Impact of Fur Seals on the Terrestrial Environment at South Georgia

Bonner, W. Nigel

doi:10.1007/978-3-642-82275-9_88

Cited by 26 publications

(23 citation statements)

References 2 publications

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Section: Consequencesmentioning

confidence: 97%

“…The dilemma has been well articulated by Bonner (1985) and Smith (1988. Although manuring by seals and seabirds constitutes an important source of nutrients for terrestrial ecosystems (Smith 1978), the recovery of fur seal populations to levels probably higher than they were before exploitation is causing widespread and perhaps irreversible damage to lowland vegetation at South Georgia (Bonner 1985) and the South Orkney Islands (Smith 1988(Smith , 1997. At Bird Island on South Georgia, trampling by fur seals and pressure from their lying on tussocks have destroyed large areas of tussock grass (Poa flabellata) and Antarctic hair grass (Deschampsia antarctica), leading to severe erosion of soil and peat, and have deprived six species of birds of breeding habitat and exposed them to predation by skuas (Catharacta lonnbergia).…”

Section: Consequencesmentioning

confidence: 97%

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Changes in Heard Island glaciers, king penguins and fur seals since 1947

Budd¹

2000

PPRST

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The purpose of this paper is to summarise and discuss the changes in glaciers, king penguins and fur seals reported by the nine wintering parties and 11 summer expeditions that have visited Heard Island since 1947, with emphasis upon those of the years between 1947 and 1971. These early years were notable for an initial period (1947-55) of minimal change, and a subsequent period(1963-71) of rapid change in which a complex pattern of asynchronous glacier retreat and readvance was observed and the main features of the island's recolonisation by king penguins and fur seals were established. Subsequent expeditions have reported continuing glacier recession, evidently in response to warmer air temperatures, and a continuing exponential increase in king penguins and fur seals. The glacier observations show that the Heard Island glaciers are sensitive indicators of climate change in the Southern Ocean, and of the interactions between climate and glacier topography. The island's recolonisation by king penguins and fur seals is attributed mainly to an improved food supply which may itself, like the glacier recession, be a response to changes in atmospheric and oceanic circulation. Glacier recession and its consequences are changing the island's coastline, and the expanding populations of king penguins and fur seals are damaging the vegetation. All these phenomena, occurring as they do in an island with a hitherto undamaged ecosystem and no introduced predators, clearly warrant continuing study.

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Section: Consequencesmentioning

confidence: 97%

Section: Consequencesmentioning

confidence: 97%

Changes in Heard Island glaciers, king penguins and fur seals since 1947

Budd¹

2000

PPRST

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“…In contrast, crevice-nesting blue penguins (Eudyptula minor) appear to be unaffected by seals and were present at 12 of the 29 fur seal breeding colonies at Otago Peninsula in our 1998 census. Fur seals can also displace seabirds ashore by reducing the area available for breeding (Bonner 1985;Croxall et al 1990a;Crawford & Payne 1995).…”

Section: Seabird Habitatmentioning

confidence: 99%

Folklore and chimerical numbers: Review of a millennium of interaction between fur seals and humans in the New Zealand region

Lalas¹,

Bradshaw

2001

New Zealand Journal of Marine and Freshwater Research

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The increase in numbers and range expansion of New Zealand fur seals (Arctocephalus forsteri Lesson) in the New Zealand region has prompted many people to comment on their effects on the marine and coastal environments. Overall there are anomalies in the data describing the distribution and abundance of fur seals in the New Zealand region, and there is a need for a better understanding of the interactions with humans and the impacts on the New Zealand environment. The distribution resulting from the present pattern of re-colonisation differs from the perception of their distribution before decimation by humans. We hypothesise that the pristine distribution was temperate rather than subantarctic. Previously published records which have documented changes in the abundance and distribution of the species are shown to be wanting. The most controversial management issue is interaction with commercial fisheries where we conclude that neither of the Corresponding author. Received 21 April 1999; accepted 20 November 2000 extreme options, culling of seals nor closure of some fishing grounds, is justified. Other issues addressed include tourism, te tikanga Maori o mahinga kai (the customary use of wildlife by Maori), and impact of fur seals on the coastal environment. This species offers a rare and exciting opportunity to test the theoretical processes of population expansion that can be investigated as a natural experiment. We suggest that the current management policy should remain unchanged until the current paucity of information on the degree of interaction between fur seals and humans has been addressed. M99022

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“…On the other hand, seal trampling can create gaps and damage the vegetation layer (Norton et al, 1997), especially when trampling occurs repeatedly or continuously (Bonner, 1985;Gremmen et al, 2003;Hall and Lamont, 2003;Favero-Longo et al, 2011). Moreover, the establishment and dispersal of exotic plant species are often facilitated in areas of increased soil disturbance (MacDougall and Turkington, 2005;Buckley et al, 2007), such as those affected by increasing seal activity.…”

Section: Introductionmentioning

confidence: 99%

Fur seal populations facilitate establishment of exotic vascular plants

Haussmann

Rudolph

Kalwij

et al. 2013

Biological Conservation

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The cessation of seal harvesting has prompted a recovery of previously decimated fur seal (Arctocephalus gazella and A. tropicalis) populations across the Southern Ocean region.Although the associated increase in seal-related soil disturbance is known to impact indigenous vegetation, the effect of increasing fur seal numbers on exotic plant species is not yet clear. Here, we compare plant species composition and cover between 26 sites with 2 high fur seal impact paired with nearby control sites on sub-Antarctic Marion Island. Sealaffected sites had a significantly higher number and cover of exotic plants, specifically of the widespread sub-Antarctic invaders, Poa annua and Sagina procumbens, than control sites. Furthermore, some of the native species, most notably the disturbance-sensitive species, Blechnum penna-marina, were significantly less abundant in seal-affected sites compared to controls. We propose that this is a result of both physical trampling, which opens up niches for exotics by damaging natives, and nutrient enrichment of the soils, giving exotic species a competitive advantage over natives. While other studies have noticed associations between exotic plant species and indigenous animal disturbance, this is, to the best of our knowledge, the first study to empirically show that the successful recovery of fur seal populations can have undesirable side-effects such as the enhanced persistence of exotic plant species. We recommend that alien plant management plans specifically include areas of increased animal disturbance into their programmes.

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Impact of Fur Seals on the Terrestrial Environment at South Georgia

Cited by 26 publications

References 2 publications

Changes in Heard Island glaciers, king penguins and fur seals since 1947

Changes in Heard Island glaciers, king penguins and fur seals since 1947

Folklore and chimerical numbers: Review of a millennium of interaction between fur seals and humans in the New Zealand region

Fur seal populations facilitate establishment of exotic vascular plants

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