Status of Coral Reefs of the World 2000

Status of Coral Reefs of Australasia
allocated for logging. There are insufficient mechanisms to prevent widespread damage to
reefs from sedimentation as a consequence of this logging. Most of PNG’s reefs are
nearshore and significant inputs of sediments will impact directly on the reefs, but there are
almost no data on elevated sedimentation from past or current logging operations, nor any
monitoring data on reefs affected by logging activities. Increasing stresses on reefs is also
coming from the growing coastal populations, though increased fishing pressure and
pollution from sewage. Fish stocks are already overfished around the largest coastal towns
and high levels of microbial contamination occur in the waters around Port Moresby.
Crown-of-thorns starfish (COTS, Acanthaster planci) are found on many PNG reefs, usually at
low densities, with isolated instances of high population densities, but not as outbreaks.
Consequently, COTS are not yet a major problem on PNG reefs. Blast fishing could be
widespread in PNG and there are examples of substantial damage to some reefs. However,
surveys in other areas where blast fishing is reported have not detected significant damage,
therefore, the effects are relatively localised. Other fishing and collecting activities
probably cause relatively minor physical damage to reefs unless the intensity of activity is
high. Coral mining for lime, oil spills, industrial pollution, mine waste, land reclamation, ship
groundings are probably localised threats.
Attempts to assess anthropogenic impacts to coral reefs in PNG are severely limited by a
lack of data on the patterns and abundances of reef organisms and few data on the
physical and chemical characteristics of the reefs. Thus, the apparent good condition of
PNG reefs must be considered acknowledging this lack of information. Reliable monitoring
programmes are needed, particularly in areas of increasing population pressure and where
anthropogenic impacts are increasing.
Australia
Human pressures are low on Australian reefs as the population density is low, the reefs are
mostly remote from the coast, fishing pressures are moderate to slight and in some areas
virtually non-existent. In particular, the offshore atoll reefs on both coasts are so remote
from the mainland influences that they are only subject to occasional fishing, although the
extent of illegal and international fishing is poorly known. Also many reefs are adjacent to
areas with low rainfall and minimal runoff. Increased levels of nutrients and sediment
entering the GBR system in river discharges are potentially a significant threat to the GBR,
particularly the inner-shelf reefs, however these impacts on coral reefs have never been
measured directly. The major sources of nutrient pollution (nitrate and phosphate) on the
GBR are increased runoff from large areas cleared for cattle grazing, enriched runoff from
sugar-cane and banana farming and domestic sewage. Education and extension
programmes run by the Department of Primary Industry and reef managers have raised
awareness and lead to improved practices in the rural sector. Monsoonal flood events are
the major vectors of sediment and nutrient pollution, particularly from grazing lands laid
bare after long periods of droughts. Cane and banana farmers are regulating their use of
fertiliser to minimise runoff loss. The practice of green tillage of crops and trash blanketing
(leaving the trash on the ground as compost and not burning crops) is increasing, which
reduces sediment and nutrient loss. All tourist resorts and cruise boats are required to
either treat sewage or dispose of it so that there is no pollution (tertiary treatment).
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