The impact on seabirds is dramatic, but the effect on other marine species will take longer to quantify.
Kim Westerskov/WWF
When wildlife photographer Kim Westerskov took to the water in the Bay of Plenty, not far from Astrolabe Reef, one sunny day in October last year, the sea looked like what he calls “a football field of solid birds”. As well as two Bryde’s whales and an immense gathering of fluttering shearwaters and storm petrels, the group of photographers he was with saw three endangered blue whales, including a mother and calf.
Westerskov didn’t make it into the murky water that day – probably caused by Nyctiphanes australis, a tiny shrimp-like creature that is preyed on by many species of whales, seabirds, fish and squid – but he now says, “I’m racking my brain to think when I have ever seen more life in the sea than on that day.”
The area around Astrolabe Reef, close to Tauranga, is rich in biodiversity, both above and below the water. It is into this environment that more than 350 tonnes of a viscous sludge-like oil – closer to the consistency of Marmite than to the oil we put in our cars – have leaked from the Liberian-registered cargo ship the Rena, which grounded on the reef in the morning of October 5. When oil started spilling from the boat and dead birds started washing up on Mt Maunganui Beach, Environment Minister Nick Smith declared it New Zealand’s “worst maritime environmental disaster”.
Oil leaking from the ship has so far affected beaches from East Cape to Coromandel, and there are concerns it may reach marine reserves around Mayor Island. While Maritime New Zealand and salvage operators work to pump oil from the Rena and eventually remove the ship from the reef, hundreds of others – from government agencies, NGOs and the local community – are taking steps to reduce the effects on local species.
The most visible impact of the disaster is on the seabirds. At press time, Maritime New Zealand’s tally of dead birds was more than 1300 – including petrels, shearwaters, penguins and even a wandering albatross. But this number is probably the tip of the iceberg, according to Brett Gartrell, director of the Oiled Wildlife Response Centre. He told the Bay of Plenty Times other studies suggest Maritime NZ is seeing only 10% of the affected birds. “So it’s likely that more than 10,000 birds have been killed by this oil spill. Most of them we don’t see simply because the tides aren’t bringing them into the beach. They’re taking them out to sea and they’re being eaten by other marine predators.”
Rebecca Bird, WWF New Zealand’s marine programme manager, joined the Oiled Wildlife Response Team a few days after the Rena grounded. “The beach was oiled as far as the eye could see; we collected so many dead birds that first day. It was horrendous and traumatic, especially as our job was to try to recover as many live birds as we could.” The team, co-ordinated by specialists from Massey University’s Wildlife Health Centre, includes vets, ornithologists and wildlife experts from around New Zealand. “Some of the birds affected by the oil were initially unidentifiable – there was just a beak sticking out of an oil patty,” says Bird.
The Wildlife Response Centre established at Tauranga is now caring for 60 endangered New Zealand dotterels – out of a population of only 100 in the Bay of Plenty – that were captured pre-emptively to ensure their safety. They also have more than 300 little blue penguins and several other birds of various species. The adult penguins – many of which were oiled on shore as they travelled from the sea to their nests – are safe but the eggs or young they were raising will not survive without them.
Although most of the spilt oil settled on the surface or washed ashore, some of the oil was dispersed. To assess the impact of the oil on the wider environment, the University of Waikato’s Chris Battershill, a Tauranga-based specialist in coastal and marine ecosystems, led a team gathering information on the “before” state of local habitats, in particular the estuaries, coastal beaches and rocky islets.
The impact on seabirds is dramatic and highly visible, but the effect on other marine species will take longer to quantify. The whales, the seabirds and krill that so wowed Westerskov on his day in the bay last year are part of a marine ecosystem that also includes common and bottlenose dolphins and many other whale species. On the Astrolabe Reef, the volcanic rock is home to forests of thick kelp and a multitude of brightly coloured sponges, urchins, anemones and bryozoans as well as starfish, molluscs and crustaceans. Around the reef, schools of trevally, mackerel and kahawai swim with the occasional shark, marlin, barracuda or tuna. In the shallow waters and on the rocky, sandy and muddy shores of the bay, 350 species of molluscs – such as paua, snails, mussels, pipi and toheroa – make up 99% of the biomass.
Battershill says a toxic component of the heavy fuel oil – the “polycyclic aromatic hydrocarbons” – is the biggest concern as it is known to cause physiological problems in fish and shellfish. He and his team are awaiting results of analysis of the seawater and coastal sediments, along with samples taken from fish and shellfish, to assess how far the hydrocarbons, or other elements from the ship and its cargo, have entered the local environment. They have yet to complete a bay-wide survey looking for mass mortality of invertebrates, but have so far found no evidence of dead or dying fish or molluscs.
Photo Joel Ford/NZH
Anton van Helden, Te Papa’s marine mammals expert, says the mammals most likely to be affected by the spill are fur seals, four of which have already been found dead. As for the whales – including the Bryde’s whales and beaked whales that feed and breed in and around the bay – that depends on what happens to the krill, fish and squid they feed on. “If prey species are reduced, the animals that depend on them may well be displaced.”
“We think this is a wake-up call,” says Bird. “It happened in relatively calm weather, with a relatively small amount of oil, and it’s killed untold numbers of wildlife, put people out of work and polluted beaches.” WWF, along with other environmental or political organisations such as Greenpeace, Forest & Bird and the Green Party, is calling for a halt to new offshore oil and gas development until the Government takes action to reduce the risk of oil spills and better respond to major spills.
The blue whale, the largest animal on the planet, is endangered, with perhaps as few as 2000 living in the Southern Hemisphere. But Westerskov says it has become an almost regular visitor to the bay. “September and October is whale season,” he says. Westerskov has seen blue whales in the Bay of Plenty for the past three years, and just last month a blue whale mother and calf were seen at Astrolabe Reef. Let’s hope it’s a more welcome marine environment when they visit next year.