Benthic Invertebrate Fauna of an Aseasonal ... - CSIRO Publishing

Ma%Freshwater Res., 1995,46,507-18

Benthic Invertebrate Fauna of an Aseasonal Tropical Mountain Stream on Bougainville Island, Papua New Guinea Catherine M. Yule Department of Zoology, James Cook University, Townsville, Australia.

Abstract. The benthic invertebrate fauna of Konaiano Creek, a small aseasonal mountain rainforest stream on Bougainville Island, Papua New Guinea, was studied over a period of 22 months. Konaiano Creek supported a diverse, mostly undescribed, fauna dominated by two closely related species of Simuliidae (55% of the total specimens collected) and two species of Hydropsychidae. Over 182 taxa were recorded, more than half of which were Diptera. Species richness in Konaiano Creek was quite high in comparison with that of similar streams in both tropical and temperate regions. There were 31 species of Trichoptera, but there were no Plecoptera, Mollusca, Psephenidae, or Megaloptera. Although many groups of marine origin such as Gastropoda, Atyidae, Palaemonidae and fish inhabited nearby coastal rivers, these animals were apparently unable to colonize high mountain streams because of the torrential, barren nature of the mid-mountain streams that sharply divide the headwater streams from the lowland rivers on Bougainville Island.

Introduction The freshwater invertebrate fauna of tropical regions remains largely unknown and undescribed, yet many tropical streams are threatened or already devastated by the pressures of growing human populations and development. The freshwater faunal communities of Bougainville Island, a small volcanic island on the western rim of the Pacific, have not previously been studied. In the present study between 1986 and 1989, the fauna of Konaiano Creek, a small pristine mountain rainforest stream on Bougainville Island, was sampled and a comparative study was made of the Bovo River (originating on the same mountain as Konaiano Creek; Yule 1993, 1995). The Jaba River, into which Konaiano Creek flows, has become a barren wasteland because of the discharge from mine tailings over many years, yet no study of the benthic fauna of this river has ever been undertaken. The present research represents one of the relatively few studies of freshwater invertebrate communities of the aseasonal tropics, where rainfall is continuously high and there is no distinct dry season. Previous aseasonal tropical surveys include those of Bishop (1973, the Sungai Gombak in Malaysia), Bright (1982, a small stream in the Caroline Islands), and Turcotte and Harper (1982, a cool Amazon headwater stream in Ecuador). The present study is one of the first long-term studies of freshwater invertebrates in Papua New Guinea. It has been stated that the freshwater fauna of New Guinea is poor (Gressitt 1982; Diamond 1984), although this conclusion was based on an extreme paucity of data. The only published study of freshwater

benthic communities is that of Dudgeon (1990) on two streams in northern Papua New Guinea. Recently, consideration has been given to the issue of temperate versus tropical species diversity of freshwater invertebrates (e.g. Fox 1977; Stanford and Ward 1983; Wolda and Flowers 1985; Pearson et al. 1986; Covich 1988; Lake et ~1.1994).Stout and Vandermeer (1975) and McElravy et al. (1982) concluded that tropical streams have greater faunal diversity than do their temperate counterparts, but other authors have reported contradictory results (e.g. Timrns and Morton 1988; Flowers 1991). The present study of an aseasonal tropical stream aimed to shed further light on the topic. This paper presents the initial results of a 22-month study of the ecology of the benthic invertebrate fauna of Konaiano Creek, in which seasonal faunal dynamics, spatial distribution and trophic ecology were examined (Yule 1993). The study came to a premature conclusion because of the activities of secessionist rebels on Bougainville Island.

Study Site Bougainville Island (Fig. 1) has a total area of about 8600 km2. Geologically, it is part of the Solomon Islands chain and is separated from the islands of New Britain and New Ireland, its closest Papua New Guinean neighbours, by a deep trench. It is comparatively recent in origin: most geological formations are 1.5 to 5.5 million years old and the oldest formations, volcanic rocks, date from the Miocene (22-30 million years ago). A row of volcanoes lies along the island, forming the Crown Prince Range, and there are large areas of uplifted coral limestone in which caves are common. It is not unusual for large rivers to suddenly disappear, flowing underground for many kilometres.

Catherine M. Yule

samples were collected each month. A 4-min kick sample was taken with the aid of a fine-mesh (175 ym) FBA (Freshwater Biological Association) net to increase the likelihood of capturing rarer species and early instars, particularly from the banks and areas inaccessible to a Surber sampler. -Samples were preserved in 70% ethanol and sorted under an Olympus SZH stereomicroscope at a magnification of X20. Adult insects were collected by means of a net swept through the riparian vegetation and preserved in 70% ethanol. Approximately monthly, adults were captured at night by means of a mercury-vapour lamp positioned over a dish of ethanol.

TUGA'NV'Ly

Pacific Ocean

Solomon Sea

*

Study Site

155"~ Fig. 1.

156"

Bougainville Island and location of the study site.

Konaiano Creek is a small stream, 1.2 km long, arising in pristine rainforest on a steep ridge on Mount Negrohead (Figs 1 and 2). It joins the Kawerong River, which flows through Panguna, a now-deserted mining town for Bougainville Copper Ltd, and is diverted around the open-pit copper mine (until 1990 one of the world's biggest) to join the Jaba River. The study site is at 6'18'S, 155"301E(grid reference: 56MQU759031). The climate of Bougainville Island is tropical and remarkably equable throughout the year with regard to temperature, rainfall and humidity. Konaiano Creek is subject to frequent, intense spates but both rises and falls rapidly. The mean annual rainfall (1968-90) at the study site was 4366.8 mm. Rainfall is fairly evenly distributed throughout the year, with no month receiving an average of less than 200 mm. Rainfall tends to be heaviest during the monsoon period from November to April, but the southeasterly trade winds also cause unpredictable torrential downpours, and the highest monthly rainfalls at Panguna were recorded in May (860 mm) and July (1218 mm). The longest recorded period without rain on Bougainville was only 16 days. In Panguna, it rains an average of 23-26 days per month and the mean daily temperature ranges from 2 2 P C to 24°C. The temperature of Konaiano Creek throughout the sampling period ranged from 19°C to 2 4 T .

Materials and Methods Konaiano Creek was sampled monthly from July 1987 until April 1989. Quantitative sampling of the fauna was undertaken with a Surber sampler 20 X 20 cm (400 cm2) in size, with a mesh of 300 ym. Twelve Surber

Results and Discussion Nearly 100000 invertebrates representing over 182 taxa were collected from Konaiano Creek (Appendix 1). Only five of these taxa had been described prior to this study. Owing to taxonomic difficulties, the discrimination of taxa within several groups remains incomplete, particularly for the chironomids, copepods, ostracods and nematodes. More than half the species sampled were Diptera, and the Trichoptera, with 31 species, were also diverse. In terms of numbers, two new species of blackflies (both species of Simulium in the subgenus Morops) were dominant, and two species of hydropsychid caddisflies and two species of baetid mayflies were also abundant in Konaiano Creek. Coleopteran adults and larvae were few in number and low in diversity. The presence of freshwater millipedes and polychaetes was unusual. No Plecoptera, Megaloptera, Mecoptera, Psephenidae, Mollusca, Decapoda (apart from crabs) or fish were found in Konaiano Creek, although snails, prawns and fish are present in coastal streams. The four insect groups occur in Australia and south-eastem Asia, and a stonefly has been recorded from New Britain, which lies between Bougainville and the mainland. It is likely that these insects are unable to cross the water barrier to Bougainville Island because they are all poor fliers. Most of the taxa collected during the sampling period were represented by only a few specimens; 65% of the species were represented by fewer than 21 individuals, an average of less than one animal collected per month. Most of these rare taxa were dipteran larvae (Appendix 1) and it is possible that many of the unidentified Diptera may have been washed in from the surrounding rainforest and so were not naturally inhabiting the stream. Some of these larvae may have been aquatic-inhabitants of phytotelmata and seepages-but without taxonomic or ecological information their status remains uncertain. Gastropods, prawns and fish, animals of marine origin, were diverse and abundant in the coastal reaches of the Bovo River, which arises within 1 km of Konaiano Creek on Mount Negrohead (Yule 1993, 1995). These animals dominated the Bovo community in terms of biomass, yet all were absent from Konaiano Creek and the other mountain streams sampled on Bougainville. The distribution of the benthic invertebrate fauna of Bougainville Island is

Aseasonal Tropical Stream Fauna

1,000 Mt Negrohead Konaiano Creek

Jaba River

0 0

5

10

15

20

25

30

35

40

Empress Augusta Bay

Distance from source (km) Fig. 2.

Elevational profile of Konaiano Creek and the Jaba River.

apparently strongly influenced by the mountainous terrain. The island is bisected along its length by a chain of young, volcanically active mountains, up to 2743 m in elevation, with precipitous slopes. Streams and rivers halfway down the steep mountains on Bougainville, particularly on the eastern slopes where rivers are shorter (the Bovo is only 13 km long), are usually so torrential that algae, moss and benthic invertebrates are very scarce in these regions. The high rainfall falling in intense cloudbursts in the river catchments, combined with the steep nature of these young mountains, means that even boulders several metres in diameter are unstable. Spates in these rivers are spectacular and dangerous. These mid-mountain streams with their frequent waterfalls present an impenetrable barrier to most aquatic animals lacking a flying adult stage. Thus, it seems likely that the gastropods, decapod crustaceans and fish present in coastal rivers such as the Bovo are prevented from colonizing the upper reaches of mountain streams. The two species of crabs in Konaiano Creek would have been able to avoid torrential sections of streams and rivers by walking along the banks. The high numbers of non-insect taxa (snails, shrimp and fish) in the coastal Bovo River compared with the montane Konaiano Creek (where they were entirely absent) is typical of other tropical regions, particularly islands (Covich 1988), but usually at least some species are able to migrate upstream. A more extensive examination along the entire length of several Bougainvillean streams is clearly warranted.

Faunal Afinities Although the freshwater fauna of Bougainville Island was hitherto poorly known and comprises many undescribed species, the new species are not necessarily endemic; knowledge of the aquatic fauna of surrounding islands is even scarcer, and the Papua New Guinean fauna is far from fully described. It is likely that many of the new species found on Bougainville will eventually be found elsewhere, particularly along the Solomon Islands chain (Bougainville is the northernmost island in the chain) and on the nearby islands of New Ireland and New Britain. However, species isolated in mountain-top streams and in volcanic crater lakes may have undergone morphogenetic changes, forming endemic taxa. Most of the fauna of Bougainville Island presumably originated in New Guinea because this large island has served as the major source for other Pacific biotas (Diamond 1984). The freshwater fauna of Bougainville Island has affinities with those of Papua New Guinea, Australia, the Pacific islands and Asia. It is likely that Bougainville has been important in the dispersal of invertebrates from Asia and Papua New Guinea to other Pacific islands owing to its position in the Solomon Islands chain. The faunal affinities of most of the taxa recorded from Konaiano Creek will remain obscure until their taxonomic status has been resolved; nevertheless, comments can be made about some of the species.

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Lieftnckia Kimmins is a genus of damselflies known only from the Solomon Islands immediately to the south of Bougainville (Lieftinck 1963). The genus was regarded by Kimmins (1957) and Lieftinck (1963) as a member of the family Platycnemididae; however, the discovery of the previously unknown larva of Lieftinckia kimminsi on Bougainville Island suggests that it is a megapodagrionid (the larva and adult were associated through rearing in the laboratory). The labial setation and cleft ligula and the horizontal nodate gills with filiform distal segments are similar to those in the Australian megapodagrionids Argiolestes and Austroargiolestes (A. Watson, personal communication). The gills are, however, unique in possessing delicate, lamellar folds on their inner surfaces. No lamellar gill folds are recorded in other Odonata; even the larvae of Lieftinckia salomonis lack them (Lieftinck 1963). However, the other megapodagrionid in Konaiano Creek is similar to Lieftinckia kimminsi in that it possesses the lamellar gill folds, but the entire thorax and abdomen are covered in long, thick hairs. It is an undescribed species, probably in the genus Lieftinckia. The blackflies Simulium (Morops) sp. 1 and sp. 2 were the most common animals in Konaiano Creek, comprising 55% of the total benthic specimens collected. These two closely related species of simuliid are undescribed species of Simulium in the subgenus Morops, the distribution of which is centred on New Guinea (R. Crosskey, personal communication). The larvae, pupae and adults were associated through dissection of larval gill spots and laboratory rearing of pupae. There appear to be at least six species of simuliid on Bougainville Island, all as yet undescribed. R. Crosskey (personal communication) collected specimens of three species in 1965, and the female of another Simulium (Gomphostilbia) species was collected near the Bovo River during the present study. One species of Blephariceridae was found in Konaiano Creek. It is possibly a new species in the genus Apistomyia (Zwick, personal communciation). The tribe Apistomyiini is mostly endemic to the Australasian region. According to Zwick (1981), it is likely that the tribe migrated from Antarctica to Asia via the inner Melanesian arc, leaving remnants in New Zealand and New Caledonia. The fauna of Australia and New Guinea consists of more advanced genera, and Apistomyia may have developed after the tribe reached the oriental mainland, with species of this genus later returning to Australia and Bougainville Island (Zwick, personal communication). Species of Apistomyia may be blown great distances by the wind. Twenty-one species of Chironomidae were identified from Konaiano Creek; three were positively identified to the species level, and the others are probably undescribed species. There were certainly more species present because identifications were not always possible, particularly for the

Catherine M. Yule

large number of very small larvae. The fauna is basically cosmopolitan with Northern Hemisphere affinities. Few chironomid taxa have an AustralianIGondwanaland origin (V. Pettigrove, personal communication). The Ephemeroptera from Konaiano Creek were all new, undescribed species except for Prosopistoma sedlaceki. Six new species (including two species in a new genus; Peters, personal communication) were collected. The genus Prosopistoma occurs in Europe, Africa, Asia, New Guinea, the Solomon Islands (Peters 1967) and north-eastern Australia (Peters and Campbell 1991). I? sedlaceki was first described from specimens collected in the highlands of New Guinea (Peters 1967) and in the Solomon Islands. This is the first record of it from Bougainville Island. Barba sp. 1 is a new species in a recently erected genus (Grant and Peters 1993). Baetis spp. 1,2 and 3 are all undescribed baetids. The Baetidae are widespread and diverse in the western Pacific (Flowers 1990). 'Pseudocloeon' spp. 1 and 2 are baetids in a new genus described from the Fiji Islands by Flowers (1990) but as yet unnamed. Mayfly adults are short-lived and fragile, hence unable to fly great distances, and so are likely to disperse in steps along closely spaced islands (Flowers 1990). Thus, it is likely that Bougainville Island was important in the dispersal of mayflies from Asia and Papua New Guinea towards the outer Pacific islands. The mayfly fauna of New Guinea is largely oriental in origin. All the genera collected from Bougainville have oriental affinities, although all the families have representatives in Papua New Guinea and Australia (Table 1). The most abundant beetles in Konaiano Creek were the hydraenids. They comprised two (or possibly three) closely related species of Hydraena. They are undescribed and unique to Bougainville (P. Perkins, personal communication). Table 1. Distribution of Ephemeroptera families -, absent; +, several species present; ++, many species present Family

Indonesia

Baetidae Caenidae Ecdyonuridae Ephemeridae Ephemerellidae Euthyplociidae Heptageniidae Leptophlebiidae Noephemeridae Palingeniidae Prosopistomatidae Polymitarcidae Siphlonuridae Tricorythidae

o or them Queensland.

New Guinea

Bougainville Australia


The Trichoptera of Konaiano Creek were diverse, with 31 taxa; however, only one species, a hydroptilid, was described prior to this study. It is likely that most of the other larvae are from undescribed species. All the families found on Bougainville are present throughout the Australasian region, except for goerids, which have previously been recorded only from Indonesia (Table 2). Orthotrichia is the most abundant and diverse hydroptilid genus in Konaiano Creek. It is likely to be oriental in origin, although it is diverse in northern Australia and in Papua New Guinea, where 28 species have been recorded (Wells 1991). Hydroptila appears to have a similar distribution pattern except that one widespread species is found in southwestern Western Australia. H. incertula, found on Bougainville, is widespread in the north of Australia and occurs in Papua New Guinea and Borneo (Wells, personal communication). Ugandatrichia cathyae (a species newly described from Konaiano Creek; Wells 1991) is the easternmost representative of a palaeotropical genus. The genus Hellyethira is probably of Australian origin, with several species in Papua New Guinea, one species in Sulawesi, and several in Borneo. The tribe Stactobiini, including Niuginitrichia and Scelotrichia, is represented by only one species in Australia, in northern Queensland. Three genera representing 20 species (13 in the endemic genus Niuginitrichia) are known from Papua New Guinea (Wells, personal communication). Table 2. Distribution of trichopteran families -, absent; ?, status uncertain; +, several species present; ++, many species present Family

lndonesiaA New GuineaA Bougainville ~ustralia*

Atriplectidae Calamoceratidae Calosidae Conoesucidae Dipseudopsidae Ecnomidae Glossosomatidae Goeridae Helicopsychidae Hydrobiosidae Hydropsychidae Hydroptilidae Lepidostomatidae Leptoceridae Molannidae Odontoceridae Philopotamidae Philorheithridae Polycentropodidae Psychomyiidae Rhyacophilidae Stenopsychidae Xiphocentronidae * ~ f t e rNeboiss (1987).

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Two species of crabs occurred in Konaiano Creek: Sendlaria salomonis (Roux) and Rouxana ?minima (Roux). The latter has previously been recorded only from Irian Jaya and the Sepik River (P. Davie, personal communication). Species Diversity The total number of taxa recorded from Konaiano Creek was quite high in comparison with results from other upstream sites sampled in similar ways throughout at least one year in both the seasonal and the aseasonal tropics and in temperate regions (Table 3). All but one of these sites (in the Caroline Islands) is in the Southern Hemisphere. Some variation in the number of species recorded at each site can be explained by the degree of sampling effort and whether difficult and often very rich groups such as chironomids, oligochaetes and nematodes were fully identified. Much of the variation in species richness among the tropical sites can be explained by biogeography. For example, the fewest species were recorded from the stream on the Caroline Islands (Bright 1982), a small, isolated group located in the Pacific Ocean about 900 km north of Papua New Guinea and 900 km east of the Philippines-a long way for freshwater invertebrates to travel. Five of the 10 species there are molluscs and crustaceans and are probably marine in origin, and the other taxa are either good fliers or tiny enough to be blown by the wind or carried by birds. Similarly, the Ecuadorian stream in the Andes, at an altitude of 3300-4000 m (Turcotte and Harper 1982), would also pose colonization problems, and although six times as many taxa were recorded there, species richness is still low. The other aseasonal tropical streams, Konaiano Creek and the Sungai Gombak (studied by Bishop 1973), clearly have many more species than do the above-mentioned two relatively isolated streams. They have a similar fauna in many respects, although Konaiano Creek lacks Plecoptera and Mollusca. Konaiano Creek has a richer fauna than that of Magela Creek in the Northern Territory of Australia (Outridge 1987), although Magela also has an extensive billabong fauna because of the flatter topography and seasonal flooding. The Magela Creek catchment is somewhat isolated from other freshwater systems (by desert rather than oceans) and hence it, too, has an absence of Plecoptera, Megaloptera and Mecoptera. In comparison with the seasonally wet-dry tropical Yuccabine Creek in northern Queensland (Pearson et al. 1986), Konaiano Creek has a poorer caddisfly, chironomid, mayfly, dragonfly and beetle fauna. Pearson et al. (1986) partly explain the richness of these groups in Yuccabine Creek by the increased range of habitats created by the periodic inundation and drying of the stream bed. These conditions have not resulted in a high number of species in Magela Creek, and when one looks at the data for the three seasonal temperate streams, where the habitats are

Catherine M. Yule

Table 3. Comparison of nine sites on tropical and temperate streams with respect to species diversity From Bishop (1973); Bright (1982); Turcotte and Harper (1982); Metzeling et al. (1984); Pearson et al. (1986); Outridge (1987); Yule (unpublished data). All single sites ampled at least three times (generally monthly) throughout the year. Nematoda and some Chironomidae in Konaiano Creek not identified to species Group

Number of Taxa Tropical-aseasonal Konaiano

Gombak

Caroline

Tropical-seasonal Andes

Yuccabine

Magela

Temperate-seasonal Toorongo

Loch

Painkalac

Coelenterata Temnocephalidea Turbellaria Nematoda Nematomorpha Mollusca Polychaeta Oligochaeta Hirudinea Diplopoda Hydracarina Araneae Cladocera Ostracoda Copepoda Syncarida Amphipoda Isopoda Decapoda Collemhola Plecoptera Ephemeroptera Odonata Herniptera Neuroptera Mecoptera Megaloptera Chironornidae Simuliidae Other Diptera Lepidoptera Trichoptera Coleoptera Total taxa

also variable with regard to inundation and undergo greater temperature changes, the species richness in these streams is clearly lower than that in both Yuccabine and Konaiano Creeks. Nevertheless, the absence of seasonality in Magela Creek and the temperate streams might result in a lowering of diversity (not an easily tested hypothesis). When one ignores the data from the three geographically isolated tropical streams (Caroline, Andes and Magela), it is clear that Yuccabine Creek, the Sungai Gombak and Konaiano Creek support a greater number of species than do the temperate Loch and Toorongo Rivers (Metzeling et al. 1984) and Painkalac Creek (Yule, unpublished data) in south-eastern Australia. The Odonata, Hemiptera, Lepidoptera and, to a lesser extent, the Diptera and Trichoptera are clearly more diverse in these tropical

streams than in the temperate ones, and only the plecopteran fauna is richer in the cooler temperate streams. Mechanisms to account for observed differences between temperate and tropical species diversities are no doubt numerous, with different groups responding to the different environments in different ways. Flowers (1991) discovered large variations in diversity of the benthic communities of 25 streams he studied in Panama in the aseasonal tropics. He concluded that patchiness of resources and local conditions are more important than latitudinal gradients in explaining the diversities of aquatic insect communities. He further argued that although the high botanical diversity of tropical rainforest has allowed a concomitant diversification of their terrestrial insect inhabitants (Erwin 1988), such great botanical diversity does not occur in tropical streams and so


diversification of aquatic insects is not necessarily to be expected. Yet, it is possible that the great diversity of detrital inputs into tropical streams could influence the diversity of consuming organisms. A possible factor involved in the issue of species diversity is the relative sizes of benthic invertebrates between temperate and tropical streams. Adult size of ectothermic taxa was found to be smallest under warmest environmental conditions in 85% of 89 cases examined by Hogue and Hawkins (1991). Further, individuals from warmer temperature regimes tend to have shorter lives (Sweeney 1984). It was noticeable that the inhabitants of Konaiano Creek and the Bovo River were all very small and that the insect larvae developed very rapidly to emerge as very small adults. The small sizes of the benthic invertebrates enabled high densities and thus potentially a larger number of species could inhabit a certain area of stream bed within a certain space of time in a tropical stream in comparison with a temperate stream, where insects tend to be larger and longer-lived. This study supports the conclusion of Stout and Vandermeer (1975) that tropical streams have greater diversity than do their temperate counterparts, although biogeography, particularly as it relates to ease of colonization, clearly has a strong influence upon species richness. Differences among streams with respect to habitats, geological age and recent geomorphological history also influence faunal diversity. The present study suggests that a larger number of species may inhabit tropical streams than inhabit temperate streams because of the smaller size and more rapid life cycles of tropical freshwater invertebrates.

Acknowledgments This paper is based on a Ph.D. thesis submitted to James Cook University, Queensland, Australia. I thank my supervisor, Dr Richard Pearson, and also Alena Glaister, who sorted many of the samples. The following are greatly thanked for their assistance in identifying the fauna: Trichoptera-Alice Wells (Museum of the Northern Territory), Ros St Clair (James Cook University), and Arturs Neboiss, John Dean and David Cartwright (Melbourne and Metropolitan Board of Works); Ephemeroptera-Bill Peters and R. W. Flowers (Florida A & M University, USA); Coleoptera-Chris Watts (South Australian Museum) and Philip Perkins (US Department of Agriculture); Chironomidae-Vince Pettigrove (Rural Water Commission, Victoria); Simuliidae-Roger Crosskey (British Museum Natural History); Blephariceridae-Peter Zwick (Limnologische Fluljstation des Max-PlanckInstituts fiir Limnologie); Odonata-Richard Rowe (James Cook University) and Tony Watson (CSIRO); CrustaceaPeter Davie (Queensland Museum); Acarina-Mark Harvey

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(Western Australian Museum). Meteorological and hydrological data were obtained from the Hydrology Section, Bougainville Copper Ltd. This research was supported by a Gordon Lewis Fellowship, for which I am very grateful. This paper is dedicated to my friends Christopher and Maria, who died during the troubles on Bougainville.

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Neboiss, A. (1987). Preliminary comparison of New Guinea Trichoptera with the faunas of Sulawesi and Cape York Peninsula. In 'Proceedings of the 5th International Symposium on Trichoptera'. (Eds M. Bournaud and H. Tachet.) pp. 103-8. (Junk: Dordrecht.) Outridge, P. M. (1987). Possible causes of high species diversity in tropical Australian freshwater macrobenthic communities. Hydrobiologia 150, 95-107. Pearson, R. G., Benson, L. J., and Smith, R. E. W. (1986). Diversity and abundance of the fauna in Yuccabine Creek, a tropical rainforest stream. In 'Limnology in Australia'. (Eds P. De Deckker and W. D. Williams.) pp. 329-42. (CSIROIJunk: Dordrecht.) Peters, W. L. (1967). New species of Prosopistoma from the Oriental Region (Prosopistomatoidea:Ephemeroptera). Tijdschrift voor Entomologie 110, 207-22. Peters, W. L., and Campbell, I. C. (1991). Ephemeroptera. In 'The Insects of Australia'. 2nd edn, pp. 279-93. (CSIROMelbourne University Press: Melbourne.) Stanford, J. A., and Ward, J. V. (1983). Insect species diversity as a function of environmental variability and disturbance in stream systems. In 'Stream Ecology: Application and Testing of General Ecological Theory'. (Eds J. R. Barnes and G. W. Minshall.) pp. 265-77. (Plenum: New York.) Stout, J., and Vandermeer, J. (1975). Comparison of species richness for stream-inhabiting insects in tropical and mid-latitude streams. American Naturalist 109. 263-80.

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Appendix 1. Species recorded from Konaiano Creek Mean, average of total monthly abundance (4800 cm2); s.e., average of monthly s.e.; C.V., coefficient of variation of monthly means; Months, number of months taxon recorded during the sampling period (max. 21); *, identification incomplete Taxon Ephemeroptera Leptophlebiidae Barba sp. 1 Baetidae 'Pseudocloeon' sp. 1 'Pseudocloeon' sp.2 Baetis sp.1 Baetis sp.2 Baetis sp.3 Prosopistomatidae Prosopistoma sedlaceki Odonata Aeshnidae Aeshnidae sp.1 Megapodagrionidae Megapodagrionidae sp.1 Liefinckia kimminsi Platycnemididae Platycnemididae sp.1 Coenagrionidae Ischnura sp.1 Trichoptera Hydropsychidae Hydropsychinae sp.1 sp.2 pupae sp. 1 pupae sp.2 Hybrobiosidae Apsilochorema sp. 1 Apsilochorema pupae sp.2 Hydroptilidae Hydroptilidae spp. sp. 1 sp.2 Orthotrichia sp. 1 Orthotrichia sp. 2 9.48 sp.2 pupae Orthotrichia sp. 3 Orthotrichia sp. 4 Orthotrichia nr aberrans Ugandatrichia cathyae Hellyethira sp.1 'Maydenoptila sp.' Maydenoptila sp.2 Hydroptila incertula Niuginitrichia sp. Scelotrichia sp. Philopotamidae Chimarra sp. 1 Chimarra sp. 1 pupae Chimarra sp. 2 Chimarra sp. 3 Unident. genus sp. 1 sp.2 Philopotamid pupae

Mean

s.e.

C.V. (%)

Months

Catherine M. Yule

Appendix 1 (continued) Taxon Polycentropodidae Nyctiophylax sp. 1 Polycentropodid pupae Leptoceridae nr Triaenodes sp. 1 nr Triaenodes sp. 2 sp. 2 pupae sp. 3 sp. 4 Leptocerid pupae Goeridae Goeridae sp. 1 Glossosomatidae Agapetus sp. 1 Calamoceratidae Anisocentropus sp. 1 Anisocentropus pupae Unidentified pupae Diptera Chironomidae Unidentified larvae Unidentified pupae Tanypodinae Procladius sp. Apsectrotanypus sp. Paramarina sp.2 Ablabesmyia sp.3 Chironominae Demicryptochironomus sp. Polypedilum nr watsoni -pupae l? tonnoiri Paralauterborniella sp. nr Conchapelopia Tanytarsus inextentus Paralauterborniella sp. Stenochironomus sp. nr Hamischia sp. nr Sactheria sp. Orthocladinae nr Pseudosmittia sp. Rheocricotopus sp.2 Thienemanniella sp.2 I: trivettata Parametriocnemus omaticornis nr Parametriocnemus sp. Corynoneura australiensis Orthocladiinae pupae Simuliidae Simulium Morops spp. 1 & 2 Simulium Morops sp.1 pupae Similium Morops sp.2 pupae Simuliidae sp.3 Empididae 5 SPP. sp.5 pupae Psychodidae 7 SPP. pupae sp.a pupae sp.b

Mean

s.e.

C.V. (%)

Months


Appendix 1 (continued) Taxon pupae sp.c Dolichopodidae Dolichopodidae sp.1 Blephariceridae Apistomyia sp.1 Apistomyia sp. 1 pupae Ceratopogonidae nr Atrichopogon nr Atrichopogon pupae 5 SPP. Dixidae Dixidae sp. 1 Canaceidae Canaceidae sp.1 Culicidae Culicinae sp.1 sp.2 Anopheles sp.1 Ptychopteridae Ptychopteridae sp.1 Tipulidae 14 spp. pupae sp.a pupae sp.b Tanyderidae Tanyderidae sp. Tabanidae Tabanidae sp.1 sp.2 Thaumaleidae? Thaumaleidae sp. Unidentified pupae-12 spp. Unidentified larvae-14 spp. Coleoptera Hydraenidae Hydraena spp.1 & 2 larvae Hydraena spp.1 & 2 adults Hydraena sp.3? Helrninthidae Graphelmis sp.larvae Notriolus sp.larvae Helodidae sp.1 larvae Staphylinidae sp.1 adults Hydrochidae sp.1 larvae Hydrophilidae sp.1 larvae sp.1 adults Lampyridae sp.1 larvae Unidentified larvae-5 spp. Unidentified adults sp.1 Hemiptera Veliidae Veliidae sp. 1 Lepidoptera Unidentified larvae sp.1 sp.2

Mean

s.e.

C.V. (%)

Months

Catherine M. Yule

Appendix 1 (continued) Taxon Pyralidae sp. 1 sp.2 Collembola sp.1 sp.2 Cmstacea Decapoda Sendlaria salomonis (Roux) Rouxana ?minima Copepoda SPP. Ostracoda SPP. Amphipoda sp.1 Arachnids Hydracarina Unidentified species Anisitsiellidae Mamersella sp.1 Hygrobatidae Australiobates sp.1 Oribatida SPP. Araneae Unidentified species Annelida Oligochaeta Naididae-nr Pristina sp. Hirudinae sp.1 Polychaeta sp.1 Turbellaria sp. 1 Diplopoda sp. 1 Nematoda SPP. Nematomorpha Cordodidae sp.1

Mean

4.71

s.e.

C.V. (%)

0.77 72.94 Not distinguished from S. salomonis

Manuscript received 9 May 1994; revised and accepted 29 July 1994

Months