forest biota will eventually recolonize streams in former garden areas once a canopy of native trees is re-established.
Oil Palm
In common with clearcut logging, oil palm plantations result in wholesale ecosystem conversion that has broad impacts across entire stream catchments. The creation of a plantation requires initial land clearing equivalent to clearcut logging (which may in fact be the first step if the proposed plantation area is covered with primary forest), after which a new canopy structure of oil palms eventually becomes established. Nutrient inputs from such plantations into adjacent streams appear to be high, probably due to fertilizer and other agrochemical runoff, leading to a proliferation of algae and consequent impacts on the benthic biota. Because oil palm development is generally undertaken on relatively flat lowland sites, it disproportionately impacts the terminal reaches of streams via clearance and drainage channelization of alluvial and swamp forests, with consequent impacts on diadromous biota similar to those described subsequently for mining.
Mining
Large-scale mining operations have had obvious local impacts to certain river systems in Papua, most notably the Ajkwa, which lies downstream of the Freeport Grasberg gold and copper mine. Although large scale-mining produces dramatic local impacts that are highly visible, reasonable attempts to mitigate these impacts, which include siltation, chemical contamination, and catchment dewatering for pipeline slurries, have been undertaken at Grasberg. A more pernicious set of impacts often arises from small-scale gold mining efforts that are common throughout the New Guinea region. As noted by Susupu and Crispin (2001): ‘‘Environmental issues do not seem to be a strong concern for members of the smallscale artisanal mining community. Issues such as damage to river beds, solids in water and destruction of riverbanks are not addressed.’’
The most persistent impact to freshwater ecosystems from such small-scale mining arises not from physical disturbance to streambeds, however, but from the mercury used in the mining process. By way of example, some 4 tons of mercury per year is presently sold to alluvial miners in Papua New Guinea, based on wholesalers’ records (Susupu and Crispin 2001). This mercury is used to extract gold from black sand either in between the sluice-box compartments or via simple panning. In the Wau/Bulolo area, where dredge mining occurred from the late 1920s through the 1960s, bulldozers still occasionally uncover large puddles of mercury, and similar situations are reported from long-term mining sites on Bougainville (Susupu and Crispin 2001). In Papua, local mercury pollution is now also occurring in the Timika area due to illicit gold refining operations being conducted by military units using barrels of concentrate stolen from Grasberg mine. Being non-soluble, mercury remains in river sediments indefinitely, and may be difficult to detect, since it is possible for river water to flow clear of mercury even when high levels of mercury are present in the river bed. Such mercury contamination, however, frequently enters the riverine food chain, where it is amplified through successive trophic levels, eventually posing severe risks to local human populations who consume fish and crustaceans.
In contrast to logging or oil palm plantations, which degrade entire catchments via wholesale landscape conversion, mining effluents generally impact only the main stem of any given catchment, leaving most tributaries undisturbed and available as potential reservoirs of biotic recolonization. The degradation of main stem rivers, however, particularly in the terminal reaches, can have serious impacts on certain diadromous faunal elements such as fish and prawns, preventing completion of the longitudinal migrations essential to their life cycles and thereby potentially extirpating them from certain river systems.
Petroleum
Petroleum development has relatively limited impact on inland waters, because the environmental disturbances associated with it tend to be small, scattered, and highly localized. Outside of the possibility of spills and pipeline leaks, which can obviously have serious short-term local impacts, the major threat from petroleum development results from forest degradation or clearance adjacent to the network of service roads, which provide conduits into previously undisturbed tracts of forest. In general, due to the scattered nature of the operations and shifting well sites, the overall ecosystem impacts of petroleum development are in some aspects similar to those of selective logging or shifting cultivation. In addition, because petroleum operations are restricted to a only a few particular areas in Papua such as the Vogelkop Peninsula, they do not appear to pose a broad-scale threat to freshwater ecosystems in Indonesian New Guinea on the same order as logging or even mining.
Dams
Dams and hydropower developments are sparse in the New Guinea region, and their impacts on freshwater systems are currently minimal. Larger scale projects, such as the proposed large dam on the main stem of the Mamberamo River in northern Papua, would clearly have significant basin-wide impacts were they to be constructed, but such plans are currently shelved due to economic constraints. By contrast, small mini-hydros, which are commonly used in the mountains of New Guinea to provide electricity for local mission stations, have minimal biotic impact.
Ungulates
The impacts of ungulates on New Guinea aquatic systems are underappreciated, but can be significant and extensive, in both upland and lowland areas. In the highlands, cattle grazing has been observed to create widespread slope terracing and converts valley bottoms into muddy marshes, increasing river siltation and water turbidity. Introduced Rusa Deer have similarly impacted savanna lowland habitats in southeastern Papua. Feral pigs, although widespread in New Guinea, have not had the same disastrous impacts to native forests as observed on smaller islands in Polynesia. Feral pigs are intensively hunted throughout the region, which probably serves to keep their numbers in check to some extent. It is unknown if they act as vectors of the water-borne disease leptospirosis, as they do in the Hawai’ian Islands, but this seems likely.
UTILIZATION OF BIOTIC RESOURCES
Live Aquarium Fish Trade
With a single exception, there appears to be little impact on the native fauna due to the live aquarium fish trade. As far as can be determined there is very little commercial harvesting of wild fishes for the aquarium trade with the exception of the illegal trade for Saratoga or Bony Tongue (Scleropages jardinii: family Osteoglossidae), which occurs in the southeastern border area of Papua. Saratoga is popular in the aquarium trade, probably because of its similar appearance to the Asian Arowana (S. formosus), which is a much sought-after ‘‘good-luck’’ fish in eastern Asia, particularly China and Japan, where they are known as Dragonfish. The huge popularity of the Dragonfish has apparently resulted in a demand for other species of bony tongues.
Saratoga is a popular aquarium and sports-fish native to southern New Guinea and northern Australia. It breeds annually just prior to the wet season (September to November). After external fertilization the female orally incubates a brood of about 30–130 eggs until they hatch 1–2 weeks later (Allen et al. 2002). The female then guards the newly hatched young, which remain close to her mouth for the next 4–5 weeks. The young fingerlings are particularly vulnerable at this stage of the life cycle and are easily harvested. The species is protected by law in Indonesia, and subject to various regulations in Australia.
Beginning in the 1990s villagers in the Torassi or Bensbach River area, in the Western Province of PNG immediately adjacent to the border with Papua, have been collecting and selling wild Saratoga fingerlings to merchants from across the border in nearby Merauke (Hitchcock, in press). These fish, as well as illegally captured fingerlings from Papua, are then exported to Asia, where they commanded considerable prices for several years. Australian fish breeders report that saturation of the market by Torassi Saratoga led to a collapse in prices and dramatic decline in demand for the species, which has negatively impacted upon the Australian export trade in wild-caught and captive-bred fingerlings. There is also evidence from local villagers living along the Bensbach River that seasonal harvesting of Saratoga over the past decade has resulted in a dramatic decline in population numbers. Therefore a critical need exists for
