. Reported observations of predation by fur seals on seabirds have increased in recent decades and threaten the continued existence of small colonies of penguins. Stochastic modelling suggests that colonies of 10 000 pairs have a 9% probability of extinction in 100 years, so smaller populations should be regarded as “Vulnerable”. However, in a period of prolonged food scarcity off southern Namibia, the regional population decreased from more than 40 000 pairs in 1956 to about 1 000 pairs in 2000, and many colonies numbering less than 1 000 pairs became extinct. The minimum viable population for African penguins is currently considered to be >40 000 pairs, likely of the order of 50 000 pairs, a figure equivalent to its level in 2000. The chance of survival of the species through the 21st century is tenuous.African Journal of Marine Science 2001, 23: 435–44

Critical review on biofilm methods

Biofilms are widespread in nature and constitute an important strategy implemented by microorganisms to survive in sometimes harsh environmental conditions. They can be beneficial or have a negative impact particularly when formed in industrial settings or on medical devices. As such, research into the formation and elimination of biofilms is important for many disciplines. Several new methodologies have been recently developed for, or adapted to, biofilm studies that have contributed to deeper knowledge on biofilm physiology, structure and composition. In this review, traditional and cutting-edge methods to study biofilm biomass, viability, structure, composition and physiology are addressed. Moreover, as there is a lack of consensus among the diversity of techniques used to grow and study biofilms. This review intends to remedy this, by giving a critical perspective, highlighting the advantages and limitations of several methods. Accordingly, this review aims at helping scientists in finding the most appropriate and up-to-date methods to study their biofilms.The authors would like to acknowledge the support from the EU COST Action BacFoodNet FA1202

Porosity of temporary denture soft liners containing antifungal agents

ABSTRACT Incorporation of antifungals in temporary denture soft liners has been recommended for denture stomatitis treatment; however, it may affect their properties. Objective: To evaluate the porosity of a tissue conditioner (Softone) and a temporary resilient liner (Trusoft) modified by minimum inhibitory concentrations (MICs) of antifungal agents for Candida albicans biofilm. Material and Methods: The porosity was measured by water absorption, based on exclusion of the plasticizer effect. Initially, it was determined by sorption isotherms that the adequate storage solution for specimens (65×10×3.3 mm) of both materials was 50% anhydrous calcium chloride (S50). Then, the porosity factor (PF) was calculated for the study groups (n=10) formed by specimens without (control) or with drug incorporation at MICs (nystatin: Ny-0.032 g, chlorhexidine diacetate: Chx-0.064 g, or ketoconazole: Ke-0.128 g each per gram of soft liner powder) after storage in distilled water or S50 for 24 h, seven and 14 d. Data were statistically analyzed by 4-way repeated measures ANOVA and Tukey's test (&#945;=.05). Results: Ke resulted in no significant changes in PF for both liners in water over 14 days (p>0.05). Compared with the controls, Softone and Trusoft PFs were increased at 14-day water immersion only after addition of Ny and Chx, and Chx, respectively (p<0.05). Both materials showed no significant changes in PF in up to 14 days of S50 immersion, compared with the controls (p>0.05). In all experimental conditions, Softone and Trusoft PFs were significantly lower when immersed in S50 compared with distilled water (p<0.05). Conclusions: The addition of antifungals at MICs resulted in no harmful effects for the porosity of both temporary soft liners in different periods of water immersion, except for Chx and Ny in Softone and Chx in Trusoft at 14 days. No deleterious effect was observed for the porosity of both soft liners modified by the drugs at MICs over 14 days of S50 immersion

Comparison of moult phenology of African penguins Spheniscus demersus at Robben and Dassen islands

Dassen and Robben islands are approximately 50 km apart, and currently support the largest and third largest populations of African penguins Spheniscus demersus respectively. At both islands, moult is the most synchronised and seasonal activity of the annual cycle. The main difference in moult phenology between the two islands is the degree of synchronisation. The peak moult period at Dassen Island is broader (less synchronous) than at Robben Island. At both islands, juvenile penguins moulted less synchronously than adults. Juvenile moult was less synchronous at Dassen Island than at Robben Island. Interannual variation in moult phenology was similar at Robben and Dassen islands. Islandlevel moult phenology was more synchronous in the year following the Treasure spill than was the case after the Apollo Sea spill.  This was attributed to the larger number and  proportion of birds that were affected by the Treasure spill. The temporal duration of the  disruption to moult phenology was also greater following the Treasure spill, especially at Robben Island. Moult counts provide a relatively reliable method of estimating the size of the adult population at Robben Island, but not at Dassen Island where the large number of birds moulting away from the shoreline results in the population size being significantly underestimated. Although  the number of active nest sites continued to increase up until 2004 at both islands, the numbers of adult moulters counted declined by 55% between 2003 and 2005 at Robben Island,  and by 50% between 2002 and 2005 at Dassen Island. The decrease in the number of moulters coincided with a decreased availability of food in the region. Keywords: African penguin, Dassen Island, moult phenology, population trend, Robben Island, Spheniscus demersusAfrican Journal of Marine Science 2009, 31(1): 19–2

Breeding and moult phenology of African penguins Spheniscus demersus at Dassen Island

The breeding and moult phenology of African penguins Spheniscus demersus at Dassen Island form part of a variable annual cycle. Between 1994 and 2006, African penguins bred throughout the year. Most of this period was characterised by favourable feeding conditions. There were definite peaks in breeding activity, but these varied between years and between colonies on the island, with no obvious seasonal pattern. Synchronisation of breeding activities was greater in colonies with higher nest densities, suggesting that breeding phenology  was influenced more by social interaction between individuals than by a wider-scale seasonal effect. Moult phenology of African penguins at  Dassen Island was more synchronous and seasonal than breeding  activities. Most penguins moulted between September and January. A large proportion (30%) of moult records was of birds moulting in nest sites rather than at landing beaches along the shore. The incidence of nest moulting was greatest from August to October, when sea conditions were generally rougher. The interval between successive moults ranged from 221 days to 546 days, with a mean of 349 days. The much greater degree of synchronisation in moult compared with breeding patterns suggests that moult, and not breeding, may represent the key driver of the annual cycle. Keywords: African penguin, annual cycle, breeding phenology, Dassen Island, moult phenology, Spheniscus demersusAfrican Journal of Marine Science 2009, 31(2): 119–13

Restoration of oiled African penguins Spheniscus demersus a decade after the Apollo Sea spill

The bulk ore carrier Apollo Sea sank south-west of Dassen Island off western South Africa in June 1994, oiling approximately 10 000 African penguins Spheniscus demersus, most of which were collected from Dassen Island. A total of 4 076 de-oiled penguins was released with flipper bands. From 1994 to 2005, follow-up research using re-sighting and capturemark-recapture methods indicated that about 73% of the de-oiled penguins observed back at Dassen Island attempted to breed, and were thus successfully restored into the breeding population. For de-oiled breeders, the median interval between their first recorded sighting and first recorded breeding attempt was 11 months, indicating a short-term delay in restoration. At least 45% of the de-oiled breeders were still being re-sighted five years after their release, and a minimum of 4% survived into their ninth year. These results represent the most successful restoration estimates anywhere in the world. The proportion of de-oiled juvenile penguins re-sighted back at Dassen Island and recorded breeding was lower than that of birds in adult plumage. De-oiled non-breeders spent significantly more time along the shore and less time within breeding colonies than de-oiled breeders. The mean proportion of de-oiled breeders that abstained from breeding each year during the study period was greater than expected. There was a negative relationship between breeding and subsequent survival and breeding, suggesting a cost of reproduction for de-oiled birds. Keywords: African penguin; Apollo Sea; breeding; capture-mark-recapture; Dassen Island; de-oiling; oiling; rehabilitation; restoration; South Africa; Spheniscus demersusAfrican Journal of Marine Science 2008, 30(2): 421–43

Breeding success of African penguins Spheniscus demersus at Dassen Island, especially after oiling following the Apollo Sea spill

The reproductive success of African penguins Spheniscus demersus at Dassen Island from 1994 to 2000 was variable, but much higher than previously reported figures for the species. Breeding success was positively related to the abundance of anchovy Engraulis encrasicolus and sardine Sardinops sagax, and the high reproductive output during the study was attributed to the large biomass and high availability of these two species for much of the study period. De-oiled penguins from the Apollo Sea spill had a slightly lower hatching success but a significantly lower overall breeding success than that of un-oiled birds, driven mainly by the reduced number of chicks which fledged. Nests with two de-oiled Apollo Sea parents were less successful than nests with one de-oiled bird. There was increased mortality of chicks 40 days and older in nests with de-oiled birds. Chicks from nests with one de-oiled Apollo Sea parent grew at a similar rate to chicks from nests with no de-oiled parents. However, chicks from nests that comprised two de-oiled Apollo Sea birds had significantly slower growth rates than these other two groups. Breeding success and chick growth at nests with de-oiled birds were more negatively impacted when feeding conditions were less favourable. These results suggest that one of the main reasons for lower breeding success in de-oiled birds was their reduced ability to provision chicks, especially during the period in which the energy demands of the chicks is greatest. The rate of mate fidelity was lower in de-oiled birds than un-oiled birds, and there was a positive association between mate fidelity and breeding success. Keywords: African penguin; Apollo Sea; breeding success; chick growth; Dassen Island; de-oiled; mate fidelity; Spheniscus demersusAfrican Journal of Marine Science 2008, 30(3): 565–58

Implications for seabirds off South Africa of a long-term change in the distribution of sardine

From 1997 to 2005, the distribution of sardine Sardinops sagax, an important prey item for four seabirds off South Africa, shifted 400 km to the south and east, influencing its availability to breeding birds. It became progressively less available to seabirds in the Western Cape Province, where the number of African penguins Spheniscus demersus breeding decreased by 45% between 2004 and 2006, survival of adult penguins decreased and penguins established a new eastern colony in 2003. In that province, the number of Cape gannets Morus capensis breeding decreased by 38% between 2001/2002 and 2005/2006 and the contribution of sardine to the diet of gannets fell from an average of 40% during the period 1987–2003 to 5–7% in 2005 and 2006. The proportions of Cape cormorants Phalacrocorax capensis and swift terns Sterna bergii breeding in the south of the province increased as sardine moved south and east. In the Eastern Cape Province, the number of penguins breeding halved between 2001 and 2003, whereas after 2002 there was an increase in the number of Cape gannets that bred and in the contribution of sardine to their diet. It is likely that in that province sardine became increasingly available to gannets but remained beyond the shorter feeding range of penguins. Management measures that may mitigate the impacts on seabirds of an unfavourable, long-term change in the distribution of their prey include the provision of breeding habitat where prey is abundant, spatial management of fisheries competing for prey, and interventions aimed at limiting mortality. Keywords: African penguin; Cape cormorant; Cape gannet; displacement of food; environmental change; mitigation; sardine; seabird; swift ternAfrican Journal of Marine Science 2008, 30(1): 177–18

Impact of the Treasure oil spill on African penguins Spheniscus demersus at Dassen Island: case study of a rescue operation

The bulk ore carrier MV Treasure sank between Robben and Dassen islands off western South Africa in June 2000. Although releasing less oil than the Apollo Sea spill six years earlier, the number of African penguins Spheniscus demersus oiled (approximately 19 000) in the Treasure spill was almost double the number oiled in the Apollo Sea incident. The majority of oiled penguins was collected from Robben Island. The capture, stabilisation and transport of oiled penguins following the Treasure spill were substantially more successful than during the Apollo Sea rescue operation and resulted in an increase in the percentage of oiled penguins that were released back to the wild. In addition to the 19 000 oiled penguins that were caught, 19 500 un-oiled birds (12 345 from Dassen Island) were evacuated to Cape Recife, 800 km to the east, to prevent them from becoming contaminated. The evacuated birds returned rapidly to Dassen Island and many resumed breeding soon after their return. The restoration success (proportion of birds observed at Dassen Island that were recorded breeding) was substantially greater for evacuated birds than for de-oiled birds. Lightly oiled birds that were released without being cleaned had lower survival rates and were less successfully restored into the breeding population than de-oiled birds, especially if more than 5% of their body was covered in oil. Reproduction exerted a greater cost to de-oiled birds than to evacuated birds. A total of 1 787 orphaned chicks was hand-reared at two separate facilities on the mainland and were released at Robben and Dassen islands. The chicks did not necessarily return to the colony at which they were released. The survival rates and restoration success of chicks reared at the two facilities differed, probably as a result of one group being overfed. Despite the death of about 2 000 African penguins in the Treasure spill, and the substantial disturbance that resulted from the rescue operation, the penguin colonies at Robben and Dassen islands increased by 18% and 26% respectively in the year following the spill. This increase was attributed to a significant increase in the biomass of anchovy Engraulis encrasicolus and sardine Sardinops sagax in 2001. These findings highlight the importance of preventing oil spills in the first place, and in the event of a large oil spill, the conservation value of evacuating un-oiled penguins to minimise their risk of becoming contaminated.Keywords: African penguin; captive rearing; Dassen Island; de-oiling; oil spill; relocation; Spheniscus demersus; South AfricaAfrican Journal of Marine Science 2008, 30(2): 405–41

Review of the rescue, rehabilitation and restoration of oiled seabirds in South Africa, especially African penguins Spheniscus demersus and Cape gannets Morus capensis, 1983–2005

South Africa is a global hotspot for oil pollution. The regional oiled seabird cleaning centre, the South African Foundation for the Conservation of Coastal Birds (SANCCOB), has handled over 50 000 seabirds from its inception in 1968 until 2005. The majority of seabirds oiled in South Africa are African penguins Spheniscus demersus, followed by Cape gannets Morus capensis, both of which are classified as Vulnerable to extinction. On the basis of the proportion of the population that has been  affected, the African penguin is considered to have suffered more from oiling than any other seabird species globally. The rehabilitation success  (proportion of birds known to have survived for at least one month in the wild) and restoration success (proportion of rehabilitated birds attempting to breed) of de-oiling penguins and gannets are higher than has been reported for any  other species. The financial costs of de-oiling African penguins are substantially lower than the costs of de-oiling seabirds in the Northern Hemisphere. De-oiling contaminated birds is thus a valuable conservation intervention for these species, both of which are relatively localised in areas within or close to major shipping routes and ports, where a single spill can threaten a large proportion of the global population. There are, however, long-term effects of oiling on penguins and gannets. De-oiled gannets survive slightly less well than un-oiled birds, but the difference is similar to inter-colony differences in survival. Approximately 27% of rehabilitated African penguins are unable to breed following their release. In addition, oiling has a long-term negative impact on the breeding productivity and cost of reproduction in de-oiled birds. The primary objective should therefore be to prevent or reduce oil spills in the first place. However, future oil spills are inevitable and the authorities need to ensure that they have plans in place and the required capacity to respond rapidly to spills when they do occur. One of the ways to reduce the number of penguins becoming oiled during a spill is to evacuate birds from the affected area. The continued capture and cleaning of penguins and gannets that do become oiled is justified on conservation grounds. Thus, de-oiling should be a twin objective to prevention in South Africa’s oil spill management strategy, and every effort should be made to further improve both of these aspects. Keywords: African penguin; Cape gannet; Dassen Island; de-oiled; Morus capensis; oil spills; rehabilitation; rescue; restoration; SANCCOB; Spheniscus demersusAfrican Journal of Marine Science 2009, 31(1): 31–5