Ecology of Indonesian Papua Part Two. Andrew J. Marshall
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ascidians (sea squirts), which produce tadpole larvae that go only short distances from their parents. As with corals and fish, the actual ranges of these species may be largely determined by their ability to raft, because rafting can spread widely even species with no larval dispersal phase.
A very different view is presented by Fenchel and Findlay (2004). They report that most microbial marine organisms are cosmopolitan, and that the percentage of species found at one temperate marine location that have large ranges decreases with increasing body size. If this should also prove true of coral reefs, then groups of small organisms that are highly endemic, like amphipods, may be unusual. It may be that only groups like amphipods, sponges, and ascidians have high rates of endemism on coral reefs. Or it may be that that the largest organisms and microbes have low endemism, but intermediate size (small) organisms have high rates of endemism.
If there are large numbers of small, undescribed, and unstudied species on coral reefs that are likely to be endemic, it will not be practical to study each species to determine its range. We will not know the ranges of even a fraction of the small species on coral reefs any time in the near future. Long before we can know which species are endemic, coral reefs may be highly degraded, and endemic species lost before they are even discovered. The primary cause of species extinctions is loss of habitat. The best way to save large numbers of small endemic undescribed coral reef species is to protect the habitat itself, without taking the time to discover all the tiny endemic species. Further, the number of small species present at a site is almost certain to be proportional to the number of large species found there. Bellwood and Hughes (2001) found that there is a high correlation between the diversity of organisms in one size group with those of another size group. Thus, the diversity of large species such as corals and fish is likely to be a good indicator for the diversity of small species. Although we know that low diversity coral reefs have a higher proportion of endemic species among large organisms than high diversity reefs, high diversity reefs are likely to have much higher absolute numbers of small endemic species than low diversity reefs. Thus, the conservation of both low and high diversity coral reefs is important. Further, while large species (‘‘charismatic megafauna’’) may capture public support, small endemic species will not (‘‘save the amphipods’’?). Coral reefs, however, are highly charismatic, and have generated significant public support for conservation.
Threats to Papuan Reefs
Coral reefs face threats from a wide variety of human sources. The ‘‘Reefs at Risk’’ program (Burke et al. 2002) identified six principle threats to coral reefs, and evaluated five of those. The five threats they evaluated were coastal development, marine-based pollution, sedimentation and pollution from inland sources, over-fishing, and destructive fishing. The sixth threat was climate change and coral bleaching. Their method was to identify sources of human pressure that produce stress on coral reefs and represent these sources of stress on a map. They developed distance-based rules by which the level of threat declines with distance from the source of the stressor, such as the distance from a river mouth, city, and so on. For Indonesia, destructive fishing (i.e., blast fishing) turned out to be the biggest threat to coral reefs, followed by overfishing, sedimentation, marine-based pollution, and coastal development, in that order. Climate change was not evaluated because of the lack of data and inability to predict strong local variations in this relatively new threat.
The Reefs at Risk program identified the reefs most at risk in eastern Indonesia (Burke et al. 2002). In Papua, reefs in the Raja Ampat area to the northwest of the western end of the Vogelkop Peninsula were shown as being under medium threat, while islands just to the south of that and straight west of the western end of the Vogelkop Peninsula, beginning with the Fam Islands and Batanta Island, were shown as being high or very highly threatened. Biak and Yapen Islands on the north side of Cenderawasih Bay were shown as experiencing medium threat, with reefs at the eastern end of Biak viewed as being under low threat. Reefs along the western side of Cenderawasih Bay were shown as having low threat, while those on the east side of the bay were shown as having high or very high threat. Reefs along the Onin Peninsula and just to the east of that on the south shore of Papua were shown as having medium to low threats. The Aru Islands south of the main landmass of Papua were shown as having high or very high threats. The primary and almost only immediate threat to the coral reefs of Papua was identified as destructive fishing. The two types of destructive fishing that were identified were poison fishing and blast fishing. Poison fishing today uses cyanide to stun and catch fish, and blast fishing utilizes homemade explosives made of fertilizer in bottles.
The Conservation International 2002 Rapid Assessment of reefs in the Raja Ampat Islands found evidence of destructive fishing practices at 13% of the sites visited. Slight fishing pressure was evident at 32 of the 45 sites, and moderate pressure observed at one site. A total of only seven sharks, two Manta Rays (Manta birostris), and only one sea turtle (Hawksbill: Erectmochelys imbricata) were observed by the reef condition team on these 45 sites. Humphead Wrasses were much less common than on less heavily fished sites (Table 5.2.1). Sixteen sites had slight siltation and one site had moderate siltation, with seven of these sites having freshwater input as well. Slight evidence of eutrophication/pollution was observed at eight sites. Nickel mining has been proposed for Gag Island, and there has been some logging of forests. Other stressors such as coral diseases, coral predators, and bleaching were rarely observed (McKenna, Boli, and Allen 2002). In the Raja Am-pats, 90% of the inhabitants lived in coastal areas and depended on marine resources for survival. Humphead Wrasse and groupers (Plectropomus leopardus and P. areolatus) were targeted for the live fish export trade, and cyanide was used to catch them. Shark fins were taken for export, and shark finning was the likely cause for the rarity of sharks. Small sea cucumber and lobster fisheries existed. Illegal fishing methods were used by the poorer communities (Amarmollo and Farid 2002). Although destructive fishing was the main threat to the coral reefs of Papua, we cannot assume that the other threats have not had effects on the coral reefs there. The study by Pandolfi et al. (2003) showed that all 14 coral reefs that they studied around the world showed degradation from human activities, and even the Great Barrier Reef, long thought to be relatively unaffected by human activities, was impacted. Fishing has been allowed on most of the Great Barrier Reef, and even though it is not intense, it has doubled since 1990 and has had an effect. Fish populations in small, strictly protected (i.e., no-take) areas on the Great Barrier Reef are higher than outside those areas. The Raja Ampat Islands to the northwest of the Vogelkop Peninsula have relatively good fish stocks. The average total biomass of fish in 2002 was 209 tons/km2, compared to 124 in Milne Bay Province, Papua New Guinea, 66 in the Togian-Banggai Islands of northern Sulawesi, Indonesia, and 17 in the Calamianes Islands, Philippines (La Tanda 2002). Further, the mean density of groupers was 5.45 per 1,000 m2, compared to 3, 2.7, and 2.9 for each of the other three areas, respectively. The average size of groupers was relatively small (about 25 cm), while at the other three sites they were 20 cm, 20 cm, and 30 cm, respectively. Humphead Wrasses were uncommon (Table 5.2.1), with most individuals under 30 cm length. This species is intensively harvested in this area for export in the live-fish restaurant trade. Further, the reef fish populations are not dominated by apex predators, such as jacks and sharks. The low populations of apex predators in the Raja Ampats indicates that fishing pressure has already made major changes to the structure of fish populations there, while the total biomass indicates that fishing has not yet caused drastic changes to fish populations such as have occurred in many other places in the region.
The long-term future threats to the reefs of Papua are not restricted to destructive fishing and overfishing. If population growth and population transmigration to Papua from western Indonesia continue or intensify, stresses to the coral reefs of Papua will increase with the increasing population and development. Deforestation is currently proceeding rapidly in most other parts of Indonesia, with deliberate forest burning during dry summers causing huge smoke clouds covering large areas where there are intense clearing efforts, such as Kalimantan and Sumatra, with clouds of smoke so large they can be carried to neighboring countries. In the major fires of 1997, smoke from fires in Sumatra provided iron that helped lead to a red tide event that in turn caused the death of coral reefs by asphyxiation. There has been no analogous coral mortality in that area in the last 7,000 years (Abram et al. 2003). Growing world