The Phoenix Islands, and now PIPA, have faced and continue to face a range of threats to both terrestrial and marine conservation values.
Invasive species are plants and animals that have been introduced to a place where they are not historically native and grow in numbers to where they negatively impact the indigenous ecosystems and species of their new home.
A key reason why the Phoenix Islands support such outstanding flora and fauna values is that the islands have been isolated for millennia. This has enabled the seabirds and other fauna to live and nest safely in the absence of invasive pests and exploit the food rich seas around the islands. Historically, impacts on the Phoenix Islands seabirds and other natural values began soon after their discovery by early Pacific seafarers and continued through the guano mining years and subsequent settlement and development of the islands. The deliberate and accidental introductions of invasive species during all of these periods have been significant in the Phoenix Islands.
Many invasive plants and animals have been introduced to the Phoenix Islands including Pacific and Asian rats, rabbits, cats, ants, pigs, dogs and lantana and other weeds. Impacts can be direct (e.g. predation) or indirect, e.g. subtle changes in habitat and loss of potential source of food (e.g. frigatebirds relying on other birds for food source). Some of the negative impacts these invasives bring include the elimination of native seabirds and plants, particularly through the destruction of the eggs and young, and introduced plants taking over other plant life, modifying the natural island ecosystem.
Mammalian pests have been the most damaging invasives in PIPA threatening the bird populations and entire ecosystems of the Phoenix Islands. Rabbits, cats and different rat species have had significant impacts over time, with some birds (e.g. Phoenix petrels and white-throated storm-petrels) and other biota being reduced to critically low numbers. In fact the most sensitive fauna species survived on only the one island (Rawaki) that escaped rat infestation. Since 2006 an eradication programme has been implemented to remove invasive mammals in PIPA and this is now seeing the gradual restoration of the islands, their habitats and fauna populations.
Invasive mammals and other potential invasives (e.g. foreign ants and weeds) pose ongoing threats to the terrestrial ecology of the islands and this is being addressed through a biosecurity programme.
Increasingly, the impacts of climate change (e.g. coral bleaching) are recognized as a threat to both terrestrial and marine values, and indeed, through sea level rise, to the islands continued existence. Kiribati, as a low lying atoll nation, faces severe threat from both the radiative (sea level rise and warming) and pollutant (acidification) impacts of increasing levels of carbon dioxide, collectively the impacts from climate change. From July to September 2002, there was a sea temperature hotspot in the Phoenix Islands which caused mass bleaching and mortality of corals, most notably in the lagoon of Kanton and leeward reefs of Kanton and Nikumaroro Islands. Monitoring pre and post bleaching indicates rapid recovery of PIPA’s coral reefs, likely due to the absence of other stressors present (e.g. over fishing, pollution, etc.) Terrestrial vegetation and nesting seabird populations are vulnerable to salinization of groundwater due to sea level rise and inundation. There is also concern over the impacts of increasing ocean acidification on coral reefs and other species in PIPA. Due to the absence of other anthropogenic stressors PIPA has a potentially important role to play in researching and understanding impacts of coral bleaching, climate change and resilience of tropical reef systems.
The Phoenix Islands are vulnerable to illegal fishing and overfishing. Most of the impact on marine values in PIPA has been due to over-harvest of marine resources which began with unsustainable whaling (largely targeted the sperm whale breeding ground in these islands during the sail whaling days), through to modern tuna fishing fleets from Distant Water Fishing Nations (DWFNs), and unsustainable and illegal harvesting of inshore resources.
In the early 2000s, a shark fishing vessel operated around several of the Phoenix Islands. The global trade in shark fins is extremely lucrative. Due to the high demand for shark fins used in shark fin soup, global waters are being pilfered for only the fins of its sharks. After an illegal visit by one vessel, shark populations were fished to near-zero levels at one atoll. It was speculated that this one vessel also reduced turtle populations in the islands visited. This case was successfully prosecuted by the Government of Kiribati in 2010.
Kiribati is party to a range of fisheries agreements but has limited capacity for surveillance, enforcement and management. Surveillance and enforcement of Distant Water Fishing Nation (DWFN) vessels, both legal and illegal, remains a significant challenge not only for PIPA but for Kiribati’s entire Exclusive Economic Zone and for the region.
The Phoenix Islands have had numerous vessel groundings over the years. One of the earliest recorded groundings was the whaleship Canton on Kanton in 1854. Undoubtedly, there have been other groundings that were not permanent, did not result in vessel loss, or were not reported. Shipwrecks cause coral damage during grounding and break-up. It is now also becoming clear that rusting shipwrecks add iron to the water around them, and since iron is severely limiting in the Central Pacific, this results in a significant shift of reef ecology to dominance by turf algae, and death of corals. A recent wreck of a fishing vessel at McKean Island in c.2001 resulted in Asian rats exterminating many bird species from the atoll.
Visitors to the Phoenix Islands largely arrive by recreational yachts or increasingly through tourist charters. Some may anchor and stay on one of the Phoenix Islands for extended periods. Some probably do not clear Customs and Immigration at Kanton first and others from fishing boats and freighters have been known to land. There are environmental concerns with unregulated visitors. These include: disposal of sewage and wastes, illegal collection and harvest of terrestrial and marine resources, potential introduction of invasive species, and disturbance of bird populations.
During the 1960s McKean was one of the flagship islands of the Phoenix Group, supporting diverse and important populations of seabirds – there were thousands of blue noddies and white-throated storm-petrels, and several other species of tern and shearwater rivaling the numbers that were present on Rawaki (Phoenix Island). However, Asian rats colonized McKean, apparently when a fishing trawler was wrecked on the island about 2002. A CI-sponsored survey by Pacific Expeditions Ltd in 2006 found that storm-petrels, blue noddies and other petrels and shearwaters had virtually disappeared from the island as a result of intensive predation of adult birds and their eggs and chicks by the rats. Upon creation of PIPA urgent management actions included a restoration program and as a first step the removal of the rats from McKean in 2008. By 2009 the response to pest removal was spectacular with seabirds nesting successfully on McKean for the first time in nearly 10 years.