in the cold, windy and wet Southern Ocean (Fig. 8.2). The PEIs are of volcanic
origin (Boelhouwers et al. 2008). They support a variety of habitat types which are
largely determined by elevation (cold high elevation areas are devoid of vascular
vegetation), the age of volcanic activity and glaciation activity (older volcanic flows
have often been exposed to glaciation), and, in the coastal zone, by nutrient inputs
due to animal activity and salt spray (Boelhouwers et al. 2008; Gremmen and Smith
2008). The highest points on Marion and Prince Edward Islands are 1242 and 672 m
above sea level respectively.
The PEIs are two of a group of sub-Antarctic islands, which are collectively
considered to be some of the most isolated places on Earth. Much of the importance
of the sub-Antarctic islands lies in the fact that they are the only pieces of land at high
latitudes in the Southern Hemisphere. They are thus essential breeding grounds for
several top oceanic predators (e.g. Reisinger et al. 2018), and are home to many
unique organisms that occur nowhere else. Some species are endemic to one or few
islands, while others are shared amongst several islands of the region (Greve et al.
2005; Griffiths et al. 2009; Shaw et al. 2010; Griffiths and Waller 2016).
Fig. 8.1 (a) A view towards the interior of Marion Island. (b) A house mouse attacking a
wandering albatross chick. Mouse-induced mortality amongst albatross chicks is high. (c) The
invasive collembolan Ceratophysella denticulata. (d) A nutrient-enriched coastal site dominated by
the invasive grass Poa annua. Additionally, a native Azorella selago cushion is being outcompeted
by the invader Sagina procumbens (centre). Photographs: (a) M. Greve; (b) S. & J. Schoombie; (c)
C. Janion-Scheepers; (d) M. Louw
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M. Greve et al.
origin (Boelhouwers et al. 2008). They support a variety of habitat types which are
largely determined by elevation (cold high elevation areas are devoid of vascular
vegetation), the age of volcanic activity and glaciation activity (older volcanic flows
have often been exposed to glaciation), and, in the coastal zone, by nutrient inputs
due to animal activity and salt spray (Boelhouwers et al. 2008; Gremmen and Smith
2008). The highest points on Marion and Prince Edward Islands are 1242 and 672 m
above sea level respectively.
The PEIs are two of a group of sub-Antarctic islands, which are collectively
considered to be some of the most isolated places on Earth. Much of the importance
of the sub-Antarctic islands lies in the fact that they are the only pieces of land at high
latitudes in the Southern Hemisphere. They are thus essential breeding grounds for
several top oceanic predators (e.g. Reisinger et al. 2018), and are home to many
unique organisms that occur nowhere else. Some species are endemic to one or few
islands, while others are shared amongst several islands of the region (Greve et al.
2005; Griffiths et al. 2009; Shaw et al. 2010; Griffiths and Waller 2016).
Fig. 8.1 (a) A view towards the interior of Marion Island. (b) A house mouse attacking a
wandering albatross chick. Mouse-induced mortality amongst albatross chicks is high. (c) The
invasive collembolan Ceratophysella denticulata. (d) A nutrient-enriched coastal site dominated by
the invasive grass Poa annua. Additionally, a native Azorella selago cushion is being outcompeted
by the invader Sagina procumbens (centre). Photographs: (a) M. Greve; (b) S. & J. Schoombie; (c)
C. Janion-Scheepers; (d) M. Louw
208
M. Greve et al.