This study aims to uncover the synoptic weather circulation pattern which is associated with the occurrence of needle ice, snowfall and the zero-curtain effect. The method of study was done through an intensive ground climate measurement campaign from April 2008 to May 2009 with a temperature logger installed throughout the recording period. Results from data analyses indicate that the complex changes in climate parameters may lead to an equally complex response in terms of spatial soil frost dynamics and its direct and indirect effects on soil sediment displacement and ecosystem dynamics. Field evidence in the study suggests that on Marion Island needle ice developed in temperatures as high as -0.2 ºC in strong winds. This confirms that the wet environment of Marion Island, which is dominated by diurnal soil frost is fundamentally different from seasonal frost and permafrost environments. The scoria material is susceptible to needle ice growth and the compacted soil alters the micro-climatology of the affected area making it more susceptible to the formation of needle ice. Soil moisture for needle ice formation and growth is provided by the misty conditions associated with the advent of the cold front (pre-cyclonic). Furthermore, observations of needle ice on Marion show that needles are mostly clear with no sediment inclusion. This is indicative of needle ice formation that has not been interrupted by a shortage of moisture. The zero-curtain effect on Marion Island can occur either as a response to the thawing of the soil after the seasonal freeze. The synoptic assessment of snowfall on Marion Island indicates that; snowfall is associated with the passage of a cold front linked to a strong meridional system of low pressure just south of the island.

In this study, hypervariable region I (HVRI) of the mitochondrial DNA (mtDNA) control region, and five microsatellite loci were used to assess genetic variability and the extent of hybridization between the two fur seals (Arctocephalus tropicalis and A. gazella), that occur on Sub-Antarctic Marion Island. Both species were harvested during the 18th and 19th centuries, leading to a reduction in population size and the extinction of A. gazella at some localities. Whilst both species have recovered and are increasing in size, it is not clear to what extent sealing has affected genetic variation, although a more pronounced effect would be expected for A. gazella, given the more intensive harvesting of this species. The current study confirmed this hypothesis and revealed that A. gazella had a nucleotide diversity of 2.9 % whilst for A. tropicalis it was 4.2 %, across the HRVI mtDNA region sequenced. For microsatellite DNA, genetic variation in A. tropicalis was higher than in A. gazella in terms of the total number of alleles detected and the level of heterozygosity (HE=0.875, HO=0.845, mean number of alleles=13.6 and HE=0.799, HO=0.781, mean number of alleles=13, respectively). Diversity in both species is among the highest recorded in pinnipeds to date, and suggests that sealing did not overly affect the levels of genetic variation in these species. In terms of population structure, A. tropicalis show a high level of population structure, as indicated by the ΦST of 0.32 between Marion and Gough Island. Furthermore, the A. tropicalis haplotype tree comprising individuals from Marion, Iles Crozet, Gough, and Amsterdam islands, recovered three divergent evolutionary lineages with bootstrap values of 86% and 98%, for two of these lineages, indicating strong genetic structure and independent evolution. Shared haplotypes between Marion and other islands confirmed genetic exchanges, whilst the grouping of Marion and Gough Islands together is indicative of regular migration between these two islands. For A. gazella, the haplotype tree recovered numerous instances of grouping of individuals from Marion and Bouvetøya Islands confirming the hypothesis Bouvetøya is likely source of immigrants to Marion Island. This was further confirmed by low population differentiation between these two islands (FST = 0.062 and ΦST of 0.08). The level of hybridization between these species was low at Marion Island with only one hybrid being detected among the 134 animals for which mtDNA data were generated, corresponding to 0.75%. The same individual was identified as a hybrid, following microsatellite profiling of 146 animals, corresponding to a hybridization estimate of 0.68 %. This hybrid individual was classified phenotypically as A. gazella and genotypically was shown to have A. tropicalis ancestry. This level of hybridization is low compared to the other islands where the two species co-occur. However as the samples used in this study were primarily collected from species-specific sites, this may be an underestimate, and the studies focusing on sites where they are known to occur symaptrically, may yield higher estimates. / Dissertation (MSc)--University of Pretoria, 2009. / Zoology and Entomology / unrestricted

Pup mortality of southern elephant seals at Marion Island from 1990 through 1999 ranged from 1.6 to 7.3%, averaging 3.8%. Pup mortality was density independent and dismissed as being a major population regulating agent at Marion Island. Juvenile survival over two periods, one during the population decline and the other after the population had stabilised, was assessed and compared using mark-recapture models. Survival was age- but not sex-related and on average, the probability of survival was 59.5%,81.4% and 78.1% for the first, second and third year respectively. There was no significant difference in survival over the two periods and juvenile survival does not appear to be an important population regulating component in the southern elephant seal population. Mark-recapture data for females from the Marion Island population since the population stabilisation (1994) was analysed and compared with similar data collected during the decline and with data collected from the increasing population in southern Argentina. Survival of prime-age adult females increased by 8% concurrent with the stabilisation at Marion Island, which ultimately compensated for an annual rate of decline of the population of 5.85% until 1994. Survival of adult females at the colony in southern Argentina was 6% greater than at Marion Island after the stabilisation. Adult female survival is concluded to predominantly regulate the population. Changes in adult female survival and breeding probabilities with age were quantified in order to measure the prevalence of senescence in the population. Less than a 1 % difference between prime-age and post prime-age survival was found over eight cohorts of marked females and no evidence of reproductive senescence in terms of reduced breeding probability with age was detected. Five percent of southern elephant seal females survived to age ten and 0.5 % to the age of seventeen. Pubescent male survival increased concordant with the population stabilisation. These animals have high energetic demands due to a secondary growth spurt during which growth is accelerated and this increase lends support to the hypothesis that food has been limiting the population at Marion Island. Future survival and breeding probabilities of females primiparous at different ages were estimated in order to investigate potential future fitness costs associated with early breeding. Annual future survival of females breeding at age three was the same as that for females primiparous at four and slightly higher than that for females primiparous at five and six. Future breeding probabilities of females primiparous at three were similar to that for females primiparous at four and older. I found no evidence for future fitness costs incurred through reproductive expenditure and conclude that age of primiparity IS determined by acquisition of a critical body mass, after which no future delay in reproduction takes place. I estimated future survival and capture probabilities of southern elephant seals that winter at Marion Island during their first three years and compared these values to similar estimates from individuals that were not observed to winter over the same time periods. There were no significant differences in survival between wintering and non-wintering elephant seals suggesting that survival is not a fitness correlate of wintering behaviour. I provide unique evidence of differential site fidelity within age- and sex classes, which has implications for population modelling. / Thesis (PhD (Zoology))--University of Pretoria, 2006. / Zoology and Entomology / unrestricted

Thesis (MSc)--University of Stellenbosch, 2006. / ENGLISH ABSTRACT: Marion Island is situated approximately 2600 km southeast of Cape Town and is the larger of the two islands that comprise the Prince Edward Island group. During past glaciation events, Marion was partially covered by ice with fauna and flora confined to isolated refugia across the island. As a result of these long-term isolation events, it is postulated that species predating these glaciation events might show geographic partitioning of genetic variation. Subsequently, the majority of Southern Oceanic islands have a history of sealing activities with vessels frequenting various islands in their hunt for seals. These combined visits to several islands could have facilitated the introduction of alien species, or the reintroduction of species already present on islands. These incidents, combined with more recent scientific voyages, have led to the establishment of several exotic species on Marion Island. Two indigenous Collembola species (Cryptopygus antarcticus (Willem, 1901) and Tullbergia bisetosa (Börner, 1903)) were chosen as model species to investigate the possible effects of glaciation on the spatial distribution of genetic variation on indigenous species. Given the negative impact that alien taxa have on indigenous species and ecosystems, the phylogeographic population structure of the recently introduced Isotomurus cf. palustris (Müller, 1876) was determined and compared to those described for the two indigenous species. To address these questions, two mitochondrial DNA genes were targeted: cytochrome oxidase subunit I (COI) and cytochrome oxidase subunit II (COII). These genes were sequenced (GENBANK accession numbers DQ147289-DQ147558) and analysed using, amongst others, AMOVA (Analysis of Molecular Variance), SAMOVA (Spatial Analysis of Molecular Variance) and NCA (Nested Clade Analysis). As expected, the two indigenous species showed distinct signs of population expansion, whilst the recently introduced species exhibits little genetic variance across its range. The life histories of species have an influence on their resultant genetic signature; therefore life history parameters were incorporated to explain differences in the phylogeographic patterns observed for these three species. / AFRIKAANSE OPSOMMING: Marion Eiland is die groter van twee eilande wat die Prins Edward eilandgroep vorm, ongeveer 2600 km suid-oos vanaf Kaapstad. Gedurende glasiasie episodes in die verlede, was Marion gedeeltelik met ys bedek en fauna en flora was geisoleer in klein gedeeltes van die eiland wat beskut was. As gevolg van hierdie langtermyn isolasie word daar voorgestel dat spesies wat op die eiland was voor hierdie gebeurtenisse plaasgevind het, ‘n geografiese verdeling van genetiese variasie sal toon. Sedertdien het die meerderheid van die eilande in die Suidelike Oseaan ook ‘n geskiedenis van skepe wat op een of meer van die eilande aangedoen het in die jag op robbe. Hierdie besoeke deur die robjagters aan die eilande het meegebring dat daar eksotiese spesies op die eiland aangekom het of dat spesies wat reeds op die eiland voorgekom het, opnuut daar geland het. Hierdie, tesame met die onlangse wetenskaplike reise na Marion Eiland, het daartoe gelei dat baie eksotiese spesies ingevoer is na die eiland. Twee inheemse spesies, naamlik Cryptopygus antarcticus (Willem, 1901) en Tullbergia bisetosa (Börner, 1903) is gekies om as model spesies te dien om die moontlike gevolge van glasiasie op die geografiese verspreiding van genetiese variasie te toets. In ag geneem die moontlike negatiewe impak wat eksotiese spesies op die inheemse spesies mag hê, is die filogeografie van ‘n uitheemse spesie, Isotomurus cf. palustris (Müller, 1876) ook bepaal en vergelyk met díe van die bogenoemde inheemse spesies. Dit is gedoen deur twee gene, sitokroom oksidase I (COI) en sitokroom oksidase II (COII) te analiseer. Hierdie gene se basispaarvolgordes is bepaal (GENBANK toetreenommers DQ147289-DQ147558), en hulle is ge-analiseer deur gebruik te maak van AMOVA (Analise van Molekulêre Variasie), SAMOVA (Ruimtelike Analises van Molekulêre Variasie) en NCA (geseteldegroepsanalises). Net soos verwag, het die twee inheemse spesies albei duidelike tekens getoon van ‘n bevolkingstoename terwyl die uitheemse spesie amper geen variasie oor sy verspreidingsgebied getoon het nie. Die lewensstyle van spesies het ‘n beduidende invloed op hulle genetiese bevolkingstruktuur. As sulks is díe in ag geneem om die verskille tussen hulle genetiese strukture te verduidelik.

Thesis (PhD)--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: Climate sets range limits in many taxa, and as climate changes, the ranges that plants and animals occupy are altered. The responses of species to climate change involve either migration or local adaptation. An investigation of the local physiological adaptation shown by indigenous and alien arthropods to temperature acclimation formed the primary focus of this study. Increased environmental temperatures favour the establishment of alien species on Southern Ocean Islands. The first records of Porce/lio scaber Latreille, 1804 (Isopoda, Porcellionidae) and an Aphidius wasp species from Marion Island were documented here. The alien wasp was discovered in 2003 and had a current known distribution along the east coast of Marion Island. Both isopods and wasps were reproducing successfully on Marion Island. The wasp species is an aphid parasitoid and had been found mummifying the alien aphid Rhopalosiphum padi. These introductions highlighted the ongoing conflict between use and conservation on the Southern Ocean Islands. Despite considerable work on the upper and lower lethal limits of insects, several major taxa have received little attention. Here this issue was addressed and the lower and upper thermal tolerances and cold hardiness strategy of Antarciopsocus jeanneli Badonnel (Psocoptera: Elipsocidae) from sub-Antarctic Marion Island was investigated. A. jeanneli is freeze intolerant, and more specifically, moderately chill tolerant. Field fresh A. jeanne li had a mean supercooling point (SCP) of -11.1oC, whereas LTSO was -7.7°C, indicating pre-freeze mortality. A. jeanneli responded to acclimation: mean SCP increased from -IS.8°C at a treatment temperature ofO°C, to -7.3°C at ISOC. Investigations of the responses to acclimation of upper and lower lethal limits and limits to activity in insects have focussed primarily on Drosophila. Halmaeusa atriceps (Staphylinidae) was examined for thermal tolerance responses to acclimation, and seasonal acclimatization. In summer and winter, lower lethal temperatures of adults and larvae were c. -7.6 ± 0.03 and -11.1 ± 0.06 °C, respectively. Supercooling points (SCPs) were more variable, with winter SCPs of -S.4 ± 0.4 °C in larvae and -6.3 ± 0.8 °C in adults. The species appeared to be chill susceptible in summer and moderately freeze tolerant in winter, thus showing seasonal acclimatization. Critical thermal minima varied between -3.6 ± 0.2 and -0.6 ± 0.2 °C in larvae, and from -4.1 ± 0.1 to -0.8 ± 0.2 °C in adults. These findings were in keeping with the general pattern found in insects, although this species differed in several respects from others found on Marion Island. In this study the differential responses of indigenous and invasive springtails to temperature were explicitly examined in the context of the beneficial acclimation hypothesis (BAH) and its alternatives. In particular, the thermal acclimation responses of desiccation resistance, supercooling ability, lower and upper thermal limits were compared. Invasive springtails (Pogonognathellus jlavescens, Isotomurus palustris and Ceratophysella denticulata) did not display greater phenotypic flexibility than indigenous springtails (Cryptopygus antarcticus and Tullbergia bisetosa), but did perform better under high temperature conditions. Indigenous species, however, performed better under low temperature conditions. In most cases the BAH was not supported, or could not be distinguished from its alternatives. The prediction that invasive species will outperform indigenous species as climates on Southern Ocean Islands warm was supported. Because temperature plays such a large role in the distribution, abundance and physiological tolerances of invertebrates, microhabitat temperatures along an altitudinal gradient (0 to 800 m above sea level (asi)) were investigated over a two-year period on Marion Island. Mean microhabitat temperatures were comparable to those from previous studies for Southern Ocean Islands, and declined with increasing altitude. The 800 m asl site had the most severe microclimate (highest absolute maximum, lowest absolute minimum and the highest frequency of freeze-thaw cycles). Year one was substantially colder than year two, indicating that interannual variation in microclimate conditions could be responsible for substantial mortality amongst. invertebrate populations. Indeed, indigenous species were best able to tolerate the high incidence of low temperatures at high altitudes, whereas alien species appeared to be confined to lower altitudinal sites on Marion Island, possibly as a consequence of extreme low temperatures at higher altitudes. / AFRIKAANSE OPSOMMING: Klimaat is een van die grootste faktore wat die verpreiding en digthede van dier en plantspesies bepaal. Soos wat klimaatsverandering plaasvind, kan spesies migreer om stresvolle klimaatstoestande te vermy, of hulle kan aanpas by plaaslike omstandighede. Dit is die laasgenoemde opsie wat in hierdie tesis ondersoek was. Die opsporing van Porcellio scaber Latreille, 1804 (Isopoda Porcellionidae) en 'n Aphidius wesp van Marion Eiland word hier aangeteken. Die huidige verspreiding van houtluise in die omgewing van die Navorsingstasie dui daarop dat hulle die eiland waarskynlik vanaf Kaapstad in bou-materiaal bereik het. Die wesp is gedurende 2003 ontdek en is tans versprei langs die oostelike kuslyn van Marion Eiland. Beide hierdie spesies plant suksesvol voort op Marion Eiland. Die wesp spesie parasiteer die uitheemse plantluis Rhopalosiphum padi. Uitheemse muise en die inheemse kleinskedebek weier tot dusver om P. scaber te eet. Die ontdekking van twee nuwe uitheemse spesies dui weereens op die konflik tussen bewaring en benutting van die Suidsee Eilande. Ten spyte daarvan dat aansienlike aandag gewy is aan die hoë- en lae temperatuur toleransies van insekte, is daar talle taksa wat selde nagevors word. Dié toleransies is dus nagevors vir die boekluis Antarctopsocus jeanneli Badennel (Psocoptera: Elipsocidae) van Marion Eiland. Die spesie is vries vermydend, en meer spesifiek, matig verkoelingsbestand. Veldvars A. jeanneli het 'n gemiddelde superverkoelingspunt van - 11.1 °C gehad, en letale temperature (LTSO) van -7.7 °C, wat aandui dat individue vrek voordat hulle vnes, Hierdie spesie reageer op akklimasie: gemiddelde superverkoelingspunt het toegeneem van -15.8 °C na akklimasie by 0 °C tot -7.3 °C na akklimasie by 15 oe. Die effek van akklimasie op temperatuur toleransie in insekte het dusver meestalop Drosophila gefokus. Hier vors ons die effek van akklimasie op die temperatuur toleransie van Halmaeusa atriceps (Styphylynidae) na. In die somer en winter was die lae letale temperature van kewers en larwes onderskeidelik -7.6 ± 0.03 en -11.1 ± 0.06 °C. Superverkoelingspunte (SVP) het meer gevarieer, met SVP van -5.4 ± 0.4 °C in larwes en -6.3 ± 0.8 oe in kewers. Die spesie IS verkoelingsvatbaar in die somer en matig vriesbestand in die winter, wat dui op akklimatisasie in hierdie spesie. Kritiese termale minima het tussen -3.6 ± 0.2 en -0.6 ± 0.2 oe in larwes, en tussen -4.1 ± 0.1 tot -0.8 ± 0.2 oe in kewers gewissel. Hierdie spesie blyk dieselfde fisiologiese tendense wat in insekte te vinde is uit te beeld, maar verskil in verskeie opsigte van ander insekte op Marion Eiland. Hierdie studie het ook die verskillende reaksies van inheemse en uitheemse springsterte met betrekking tot temperatuur akklimasie bestudeer. Die voordelige-akklimasie hipotese en sy alternatiewe hipoteses is in terme van akklimasiereaksies tot desikkasie weerstand, superverkoeling en lae- en hoë temperatuur bestandheid in Marion Eiland springsterte getoets. Die uitheemse springsterte (Pogonognathellus jlavescens, Isotomurus cf palustris en Ceratophysella denticulata) het nie beter fenotipiese plastisiteit getoon as die inheemse spesies (Cryptopygus antarcticus en Tullbergia bisetosa) nie. Die inheemse spesies het egter beter gevaar onder lae-temperatuur toestande. Die voordeligeakklimasie hipotese ontvang nie veelondersteuning in die huidige studie nie, maar kon in sommige gevalle nie van die alternatiewe hipoteses onderskei word nie. Klimaatsverandering mag uitheemse spesies bevoordeel. Die rol wat temperatuur in die verspreiding en fisiologiese toleransies van invertebrate speel word lank reeds waardeer. Daarom vors hierdie studie die mikrohabitat temperature teen 'n gradient tussen seespieël en 800 m bo seespieël (m bs) oor 'n tydperk van twee jaar op Marion Eiland na. Gemiddelde temperature is vergelykbaar met die van vorige studies op Marion Eiland, en neem af soos wat hoogte bo seespieël toeneem. Die 800 m bs studie-gebied het die mees stresvolle mikrohabitat-toestande ondervind (die hoogste absolute maksimum, laagste absolute minimum temperature, en die meeste vries-ontdooi siklusse). Inheemse spesies op Marion Eiland toon hoër.toleransies tot lae temperature as uiheemse spesies, laasgenoemde kom slegs voor by laer hoogtes bo seespieël, waar ekstreme ternperatuur-toestande dalk minder volop is. Klimaatsverwarming mag egter tot 'n toename in ekstreme weerstoestande lei op Marion Eiland, wat aansienlike mortaliteit in invertebraat populasies kan veroorsaak.

In a tale of survival, dubbed that of the “South Seas Crusoes”, a group of men overcame the odds by setting up camp on a deserted volcanic sub-Antarctic island in the middle of the Southern Indian Ocean. This group of men formed the crew of the Norwegian SS Solglimt sealing vessel which had wrecked on the sub-Antarctic Marion Island in October 1908. More than a century later remains of the shipwreck of the SS Solglimt can still be found lying exposed below the water in the bay of Ships Cove. In the valley north of the bay, the remnants of the shipwreck survivor camp associated with the wreck holds hidden stories of a terrestrial maritime landscape formed out of tragedy and the need to survive. It is mainly the remains of this camp which forms the basis of the research and discussion for this dissertation. The following study is not only an attempt to add to our knowledge and understanding of the archaeological remains on Marion Island, it is also to add to an existing body of knowledge involving shipwreck survivor camps. The remains on Marion Island have produced the perfect opportunity to fill gaps within the discipline of Maritime Archaeology, especially in South Africa where too often emphasis is placed on shipwreck studies and not enough on the events taking place before or after the crisis event. The following dissertation uses archaeological techniques alongside historical documents as a way to better understand the socio-cultural behaviour of survivors during events of disaster, isolation and the necessity to survive. The study will be used as a comparison to similar studies around the world and hopes to add to an existing body of knowledge involving survivor camps and disaster-response studies from an archaeological and anthropological perspective. / Anthropology and Archaeology / M.A. (Archaeology)

Thesis (MSc )--Stellenbosch University, 2010. / ENGLISH ABSTRACT: The patterns of spread of non-indigenous species and the factors influencing their distribution have been studied infrequently on Southern Ocean Islands, where the prevention and control of biological invasions is a priority for conservation management. Owing to its remoteness and relatively small size, sub-Antarctic Marion Island provides an ideal opportunity to investigate the patterns of spread of invasive species and the factors likely influencing the distribution of alien species. Therefore, this study provides a spatially explicit documentation of the alien and invasive vascular plant species on Marion Island, the change in their distribution patterns through time, an assessment of the correlates of the current distributions, documentation of species rich areas, and provides recommendations for control based on these data and life history data available for each species. To ensure comprehensive coverage for the current estimate of distributions, a combination of a systematic (spatially explicit) survey and an ad hoc data collection method was used to examine the abundance and occupancy of each alien plant species across the island. The spatially explicit survey was used to identify sampling sites on a ½ minute by ½ minute scale (926 m × 926 m) which resulted in 348 sites across the island, whereas 2356 additional presence records were added during the ad hoc sampling. The residence time of each species was also estimated from the first records reported in various literature. While it has been documented in many studies that residence time is an important factor explaining species distribution, this study showed that distribution of alien species on Marion Island is not explained by residence time. The alien plant species on Marion Island differ markedly in their occupancy, distribution and rate of expansion. Agrostis stolonifera, Cerastium fontanum, Poa annua and Sagina procumbens are all expanding their ranges, whereas the range of Stellaria media appears to be contracting. Cerastium fontanum is the most widespread species on Marion Island while Sagina procumbens is the most abundant (number of records) and most rapidly expanding species on both Marion and Prince Edward Islands. Generalized linear models demonstrated that altitude, distance to human disturbed sites, and nearest neighbour presence are all significant and often strong correlates of spatial variation in alien vascular plant species richness and individual species presences on Marion Island. In particular, alien species richness on Marion Island declines sharply with increasing elevation, and that the distribution of the most widespread species is spatially aggregated. The surroundings of the Meteorological station and Mixed Pickle hut exhibit high richness and a high likelihood of the presence of individual species. None of the models developed for this study resulted in habitat type being significant explanatory variable for the distribution of any of the alien plant species, although from the records alone it is clear that the salt spray vegetation type is avoided. Together with assessments of the life history of the species, the current distribution data suggest that few alien plant species can be easily eradicated. Most are already too widespread already for cost effective eradication. Moreover, given the current rate of spread of Agrostis stolonifera, Cerastium fontanum, Poa annua and Sagina procumbens, and their apparent lack of habitat preference, it seems likely that within the next few decades many lowland habitats will be dominated by these species. By contrast, Rumex acestosella, Agrostis gigantea, Agropyron repens, Juncus effusus, Luzula cf. multiflora and the newly established shrub species should be the subject of control or eradication efforts. This thesis provides comprehensive baseline data on alien vascular plant distributions as a benchmark for future assessments. / AFRIKAANSE OPSOMMING: Die verspreidingspatrone van uitheemse spesies en die faktore wat hulle verspreiding beïnvloed is selde op Suidelike Oseaan Eilande bestudeer, waar die voorkoming en beheer van biologiese indringing ‘n prioriteit is vir bewaringsbestuur. Te danke aan sy afgeleëndheid en relatiewe klein grootte, voorsien sub-Antarktiese Marion Eiland ‘n ideale geleentheid om die patrone van verspreiding van indringer spesies en die faktore wat moontlik die verspreiding van uitheemse spesies beïnvloed te ondersoek. Daarom voorsien hierdie studie ‘n ruimtelik eksplisiete dokumentering van die uitheemse en indringer vaatplant spesies op Marion Eiland, die verandering in hulle verspreidingspatrone oor tyd, ‘n bepaling van die korrelasies van die huidige verspreidings, dokumentering van spesiesryke areas, en voorsien aanbevelings vir beheer gebasseer op hierdie data en die lewensloopdata beskikbaar vir elke spesie. Om omvattende dekking vir die huidige skatting van vespreidings te verseker, is ‘n kombinasie van sistematiese en ad hoc metodes gebruik om die talrykheid en besetting van elke uitheemse spesie oor die eiland te ondersoek. Die ruimtelik eksplisiete opname is gebruik om moniteringsplotte op ‘n ½ minuut by ½ minuut skaal (926 m × 926 m), met die resultaat van 348 plotte oor die eiland, terwyl 2356 addisionele voorkomsrekords bygevoeg is tydens die ad hoc versameling. Die verblyftyd van elke spesie is ook beraam vanaf die eerste rekords in die literatuur. Terwyl dit aangeteken is dat verblyftyd ‘n belangrike faktor is om spesie verspreiding te verduidelik, wys hierdie studie dat verspreiding van uitheemse spesies op Marion Eiland nie verduidelik word deur verblyftyd nie. Die uitheemse spesies op Marion Eiland verskil aansienlik in hulle besetting, verspreiding en tempo van uitbreiding. Agrostis stolonifera, Cerastium fontanum, Poa annua en Sagina procumbens brei almal hulle areas uit, terwyl die area van Stellaria media bleik te krimp. Cerastium fontanum is die mees wydverspreide spesie op Marion Eiland, terwyl Sagina procumbens die oorvloedigste (aantal rekords) en die vinnigste uitbreidende spesie is op beide Marion en Prince Edward Eiland. Veralgemeende lineêre modelle het aangetoon dat hoogte, afstand na menslike versteurde plotte, en naaste buurman teenwoordigheid almal betekenisvol is en gereeld sterk korreleer met ruimtelike variasie in uitheemse vaatplant spesierykheid en individuele spesie voorkoms op Marion Eiland. Uitheemse spesierykheid op Marion Eiland neem in besonder sterk af met ‘n toename in hoogte en die verspreiding van die mees wyduitgebreide spesies is ruimtelik saamgesteld. Die omgewing om die Weerstasie en Mixed Pickle hut toon hoë rykheid en ‘n hoë waarskynlikheid van die voorkoms van individuele spesies. Nie een van die modelle wat vir hierdie studie ontwikkel is toon ‘n belangrikheid in habitat tipe as ‘n verduidelikbare veranderlike vir die verspreiding van enige van die uitheemse plant spesies nie, alhoewel vanuit die rekords alleen is dit duidelik dat soutsproei plantegroei nie verkies word nie. Tesame met ondersoeke oor die lewensloop van die spesies, stel die huidige verspreidingsdata voor dat min uitheemse plant spesies maklik uitgeroei kan word. Die meeste is eenvoudig te wydverspreid vir koste effektiewe uitroeiing. Voorts, gegewe die huidige tempo van uitbreiding van Agrostis stolonifera, Cerastium fontanum, Poa annua en Sagina procumbens en hulle skynbare gebrek aan habitat voorkeur, is dit hoogs waarskynlik dat baie van die laerliggende habitatte binne die volgende paar dekades gedomineer sal word deur hierdie spesies. In teenstelling, Rumex acestosella, Agrostis gigantea, Agropyron repens, Juncus effusus, Luzula cf. multiflora en die nuutgevestigde struik spesie moet die fokus wees van beheer/uitroeiing pogings. Hierdie tesis voorsien omvattende basislyn data oor uitheemse vaatplantverspreidings as ‘n standaard vir toekomstige ondersoeke. / This project was funded by the South African National Antarctic Programme of the National Research Foundation (NRF – SANAP). Additional funding was provided by The Prince Edward Islands book fund.

Thesis (MSc)--Stellenbosch University, 2005. / ENGLISH ABSTRACT: Evidence for widespread ecological impacts due to rapid climate change is on the increase, with further warming predicted over the next century. This increase in warming has lead to organisms adjusting their distribution range and where this is not possible organisms must cope with the stressful environments in a different way. One potential way to handle environmental stress is via a mechanism known as phenotypic plasticity, which allows an organism to express different phenotypes depending on the biotic or abiotic environment in a way that may alter that organism's fitness. Acclimation temperatures can potentially cause plastic (reversible and irreversible) changes in the response of individuals to stressful experimental conditions that could increase their survival. The issue of whether this acclimation will be beneficial to the organism or not remains contentious, with support offered both for and against the idea of beneficial acclimation. The aims of the investigation were to determine the thermal limits of five ameronothrid mite species (Halozetes marinus, H marionensis, H belgicae, H. fulvus and Podacarus auberti) from varying terrestrial habitats and to test whether there is beneficial acclimation on the thermal traits. Along with the beneficial acclimation hypothesis several alternative hypotheses were also tested. In addition, locomotor performance was determined as it has been suggested that locomotion performance is a reliable and practical measure of potential fitness of animals. The same hypotheses testing the effects of acclimation temperature on the thermal limits were tested on three performance traits; performance breadth, optimum speed and optimum temperature. Support for beneficial acclimation was found in the performance breadth and optimum speed traits for all species except for Halozetes marinus. For the optimum temperature trait the prediction for the compensation hypothesis was met and that of the beneficial acclimation hypothesis rejected, with the only exception again being that of H marinus. In the case of the locomotor performance traits the prediction for the beneficial acclimation hypothesis in the performance breadth and optimum speed traits are the same for that of the compensation hypothesis, therefore the overall response of the more terrestrial mite species is one of compensation. However, support for beneficial acclimation was not found in the thermal limit traits of all five species, with the higher acclimation temperatures (specifically 150 C) resulting in negative responses in LLT in H. marinus and H. belgicae, and in ULT in H. fulvus. Phenotypic flexibility varied between marine and terrestrial species. The less variable marine environment showed lower flexibility than that of terrestrial species in the performance breadth trait and optimum temperature trait, but there was a lack of variation between the marine and terrestrial species in the temperature tolerance traits. These results show that the effects of acclimation on various traits, especially fitness related traits, are complex and require more attention if the consequences are to be fully explained. This study therefore provides insight into the effects of acclimation on performance traits and thermal limit traits and has implications for the evolution of plastic responses in terrestrial arthropods. / AFRIKAANSE OPSOMMING: Bewys vir wye ekologiese impakte as gevolg van vinnige klimaatsverandering is aan die toeneem, met verdere verwarming wat voorspel word gedurende die volgende eeu. Dié toename in verwarming het alreeds veroorsaak dat organismes hulle verspreidings verander, of waar dit nie moontlik is nie, moet hulle stresvolle omgewingstoestande op 'n ander wyse hanteer. Een moontlike manier om omgewingsstres te hanteer is deur gebruik te maak van 'n meganisme wat bekend staan as fenotipiese plastisiteit, wat dit vir 'n organisme moontlik maak om ander fenotipes te toon afhangende van die biotiese of abiotiese omgewing in 'n wyse wat die organisme se fiksheid beinvloed. Temperatuur akklimasie kan moontlik plastisiteit (omkeerbaar of onomkeerbaar) veranderinge in die reaksie van individue tot stresvolle eksperimentele toestande tot gevolg hé, wat gevolglik hulle oorlewing kan verhoog. Die kwessie of hierdie akklimasie wel voordelig vir die organisme is of nie is steeds betwisbaar, met beide steun vir en teen die idee van voordelige akklimasie. Die doel van hierdie ondersoek was om vas te stel wat die termiese limiete van vyf ameronothrid myt spesies (Halozetes marinus, H marionensis, H belgicae, H fulvus en Podacarus auberti) van verskeie terrestriële habitatte is, en om te toets of daar voordelige akklimasie in die termiese eienskappe voorkom. Tesame met die voordelige akklimasie hipotese is daar verskeie alternatiewe hipoteses ook getoets. Verder, is bewegings prestasie vasgestelomdat dit al voorgestel is dat bewegings prestasie 'n betroubare en praktiese mate van die potensiële fiksheid van 'n dier aantoon. Dieselfde hipotese wat die effek van akklimasie temperatuur op die termiese limiete toets, is op drie prestasie eienskappe getoets; prestasie wydte, optimale spoed en optimale temperatuur. Bewyse vir voordelige akklimasie is gevind in die prestasie wydte en optimale spoed eienskappe vir alle spesies behalwe Halozetes marinus. Vir die optimale temperatuur eienskap was die voorspelling vir die kompensasie hipotese korrek maar dié van die voordelige akklimasie verkeerd, met H. marin us die enigste uitsondering. In die geval van die bewegings prestasie eienskappe is die voorspelling vir die voordelige akklimasie hipotese in die prestasie wydte en optimale spoed eienskappe die selfde as vir die kompensasie hipotese. Daarom is die algemene reaksie vir die meer terrestriële spesies een van kompensasie. Bewyse vir voordelige akklimasie is egter nie gevind in die termiese limiet eienskappe van die vyf spesies nie, met die hoér akklimasie temperature (spesifiek 15° C) wat 'n negatiewe reaksie in LLT in H. marin us en H. belgicae, en in UL T in H. fulvus veroorsaak het. Fenotipiese buigsaamheid het verskil tussen mariene en terrestriële spesies. Die minder variërende mariene omgewing het 'n laer buigsaamheid in die prestasie wydte en optimale temperatuur eienskappe getoon as die van terrestriële spesies, maar daar was geen variasie tussen mariene en terrestriële spesies in die temperatuur toleransie eienskappe nie. Die resultate wat hier voorgelê word wys dat die gevolge van akklimasie op verskeie eienskappe, veral fiksheids verwante eienskappe, ingewikkeld is en vereis meer aandag om die gevolge volledig te verduidelik. Hierdie studie verskaf dus insig in die gevolge van akklimasie vir prestasie eienskappe en termiese limiet eienskappe en het gevolge vir die evolusie van plastiese reaksies in terrestriële arthropoda.

Thesis (MSc)--University of Stellenbosch, 2007. / ENGLISH ABSTRACT: Climate has shown some remarkable changes over the past century, especially at the polar and sub-polar regions. Southern Ocean Islands provide good models for studies related to climate change effects, since effects may be evident in the short term and may also be clearer. Marion Island is an example of such a system with a harsh abiotic environment, and low species richness often vulnerable to change. Climate change is predicted, and also reported, to have biological consequences on plant communities, affecting the phenology, morphology, and the interaction between individuals and species. This study examines the association between the keystone plant species, Azorella selago Hook. (Apiaceace), and its dominant epiphyte Agrostis magellanica Lam. (Poaceae). Two complimentary approaches were used, one observational and the other experimental. The main objective for the observational study was to quantify bioticallyrelevant microclimate temperature, as well as the morphology, epiphyte load and phenology of A. selago at three different altitude sites on Marion Island. This provided information on baseline variation for understanding specific variability in plant response to the experimental part of this study, against which future patterns arising from biological monitoring can be compared. Studying plants at different altitudes provides a possible analogue for temperature-related climate change consequences for the ecology of A. selago, and its interaction with A. magellanica. The microclimate temperature associated with A. selago differed between the three sites examined. This difference was related to local topographic conditions and altitude differences. Cushion size differed distinctively between the three altitude sites, with this difference related to environmental heterogeneity such as differences in age and substrate structure. Azorella selago annual growth rate was estimated through stem length and the number of leaves on both exposed and shaded stems. Within-site variability, as well as epiphyte cover were found to be the contributing factors on A. selago annual growth rate. This highlights the importance of site-specificity when estimating growth rate within and between different altitude sites. Leaf characteristics differed between the sites, with this attributed to local habitat conditions, such as topography, as well as epiphyte cover. As expected, the difference in leaf size between exposed and shaded leaves demonstrated a larger specific leaf area on leaves shaded by A. magellanica. Agrostis magellanica abundance and density were altitudinally related, with A. selago demonstrating facilitation effects on A. magellanica. The trend shown in this study suggests that in spite of general facilitative effect of A. selago on A. magellanica towards higher altitudes, the abiotic environmental threshold for A. magellanica occurs at lower altitudes than it does for A. selago. Phenological differences were also apparent between the three sites. The objectives of the experimental part of this study were to quantify the effect of the dominant epiphyte, A. magellanica on biotically-relevant microclimatic temperatures, as well as on the phenology and physical condition of A. selago. Different treatments were applied to cushions at the three altitude sites to examine the shading effect of epiphytic A. magellanica on cushion plants, as well as the effect of treatment-related disturbance. Azorella selago microclimate temperature showed no significant difference between treatments, suggesting that on average epiphytic A. magellanica cover has no effect on cushion microclimate temperature. The percentage of flower budding and flowering of A. selago was negatively related to epiphyte cover. Cushion vitality was also responsive to epiphyte cover, with higher vitality scores on low grass covered cushions than on high grass cushions. This shows that A. magellanica competes with A. selago, while A. selago facilitates A. magellanica. Heavy epiphyte numbers impose negative effects on A. selago vegetative and reproductive performance, as well as cushion vitality. Therefore, the results of this research show that the vegetative and reproductive performance of A. selago and cushion vitality are likely to be negatively affected under ongoing climate change on Marion Island if this brings about heavier epiphyte loads on this keystone cushion plant species. / AFRIKAANSE OPSOMMING: In die afgelope eeu het die klimaat in die Antarktiese en sub-Antarktiese gebiede merkwaardige verandering getoon. Die Suidelike See Eilande dien as goeie modelle vir studies verwant aan die gevolge van klimaatsverandering, aangesien die kort termyn effekte in die gebiede duideliker mag wees in die toekoms. Marion Eiland is ‘n voorbeeld van so ‘n sisteem, met ‘n ruwe abiotiese omgewing en lae spesies rykheid, wat vatbaar is vir verandering. Daar word voorspel, en is reeds bevind dat klimaatsverandering biologiese gevolge op plant gemeenskappe het, in terme van morfologie, fenologie en die interaksie tussen individue en spesies. Hierdie studie ondersoek die assosiasie tussen die hoeksteen plant spesie, Azorella selago (Apiaceace), en sy dominante epifietiese gras, Agrostis magellanica Lam. (Poaceae). Die studie is op twee komplimentêre maniere benader, naamlik deur waarneming en eksperiment. Die hoof doel van die studie was om die biotiese belang van mikroklimaat temperatuur te kwantifiseer, en die hoeveelheid epifiete, die morfologie en die fenologie van A. selago te bepaal by drie verskillende hoogtes op Marion Eiland. Laasgenoemde het inligting verskaf oor die variasie in die reaksie van plante tot die eksperimentele aspek van die studie, waarteen patrone vanaf toekomstige biologiese beheer vergelyk kon word. Deur plante te bestudeer by verskillende hoogtes bo seespieël word ‘n moontlike analoog vir die gevolge van temperatuur-verwante klimaatverandering in terme van die ekologie van A. selago, en laasgenoemde se interaksie met A. magellanica verskaf. Die mikroklimaat temperatuur geassosieer met A. selago verskil tussen dié drie liggings. Die versil was verwant aan die plaaslike topografiese toestande en die verskillende hoogtes bo seespieël. Die grootte van die kussingplante het duidelik versil tussen die drie liggings, met die verskille verwant aan die omgewing se heterogeneïteit, byvoorbeeld die verskille in ouderdom en substraat struktuur. Azorella selago se jaarlikse groeitempo was bepaal deur die stingel lengte en die aantal blare, op beide die wat oorskadu is deur die gras, en die was nie oorskadu is nie. Daar is gevind dat die faktore wat bygedra het tot die jaarlikse groeitempo van A. selago, varieër binne die verskillende liggings, en bedekking deur epifiete. Dit beklemtoon die belang van spesifisiteit van ligging wanneer groeitempo in en tussen die liggings van verskillende hoogtes bepaal word. Die blaar eienskappe het verskil tussen verskillende liggings, as gevolg van plaaslike habitat toestande, soos topografie en bedekking deur epifiete. Soos verwag, het die blare wat oorskadu was deur A. magellanica ‘n groter spesifieke blaar area getoon as blare wat blootgestel was. Die hoeveelheid en digtheid van Agrosits magellanica was verwant aan hoogte bo seespieël, met A. selago wat fasiliterende effekte toon op A. magellanica. Die tendens waargeneem in hierdie studie is dat ten spyte van die algemene fasiliterende effek van A. selago op A. magellanica, die abiotiese omgewingsdrempel op ‘n laer hoogte is vir A. magellanica as vir A. selago. Fenologiese verskille was ook duidelik tussen die drie liggings. Die doel van die eksperimentele deel van die studie was om die effek van die dominante epifiet, A. magellanica, te bepaal op bioties relevante mikroklimaat temperature, asook op die fenologie en fiesiese toestand van A. selago. Verskeie behandelings is aangewend op die kussingplante by die drie liggings om die effek van skaduwee van die epifietiese A. magellanica op die plante te bepaal, asook die effek van versteurings versoorsaak deur die behandelings. Azorella selago se mikroklimaat temperatuur het geen betekenisvolle verskille tussen behandelings getoon nie, wat voorstel dat epifitiese A. magellanica oor die algemeen geen effek op die kussingplante se mikroklimaat temperatuur het nie. Daar was ‘n negatiewe verwantskap tussen die hoeveelheid epifiete op A. selago en die persentasie blomme en blomknoppe op die kussingplante. Die plante se vitaliteit was ook afhanklik van epifiet bedekking, met ‘n hoër vitaliteit telling vir kussingplante bedek met lae gras as die bedek met hoë gras. Dit toon dat A. magellanica met A. selago wedywer, terwyl A. selago vir A. magellanica fasiliteer. Hoë epifiet getalle het negatiewe effekte op A. selago se vegetatiewe en reproproduktiewe nakoming, asook die kussingplante se vitaliteit. Die resultate van hierdie studie toon dus dat die vegetatiewe en reproduktiewe nakoming van A. selago en kussingplant vitaliteit heel moontlik negatief geaffekteer sal word indien klimaatsverandering op Marion Eiland hoër epifiet getalle op die sleutel kussingplant spesie tot gevolg sal hê.

Thesis (MSc)--University of Stellenbosch, 2006. / ENGLISH ABSTRACT: Understanding the responses of species to climate change is a scientific problem that requires urgent attention, especially under current conditions of global climate change. The large and rapid rates of climate change reported for sub-Antarctic Marion Island makes the island highly suitable for studying the biotic consequences of climate change. Furthermore, the extreme environments on the island result in a close coupling of the biotic (e.g. population dynamics) and abiotic (e.g. climate) factors. Therefore, examining the response of the dominant and keystone plant species on the island, Azorella selago Hook. (Apiaceae), to climate-associated environmental change (e.g. temperature) may provide insight into how A. selago and the associated species communities will be affected by climate change. This study described the variability in microclimate temperatures associated with A. selago across altitudinal gradient and between the eastern and western sides of Marion Island. Microclimate temperatures were also compared to the island’s Meteorological data to determine variation between temperatures experienced by A. selago cushion-plants in the field and those recorded at the island’s Meteorological Station. Temperature variation inside and outside A. selago cushions was also examined. Azorella selago cushions were found to have a buffering effect on temperature, such that species occurring epiphytically on A. selago experience more moderate temperatures than the surrounding environment. However, A. selago were found to experience more extreme temperatures than temperatures recorded at the Meteorological Station. Therefore, A. selago may possibly experience greater environmental warming than recorded by the Meteorological Station. While temperatures decline with altitude, temperature conditions on the western side of the island were more temperate than the eastern side. This presents the first record of temperature conditions on the western side of the island. This study also quantified fine-scale (e.g. within-site) and broad-scale (e.g. island-wide) variability patterns of A. selago (morphology, phenology, and epiphyte load) across Marion Island. Altitudinal gradient and climatic exposure at different sides of the island were used to understand the likely effects of climate associated environmental change on this dominant component of the fellfield habitat. Site-specific processes were found to determine the spatial structure of A. selago characteristics at fine-scales. However, broad-scale observations established strong responses of A. selago characteristics to altitudinal gradients and different sides of the island. Azorella selago morphological features (e.g. plant size and leaf size) were found to be more responsive to differences between the eastern and western sides of the island than to altitudinal gradient. Azorella selago micro-morphological features (e.g. leaf trichomes and stomatal densities) were also found to be more responsive to climatic exposure at different sides of the island than to altitudinal gradient. However, differences in A. selago epiphyte density (e.g. Agrostis magellanica) and phenology resembled microclimate temperatures in that they were more responsive to altitudinal gradient than to side of the island differences. From these results it can therefore be predicted that the A. selago of Marion Island is likely to be morphologically fairly resilient to moderate climatic shifts, although at lower altitudes and on the eastern side of the island, it may be outcompeted by the epiphytic grass, Agrostis magellanica. The results also suggest that the warming climate of Marion Island may result in an early occurrence of phenological processes particularly at lower altitudes and the eastern side. Azorella selago at lower altitudes and on the eastern side of Marion Island are therefore expected to largely show more symptoms of climate change (e.g. warming) on this species. Azorella selago is also predicted to move up altitudinal gradients in response to warming. / AFRIKAANSE OPSOMMING: ’n Begrip van hoe spesies reageer op klimaatsverandering is ’n wetenskaplike vraag wat onmiddellike aandag benodig, veral onder huidige globale klimaatsverandering. Die groot en snelle tempo waarteen klimaatsverandering waargeneem word op sub-Antarktiese Marion Eiland, maak die eiland hoogs geskik om die biotiese gevolge van klimaatsverandering te bestudeer. Verder veroorsaak die uiterste omgewing van die eiland tot ’n nabye koppeling tussen die biotiese (bv. populasie dinamika) en abiotiese (bv. klimaat) faktore. Dus, deur die reaksies van ’n dominante- en sleutel-spesie op die eiland, Azorella selago Hook. (Apiaceae), op klimaat-geassosieerde omgewings verandering (bv. temperatuur) te bestudeer, mag insig verskaf hoe A. selago en geassosieerde spesie gemeenskappe geaffekteer sal word deur klimaatsverandering. Hierdie studie beskryf die wispelturigheid in mikroklimaat temperature geassosieer met A. selago oor ’n hoogte gradiënt asook tussen die oostelike en westelik dele van Marion Eiland. Mikroklimaat temperature was ook vergelyk met die eiland se Meteorologiese data met die doel om die mate van variasie tussen temperature verduur deur A. selago kussing-plante in die natuurlike omgewing met die van die eiland se Meteorologiese stasie te vergelyk. Temperatuur variasie binne en buite A. selago kussing-plante is ook vasgestel. Dit was gevind dat Azorella selago kussing-plante die temperatuur buffer, met die gevolg dat spesies wat epifities op A. selago voorkom, meer gematigde temperature ondervind as die onmiddellike omgewing om die plant. Daar is egter gevind dat A. selago meer uiterste temperature ondervind as temperature gemeet by die Meteorologiese stasie. Dus mag A. selago groter omgewings verwarming ervaar as wat temperature gemeet by die Meteorologiese stasie dui. Terwyl temperatuur afneem met ’n toename in hoogte, was temperatuur aan die westekant van die eiland mere gematig as die oostekant. Dit verskaf die eerste rekord van temperatuur toestande aan die westekant van die eiland. Hierdie studie bepaal ook die fyn-skaal (e.g. binne-terrein) en groot-skaal (e.g. oor die eiland) variasie patrone van A. selago (morfologie, fenologie, en epifiet lading) oor Marion Eiland. Die hoogte gradiënt en klimaat blootstelling aan verskillende kante van die eiland is gebruik om die waarskynlike effekte van klimaats-geassosieerde omgewings verandering op die dominante deel van die felfield habitat te verstaan. Daar is gevind dat terrein spesifieke prosesse die ruimtelike struktuur van A. selago se klein-skaal eienskappe bepaal. Groot-skaalse waarnemings dui egter ’n sterk antwoord van A. selago eienskappe op die hoogte gradiënt en aan verskillende kante van die eiland. Azorella selago morfologiese eienskappe (e.g. plant- en blaar grootte) is gevind om meer te reageer op verskille tussen oostelike en westelike kante van die eiland as op die hoogte gradiënt. Azorella selago mikromorfologiese eienskappe (e.g. blaar trigome en stomata digtheid) is ook gevind om meer te reageer op omgewings blootstelling tussen verskillende kante van die eiland as op die hoogte gradiënt. Verskille in A. selago epifiet digtheid (e.g. Agrostis magellanica) en fenologie het egter mikroklimaat temperature gevolg, in dat beide meer gereageer het op die hoogte gradiënt as eiland-kant verskille. Hierdie resultate voorspel dus dat dit waarskynlik is dat A. selago van Marion Eiland morfologies redelik terugspringend sal wees ten opsigte van matige klimaatsverandering, al mag dit uitgekompeteer word deur die epifitiese gras, Agrostis magellanica by lae hoogtes en aan die oostekant van die eiland. Hierdie resultate dui ook dat verwarming van Marion Eiland se klimaat ’n vervroeging van fenologiese prosesse mag hê, veral by lae hoogtes en aan die oostekant van die eiland. Dus word dit verwag dat Azorella selago by lae hoogtes en aan die oostekant van Marion Eiland om meer simptome van klimaatsverandering (e.g. verwarming) te dui. Dit word ook voorspel dat Azorella selago opwaarts teen die hoogte gradiënt sal beweeg in reaksie tot verwarming.