Sustainable harvesting of Conomurex luhuanus and Rochia nilotica by Indigenous Australians on the Great Barrier Reef over the past 2000 years

Offshore island colonisation and use around the northern Australian coastline in the mid-to-late Holocene is associated with expanding Aboriginal and Torres Strait Islander populations and intensifying land-use activities. However, few explicit tests of the long-term effects of shellfish forager decision-making and associated impacts on intertidal ecosystems in these newly colonised island environments have been undertaken. We report morphometric analyses on two key reef flat Great Barrier Reef shellfish species, strawberry conch Conomurex luhuanus (n = 360) and top shell Rochia nilotica (n = 45), from two late Holocene archaeological shell midden assemblages on Lizard Island, northeast Queensland. Human foraging pressure was assessed through reconstructions of population age structure across time, highlighting the importance of determining size-at-age habitat preferences and species behaviour patterns when assessing long-term anthropogenic impacts on shellfish populations. Results show no evidence for resource depression across the late Holocene which is broadly in keeping with previous findings at other locales on the Great Barrier Reef, but contrary to expectations of resource intensification models. We conclude that the rich and abundant resources of reef flat environments were resilient to relatively low intensity and likely episodic Indigenous foraging. This sustainability contrasts with the scale and impacts of intensive industrialised harvesting in the historic period

A Holocene record of savanna vegetation dynamics in southern lowland Papua New Guinea

The southern lowlands of Papua New Guinea (PNG) are biogeographically distinct. Vast tracts of savanna vegetation occur there and yet most palaeoecological studies have focused on highlands and/or forest environments. Greater focus on long-term lowland environments provides a rare opportunity to understand and promote the significance of local and regional savannas, ultimately allowing non-forested and forested ecosystem dynamics to be compared. This paper examines palaeoecological and archaeological data from a lowland open savanna site situated on the south-central PNG coastline. The methods used incorporate pollen and micro-charcoal analyses, artefact recovery and sediment descriptions. We conclude with an environmental model of sedimentation and vegetation change for the past c. 5,800 years, revealing a mid to late Holocene savanna interchange between herbaceous and woody plant growth, with fluctuating fire occurrence increasing toward the present day. Increased silt deposition and modified regional hydrology are also recorded. Environmental changes correspond in timing with the start of permanent settlements and human use of fire. In particular, landscape burning for hunting and gardens for agriculture have helped create the open ecosystem still evident today

Changing use of Lizard Island over the past 4000 years and implications for understanding Indigenous offshore island use on the Great Barrier Reef

Archaeological records documenting the timing and use of northern Great Barrier Reef offshore islands by Aboriginal and Torres Strait Islander peoples throughout the Holocene are limited when compared to the central and southern extents of the region. Excavations on Lizard Island, located 33 km from Cape Flattery on the mainland, provide high resolution evidence for periodic, yet sustained offshore island use over the past 4000 years, with focused exploitation of diverse marine resources and manufacture of quartz artefacts. An increase in island use occurs from around 2250 years ago, at a time when a hiatus or reduction in offshore island occupation has been documented for other Great Barrier Reef islands, but concurrent with demographic expansion across Torres Strait to the north. Archaeological evidence from Lizard Island provides a previously undocumented occupation pattern associated with Great Barrier Reef Late Holocene island use. We suggest this trajectory of Lizard Island occupation was underwritten by its place within the Coral Sea Cultural Interaction Sphere, which may highlight its significance both locally and regionally across this vast seascape

Moiapu 3: Settlement on Moiapu Hill at the very end of Lapita, Caution Bay hinterland

The Caution Bay archaeological project on the south coast of mainland Papua New Guinea has excavated 122 sites over a 9 km² area. Lapita ceramics appear at a number of sites at c. 2900 cal. BP. Here we present the results of excavations at Moiapu 3, a site that helps define the end of the dentate-stamped Lapita phase of this region. It is suggested that the decline and ultimate cessation of dentate stamping related to a loss of symbolism during a period of major socioeconomic readjustment and innovation

Hypoxia Sensitive Metal β-Ketoiminate Complexes Showing Induced Single Strand DNA Breaks and Cancer Cell Death by Apoptosis

A series of ruthenium and iridium complexes have been synthesised and characterised with 20 novel crystal structures discussed. The library of β-ketoiminate complexes has been shown to be active against MCF-7 (human breast carcino-ma), HT-29 (human colon carcinoma), A2780 (human ovarian carcinoma) and A2780cis (cisplatin resistant human ovarian carcinoma) cell lines, with selected complexes being more than three times as active as cisplatin against the A2780cis cell line. Complexes have also been shown to be highly active under hypoxic conditions, with the activities of some complexes increasing with a decrease in O2 concentration. The enzyme thioredoxin reductase is over-expressed in cancer cells and complexes reported herein have the advantage of inhibiting this enzyme, with IC50 values measured in the nanomolar range. The anti-cancer activity of these complexes was further investigated to determine whether activity is due to effects on cellular growth or cell survival. The complexes were found to induce significant cancer cell death by apoptosis with levels induced correlating closely with activity in chemosensitivity studies. As a possible cause of cell death, the ability of the complexes to induce damage to cellular DNA was also assessed. The complexes failed to induce double strand DNA break or DNA crosslinking but induced significant levels of single DNA strand breaks indi-cating a different mechanism of action to cisplatin

Middle to Late Holocene near-shore foraging strategies at Caution Bay, Papua New Guinea

Caution Bay, on the South Coast of Papua New Guinea, offers a unique opportunity to assess the possible impacts of predation by pre-Lapita, Lapita, and post-Lapita peoples on local mollusc resources from at least 5000 years ago. Using biometric analysis of the bivalve Anadara antiquata and gastropod Conomurex luhuanus from the site of Tanamu 1, we examine trends in size and maturity variability through time. Results indicate a reduction in valve size of A. antiquata from c. 5000–2800 cal BP (the pre-Lapita period) to c. 2800–2750 cal BP (falling during the Lapita period), while C. luhuanus undergoes a change in maturity categories between the Lapita period and c. 700–100 cal BP (post-Lapita), with the latter containing lower proportions of both immature and mature individuals. Considering that these two mollusc taxa have the capacity to resist high predation pressures through their reproductive strategies and growth rates, in combination with low discard rates throughout Tanamu 1, it is unlikely that the observed trends are solely related to human predation. Rather, set against a context of significant environmental variability and shifting habitats through time, the pre-Lapita, Lapita, and post-Lapita phases represent significant socio-economic changes, whereby there is a shift from mobile foraging to an increasing reliance upon agriculture. It is therefore likely that there were a range of environmental and socio-economic factors influencing mollusc harvesting and the foraging economy more broadly through time