Mycoplasma sp. strain 56A97 was isolated from the liver of a 10-day-old Humboldt penguin from a breeding colony at Chester Zoo. The Humboldt penguin is an endangered species and breeding programmes have been established in zoos worldwide. Initial testing of strain 56A97 indicated that it cross-reacted serologically with Mycoplasma gallisepticum, an important respiratory pathogen of poultry. Mycoplasma imitans, found in ducks and geese, also shows serological cross-reactions with M. gallisepticum but it is a distinct species, although their 16S rRNA genes have 99.9% similarity. Characterisation studies were undertaken to establish the taxonomic status of strain 56A97 to fulfil the minimum standards for description a new species within the class Mollicutes. Electron microscopy confirmed that strain 56A97 lacked a rigid cell wall, was bounded by a tri-laminar membrane and had an attachment organelle. It required sterol and did not catabolise urea and could thus be assigned to the class Mollicutes, order Mycoplasmatales, family Mycoplasmataceae genus Mycoplasma. Strain 56A97 was serologically distinct from 107 recognised Mycoplasma spp. as determined by growth inhibition and immunofluorescence. Metabolism inhibition strongly suggested that it was distinct from M. gallisepticum and M. imitans. The 16S rRNA gene of strain 56A97 was 99.6% similar to that of M. gallisepticum and 99.6% similar to M. imitans. It was possible to distinguish between the three species without DNA sequencing by restriction fragment length polymorphism (RFLP) of the 16S rRNA genes. Furthermore a 400 base pair target within the rpoB of strain 56A97 was 91 - 92% similar to the same target in five M. gallisepticum strains, which themselves were 98-100% similar. The 16S-23S rRNA intergenic spacer region (ISR) of strain 56A97 was 72-73% similar to the five M. gallisepticum strains, whose similarity ranged from 96 100%. Phylogenetic analysis of the three genomic regions was performed. A strain 56A97-specific PCR was developed using a primer targeting the ISR. Preliminary pathogenicity studies in chick embryo tracheal organ cultures (TOCs) and embryonated chicken eggs showed that strain 56A97 caused ciliostasis in the TOCs and mortality and stunting in embryos. Strain 56A97 DNA was detected in 82% of 101 healthy Humboldt penguins from eight collections and in 62% African penguins (Spheniscus demersus) in another. Isolates were recovered from 14 healthy Humboldt penguins and two African penguins. They were typed serologically and by RFLP as strain 56A97. King and Rockhopper penguins, which belong to another genus, did not appear to be infected despite co-habiting with infected penguins. In a parallel study the 16S-23S rRNA ISR and a target within the mgc2 gene of M. gallisepticum were amplified in 57 strains of M. gallisepticum and analysis of the results indicated a potential value for strain differentiation and epidemiological investigations.

No description available.

No description available.

No description available.

It is widely recognised that both nutrient-driven processes acting from the “bottom-up” and predator-driven processes acting from the “top-down” are important drivers of population change. However, studies that examine how these joint forces influence the population dynamics of oceanic species are lacking. In the Antarctic and Sub-Antarctic ecosystem, human-mediated changes have driven biological change at both ends of the food chain; rapid regional warming at the bottom and heavy exploitation of apex predator populations at the top. Consequently, many populations of marine predators have rapidly changed in size over the last 50-years. Unravelling the effects of bottom-up and top-down forcing on these open ocean ecosystems, has thus been highlighted as an immediate priority for polar scientists. The overall aims of this study were to use demographic, environmental and diet data to unravel the processes that contributed to a population of macaroni penguins at South Georgia declining rapidly between 1985 and 2012. I use mark–recapture modelling to examine the survival rates of macaroni penguins. Over 10 years, birds were marked with subcutaneous electronic transponder tags and re-encountered using an automated gateway system fitted at the entrance to the colony. These findings were combined with a 28-year time series of population counts and productivity measurements in an age-structured state-space population model to disentangle the processes underlying the observed population decline. Finally, I combined stable isotope analysis and tracking data to investigate the individual strategies macaroni penguins might employ to mitigate the effects of density-dependence during the breeding season. Macaroni penguins at South Georgia declined at 6% per year between 1985 and 2000, stabilising thereafter. This study indicates that the population declined in response to recruitment rates being lower than adult mortality. This trend was potentially accelerated by three large mortality events that were possibly associated with top-down predation pressure from giant petrels. Survival rates were low and variable during the fledging year, increasing to much higher levels from age 1 onwards. Year-to-year variability in demographic rates was induced by a combination of individual quality, top-down predation pressure and bottom-up environmental forces. The relative importance of these covariates on survival rates was age-specific, whereby predation pressure had a considerably greater effect during the fledgling year compared with birds older than 1-year. The population trajectory stabilised after 2000 in response to an increase in survival, as well as density-dependent feedbacks upon productivity. In order to minimise the effects of density-dependence during the breeding season and optimise daily energy expenditure, macaroni penguins appeared to make distinct dietary choices that remained highly consistent from year-to-year. Individually specialised foraging strategies occurred in response to seasonal variations in foraging range, conspecific density and prey availability at the foraging sites. The future stability of this population will depend on the carrying capacity of the environment supporting productivity rates at their present level, and the population size and breeding success of giant petrels not increasing so that adult survival rates can remain stable. More broadly, this study highlights the importance of considering multiple causal effects across different life-stages when examining the demography of seabirds, and demonstrates the additional insights that can be gained by using models with increased precision.