Kimberley Coast Research Articles

Aboriginal flood narratives and the thunder complex in Southeast Asia

AbstractThe ancestors of the dingo were brought to mainland Australia around 4000 years ago by people who arrived by boat. The identity of these voyagers from the north, however, and the nature of their interactions with the Aboriginal population of Australia, are unknown. Here, we propose that Indigenous flood narratives from the Kimberley contain evidence for contact between Aboriginal people and early Asian seafarers in the form of the “thunder complex”. The latter is a very specific repertoire of taboos, rituals and stories that occurs widely among ethnographically known societies of Indonesia, the Philippines and peninsular Malaysia, but has not previously been identified in Australia. Among Southeast Asian groups, this cultural complex revolves around the idea that certain prohibited acts perpetrated against animals – especially “mocking” them by treating them as though they were human – precipitate a punitive storm and/or flooding. We show that in some oral traditions of the Kimberley region animal mockery is similarly held to be the causative agent behind disastrous flooding events that took place in the past creationary epoch. We contend that this localised Aboriginal variant of the thunder complex reflects an episode of close interaction with early Austronesian‐speaking voyagers who introduced ancestral dingoes to mainland Australia, apparently via the Kimberley coast.

Ocean connectivity and habitat characteristics predict population genetic structure of seagrass in an extreme tropical setting

AbstractUnderstanding patterns of gene flow and processes driving genetic differentiation is important for a broad range of conservation practices. In marine organisms, genetic differentiation among populations is influenced by a range of spatial, oceanographic, and environmental factors that are attributed to the seascape. The relative influences of these factors may vary in different locations and can be measured using seascape genetic approaches. Here, we applied a seascape genetic approach to populations of the seagrass, Thalassia hemprichii, at a fine spatial scale (~80 km) in the Kimberley coast, western Australia, a complex seascape with strong, multidirectional currents greatly influenced by extreme tidal ranges (up to 11 m, the world's largest tropical tides). We incorporated genetic data from a panel of 16 microsatellite markers, overwater distance, oceanographic data derived from predicted passive dispersal on a 2 km‐resolution hydrodynamic model, and habitat characteristics from each meadow sampled. We detected significant spatial genetic structure and asymmetric gene flow, in which meadows 12–14 km apart were less connected than ones 30–50 km apart. This pattern was explained by oceanographic connectivity and differences in habitat characteristics, suggesting a combined scenario of dispersal limitation and facilitation by ocean current with local adaptation. Our findings add to the growing evidence for the key role of seascape attributes in driving spatial patterns of gene flow. Despite the potential for long‐distance dispersal, there was significant genetic structuring over small spatial scales implicating dispersal and recruitment bottlenecks and highlighting the importance of implementing local‐scale conservation and management measures.

Production and accumulation of reef framework by calcifying corals and macroalgae on a remote Indian Ocean cay

Abstract. Coral reefs face increasing pressures in response to unprecedented rates of environmental change at present. The coral reef physical framework is formed through the production of calcium carbonate (CaCO3) and maintained by marine organisms, primarily hermatypic corals, and calcifying algae. The northern part of Western Australia, known as the Kimberley, has largely escaped land-based anthropogenic impacts and this study provides important metabolic data on reef-building organisms from an undisturbed set of marine habitats. From the reef platform of Browse Island, located on the mid-shelf just inside the 200 m isobath off the Kimberley coast, specimens of the dominant coral (six species) and algal (five species) taxa were collected and incubated ex situ in light and dark shipboard experimental mesocosms for 4 h to measure rates of calcification and production patterns of oxygen. During experimental light and dark incubations, all algae were net autotrophic producing 6 to 111 mmolO2m-2d-1. In contrast, most corals were net consumers of O2 with average net fluxes ranging from −42 to 47 mmolO2m-2d-1. The net change in pH was generally negative for corals and calcifying algae (−0.01 to −0.08 h−1). Resulting net calcification rates (1.9 to 9.9 gCaCO3m-2d-1) for corals and calcifying algae (Halimeda and Galaxura) were all positive and were strongly correlated with net O2 production. In intertidal habitats around Browse Island, estimated relative contributions of coral and Halimeda to the reef production of CaCO3 were similar at around 600 to 840 gm-2yr-1. The low reef platform had very low coral cover of < 3 % which made a smaller contribution to calcification of ∼ 240 gCaCO3m-2yr-1. Calcification on the subtidal reef slope was predominantly from corals, producing ∼ 1540 gCaCO3m-2yr-1, twice that of Halimeda. These data provide the first measures of community metabolism from the offshore reef systems of the Kimberley. The relative contributions of the main reef builders, in these undisturbed areas, to net community metabolism and CaCO3 production is important to understand exclusively climate-driven negative effects on tropical reefs.

Human occupation of the Kimberley coast of northwest Australia 50,000 years ago

The peopling of Sahul (the combined landmass of New Guinea and Australia) is a topic of much debate. The Kimberley region of Western Australia holds many of Australia's oldest known archaeological sites. Here, we review the chronological and archaeological data available for the Kimberley from early Marine Isotope Stage 3 to the present, linking episodes of site establishment and the appearance of new technologies with periods of climatic and sea-level change. We report optical ages showing human occupation of Widgingarri 1, a rockshelter located on the Kimberley coast of northwest Australia, as early as 50,000 years ago, when the site was located more than 100 km from the Late Pleistocene coastline. We also present the first detailed analysis of the stone artefacts, including flakes from ground stone axes, grinding stones and ground haematite recovered from the deepest excavated layer. The high proportion of flakes from ground axe production and resharpening in the earliest occupation phase emphasises the importance of this complex technology in the first peopling of northern Sahul. Artefact analyses indicate changes in settlement patterns through time, with an increase in mobility in the terminal Pleistocene and a shift to lower mobility during the late Holocene. The optical ages for Widgingarri 1 mean that the Kimberley now contains the greatest number of sites in Sahul with earliest occupation dated to more than 46,000 years ago, overlapping with the time of initial occupation of sites in other regions across the continent.

Wildfires enhance phytoplankton production in tropical oceans

Wildfire magnitude and frequency have greatly escalated on a global scale. Wildfire products rich in biogenic elements can enter the ocean through atmospheric and river inputs, but their contribution to marine phytoplankton production is poorly understood. Here, using geochemical paleo-reconstructions, a century-long relationship between wildfire magnitude and marine phytoplankton production is established in a fire-prone region of Kimberley coast, Australia. A positive correlation is identified between wildfire and phytoplankton production on a decadal scale. The importance of wildfire on marine phytoplankton production is statistically higher than that of tropical cyclones and rainfall, when strong El Niño Southern Oscillation coincides with the positive phase of Indian Ocean Dipole. Interdecadal chlorophyll-a variation along the Kimberley coast validates the spatial connection of this phenomenon. Findings from this study suggest that the role of additional nutrients from wildfires has to be considered when projecting impacts of global warming on marine phytoplankton production.

Habitats and benthic biodiversity across a tropical estuarine–marine gradient in the eastern Kimberley region of Australia

The Kimberley coast situated in north-western Australia has been recognised as one of the world’s least human-impacted coastal areas as well as being rich in wilderness and biodiversity values. However, the region is vast and patchily surveyed with many knowledge gaps remaining about the diversity and extent of marine life in nearshore habitats. The King George River, in the far north-east of the region is an area where knowledge is lacking and consequently, to fill these gaps, a multi-taxon biodiversity and habitat survey was conducted in 2014. The survey extended from the base of the King George River twin waterfalls, which mark the upstream limit of marine influence, to the mouth of the river and 15 km offshore into the Timor Sea. At least eleven habitat types were identified. These include extensive stands of mangroves, rocky shores and sandy beaches extending out through the estuary and along the coast. Offshore from the estuary, Lesueur Islet is a low, vegetated islet surrounded by a fringing coral reef that supports a diverse benthic invertebrate fauna and algal flora. Deep-water sedimentary and hard-bottom filter-feeder communities also occur between the estuary and Lesueur Islet and around it. A total of 1374 animal and plant lots were collected, comprising about 3500 specimens with 796 species recorded. There were at least nine new species discovered of which five have since been named. The new species included five crustaceans and four echinoderms. In addition, there were at least twelve new records for Australia (one cnidarian, two echinoderms, nine crustaceans and some molluscs). Eighteen new records of crustaceans were made for Western Australia. Species accumulation curve analyses suggest true species richness may be higher than observed here if greater sampling were conducted on deep hard-bottom substrates in the region. Nevertheless, these results confirm this region contains a highly diverse community of regional and national significance.

Phytoplankton Responses to Climate‐Induced Warming and Interdecadal Oscillation in North‐Western Australia

AbstractGrowing evidence has suggested that ocean warming could cause a decline in marine phytoplankton productivity. However, studies in tropical waters have discovered that evolutionary adaptation of local species to warming and positive response to increasing rainfall could avoid the sharp decline in productivity. Here, the decadal trends of phytoplankton biomass, reconstructed using the biomarkers of brassicasterol (diatoms) and dinosterol (dinoflagellates), showed a 1.5–3 times increase since the 1950s along a large section of the Kimberley coast, north‐western Australia. Principal component analysis found that 56% of the phytoplankton variance was linked with climate change‐induced increases in sea surface temperature and rainfall associated with increased tropical cyclones, which can enhance nutrient supply favoring phytoplankton growth and production; 20.4% of the phytoplankton variance tended to be related to the Interdecadal Pacific Oscillation through a mechanism of ocean‐coast interaction. We empirically predict that the negative impact of rising temperatures on phytoplankton in north‐western Australia could be buffered by the increasing tropical cyclones and the coming warm phase of Interdecadal Pacific Oscillation.

Biophysical oceanography of tidally-extreme waters of the southern Kimberley coast, Western Australia

The continental shelf of the South Kimberley region of Western Australia is wide (~300 km) and interactions with the Indian Ocean culminate in extreme tides. This results in some of the largest tropical tides in the world (reaching 11 m on spring tide) measured in King Sound (KS), a large embayment which opens to the Indian Ocean. This remote area of Australia is very rich in natural resources and under increasing developmental pressures, but despite this the marine environment has been poorly studied. In Austral autumn (April/May) 2010, we examined phytoplankton biomass and production across four onshore-offshore transects from coastal waters (also within KS) to the 1000 m isobath, and their responses to physical and chemical environmental variables associated with tidal forces during a four week voyage aboard the RV Southern Surveyor. Using temperature and salinity relationships we found three distinct water masses; KS, Kimberley Shelf, and Kimberley Shelf break waters. The highest chlorophyll-a biomass in the study area was measured in a band along the 200 m isobath (27–46 mg Chl a m−2), and associated with greater concentrations of nutrients (332–392 mmol NO3- m−2, 650–823 mmol Si m−2, 21–39 mmol PO43- m−2). Phytoplankton biomass inside KS was dominated by large diatoms (as determined from accessory pigment analyses), shifting to a community largely comprised of picophytoplankton offshore. Rates of primary production (PP) on the shelf, via measurements of phytoplankton carbon (14C) uptake from photosynthesis versus irradiance incubations, decreased from coastal areas (222–560 mg C m−2 d−1) to offshore waters (45–78 mg C m−2 d−1). In KS, PP was highest (1692 mg C m−2 d−1) despite low standing stock nutrient concentrations (0.02–1.5 mmol NO3- m−2) and relatively high concentrations of suspended particulate material reducing light availability (Kd = 0.27 m−1).

Kimberley Coast, Western Australia

Kimberley Coast, Western Australia

Evidence for a widely expanded humpback whale calving range along the Western Australian coast

AbstractThe recognized calving grounds of humpback whales (Megaptera novaeangliae) that breed along the Western Australian coast (Breeding Stock D) extend along the Kimberley coast between Camden Sound and Broome (15°–18°S). However, there are reports of neonates further south, suggesting that the calving areas may be poorly defined. During aerial photogrammetric research in 2013 and 2015, we sighted large numbers of humpback whale calves along North West Cape (21°47′–22°43′S). We estimated the minimum relative calf abundance to be 463–603 in 2013 and 557–725 in 2015. We categorized the calves as either neonate or post neonate according to their color and size. The majority of calves sighted in both years (85% in 2013; 94% in 2015) were neonates. Our observations indicate that a minimum of approximately 20% (17.1%–24.3%) of the expected number of calves of this population are born near, or south of, North West Cape. We thus demonstrate that the calving grounds for the Breeding Stock D population extend south from Camden Sound in the Kimberley (15°S) to at least North West Cape (22°43′S), 1,000 km southwest of the currently recognized calving area.

Plankton Respiration, Production, and Trophic State in Tropical Coastal and Shelf Waters Adjacent to Northern Australia

In a changing ocean, tropical waters can be instructive as to the potential effects of climate induced changes on marine ecosystem structure and function. We describe the relationships between planktonic community respiration (CR), net community production (NCP), gross primary production (GPP) and environmental variables in 14 regions and three ecosystem types (coastal, coral reef and open sea) from Australia, Papua New Guinea and Indonesia. The data are compiled from separate studies conducted between 2002 and 2014 with the goal of better parameterizing the metabolic balance in tropical marine waters. Overall, these regions were strongly autotrophic (average GPP:CR ratio: 2.14 ± 0.98), though our dataset of 783 paired measurements did include some oceanic stations where heterotrophy (GPP:CR < 1) was predominant, and some coastal stations that were intermittently heterotrophic. Our statistical analysis suggested that temperature was the most important determinant of CR in coral reef and ocean ecosystems but less so in coastal ecosystems, where chlorophyll concentration was more important. In contrast, chlorophyll and sampling depth were more important in regulating GPP than temperature. The relationships between temperatures and metabolic rates showed that these were ecosystem-dependent, with coastal ecosystems showing less response to temperature than coral reef and open sea sites. The threshold of GPP to achieve metabolic balance fell in a range between 0.715 mmol O2 m-3 d-1 in the Coral Sea to 10.052 mmol O2 m-3 d-1 in mangrove waterways of Hinchinbrook Channel. These data allow regions in and around northern Australia to be ranked in terms of trophic state, ranging from the oligotrophic Scott Reef (GPP:CR = 0.84 ± 0.08) to productive surface waters of the Kimberley coast (GPP:CR = 5.21 ± 0.62). The measurement of pelagic metabolism shows potential as a quantitative tool to monitor the trophic state of coastal waters.

Island refuges: Conservation significance of the biodiversity patterns resulting from ‘natural’ fragmentation

The near-pristine continental-shelf islands along the remote and rugged Kimberley coast of north-western Australia are important natural refuges that have been isolated from many of the threatening processes affecting the adjacent mainland. Between 2007 and 2014, 27 of the largest of these islands were sampled for non-volant mammals, bats, reptiles, birds and vascular plants. Here, we evaluate the congruent patterns in species richness and composition among the taxonomic groups and relate these to island-wide attributes. We consider the conservation implications of the observed biodiversity patterns in the context of species replacement, nestedness and the minimum number of islands required to represent all species. While the species-area relationship was consistently supported, the effect of island isolation was observed for the non-volant mammals only. Environmental heterogeneity and spatial arrangement of islands strongly influenced species compositional patterns. We show that this pattern was largely due to species replacement among islands, rather than nestedness. These patterns reflect the greater diversity of regionally endemic species that are largely restricted to the more mesic and extensively rocky islands; whereas the drier islands typically support more widespread generalists. The combined measures of biodiversity patterns we observed indicate that all of the sampled islands have high conservation value. The conservation implications of the apparent lack of nestedness in this island system have relevance for other similar systems including fragmented landscapes.

Geomorphology and late Holocene accretion history of Adele Reef: a northwest Australian mid-shelf platform reef

The mid-shelf reefs of the Kimberley Bioregion are one of Australia’s more remote tropical reef provinces and such have received little attention from reef researchers. This study describes the geomorphology and late Holocene accretion history of Adele Reef, a mid-shelf platform reef, through remote sensing of contemporary reef habitats, shallow seismic profiling, shallow percussion coring and radiocarbon dating. Seismic profiling indicates that the Holocene reef sequence is 25 to 35 m thick and overlies at least three earlier stages of reef build-up, interpreted as deposited during marine isotope stages 5, 7 and 9 respectively. The cored shallow subsurface facies of Adele Reef are predominantly detrital, comprising small coral colonies and fragments in a sandy matrix. Reef cores indicate a ‘catch-up’ growth pattern, with the reef flat being approximately 5–10 m deep when sea level stabilised at its present elevation 6,500 years BP. The reef flat is rimmed by a broad low-relief reef crest only 10–20 cm high, characterised by anastomosing ridges of rhodoliths and coralliths. The depth of the Holocene/last interglacial contact (25–30 m) suggests a subsidence rate of 0.2 mm/year for Adele Reef since the last interglacial. This value, incorporated with subsidence rates from Cockatoo Island (inshore) and Scott Reefs (offshore), provides the first quantitative estimate of hinge subsidence for the Kimberley coast and adjacent shelf, with progressively greater subsidence across the shelf.

Marine spatial planning for the future: Using Public Participation GIS (PPGIS) to inform the human dimension for large marine parks

Marine protected area (MPA) research continues to be dominated by biophysical interests. However, understanding social data, including people's values and preferences, is critical to both effective planning and management and long-term MPA success. Having these social data in a spatial form is essential, given that MPA planning and management increasingly uses marine spatial planning (MSP) approaches to carefully locate and mediate among potentially competing uses in both space and time. An online Public Participation GIS (PPGIS) survey was used to collect spatially explicit information on stakeholder values and management preferences for Australia's remote Kimberley region. The Kimberley coast and marine environment is characterised by a multiplicity of values and preferences. Key values included biological conservation, aesthetics, recreational fishing, Aboriginal culture and heritage, and nature based tourism. Management preferences were dominated by the desire to increase conservation/protection, exclude oil/gas development and commercial fishing, and to increase Aboriginal management. The diversity of values and preferences present suggests potential for conflict over management and permitted uses. Significant associations between value and preference distribution and the Kimberley's five marine protected areas were analysed. Accessibility and respondent familiarity appear linked to value attribution. More accessible MPAs were significantly associated with recreation values while more remote MPAs were characterised by a conservation ethos and general aversion to development. Our research demonstrates that PPGIS enables documentation of spatially explicit social data across large scales, highlighting potential synergies and conflicts in values and permitted uses, in a manner that can readily integrate with ecologically based marine spatial planning processes.

Valuing the wild, remote and beautiful: using public participation GIS to inform tourism planning in the Kimberley, Western Australia

The remote Kimberley region in Western Australia presents a unique nature-based tourism destination. One of the world’s last wildernesses, the Kimberley is one of the least-impacted marine environments in the world. Tourism in the region is growing rapidly, driven by stunning natural landscapes, unparalleled nature-based experiences and a vibrant indigenous culture. Despite this, there has been virtually no research into how stakeholders value the Kimberley and spatially explicit investigations are lacking. State marine protected area planning, currently in a formative stage in the region, requires such spatially explicit social data to complement existing biophysical information. This paper reports on findings from a Public Participation GIS survey with 206 stakeholders undertaken in 2015 as part of a broader research project into socio-cultural values and management preferences for the Kimberley coast. Stakeholders’ spatially linked values were collected via an internet-based mapping survey for the purpose of supporting future planning and management in the region. Stakeholders mapped over 4,100 value locations, with values relating to scenery/aesthetics, recreational fishing, Aboriginal culture and nature-based tourism being most prominent. Analysis identified a clear spatial clustering of values across the region with a number of value ‘hotspots’ evident. Tourism planners and managers can analyse these hotspots to identify areas of potential congruence and conflict, thus assisting in retaining the qualities of the region that support ongoing tourism. By generating spatially explicit information on stakeholder values and areas of importance, this research makes an important contribution to tourism planning and management in the Kimberley.

Holocene reef evolution in a macrotidal setting: Buccaneer Archipelago, Kimberley Bioregion, Northwest Australia

This study uses information derived from cores to describe the Holocene accretion history of coral reefs in the macrotidal (up to 11 m tidal range) Buccaneer Archipelago of the southern Kimberley coast, Western Australia. The internal architecture of all cored reefs is broadly similar, constituting well-preserved detrital coral fragments, predominantly branching Acropora, in a poorly sorted sandy mud matrix. However, once the reefs reach sea level, they diverge into two types: low intertidal reefs that maintain their detrital character and develop relatively narrow, horizontal or gently sloping reef flats at approximately mean low water spring, and high intertidal reefs that develop broad coralline algal-dominated reef flats at elevations between mean low water neap and mean high water neap. The high intertidal reefs develop where strong, ebb-dominated, tidal asymmetry retains seawater over the low tide and allows continued accretion. Both reef types are ultimately constrained by sea level but differ in elevation by 3–4 m.

Zooplankton Growth, Respiration and Grazing on the Australian Margins of the Tropical Indian and Pacific Oceans

The specific activity of aminoacyl-tRNA synthetases (spAARS), an index of growth rate, and of the electron transport system (spETS), an index of respiration, was measured in three size fractions (73–150 μm, >150 μm and >350 μm) of zooplankton during five cruises to tropical coastal waters of the Kimberley coast (North West Australia) and four cruises to waters of the Great Barrier Reef (GBR; North East Australia). The N-specific biomass of plankton was 3–4-fold higher in the Kimberley than on the GBR in all 3 size classes: Kimberley 1.27, 3.63, 1.94 mg m-3; GBR 0.36, 0.88 and 0.58 mg m-3 in the 73–150 μm, >150 μm and >350 μm size classes, respectively. Similarly, spAARS activity in the Kimberley was greater than that of the GBR: 88.4, 132.2, and 147.6 nmol PPi hr-1 mg protein -1 in the Kimberley compared with 71.7, 82.0 and 83.8 nmol PPi hr-1 mg protein -1 in the GBR, for the 73–150 μm, >150 μm and >350 μm size classes, respectively. Specific ETS activity showed similar differences in scale between the two coasts: 184.6, 148.8 and 92.2 μL O2 hr-1 mg protein-1 in the Kimberley, against 86.5, 88.3 and 71.3 μL O2 hr-1 mg protein-1 in the GBR. On the basis of these measurements, we calculated that >150 μm zooplankton grazing accounted for 7% of primary production in the Kimberley and 8% in GBR waters. Area-specific respiration by >73 μm zooplankton was 7-fold higher in the Kimberley than on the GBR and production by >150 μm zooplankton was of the order of 278 mg C m-2 d-1 in the Kimberley and 42 mg C m-2 d-1 on the GBR. We hypothesize that the much stronger physical forcing on the North West shelf is the principal driver of higher rates in the west than in the east of the continent.

The Brremangurey pearl: A 2000 year old archaeological find from the coastal Kimberley, Western Australia

A small marine pearl was recovered at the Brremangurey rockshelter, on the Kimberley coast, from layers dating to approximately 2000 years ago. In an area famous for its pearls and history of cultured pearl production, public interest centred on whether the pearl was as old as the layer in which it was contained, or whether it was a recent cultured pearl that had infiltrated down from above. The near-spherical shape of the pearl hinted at a possible cultured origin. Owing to the uniqueness and historic cultural significance of this find, non-invasive analytical techniques were used to investigate whether the Brremangurey pearl was cultured or natural. Midden analysis was further used to assess the likely origin of the pearl within the stratified deposits. Analysis confirmed that the pearl is of natural origin and a dense midden lens of Pinctada albina shells is its likely origin.

Plankton community structure and connectivity in the Kimberley-Browse region of NW Australia

We describe the zooplankton and ichthyoplankton communities of coastal waters of the Kimberley coast (North West Australia), sampled in macrotidal Camden Sound during both the wet and dry seasons of 2011, and compare these to six other Kimberley embayments during the wet season of 2013. Zooplankton abundance in Camden Sound was 7038 ± 3913 SD ind. m−3 in the wet season and 1892 ± 708 SD ind. m−3 in the dry season, with copepods accounting for 85% by number. In all, 78 species of copepods were recorded, with the families Paracalanidae and Oithonidae dominant. In Camden Sound, 48 families of larval fish occurred, with ichthyoplankton more abundant in the wet season than the dry season (1.16 ± 0.2ind. m−3 cf 0.76 ± 0.2ind. m−3). Larval gobiids (Subfamily Gobiinae) were most abundant, with other common families associated with either pelagic or soft-bottom habitats as adults. Multivariate analyses of both copepod and ichthyoplankton communities demonstrated strong seasonal contrasts, although an along-shelf gradient in copepod community composition was apparent along the embayments sampled in 2013. There was little spatial variation in plankton communities within Camden Sound as a result of the large tidal range (up to 11.7 m, with 2.5 m−1 velocities), although gradients in abundance and composition on cross-shelf transects occurred in the more northern embayments that had a lower tidal range, such as Napier Broome Bay. Copepod communities of the Kimberley-Browse region were placed in regional perspective by multivariate analyses of similar data collected in the eastern Indian Ocean at Scott Reef, in the Arafura Sea and on the southern North West (NW) shelf. The plankton communities of the NW shelf form a series of along-shore metacommunities linked by advection, with weaker cross-shelf connectivity. The presence of the larvae of mesopelagic fishes of the family Myctophidae in coastal waters confirms seasonal cross-shelf connectivity.

Flora and vegetation communities of selected islands off the Kimberley coast of Western Australia

A systematic survey of flora and floristic communities was undertaken on 24 selected inshore islands off the Northern Kimberley (NK) coast between 2007 and 2010. One hundred and thirty seven 50 x 50 m quadrats were sampled for floristics and surface soils, and site attributes recorded. Quadrat sampling was supplemented by general collecting to further document the floristics of major substrates and habitats of each island. We recorded 1005 taxa from the surveyed islands, of which, 403 taxa were new records for the collective islands of the NK bioregion. Based on existing Western Australian Herbarium collections and current survey records, the flora recorded from the islands represents approximately 49 percent of the NK bioregion flora. A total of 57 taxa of conservation significance were recorded from the surveyed islands. Few taxa appear to be restricted to islands. Very few weed species were recorded, except from the islands with a modern history of settlement. Ten floristic groups were defined by the classification of species presence/absence within quadrats. Broad geology coupled with climate and local edaphic parameters appeared to be the main factors influencing the vegetation patterns observed on the islands sampled. Among quadrats on the hard/ rocky substrates, there was a compositional gradation from the plant communities of the sandstone geologies to the more fertile volcanic/dolerite substrates, which was reflected in the values of the soil parameters. In terms of the conservation significance of the islands as a whole, the largest and wettest islands were shown to be particularly important as they supported the highest number of NK bioregion endemic plant species. Highest numbers of priority taxa also tended to occur on the largest islands. However, some of the drier islands had unique species assemblages with elements of arid/semi-arid zone flora that were not well represented on other islands. Future management of the islands requires strategies that minimize both the risk of exotic weed introductions, and inappropriate fire that would threaten the persistence of fire-sensitive vegetation.