Petroleum Products

It has been variously estimated that >106 tonnes of petroleum hydrocarbons are yearly released into the marine milieu (NAS, 1975). Public sensitivity to the visual effects of oil slicks and tar balls (Butler, 1975a) ensures that this pollution problem attracts wide attention. The global distribution of pelagic oil and tar balls closely follows established tanker shipping routes (Levy et al., 1981). Anecdotal evidence, and what few data there are (e.g., Benzhitsky and Polikarpov, 1977; Mileykovskiy, 1979; Levy etal., 1981; Maslov and Nesterova, 1981; Ventajasand Comes, 1982), indicate that, by comparison with the North Atlantic and other heavily traversed waters, or near major industrial and population centres, those encircling Antarctica remain virtually pristine. Nevertheless, Maslov and Nesterov (1981, fig. 1), in a small scale and much simplified map, defined an isolated patch of Subantarctic water to the south of New Zealand and Tasmania where surface oil film occurs in 5% of observations (number of stations is not stated).

With increased tanker and other shipping traffic around southern Africa over the past two decades, there have been several major accidental oil spills and numerous minor incidents, and today relatively high levels of chronic oil pollution exist around the region (cf. Watling, 1980). Oil slicks and tar balls are not uncommon in surface waters around and south of Cape of Good Hope, but they disperse rapidly in these stormy seas (Eagle et al., 1979). As the "residence time" is unlikely to exceed one year (Butler, 1976b) and may be as little as 58 days (Levy and Walton, 1976), it is highly improbable pollutants from this source would ever reach waters to the south of New Zealand, for the drift transit time is a year or so (Gregory, 1987).

In August 1974, following the grounding of the VLCC Metula, over 400,000 barrels of light Arabian Crude were released into the Straits of Magellan. There was no clean-up response, and approximately 250 km of shoreline were contaminated. The environmental impact was considerable and included destruction of a tern (Sterna hirundinaceae) breeding colony which had not re-established 5 years after the event (Guzman and Campodonico, 1980). On the other hand, kelp (Macrocystis yyrifera) beds were little affected. Extensive ashphaltic pavements persist to this day, with some samples showing little evidence of weathering (Gundlach et al., 1982; Owens et al., 1987).

Similarly, there is evidence from South Georgia's abandoned shore whaling station that the impact of massive local hydrocarbon spills persists for many years, although the marine environment ultimately recovers (Piatt, 1979).

New Zealand Waters

Stranded pelagic tar balls and degrading oily residues are rare to absent on New Zealand shores (Gregory, 1977; Oostdam, 1984) as they are elsewhere across the South Pacific Ocean (Lee, in Butler et al., 1973; Bourne, 1976; Oostdam, 1984). Even near production, storage and refinery facilities at New Plymouth and Whan-garei, as well as other major ports, they are rarely encountered, and those that are have a short life expectancy on either beaches or rocky shores (pers. observ.). Whilst minor oil spills occur from time to time, clean-up response is quick, environmental impacts appear minimal, and the visual evidence seldom persists (Fig. 11.10).

Fig. 11.10. A rare sight: tar balls stranded on a sandy beach near Whangarei, northern New Zealand.

Rare oily residues and tar flecks have been recorded from Cook Strait, off Banks Peninsula as well as east of the southern South Island of New Zealand and across Chatham Rise. None has yet been recognized at over forty stations southwards across Subantarctic waters and the Polar Front to the Ross Sea (Fig. 11.5; Gregory et al., 1984b; Gregory, 1987). No tar balls or tarry encrustations have been observed on Ross Sea shores or those of New Zealand's Sub-antarctic islands despite the high level of fishing activity around the latter region (Gregory et al., 1984b; Gregory, 1987).

Oiling of Penguins and other Seabirds

Being completely aquatic, penguins are far more vulnerable to oil pollution than flighted seabirds (Clark, 1984). Around southern Africa, the Jackass Penguin (Spheniscus demersus) has been subjected to quite severe oil pollution with fatalities numerous and frequent (e.g., Randall et al., 1980), although an extensive bird-cleaning programme has been initiated (Kerley and Erasmus, 1987). Deaths amongst the sympatric Cape Gannet (Sula capensis) are less common. The Magel lanic Penguin (Sphensicus magellanicus) of Argentinian shelf waters is under similar threat (Jehl, 1975; Perkins, 1983) but the problem here appears much less than around southern Africa.

Other major penguin populations lie south of, or remote from, major shipping routes, and are unlikely to be subjected to other than occasional oil pollution. However, there are a disturbing number of oiling reports from higher southern latitudes, which fortunately to date have involved only a few individuals. Although Croxall et al. (1984) has noted that oil pollution is not a problem for seabirds around the Antarctic Peninsula, isolated instances of fouling of Adelie Penguins (Pygoscelis adeliae) in the vicinity of Palmer Station are known (Parker, 1971). From South Georgia, Jehl et al. (1979) have reported freshly oiled Gentoo Penguins (Pygoscelis papua), while Copestake et al. (1983) recorded the oil staining of a single King Penguin (Aptenodytes patagonica). At Marion Island, several hundred oiled Rockhopper Penguins (Eudyptes crestatus) have been seen (Kerley and Erasmus, 1987). Minor oil pollution has occurred at Biae du Marin, lie de la Possession, Crozet Islands, and also at Grande Terre, Kerguelen Islands, where in 1980 a Russian tanker ran aground spilling 600 tonnes of petroleum (Jouventin et al., 1984). In none of these instances does the writer know of any report of seabird fatalities.

Sightings of oiled seabirds are not infrequent around New Zealand. Fortunately, the numbers involved are generally low. An environmentally more serious incident was the spillage of over 20,000 litres of fuel oil in Lyttelton Harbour in July 1965, which spread over a distance of almost 50 km and resulted in the loss of many seabirds (Norris, 1965). The worst affected were Spotted Shags (Stictocarbo punctatus) and White-flippered Penguins (Euptytula albosignata). Giant Petrels (Macronectes giganteus), Red-billed Gulls (Larus novaehollandiae scopulinus) and Black-backed Gulls (Larus dominicanus) were also affected.

During the 1972 Snares Islands Expedition, D.S. Horning (pers. comm.) observed the landing of a Snares Crested Penguin (Eudyptes robustus) with oil staining on its chest. There have been no further reports to this author's knowledge. During the 1985 Subantarctic Islands Expedition, no sightings were made of oil-fouled penguins or any other seabird for that matter (Gregory, 1987).

In January 1979, at least 20 oil-fouled Adelie Penguins (Pygoscelis adeliae) were seen at Cape Bird, Ross Island, Antarctica (Wilson, 1980). The source of this contamination was never established. It most probably came from either bilge pumping or a small spill from a passing vessel. However, there is also the possibility of a natural seep, although none has yet been reported from Antarctica (cf. Wilson et al., 1974).

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