Huon Gulf Research Articles

Evaluating the knowledge and perceptions of local farmers in Tanam Village, Morobe Province regarding Fall Armyworm infestation

This research presents farmers’ knowledge, attitudes, and management strategies for the autumn armyworm (Spodoptera frugiperda) in the Huon Gulf District and Tanam Village Market in Morobe Province, Papua New Guinea. This is the first study that focuses on the opinions and expertise of local farmers in the region, identifying crop-related issues and learning about their management techniques. The survey sites chosen were the Huon Gulf District and Tanam Village Market in Morobe Province, Papua New Guinea. Various farmers who grew different crops, such as sweet potatoes, bananas, taro, greens, maize, peanuts, fruits, and more, were interviewed during the research. Findings reveal that around 20 farmers participated in this random survey, with 55% falling between the ages of 25 and 35. However, there was a significant variation in age distribution, with 15% being quite old (51–70 years old) and 30% in the medium age range (36–50 years old). In conclusion, it is crucial to understand the perspectives and knowledge held by the local farmers in Papua New Guinea regarding fall armyworms. This will help develop innovative solutions to mitigate the consequences of this pest before they worsen and spread to other nations. This report emphasizes the importance of creating autumn armyworm management plans that consider farmers’ needs and goals.

Community consensus and social identity in alphabet development

In the Huon Gulf area of Papua New Guinea, the indigenous language Jabêm was one of the languages of first contact for Lutheran German Missionaries, circa 1900. As a result, Jabêm became a language of the church and, later, a language of education. In both domains, written materials were commonly produced and generations of children were schooled in Jabêm rather than their own mother tongues. This paper discusses the relationship between Jabêm and Kala, an indigenous language spoken in six villages along the Huon Gulf Coast. Kala was without a standard orthography until recent collaborations between members of the communities and researchers from UBC Okanagan. This paper, therefore, also describes the development of the Kala standardized orthography and examines the distinct influences Jabêm has in both spoken and written domains. For instance, Jabêm’s role as a written authority retains positive connotation, which influenced the newly created Kala orthography.

Community dynamics of Pleistocene coral reefs during alternative climatic regimes

Reef ecosystems built during successive periods of Pleistocene sea level rise have shown remarkable persistence in coral community structure, but little is known of the ecological characteristics of reef communities during periods of low sea stands or sea level falls. We sampled the relative species abundance of coral, benthic foraminifera, and calcareous red algae communities from eight submerged coral reefs in the Huon Gulf, Papua New Guinea, which formed during successive sea level fall and lowstand periods over the past approximately kyr. We found that dissimilarity in coral species composition increased significantly with increasing time between reef-building events. However, neither coral diversity nor the taxonomic composition of benthic foraminifera and calcareous red algae assemblages varied significantly over time. The taxonomic composition of coral communities from lowstand reefs was significantly different from that of highstand reefs previously reported from the nearby Huon Peninsula. We interpret the community composition and temporal dynamics of lowstand reefs as a result of shifting energy regimes in the Huon Gulf, and differences between low and highstand reefs as a result of differences in the interaction between biotic and environmental factors between the Huon Gulf and Huon Peninsula. Regardless of the exact processes driving these trends, our study represents the first glimpse into the ecological dynamics of coral reefs during low sea level stands when climatic conditions for reef growth were much different and less optimal than during previously studied highstand periods.

Coral reef evolution on rapidly subsiding margins

A series of well-developed submerged coral reefs are preserved in the Huon Gulf (Papua New Guinea) and around Hawaii. Despite different tectonics settings, both regions have experienced rapid subsidence (2–6 m/ka) over the last 500 ka. Rapid subsidence, combined with eustatic sea-level changes, is responsible for repeated drowning and backstepping of coral reefs over this period. Because we can place quantitative constraints on these systems (i.e., reef drowning age, eustatic sea-level changes, subsidence rates, accretion rates, basement substrates, and paleobathymetry), these areas represent unique natural laboratories for exploring the roles of tectonics, reef accretion, and eustatic sea-level changes in controlling the evolution of individual reefs, as well as backstepping of the entire system. A review of new and existing bathymetric, radiometric, sedimentary facies and numerical modeling data indicate that these reefs have had long, complex growth histories and that they are highly sensitive, recording drowning not only during major deglaciations, but also during high-frequency, small-amplitude interstadial and deglacial meltwater pulse events. Analysis of five generalized sedimentary facies shows that reef drowning is characterized by a distinct biological and sedimentary sequence. Observational and numerical modeling data indicate that on precessional (20 ka) and sub-orbital timescales, the rate and amplitude of eustatic sea-level changes are critical in controlling initiation, growth, drowning or sub-aerial exposure, subsequent re-initiation, and final drowning. However, over longer timescales (> 100–500 ka) continued tectonic subsidence and basement substrate morphology influence broad scale reef morphology and backstepping geometries. Drilling of these reefs will yield greatly expanded stratigraphic sections compared with similar reefs on slowly subsiding, stable and uplifting margins, and thus they represent a unique archive of sea-level and climate changes, as well as a record of the response of coral reefs to these changes over the last six glacial cycles.

Beach Use, Internesting Movement, and Migration of Leatherback Turtles, Dermochelys coriacea, Nesting on the North Coast of Papua New Guinea

Internesting and migratory movements of female leatherback turtles (Dermochelys coriacea) from Kamiali Wildlife Management Area were tracked by satellite telemetry during the 2001–2002 and 2002–2003 nesting seasons, and an aerial survey of nearly 2800 km of the north Papua New Guinea coastline and New Britain Island was conducted during January 2004. Nesting occurred during November–March at the Kamiali Wildlife Management Area monitoring beach with peak activity during December–January. Telemetry results indicated that nesting females used Huon Gulf waters adjacent to the nesting beach and renested inside and outside the protected area within the Kamiali Wildlife Management Area. After nesting, the turtles migrated over deep waters in a southeastern direction to high latitude waters of the South Pacific Ocean.

ERNST MAYR AND SOUTHWEST PACIFIC BIRDS: INSPIRATION FOR IDEAS ON SPECIATION

Ernst Mayr's empirical research at the American Museum of Natural History between 1931 and 1953 was focused largely on speciesand genus-level systematics in the rich but then little-known bird fauna of the Southwest Pacific. Here, through four case studies, I trace the enormous advances he made in systematics knowledge, practice, and theory, culminating in his development of the Biological Species Concept, with its supporting treatise, Systematics and the Origin of Species (Mayr 1942). Resumen.La investigacion empirica de Ernst Mayr en el Museo Americano de Historia Natural entre 1931 y 1953 se enfoco principalmente en la sistematica a nivel de especies y generos de la avifauna rica pero entonces poco conocida del sudoeste del Pacifico. En este ensayo, a traves de cuatro estudios de caso, recapitulo los enormes avances que el hizo sobre el conocimiento, la practica y la teoria de la sistematica, culminando en su desarrollo del concepto biologico de especie, con el tratado que lo avala, Sistematica y el Origen de las Especies (Systematics and the Origin of Species, Mayr 1942). In 1929, the grand old man of systematic ornithology in Europe, Ernst Hartert, wrote the 25-year-old Ernst Mayr a prophetic letter. There is no other place in the world, wrote Hartert, favorable for the study of speciation in birds than the Solomon Islands (Mayr and Diamond 2001). Mayr was then in the Solomons as a member of the American Whitney South Sea Expedition and on the brink of heady events. Fresh from taking his doctorate under Erwin Stresemann in Berlin and groomed unwittingly to take over from Hartert at the great Rothschild collection in Tring, England, Mayr was on prolonged field work in Melanesia. In 1928, he had been in West Papua (formerly Irian Jaya or West Irian), putting together a collection of 2,700 bird skins that included two new species (Hartert 1930, Mayr 1930). Then he moved to the mountains of the Huon Gulf in Papua New Guinea, where he stayed until he joined the Whitney Expedition in 1929. In 1930, Mayr returned to Germany, but by January 1931, he was at the American Museum of Natural History (AMNH) in New York to ^-mail: richard.schodde@deh.gov.au curate and write up the Whitney Expedition collections (Bock 1994, 2005; LeCroy 2005). At almost the same time, events in Europe changed the global balance of research power in systematic ornithology: the financially troubled Lord Walter Rothschild sold his huge collection to the AMNH in February 1932 (Rothschild 1983). Both the Rothschild Museum and the Whitney Expedition had focused on the bird faunas of the Southwest Pacific; their combined holdings made them, by far, the most formidable research collections for this region. And Mayr was given sole responsibility for working up and inventorying the faunas and their novelties. Although it was the end of serious field experience for him, the knowledge already gained still gave him, with his Bildung education and training under Stresemann (Haffer 2002, Bock 2005), his first platform for beginning an intellectual career in systematic ornithology and, ultimately, evolutionary biology. In his first year at the AMNH, Mayr published 14 papers, some of them carried over from his previous year in Berlin but 7 based directly or extensively on Whitney Expedition material. Over the next 22 years at the museum, he produced more than 200 further publications, including four books. Most of this prodigious

Drowned carbonate platforms in the Huon Gulf, Papua New Guinea

The western Huon Gulf, Papua New Guinea, is an actively subsiding foreland basin dominated by drowned carbonate platforms. We investigated these platforms using new high‐resolution multibeam, side‐scan sonar and seismic data, combined with submersible observations and previously published radiometric and sedimentary facies data. The data reveal 14 distinct drowned carbonate platforms and numerous pinnacles/banks that increase in age (∼20–450 kyr) and depth (0.1–2.5 km) NE toward the Ramu‐Markham Trench. Superimposed on this overall downward flexing of the platforms toward the trench is a systematic tilting of the deep platforms 15 m/km toward the NW and the shallow platforms 2 m/km toward the SE. This may reflect the encroaching thrust load from the NW (Finisterre Range) and spatial variations in the flexural rigidity of the underlying basement. The drowned platforms form a complex system of promontories and reentrants, with abundant pinnacles and banks preserved at similar depths seaward of the main platforms. This configuration closely mimics the present‐day Huon coastline and its seaward islands fringed by modern coral reefs. The platforms retain structural, morphologic, and sedimentary facies evidence of primary platform growth, drowning, and subsequent backstepping, despite some lateral erosion of the platform margins (<100 m slope defacement) by mass wasting. Both platforms and pinnacles are composite features containing multiple terrace levels and notches, corresponding to multiple phases of growth, emergence, and drowning in response to rapid climatic and sea level changes during the evolution of each structure. On the basis of all observational and numerical modeling data, we propose a chronology for the initiation, growth, and drowning of the 14 platforms. Over shorter timescales (≤100 kyr) the rate and amplitude of eustatic sea level changes are critical in controlling initiation, growth, drowning or subaerial exposure, subsequent reinitiation, and final drowning of the platforms. However, continued tectonic subsidence and basement substrate morphology influence the overall backstepping geometry and subsequent tilting of the platforms over longer timescales (≥100–500 kyr).

Coralgal composition of drowned carbonate platforms in the Huon Gulf, Papua New Guinea; implications for lowstand reef development and drowning

Collision between the South Bismarck plate and the northern edge of the Australian plate has produced an actively subsiding foreland basin in the western Huon Gulf. A series of drowned carbonate platforms and pinnacles are preserved on this margin due to a combination of this rapid subsidence and eustatic sea-level changes over the last 450 ka. We analyzed sedimentary and coralgal data from the platforms to better understand lowstand reef development and drowning in the Huon Gulf. The recovered limestones are divided into five main sedimentary facies: coral reef, coralline–foraminiferal nodule, coralline–foraminiferal crust, Halimeda, and planktonic foraminiferal limestones. Based on a comparison with modern analogues in the Indo-Pacific and elsewhere, we identified coral reef, deep fore-reef slope, deeper fore-reef slope, and pelagic/hemipelagic paleoenvironmental settings. An analysis of facies relationships and their paleoenvironmental meanings revealed lowstand corals reefs preserved at the top of the platforms that grew within ∼10 m of sea level. Two different coral assemblages were identified within this facies: (1) a shallow, high energy reef community characteristic of windward margins and limited to the deep platforms (1947, 2121, 2393 m), and (2) another shallow community but indicative of more moderate lower energy reef conditions and limited to the middle (1113, 1217, 1612 m) and shallow platforms (823 m). The change from high to lower energy reef growth conditions suggests that oceanographic/climatic conditions in the Huon Gulf have changed substantially through time, primarily through the closure of the Gulf as a result of tectonic rotation and uplift of the Huon Peninsula over the last 450 ka. Despite major environmental perturbations (i.e. relative sea-level and temperature changes) the platforms and the shallow water coral reefs exposed at the top have been able to re-establish themselves time and time again over the last 450 ka. We also identified two different incipient drowning scenarios influenced by the rate of relative sea-level rise. More rapid drowning in the middle and deep platforms produced a thin veneer of coralline–foraminiferal nodule and Halimeda limestones over the shallow coral reef material while the slower drowning experienced by the shallowest platforms allowed thick coralline–foraminiferal crust limestones to develop. We recognize three main stages of platform development: (1) initiation and growth characterized by shallow coral reef growth as the platforms grew close to sea level during the lowstands, (2) incipient drowning marked by a shift to coralline–foraminiferal nodule, crust and Halimeda limestones as the platforms began to drown during rapid eustatic sea-level rise and continued subsidence, and (3) the complete drowning of the platforms characterized by platform ‘turn off’, increased bioerosion, Fe–Mn precipitation and pelagic/hemipelagic sedimentation as the platform surfaces finally drop below the photic zone.

Geophysical contributions to the COASTPLAN project, Lae area, Papua New Guinea, 1998

The Lae Coastal Hazards study is one of three pilot projects currently sponsored by CCOP as part of the overall COASTPLAN programme. The aim of the study is to assess the vulnerability of the coastal region at the head ofthe Huon Gulf, and particularly the Lae urban area, to natural disaster. Detailed investigations of possible risk made in early 1998 by the COASTPLAN team were supported by a gravity survey designed to clarify the factors controlling uplift and subsidence in this tectonically active region. The total of93 new gravity stations established in the Leron-Lae-Finschafen area confirmed the presence of a major foreland basin gravity low in the northern Markham Valley and the probability of an extension of the Papuan Ultramafic Belt beneath the Huon Peninsula. Correlations between gravity patterns and local and regional seismicity suggest that some potential long term and short term sources of geological hazards may have been overlooked.

The dynamics of foreland basin carbonate platforms: tectonic and eustatic controls

A numerical model linking a coral growth algorithm and an algorithm for flexural subsidence reproduces many of the characteristics of drowned foreland basin carbonate platforms. This model successfully matches the observed distribution and drowning age of drowned carbonate platforms in the Huon Gulf, Papua New Guinea, a modern submarine foreland basin. Analysis of equations describing flexural subsidence and eustatic sea‐level variations suggest that there are minimum convergence rates and periodicities of sea‐level variation required to drown foreland basin carbonate platforms. For convergence rates on the order of a few millimetres per year, sea‐level must vary on time‐scales of about 105 years in order to induce a rate of relative sea‐level rise great enough to drown an otherwise healthy foreland basin carbonate platform.

Estimation of current plate motions in Papua New Guinea from Global Positioning System observations

Plate tectonic motions have been estimated in Papua New Guinea from a 20 station network of Global Positioning System sites that has been observed over five campaigns from 1990 to 1996. The present velocities of the sites are consistent with geological models in which the South Bismarck, Woodlark, and Solomon Sea Plates form the principal tectonic elements between the Pacific and Australian Plates in this region. Active spreading is observed on the Woodlark Basin Spreading Centre but at a rate that is about half the rate determined from magnetic reversals. The other major motions observed are subduction on the New Britain Trench, seafloor spreading across the Bismarck Sea Seismic Lineation, convergence across the Ramu‐Markham Fault and left‐lateral strike slip across the Papuan Peninsula. These motions are consistent with a 8.2° Myr−1 clockwise rotation of the South Bismarck Plate about a pole in the Huon Gulf and a rotation of the Woodlark Plate away from the Australian Plate. Second order deformation may also be occurring; in particular, Manus Island and northern New Ireland may be moving northward relative to the Pacific Plate at ∼5–8 mm yr−1 (significant at the 95% but not at the 99% confidence level) which may suggest the existence of a North Bismarck Plate.

Another Look at Velar Lenition and Tonogenesis in Jabem

Malcolm Ross's account of tonogenesis in Jabem (his Yabem), an Austronesian language in the Huon Gulf region of Papua New Guinea, ends with a diachronic puzzle ... namely that in certain cases where PHG [Proto-Huon Gulf] *y is reconstructible, Yabem has high (I993:147). Elsewhere (1988:132-I60, 418-419; 1993:143-144), Ross reconstructs PHG *y as the lenis reflex of Proto-Oceanic (POc) *k and (nonfminal) *q to account for correspondences between generally voiced velar (g) reflexes in the Markham languages and mostly zero reflexes in other Huon Gulf languages. This correspondence set is said to be clearly distinguishable from that for the fortis reflex of POc *k, which yields a voiceless velar (k) in nearly every descendant of PHG. The puzzle arises because Ross finds that in four cases PHG *y gives rise to low tone in Jabem, as did all the other PHG voiced obstruents (*b, *d, *g, *v, *j), even where *v was later lost or weakened to w and *j was devoiced to (n)s. In four other cases, however, Ross's *y yields high tone. This forces him reluctantly to reconstruct an unconditioned split of PHG *y into ProtoNorth Huon Gulf *x where it yields high tone in Jabem, and zero where it yields low tone.

Combining AIRSAR data of Huon peninsula and Hawaii MR1 data of Huon Gulf, Papua New Guinea, for studies of tectonic and sedimentary processes

Two swaths of airborne synthetic aperture radar (AIRSAR) imagery, acquired over the southern Huon Peninsula, Papua New Guinea, have been digitally merged with aerial photogrammetric topography and with Hawaii MR] acoustic side‐scan imagery and bathymetry of the adjacent seabed of Huon Gulf. This example of land‐sea integration provides a means of examining relationships between tectonic lineaments and sediment transport pathways on land and on the subjacent seabed. Imaging methods and geometries dictate both the regions covered and the information content of the data. The principal limitations in merging the two data sets arise because the coastal and inner shelf zone, in water depths less than 500 m, is inaccessible to the imaging techniques that were used. Indirect methods allow some inferences to be made about the geomorphology of this zone, using surface sound channel data and sea surface imagery. The area examined is part of an active tectonic collision zone in which the northern margin of the Australian plate is being subducted beneath the South Bismarck plate. The edge of the South Bismarck plate has been uplifted 4,000 m since the late Pliocene, forming the Finisterre Range on Huon Peninsula. The record of relative emergence and submergence is seen in subaerially exposed Quaternary marine sediments and in drowned carbonate reefs. The merged radar and sonar imagery clearly indicate rapid erosion and deformation, both on land and under water. The imagery shows details of sediment transport and depositional systems, which are generating large terrestrial fluvial/alluvial plains, coastal fan deltas, and submarine channel deposystems. Fault structures and outcrops of bedrock units are clearly delineated both on land and on the seabed. These observations help explain patterns of onshore and submarine outcrops in terms of interactions between modern offshore sedimentation patterns and progressive deformation.

Foredeep tectonics and carbonate platform dynamics in the Huon Gulf, Papua New Guinea

HAWAII MR1 side-scan sonar and six-channel seismic reflection data reveal a history of carbonate platform growth, drowning, and back stepping in the Huon Gulf, Papua New Guinea. This is one of the few modern sites where active carbonate platform development and foredeep subsidence are linked. 230 Th methods date aragonitic shallow-water corals, recovered from a modern depth of 2000 m, at 348 ± 10 ka. This documents rapid subsidence of the Huon Gulf in response to the encroaching Finisterre Mountains at an average rate of 5.7 mm/yr for the past 348 k.y., the highest subsidence rate reported from any foredeep setting. Carbonate deposition has moved toward the foreland at an average rate of 110 mm/yr over the same period. Comparisons of the measured age with sea-level history (derived from the oxygen isotope record) suggest that the reefs may have formed during sea-level lowstands and drowned during rapid rates of sea-level rise.

Submarine features of modern open-sea fan deltas, Huon Peninsula, Papua New Guinea

A series of fan deltas has been delineated in water depths between 300 and 1900 m along the 75 km shelf and slope of the northern Huon Gulf, Papua New Guinea using the HAWAII MR1 side-scan system. Comparison of these fan deltas suggests that submarine slope profiles and feeder systems (i.e., type and size) are the most important factors controlling the construction and the geometry of the submarine fan deltas. Fan deltas are fully developed only at large rivers in areas with a SS-shaped slope profile.Six zones are recognised on the SS-profiled fan delta surface based on the submarine topographic characteristics, dominant acoustic facies and slopes. The zonation differs from that of Prior and Bornhold (1989) from fan deltas in a British Columbian fjord in terms of magnitude, slope profiles and submarine channelling patterns. The Huon fan deltas represent larger, more dynamic, deep-water delta systems with individual fan deltas up to 200 km 2. The main parts of the Huon fan deltas are deposited below 500 m, 5 km from river mouths. Large quantities of coarse-grained sediments are found in water depths over 1400 m, 13 km from river mouths. The relief of the interfingered narrow ridges and gullies in Zone 3 is up to 100 m. Zone 6 has a slope gradient of 4.4°, much steeper than Zone 5 (1.5°).The Huon fan deltas can not be easily fitted into any of the existing classification. They warrant a comparative study of fan deltas with similar feeder systems but different slope profiles, and with similar slope profiles but different feeder systems in the same basin regime. Delta classification and nomenclature needs to reflect seven attributes: feeder system, basin dynamics, water depth (depth ratio), slope profile, dominant slope process, delta-front grain size and geometry.

Northern Papua New Guinea: Structure and Sedimentation in a Modern Arc-Continent Collision: ABSTRACT

Northern Papua New Guinea and the Solomon Sea are the site of a modern oblique, arc-continent collision, which is progressing from northwest to southeast. By combining offshore seismic data from the Solomon Sea with geologic mapping in the Markham Valley area of northern Papua New Guinea the authors are predicting the outcome of this collision. The Huon Gulf is the present site of initial collision. Seismic profiles show this area is dominated by thin thrust sheets. Onshore, the bulk of the uplifted accretionary wedge is a melange with exotic blocks of a variety of lithologies. Structurally below the melange lies the Leron Formation composed of thick channelized sandstone and conglomerate. It dips north at approximately 40{degree} and is cut by several thrust fault with associated folds. Limestone blocks within the melange are reported to be 2 Ma, and Beryllium 10 anomalies from Bismarck arc volcanoes suggest that initial collision of the Finisterre block (375 km northwest of the present collision point) began no earlier than 3 Ma. This implies the collision is propagating laterally at about 125 km/m.y.. Large outcrops of basalt and gabbro within the melange suggest that segments of oceanic crust were incorporated into the accretionary wedge. Modernmore » sedimentation within the collision zone grades from fluvial sediments in the Markham Valley to deep-water turbidites ponded behind a structural ridge near the point of incipient collision. The Markham submarine canyon occupies the collision front here, and efficiently erodes the accretionary wedge. This setting may serve as a modem analog for deposition of much of the Leron Formation which exhibits tremendous sediment reworking.« less

Suturing history of an allochthonous terrane at a modern plate boundary traced by flysch-to-molasse facies transitions

The southern boundary of the South Bismarck plate in Papua New Guinea changes character from west to east as a consequence of oblique collision and suturing of the allochthonous Finisterre Terrane with the margin of the Australian continent and plate. Plate rearrangements are occurring, and a triple junction is migrating eastwards along the plate boundary. Characterization of modern sedimentary facies leads to the following correlations between facies and tectonic settings: Tectonic setting Sector of plate boundary Facies terrane already docked Markham Valley fluvial molasse terrane now docking Huon Gulf marine molasse terrane yet to dock western New Britain Trench conglomeratic flysch These relationships provide the basis for a tectonic-depositional model showing the distribution and relationships between facies, in time-distance space, along the plate boundary. Facies transitions are time-transgressive and their trajectories provide a measure of the rate of triple-junction migration. Rapid uplift of the southern margin of the South Bismarck plate has exposed older sediments related to this history of terrane suturing. Their facies characterization provides support for the model, but age control is insufficient for conclusive demonstration of its validity.

The New Britain trench and 149° embayment, Western Solomon Sea

The western New Britain Trench contains relatively thin sediment fill in the east, compared to the west where a sequence of thick turbidites is ponded behind a basement high in the trench axis, The trench trends toward Huon Gulf, but intersects the Trobriand Trench at an acute angle at the 149° Embayment, where both trenches end. Seismic structure west of the trench is incoherent, related to incipient collision of the Indian-Australia Plate and the South Bismarck Plate. The collision suture is marked by the Markham Canyon, continuous in its upper reaches with the Ramu-Markham Fault Zone on shore.

Seasonal and depth variation in fecundity of Acropora palifera at two reefs in Papua New Guinea

Fecundity and abundance of Acropora palifera and the abundance of other scleractinians were compared at two reefs in the Huon Gulf, Papua New Guinea. While temperature and salinity were similar at both reefs, turbidity and sedimentation were higher on one of the reefs. A negative correlation was found between fecundity of A. palifera and three factors: depth, turbidity and sedimentation rate. There was also a negative correlation between coral cover and water transparency and sedimentation. The results suggest that high rates of sedimentation and low transparency depress fecundity of A. palifera, and limit the depth distribution and reduce the abundance of this species and other scleractinians. Lower fecundity in February and March was correlated with higher water temperatures. It is suggested that coral reproduction can be used as a biological indicator of stress on coral reefs.

Wrench Fault Tectonics in Northern New Guinea Basin, Papua New Guinea: ABSTRACT

New Guinea lies on the northern Australian plate boundary and has been a sensitive tectonic recorder of Cenozoic plate interactions between the Australian and Pacific plates. The specific plate interactions are documented by the evolution of the Northern New Guinea fault system and End_Page 535------------------------------ the basin it overprints, the Northern New Guinea basin. Consideration of plate kinematics suggests convergence became increasingly oblique during the Cenozoic. We have calculated an average convergence of N6°E at 11.9 cm/year (4.7 in./year) during the Paleocene to Eocene, N60°E at 6.8 cm/year (2.7 in./year) during the Eocene to Miocene, and N60°E at 9.3 cm/year (3.7 in./year) during the Miocene to Holocene. Present-day Australian and Pacific plate vectors indicate predominantly left-lateral strike-slip motion in northern New Guinea. The sinistral Northern New Guinea fault system defines this zone of plate interaction and represents a suture between continental crust to the south and intermediate crust to the north. The fault system extends more than 3,000 km (1,900 mi) from the Huon Gulf of Papua westward into eastern Indonesia, and is comprised of the Ramu-Markham (Papua) and Sorong (Indonesia) faults. This system is particularly well defined along the Ramu-Markham valley by recent earthquakes of focal depths between 41 and 300 km (25 and 186 mi). First motion studies of these earthquakes indicate both compressional and strike-slip events. Maximum compressive stresses delineated from conjugate shear fractures studied in the field closely agree with the first motion solutions. When combined with the trend analyse of surface fold axes and reflective seismic structural information, these data are consistent with the regional left-lateral deformation of this Tertiary basin. Hydrocarbon exploration strategies within the Northern New Guinea basin must address not only sedimentation, but also must deal with the basin's complex structural and tectonic evolution. A static tectonic classification will not adequately define the Northern New Guinea basin. It is better described as an evolving basin being overprinted by wrenching. End_of_Article - Last_Page 536------------