Jul 24th - Aug 4th, 2000.
The RV Heraclitus followed up this study with another in April 2002.
25.8°C to 30.5°C
The bleaching present appeared to be a natural cycle of random bleaching rather than the beginning of an epidemic.
generally very high, 20m or more
The reef that we chose to study lies on the north side of Nusa Island. On the east side of the reef, closest to the channel between Nusa and Kavieng, the reef slopes quite steeply from 14m up to about 6m then levels off to a long reef flat. This part of the reef receives the brunt of quite heavy wave action.
Further along the reef edge to the west, the wall tends to become steeper - in some places almost vertical - and has developed some recessed ledges where we frequently saw some very large rock lobsters. At this end of the reef, the wave action is a lot less brutal and this was very well reflected in the coral growth.
Coral: The eastern side of the reef comprises a rubble bed upon which small hardy corals are able to colonize. There seemed to be some evidence of storm damage since the reef flat was populated predominantly by small Acropora colonies and little else. The reef slope was covered with fields of Echinopora and Acropora. The rubble/sand flat at the bottom of the reef wall again had small colonies of hard corals. The western end of the reef showed a much higher diversity in hard coral species and also much larger colonies. This reflects the more sheltered environment in which they were growing. Along the rim above the ledges, there were large fields of dead man's fingers soft corals. The site showed all the signs of being a backreef - with strip like valleys on the bottom showing the action of surge.
The general health of the corals was good, but there were random colonies which suffered from overgrowth by coralline algae, macroalgae, sponge or the green and white tunicate.
A small pile of live coral was observed to have been taken from the reef and was drying on a beach on the island - they use coral locally to make lime powder which they chew with their betel nut. However, the amount of coral used in this way is miniscule.
Fish: the predominant fish life at this site is small reef fish - the topography and depth lend themselves perfectly to large aggregations of damsels, parrot, surgeon, butterflyfish, wrasses. The biodiversity within these fish families was incredibly high, especially noticeable among the wrasses - for example, in the course of four fish identification dives, over twenty different species were observed. There were no cardinal fish at all. The reef was a flourishing nursery for juvenile flagtail and peacock groupers and leopard hinds. There were reasonable numbers of snappers and emperors but very few sweetlips. At the bottom of the wall, there were regular passages of jacks, large dogtooth tunas and very large schools of striped mackerel. An eagle ray was spotted once during the study.
The reef is used by the islanders of Nusa for subsistence fishing. There are no large scale fishing operations in the immediate area here right now. Some Japanese and Taiwanese ships passed through a couple of years ago but didn't stay long and didn't cause too much harm by local accounts. The most common fishing method is line fishing - there were few spear fishermen. The fishermen have nets but use these at sea, not on the reefs. There is a very large population of the highly prized barramundi cod and rock lobsters a little further out to sea from our study site. The fact that these two valuable commodities have not been exploited by the local fishermen for profit reflect their lack of intent to exploit the reefs for commercial benefit. There is a strong sense of understanding amongst the islanders of how important a healthy reef is to their future and a very keen desire to see more of what it is they hold in their hands - we videoed the reef and they were desperate to see the footage.
The shoreline is a little rugged. The tides are fairly large.
Nusa Channel appears to be a stopover for live-aboard boats in PNG - during our month's stay here we encountered three large live-aboard vessels. They dived frequently at a site north of our study site called Echuca Patch - a reef patch that starts at 16m with a small wreck. They did not dive near the study site.