South Wales Coast Research Articles

Spatially varying impacts of pacific and southern ocean climate modes on tidal residuals in New South Wales, Australia

Still water levels along the New South Wales (NSW) coast often vary from those predicted by harmonic analysis based purely on astronomical forcing. This variation can lead to unexpected inundation episodes along the coast and in estuaries. This study investigates the large-scale ocean-atmosphere drivers that can contribute to these unexpected water levels. Time series regressions and cross- and coherence-wavelet transforms were used to investigate relationships between six tidal residual datasets from NSW ocean gauges and three indices of large-scale climate modes: canonical El Niño Southern Oscillation (ENSO), ENSO Modoki, and Southern Annular Mode (SAM). Significant relationships were identified between canonical ENSO and SAM and the tidal residual datasets; however, ENSO Modoki did not have a significant impact. Collectively, SAM and canonical ENSO account for up to 45% of the variance in tidal residuals along the NSW coast, with impacts increasing southwards. Wavelet coherences showed that tidal residuals covary significantly with SAM and ENSO, with the largest peaks in the two- and eight-year frequency bands. These results demonstrate a strong dependence of tidal residuals on the phasing of SAM and canonical ENSO. With continued improvements in seasonal forecasts of climate modes, including canonical ENSO and SAM, this research presents important new insights that may contribute to improved management of inundation along the NSW coast. The research also provides a baseline of natural variability on which climate change projections can be considered, given that inundation events are projected to become more frequent.

Foredune morphology: Regional patterns and surfzone–beach–dune interactions along the New South Wales coast, Australia

AbstractForedunes constitute a fundamental part of the coastal environment, acting as a buffer against storm erosion and natural coastal defence. Foredune size and volume play a pivotal role in determining coastal vulnerability to marine hazards, and the governing processes driving variations in foredune morphology, particularly over regional, or larger spatial scales, are still relatively poorly understood. This paper presents a regional‐scale investigation into foredune morphology along the New South Wales (NSW) coast (SE Australia), comprising not only a state‐wide inventory of foredune morphology for use in management/hazard assessment, but also testing long‐standing hypotheses and conceptual models of the physical processes that are driving, or influencing, foredune size. We applied a remote sensing protocol to 47 foredune environments, covering the length of the NSW coastline, comparing morphology (including dune height, width, shape, and volume) of established and incipient foredunes both along, and between, sandy embayments. Results, at regional spatial scales, show that the largest foredunes (volumes up to 850 m3 m−1) occur along the central coast as large, steep landforms; intermediate‐sized dunes (550–650 m3 m−1) were found on both the Mid‐north and Far North coast, and the smallest foredunes (334–380 m3 m−1) occur on the south coast as wider dunes with steep stoss slopes. Surfzone–beach state was found to be the most significant factor influencing foredune size and volume. The more energetic and more dissipative/high‐energy intermediate surfzone–beach states were correlated with larger foredunes (i.e. greater dune volume, width and crest elevation), whereas the lower‐energy surfzone–beach states generally had smaller dunes. Changes in vegetation cover, shoreline orientation and associated onshore (and alongshore) wind systems were also demonstrated to be important factors in determining foredune morphology. The largest foredunes in NSW generally occur to the north of embayments, with dune size decreasing southward with decreasing exposure to wind/wave energy.

Monitoring Coastal Water Body Health with Sentinel-2 MSI Imagery

The Australian ‘New South Wales Estuary health assessment and biodiversity monitoring program’ has set state-wide targets for estuary health. A selection of water bodies is being monitored by in situ chlorophyll a concentration and turbidity measurements, indicators for water quality. We investigate whether the current monitoring program can benefit from the use of remote sensing derived data, analyzing chlorophyll a and water clarity estimates by the C2RCC and ACOLITE products based on Sentinel-2 MSI imagery for three lakes along the New South Wales coast. The C2RCC and ACOLITE products were partly successful in predicting chlorophyll a concentration and water clarity. Estimates based on Sentinel-2 MSI imagery were in the range of in situ measurements. However, results varied across years and lakes, and a significant correlation could not be found in every case. It is likely that the physical differences between the systems, such as nutrient input, tannins, and suspended algae/sediment matrix, influence the output of the algorithm. This may preclude the application of a ‘one size fits all’ monitoring approach, given the importance of local ecological phenomena in both influencing remote sensing observations and the nature of appropriate targets. However, the design of a monitoring program that incorporates remote sensing provides a way forward.

The race for space: Modelling the landward migration of coastal wetlands under sea level rise at regional scale

Globally, sea-level rise (SLR) is a major environmental challenge for coastal ecosystems. Of particular concern are the impacts on intertidal wetlands, the loss of which would have detrimental consequences for both human and ecological communities. On the south-east Australian coast, case studies suggest that the future of intertidal wetlands will greatly depend on landward migration as surface accretion may not keep up with the predicted SLR in many estuaries. However, due to differences in geomorphological settings and land-use, estuaries vary in their capacity to accommodate lateral migration. Regional scale assessment of the lateral accommodation space is therefore critical for pre-emptive planning to conserve these valuable coastal ecosystems. In this study, we analysed wetland lateral accommodation space distribution within 110 estuaries under three SLR scenarios and three land management options on the New South Wales coast, south-east Australia. From the wetland distribution predictions, we calculated and mapped the lateral accommodation space in each estuary associated with each sea level and land use scenario. We further investigated the relationships between wetland migration capacity, intertidal hypsometry represented by elevation skewness, and estuary type within a Bayesian analysis framework. Our results showed that while a few large riverine estuaries dominated the state's total accommodation space, saline wetlands were at risk of disappearing from most intermittently closed-open estuaries if they cannot vertically accrete at the pace of SLR. These distinct responses to SLR are due to different elevation distributions. Furthermore, our assessment of land use adaptation options suggested that the promotion of landward migration without impairing other important ecosystems could be achieved by making low intensity land uses available within several riverine estuaries and barrier (open entrance) estuaries. Through identifying migration opportunities and barriers, the findings of the study could support regional scale adaptation strategies to ensure the sustainability of wetland-associated ecosystem goods and services.

Insights from a small sea cave: Reanalysis of the bone technology from Durras North, Yuin Country, Coastal New South Wales, Australia

Almost 60 years ago, the small cave of Durras North was excavated to learn more about the Walbunga Yuin People who have lived along this part of the New South Wales coast for thousands of years. From a 2 m × 2 m pit, an extensive shell midden recording some 500 years of site use was uncovered. Amongst the many kilograms of marine shell were a small number of stone and shell artefacts and almost 500 tools made primarily on short-tailed shearwater bone. Such large collections of osseous technology are rare in the Australian archaeological record and consequently this assemblage provides a unique opportunity to better understand the use of bone on this continent. We revisited this remarkable bone tool assemblage and discovered that the fishing-spear tips indicate several distinctive approaches in their manufacture and style – including some ingeniously utilising the natural structure of the bird bone to create tangs. In addition, we also identified tools used in working organic fibres or leathers, as well as a rare interpersonal weapon. In total, the Durras North osseous assemblage not only provides unprecedented detail on the construction of the multipronged fishing spears which were so common a sight in southeast Australia on European arrival, but also insights into more ephemeral cultural manufacturing and use practices.

Long-Term Dataset of Tidal Residuals in New South Wales, Australia

Continuous water level records are required to detect long-term trends and analyse the climatological mechanisms responsible for extreme events. This paper compiles nine ocean water level records from gauges located along the New South Wales (NSW) coast of Australia. These gauges represent the longest and most complete records of hourly—and in five cases 15-min—water level data for this region. The datasets were adjusted to the vertical Australian Height Datum (AHD) and had the rainfall-related peaks removed from the records. The Unified Tidal Analysis and Prediction (Utide) model was subsequently used to predict tides for datasets with at least 25 years of records to obtain the associated tidal residuals. Finally, we provide a series of examples of how this dataset can be used to analyse trends in tidal anomalies as well as extreme events and their causal processes.

Unintentional Tipping of Waterway Channels into Long-Term Scour Modes

Abstract An investigation into a proposal for a relatively minor expansion of a small fishing port on the mid New South Wales (NSW) coast in Australia uncovered unexpected channel scouring that was...

Linking the Pleiades to a reawakened Black Duck Songline in Southeastern Australia

AbstractThis article presents an analysis of an Aboriginal songline in South‐eastern Australia that has not been previously recorded. As part of a project examining the astronomy and songline connections of the Saltwater Aboriginal peoples of the New South Wales coast, the Black Duck Songline was identified that may have links to the Pleiades star cluster. The Pleiades, known by many peoples as the Seven Sisters, is one of the most important elements of Aboriginal cosmologies across Australia, and features in songlines and oral traditions, as well as being a resource calendar identifier. Aboriginal songlines are a unique development of Aboriginal culture that celebrate the travels of the Creator Ancestors as they shaped the landscape. The identification of the Black Duck Songline and its possible connection to the Pleiades is an example of the potential reawakening of other long‐distance songlines in Australia and their connection to the cosmology of their communities.

Population genomics of the Eastern Rock Lobster,Sagmariasus verreauxi, during spawning stock recovery from over-exploitation

AbstractFisheries are currently under pressure to provide increasing amounts of seafood, causing a growing number of marine stocks to be harvested at unsustainable levels. To ensure marine resources remain sustainable, careful management of biological stocks and their genetic integrity is required. The Eastern Rock Lobster, Sagmariasus verreauxi, is commercially harvested along the New South Wales (NSW) coast of eastern Australia and is managed as a single unit. Due to overfishing, the NSW S. verreauxi stock was severely depleted in the mid-1990s but has since been rebuilding. This study evaluates the population genetic structure, putative local adaptation, and potential of a population bottleneck for NSW S. verreauxi. Using neutral single nucleotide polymorphisms (SNPs), we determined NSW S. verreauxi consist of a single genetic stock, with outlier SNPs detecting weak genetic divergence among offshore locations, and evidence of population bottlenecks at all locations. Our findings (i) confirm a single management unit is appropriate; (ii) can be used as a baseline for future genetic monitoring of NSW S. verreauxi; and (iii) highlights the importance of implementing routine genetic monitoring and collecting temporal samples to understand the full impact of overfishing on a species resilience.

Gymea and the Fishing Technologies of the New South Wales Coast, Australia

Stories are important to all modern peoples, and this behaviour was no doubt also the case during the deep past. Consequently, it is important that archaeologists understand that artefacts made and discarded thousands of years ago were woven with stories by the peoples who produced them. In some regions of the world, these stories remain accessible by collaborating with the Traditional Owners of the lands from which they were recovered, while in others such an approach is impossible. Nevertheless, researchers need to remember that items carried meaning usually invisible to those outside communities—a principle often taught and cited, but possibly not fully appreciated. Here we tell the Yuin (coastal New South Wales, Australia) story of Gymea and her connection to fishing technologies. This story is told in order to demonstrate the depth of information that is not accessible to archaeologists if Indigenous collaborators are not sought out or available.

HOLOCENE EVOLUTION OF A WAVE-DOMINATED BARRIER-LAGOON SYSTEM IN RIO DE JANEIRO, BRAZIL

ABSTRACTIn a wave-dominated coast, most of the Jacarepaguá coastal plain is occupied by buildings. During a new construction in this region at Barra da Tijuca, the subsurface area was excavated, exposing its quartzose sand nature, with a high mollusk shell concentration and in situ echinoderms at –10 m depth. The possibility to access this area encouraged us to investigate the evolution of the coastal plain. A 7.84-m-long core was recovered by percussion drilling. Stratigraphic, grain size, and geochemical analysis were undertaken. Three carbonate samples were dated by radiocarbon accelerator mass spectrometry (14C AMS). The revised sea-level variation curve revealed that the last postglacial marine transgression reached the present mean sea-level at 7945–7500 cal BP. The sandy deposit bottom was an ancient shoreface, with in situ echinoderms buried at 7770–7540 cal BP by the Pleistocene inner barrier reworking due to the last marine transgression. The Holocene outer barrier-lagoon and its flood tidal delta were formed from 5440–5070 cal BP. Mid-Holocene marine regression allowed the outer barrier progradation and the lagoon shallowing/infill. This paper confirms prior models proposed by other researchers for the Rio de Janeiro central coast and shows its similarity with the New South Wales coast, Australia.

Analysis of a southerly buster event and associated solitary waves

This paper is a detailed case study of the southerly buster of 6–7 October 2015, along the New South Wales coast. It takes advantage of recently available Himawari-8 high temporal- and spatial-resolution satellite data, and other observational data. The data analyses support the widespread view that the southerly buster is a density current, coastally trapped by the Great Dividing Range. In addition, it appeared that solitary waves developed in this event because the prefrontal boundary layer was shallow and stable. A simplified density current model produced speeds matching well with observational southerly buster data, at both Nowra and Sydney airports. Extending the density current theory, to include inertia-gravity effects, suggested that the solitary waves travel at a speed of ~20% faster than the density current. This speed difference was consistent with the high-resolution satellite data, which shows the solitary waves moving increasingly ahead of the leading edge of the density current.

A warm-front triggered nocturnal tornado outbreak near Kiama, NSW, Australia

This paper documents the case of a nocturnal outbreak of tornadoes on the New South Wales (NSW) south coast on 23 February 2013, and provides an analysis of the conditions that led to the outbreak. These tornadoes were associated with the passage of a warm front which had developed on the eastern flank of a mature extratropical cyclone.The damage from the tornadoes is discussed, and an analysis of the synoptic and mesoscale conditions that led to the event is provided. An analysis of radar at the time of the event shows a series of vortices developing within a zone of horizontal shear just prior to the tornadoes developing. The tornadoes were difficult for operational forecasters to predict, partly due to the infrequent occurrence of nocturnal tornadoes of this type in NSW, and in part due to operational demands from the broader scale severe weather event that resulted from the low-pressure system. This paper presents an analysis of the event that may assist forecasters in identifying similar events in the future.

Assessment of rock pool fish assemblages along a latitudinal gradient

Increased understanding of latitudinal gradients and patterns of biodiversity at a regional scale is important for many reasons (e.g. biodiversity conservation, species management, climate change). This study assessed rock pool fish assemblages and their relationship to latitude at 39 locations along 860 km of the New South Wales (NSW) coast, eastern Australia, from Sandon to Merimbula (29.67816°S to 36.90046°S). Thirty-minute deployments of miniature baited remote underwater video (mini-BRUV) were used to survey five or more replicates (rock pools) at each location for species richness and maximum number (MaxN) of individual fishes. A total of 371 rock pools were sampled, with 7070 fish recorded from 46 families and 115 species. Fish species richness was greatest in northern NSW, with a significant decline in species richness with increasing latitude, at a rate of 1.7 species per degree of latitude south. Tropical species were dominant in northern NSW (Coffs Harbour ∼30°S), whilst temperate species diversity was greatest towards central NSW (Port Stephens 32.7°S). Differences amongst rock pool assemblages were primarily driven by eight species from eight different families. This study documents latitudinal fish assemblage patterns along the east Australian coast and provides a baseline for elucidating future changes.

Is Port Stephens, eastern Australia, a global hotspot for biodiversity of Aplysiidae (Gastropoda: Heterobranchia)?

ABSTRACTPort Stephens, a large natural harbour on the central New South Wales (NSW) coast, provides ideal oceanographic and benthic conditions for the growth of marine algae and seagrasses, and this promotes a suite of herbivorous heterobranch sea slugs such as sea hares and sap-sucking sea slugs. In this article we document both historic and recent observations of sea hares (family Aplysiidae) from Port Stephens with the intention of recording species diversity. The western South Pacific region has the richest aplysiid fauna in the world, with 16 species now recorded in Port Stephens. This location is the most taxonomically diverse for this family in Australia. Despite this hotspot of aplysiid diversity, the taxonomy and nomenclature of 12 species is uncertain, a fact highlighted by a series of nomenclatural notes included in this article. We herein report the first observation of Petalifera sp. in Australian waters. Dolabrifera jacksoniensis Pilsbry, 1896 is newly synonymised with D. brazieri G.B. Sowerby II, 1870. Recent reports of southern range extensions for other heterobranch sea slugs, both in Port Stephens and elsewhere in NSW, highlight the importance of recording the existing aplysiid diversity in the port. Thus, any future alteration to species composition and range shifts driven by climate change may be detected.

Rural transitions in the Nambucca Valley: Socio-demographic change in a disadvantaged rural locale

Within current rural research, an ongoing challenge has been to conceptualise the overarching dynamics driving rural transitions in affluent societies, while also recognising diversity and complexity in driving forces and trajectories over time and place. While amenity migration may continue to be influential, more recent research has revealed that there are multiple driving forces leading towards diverse multifunctional rural occupance modes and trajectories. With its oversupply of desirable rural destinations, transitions along the subtropical New South Wales coast have been marked by increasingly divergent socioeconomic trajectories, tied to perceived gradients in amenity and sequential gradients in affordability related to inherent and constructed place imagery. We explore early- and late-phase transitions in the Nambucca Valley, one region within this zone. Initially available at exceptionally low entry costs, a plentiful supply of former dairyfarms attracted undercapitalised migrants seeking a rural lifestyle and possibly a livelihood from on-farm or non-farm sources. With limited finances, near-zero borrowing capacity and an ill-informed, opportunistic approach towards initiating their prospective cropping and/or livestock ventures, newcomers were destined to fail. Notwithstanding its high natural landscape and liveability values, the Nambucca Valley has been bypassed during the later-phase, locationally selective commodification of rural hinterlands. With its now-entrenched image of disadvantage, Nambucca lacks the market-oriented positional values accruing to prime destinations elsewhere along the subtropical coast. Given the continuing inability of Nambucca’s rural landholdings to support cropping and livestock livelihoods, and the compatibility between consumption and protection outcomes, there is a high probability of entrenching a complex multifunctional mode of rural occupance for the foreseeable future. In this mode, ’consumption of the countryside’ by residents with modest incomes will be most influential in shaping rural socioeconomic futures, but with desultory production and protection activity together with reduced inputs into property management shaping rural landscapes.

Southern range extensions for twelve heterobranch sea slugs (Gastropoda: Heterobranchia) on the eastern coast of Australia

Port Stephens, on the central New South Wales coast, provides ideal oceanographic and benthic conditions for the settlement and growth of larvae of tropical species delivered from the north by the East Australian Current. The popularity of the bay for recreational and scientific diving has facilitated extensive documentation of the biota over several decades, confirming its high biodiversity. Of the 313 species of heterobranch sea slugs recorded from Port Stephens to date, 30 are not known to occur further south. Our observations increase the number of taxa with a southern distribution limit at Port Stephens by 12 species and add to a growing list of marine taxa that are progressively extending their southern range, potentially as a result of climate change.

An illustrated inventory of the sea slugs of New South Wales, Australia (Gastropoda: Heterobranchia)

Although the Indo-Pacific is the global centre of diversity for the heterobranch sea slugs, their distribution remains, in many places, largely unknown. On the Australian east coast, their diversity decreases from approximately 1000 species in the northern Great Barrier Reef to fewer than 400 in Bass Strait. While occurrence records for some of the more populated sections of the coast are well known, data are patchy for more remote areas. Many species have very short lifecycles, so they can respond rapidly to changes in environmental conditions. The New South Wales coast is a recognised climate change hot-spot and southward shifts in distribution have already been documented for several species. However, thorough documentation of present distributions is an essential prerequisite for identifying further range extensions. While distribution data are available in the public realm, much is also held privately as photographic collections, diaries and logs. This paper consolidates the current occurrence data from both private and public sources as part of a broader study of sea slug distribution in south-eastern Australia and provides an inventory by region. A total of 382 species, 155 genera and 54 families is reported from the mainland coast of New South Wales.

A taxonomic study on the Phtisicidae (Crustacea: Amphipoda) of New South Wales, Australia

abstractThe present study reviews the taxonomy of the Phtisicidae (Crustacea: Amphipoda) from the coast of New South Wales, Australia. The following seven species are described; Dodecas decacentrum Stebbing, 1910b, Dodecas hexacentrum Mayer, 1903, Hircella cornigera (Haswell, 1879b), Metaproto novaehollandiae (Haswell, 1879a), Notoprotomima smithi gen. nov., sp. nov., Paraproto sp. and Perotripus sp. Generic diagnoses of Notoprotomima gen. nov., Dodecas, Hircella and Metaproto are provided based on the present materials. Notoprotomima smithi is fully described as a new species of the new genus. Dodecas decacentrum differs from Dodecas hexacentrum by the presence of paired dorsodistal projections on pereonite 2, paired mid-dorsal projections on pereonites 3 and 4 and shorter gill length on pereonites 2 and 3. Hircella cornigera and Metaproto novaehollandiae are described in detail. The larger mature males of M. novaehollandiae possess the unusual massive type of the propodus of gnathopod 2. The extended distribution of Perotripus to the New South Wales coast is noted. A key for these phtisicid amphipods from New South Wales, Australia is provided.

Hormosira banksii (Phaeophyceae): a tough survivor in the harsh conditions of high intertidal pools in southeast Australia

Hormosira banksii, the most successful intertidal fucoid in the southern hemisphere, usually inhabits only the lower shore. On Kainga Reef, at 36°S on the New South Wales coast, it is one of only two macroalgae in most of the pools on a platform above xthe lowest high water; 29 pools in the middle of the platform were monitored photographically for 12 years. Recruitment was not seasonal. It took about 5–8 months for germlings to become visible, when they consisted of about 3 vesicles. The growth rate of germlings was between linear and exponential. Individuals could become fertile when they were 11–14 months old. Adult frond growth rate in the mid-platform pools, measured in situ, was highest in autumn but similar in the other seasons. In summer, however, in pools at the edge of the reef, often flushed by waves, the growth rate was as fast in summer as in autumn, either because of better provision of scarce nutrients or because of less inhibition by high temperature. Mortality, both of individuals and of fronds, was highest in the summer when pool isolation for one or more tidal cycles, caused by the coincidence of low high tide levels and a calm sea, was more common. Hormosira could tolerate full summer sunlight, water temperatures of up to 40°C, 140 psu (four times the strength of seawater) but not dehydration. Dehydration caused inter-annual variation in cover and in the total number of plants present, but with no overall trend over 12 years. Sand cover and rotting cast weed could also cause mortality. Survivorship was Slobodkin’s Type IV, with few plants reaching 4 years but high longevity after that, due to the establishment of a holdfast which could regenerate new fronds. Compared with other fucoids, growth was slow. The lifestyle resembles that of Ascophyllum nodosum.