Western Coast Of Australia Research Articles

New findings on the route of heat transport between the Indo-Pacific and Southern Ocean

Since the end of the twentieth century, the global mean surface temperature (GMST) exhibited a shift from a rapid warming to an unexpected deceleration. An anomalous heat was transported from the Pacific Ocean into the Indian Ocean through a strengthened Indonesian Throughflow during the same period. Within this background, it is essential to continue tracking the fate of the anomalous heat arriving in the Indian Ocean to form a comprehensive picture of the global ocean energy redistribution. The anomalous heat may continue flowing westward into the Atlantic Ocean along the main pathway of the regional ocean currents via the South Equatorial Current (SEC) and Agulhas Current. However, here we examine an alternate pathway: a southward heat transport in conjunction with a weakened SEC, diverting the canonical westward transport. This additional transport pathway causes an increase in heat content in the South Indian Ocean mid-latitudes (15–30°S, 95–110°E), may contribute to the Southern Ocean warming, and intensifies hemispheric asymmetry of oceanic heat content. The heat increase has important climate impacts such as changes to rainfall and increased coral bleaching over the western coast of Australia. The new path discovered here may be an essential route of heat transport linking the tropical Indo-Pacific Ocean and the Southern Ocean in 2003–2012.

Records of Australian humpback dolphins (Sousa sahulensis) from an offshore island group in Western Australia

We report records of humpback dolphins at the Montebello Islands (20°26’S, 115°33′E) approximately 80 km from the mainland coast of Western Australia. This island group is a marine protected area (MPA), with approximately half of the area a sanctuary (no take) zone managed solely for nature conservation that excludes activities such as fishing and resource extraction, activities known to impact dolphins elsewhere. The habitat varies but includes fringing coral reef and shallow, sheltered sandy lagoons mostly < 10 m water depth and not exceeding 20 m. Several opportunistic sightings and one targeted five-day survey have resulted in 28 dolphins being catalogued in the MPA through photo-identification of natural marks on the dorsal fin and are considered to be recognisable through either distinctive or subtle marks. The species was initially reported in the MPA in June 2015 and was present in summer, autumn and winter of 2017. Six calves have been observed in the MPA, with one a neonate. Given the recent listing of the species as Vulnerable on the IUCN Redlist, and increasing pressure on near-shore coastal habitat, recognising the presence of this species at offshore islands such as these, and understanding their status and connectivity is a priority for the conservation and management of the species in Western Australia.

Hydrodynamics of a conceptual FLNG system in side-by-side offloading operation

ABSTRACTThis paper investigates the hydrodynamics of an floating liquefied natural gas (FLNG)–liquefied natural gas (LNG) offloading system in a side-by-side configuration using potential flow solver AQWA. The system is moored by an internal turret mooring system allowing itself to weathervane under external disturbances and is designed to operate in a sea environment close to that on the coast of Western Australia. Initially, validations are presented for the computed wave loads, representative motion responses and mooring loads. The results are compared against experimental data and those gathered from literatures. Time domain analyses are carried out for the FLNG–LNG system coupled with hawser, fender and mooring systems under the combination of wind, current and waves. The relative motions between the FLNG and LNG in the horizontal plane as well as the mechanical loads on the hawsers, fenders and moorings are computed. Furthermore, the effects of varying hawser pretension and stiffness on the hydrodynamic performance are investigated.

Mechanisms and seasonal drivers of calcification in the temperate coral Turbinaria reniformis at its latitudinal limits.

High-latitude coral reefs provide natural laboratories for investigating the mechanisms and limits of coral calcification. While the calcification processes of tropical corals have been studied intensively, little is known about how their temperate counterparts grow under much lower temperature and light conditions. Here, we report the results of a long-term (2-year) study of seasonal changes in calcification rates, photo-physiology and calcifying fluid (cf) chemistry (using boron isotope systematics and Raman spectroscopy) for the coral Turbinaria reniformis growing near its latitudinal limits (34.5° S) along the southern coast of Western Australia. In contrast with tropical corals, calcification rates were found to be threefold higher during winter (16 to 17° C) compared with summer (approx. 21° C), and negatively correlated with light, but lacking any correlation with temperature. These unexpected findings are attributed to a combination of higher chlorophyll a, and hence increased heterotrophy during winter compared with summer, together with the corals' ability to seasonally modulate pHcf, with carbonate ion concentration [Formula: see text] being the main controller of calcification rates. Conversely, calcium ion concentration [Ca2+]cf declined with increasing calcification rates, resulting in aragonite saturation states Ωcf that were stable yet elevated fourfold above seawater values. Our results show that corals growing near their latitudinal limits exert strong physiological control over their cf in order to maintain year-round calcification rates that are insensitive to the unfavourable temperature regimes typical of high-latitude reefs.

Oldest message in a bottle discovered, and an ancient medical text revealed

World record set for oldest message in a bottle For Tonya Illman, a stroll on an Australian beach in January yielded a spectacular souvenir: a 132-year-old message in a bottle—the oldest such bottle ever found. She saw the dark glass container sticking out of the sand on the western coast of Australia, about 180 km north of Perth. A tightly rolled piece of paper was inside, tied with a piece of twine. The message wasn’t a cry for help from an island castaway or a love letter from a grieving widower. Rather, it was a form, in German, filled out with the details of how the bottle came to embark on its oceanic journey. The bottle was jettisoned from a German sailing ship, Paula, on June 12, 1886, 950 km from the spot where it was eventually found. From 1864 to 1933, the German Naval Observatory ran a drift bottle

Crambescidin 800, Isolated from the Marine Sponge Monanchora viridis, Induces Cell Cycle Arrest and Apoptosis in Triple-Negative Breast Cancer Cells.

Triple negative breast cancer (TNBC) is currently the only group of breast cancers without an effective targeted therapy. Marine sponges have historically been a source of compounds with anticancer activity. In this study, we screened extracts from twenty marine sponges collected off the coast of Western Australia for cytotoxic activity against TNBC cells. One very active extract derived from the sponge Monanchora viridis was selected for bioactivity-guided fractionation. Through multiple steps of purification, we isolated a potent cytotoxic compound, which was identified as crambescidin 800 (C800). We found that C800 exhibited cytotoxic potency in a panel of breast cancer cells, of which TNBC and luminal cancer cell models were the most sensitive. In addition, C800 induced cell cycle arrest at the G2/M phase, resulting in a decline in the expression of cyclin D1, CDK4, and CDK6 in TNBC cells. This effect was associated with the inhibition of phosphorylation of Akt, NF-κB, and MAPK pathways, resulting in apoptosis in TNBC cells.

Contrasting Heat Budget Dynamics During Two La Niña Marine Heat Wave Events Along Northwestern Australia

AbstractTwo marine heat wave events along Western Australia (WA) during the alternate austral summer periods of 2010/2011 and 2012/2013, both linked to La Niña conditions, severely impacted marine ecosystems over more than 12° of latitude, which included the unprecedented bleaching of many coral reefs. Although these two heat waves were forced by similar large‐scale climate drivers, the warming patterns differed substantially between events. The central coast of WA (south of 22°S) experienced greater warming in 2010/2011, whereas the northwestern coast of WA experienced greater warming in 2012/2013. To investigate how oceanic and atmospheric heat exchange processes drove these different spatial patterns, an analysis of the ocean heat budget was conducted by integrating remote sensing observations, in situ mooring data, and a high‐resolution (∼1 km) ocean circulation model (Regional Ocean Modeling System). The results revealed substantial spatial differences in the relative contributions made by heat advection and air‐sea heat exchange between the two heat wave events. During 2010/2011, anomalous warming driven by heat advection was present throughout the region but was much stronger south of 22°S where the poleward‐flowing Leeuwin Current strengthens. During 2012/2013, air‐sea heat exchange had a much more positive (warming) influence on sea surface temperatures (especially in the northwest), and when combined with a more positive contribution of heat advection in the north, this can explain the regional differences in warming between these two La Niña‐associated marine heat wave events.

Gradients of disturbance and environmental conditions shape coral community structure for south‐eastern Indian Ocean reefs

AbstractAimTo describe, model and assess the relative importance of environmental and climatic factors likely influencing the regional distribution of coral cover and assemblages with contrasting life histories and susceptibilities to bleaching.LocationWe compiled the first comprehensive empirical dataset for coral communities in the south‐eastern Indian Ocean (SEIO), incorporating information from 392 sites along the western coast of Australia and offshore atolls/islands across ~19° of latitude.MethodsWe assessed hard coral cover and community composition to genus using point‐intercept transects or point‐count analysis of digital images taken along transects. We explored spatial variation in environmental conditions and in composition of corals with contrasting life histories. After de‐trending the temporal patterns, we assessed the relative importance of environmental metrics to coral cover, life histories and bleaching susceptibility using a full subsets model‐selection approach with generalized additive mixed models, accounting for both temporal and among site variation.ResultsThe distribution of temperature, light, the frequency of temperature anomalies and tropical cyclones appear to be drivers of coral community structure. Functional diversity of low‐ to mid‐latitude coral communities may convey some resilience to thermal stress, while higher latitude communities dominated by Competitive and Bleaching‐Susceptible taxa may lack this functional resilience. These patterns likely reflect varying historical exposure to cyclones and temperature anomalies.Main conclusionsAs evident in recent years, changing background conditions and regimes of disturbance in coming decades will shift the distribution, functional diversity and resilience of coral reefs throughout the SEIO. The rate and magnitude of environmental change will ultimately determine the future of the tropical reefs and whether the higher latitude reefs provide some refuge from climate change. Our study highlights the need to quantify the distributional properties of key environmental metrics to better understand and predict reef condition through coming decades.

The Shallow Overturning Circulation in the Indian Ocean

AbstractThe number of in situ observations in the Indian Ocean has dramatically increased over the past 15 years thanks to the implementation of the Argo profiling float program. This study estimates the mean circulation in the Indian Ocean using hydrographic observations obtained from both Argo and conductivity–temperature–depth (CTD) observations. Absolute velocity at the Argo float parking depth is used so there is no need to assume a level of no motion. Results reveal previously unknown features in addition to well-known currents and water masses. Some newly identified features include the lack of an interior pathway to the equator from the southern Indian Ocean in the pycnocline, indicating that water parcels must transit through the western boundary to reach the equator. High potential vorticity (PV) intrudes from the western coast of Australia in the depth range of the Subantarctic Mode Water, which leads to a structure similar to a PV barrier. The subtropical anticyclonic gyre retreats poleward with depth, as happens in the subtropical Atlantic and Pacific. An eastward flow was found in the eastern basin along 15°S at the depth of the Antarctic Intermediate Water—a feature expected from property distributions but never before detected in velocity estimates. Meridional mass transport indicates about 10 Sv (1 Sv ≡ 106 m3 s−1) southward flow at 6°S and 18 Sv northward flow at 20°S, which results in meridional convergence of currents and thermocline depression at about 16°–20°S. These estimated absolute velocities agree well with those of an ocean reanalysis, which lends credibility to the strictly databased analysis.

Bad news for bobtails: understanding predatory behaviour of a resource-subsidised corvid towards an island endemic reptile

Context Resource subsidisation as a result of urbanisation and other human activity can have positive impacts for some opportunistic predators. Many species of corvid have benefitted from the expansion of human-dominated habitats; however, their impacts on co-occurring prey fauna are generally poorly understood. Aims We aimed to test the hypothesis that urbanisation associated with tourism impacts the predator–prey relationship between Australian ravens, or wardongs (Corvus coronoides), a ubiquitous corvid of southern Australia, and Rottnest Island bobtails (Tiliqua rugosa konowi), a subspecies of bobtail lizard isolated to a small (19km2) island off the coast of Western Australia. Methods Using clay model lizards and camera traps, we assessed the wardongs’ attack rates by distance from the settlement and by whether the model was in closed or open habitat. Key Results We found that while wardongs preyed upon Rottnest Island bobtails, predation was not affected by proximity to human settlement despite the highest number of wardongs being found there. Models in closed vegetation were attacked by wardong significantly more than were those in open vegetation. Implications Increased predation rates in closed vegetation suggests that current revegetation efforts on the island may be increasing the availability of preferred hunting habitat for the wardong. This finding may influence decisions by management on whether to control the large population of wardongs on the island.

Geopolitics in the search for the disappeared Malaysian Airlines Flight MH370

Malaysian Airlines Flight MH370 flying on a routine flight from Kuala Lumpur to Beijing disappeared in the early morning of 8 March, 2014. The last radar-tracked position of the aircraft was some 400 km off Penang Island. After nearly three years of oceanic search of the anticipated crash site of MH370 in the area off the western coast of Australia, absolutely nothing tangible has been found to date. In mid 2015, some debris of the missing aircraft were found off the coast of southeastern Africa. The origin of the recovered flotsam (of MH370) could have been almost anywhere in the western half of the Indian Ocean. The probable crash site might be better identified if the fundamentals of the causes of the crash were examined additionally from the viewpoint of prevailing geopolitics and social psychology of the pilots.

Focus: Offshore Workers Challenge Chevron's Offshore Tax: A $10B Win for Australia &amp; Wins for Workers

6 | International Union Rights | 25/1 FOCUS | TAX AND TRADE UNION RIGHTS Offshore Workers Challenge Chevron’s Offshore Tax: A $10B Win for Australia & Wins for Workers An international coalition of unions recently established a new centre for corporate tax accountability. International research will help unions better campaign on corporate tax issues To fight back against a frontal assault on labour standards in Australia, the ITF took on Chevron, the US-based global oil giant. The ITF’s Chevron campaign has been a huge success and should be a lesson for global unions. Unions need to avoid the temptation to bunker down and fight for a shrinking number of members. If unions are going to succeed in turning the tide against a weakening labour movement and growing corporate dominance, we need to adopt new strategies and new tactics that will also help organise and win for new members. The global trade union movement must expand our fight against capital and directly challenge corporate power beyond the shopfloor. Every dollar in tax avoided by multinationals is making inequality worse. It is a theft from our children’s schools, our hospitals, care and dignity for our elders, our communities and other essential public services that workers rely on everyday. Along with actions by the Australian Tax Office (ATO), the ITF’s efforts have helped the Australian government collect an estimated one billion in back taxes from Chevron. The Australian government has predicted that new tax rules -resulting from a major court victory by the ATO against Chevron- will bring in over $10 billion in additional tax revenue from Chevron and other multinationals over the next decade. The ITF has led the way globally in teaching one of the world’s largest and most agressive multinationals that attacking workers and ignoring unions can have serious and costly consequences far removed from any industrial disputes. As a consequence of the ITF’s campaign, corporate tax dodging continues to be a major political and public issue in Australia and even the current conservative government has been forced to take action. Chevron, Offshore Labour Standards & Maritime Unions Chevron and other companies have operated in Australia’s offshore oil and gas industry for decades and have had positive working relationships with the Maritime Union of Australia (MUA) and other unions. In 2009, when Chevron began the constructing the massive Gorgon project off the coast of Western Australia things changed. Chevron and it’s contractors refused to engage in any meaningful dialogue with unions, employed exploited foreign workers and dramatically undercut existing wages and conditions. Several actions were taken by the MUA, culminating in a strike in 2012 which shut down the project for 2 days. Chevron took the union to court. In 2014, federal judges ruled that the strike action was illegal. Chevron pursued the union through the courts and sought $20 million in damages1. The federal court proceedings over damages are still ongoing. Meanwhile, the MUA won a landmark high court decision in mid-2016 which ruled that offshore workers must be covered by Australia’s labour and immigration laws2. In mid-2017, Chevron reached a landmark settlement with the ATO to pay one billion in back taxes and will likely pay hundreds of millions in additional tax payments every year3. The huge tax payments should make Chevron and other multinationals think twice about taking on the MUA and other unions. The ITF: Stand Up, Fight Back! The ITF determined that Chevron’s refusal to engage with the union could not be left unchallenged and that traditional labour tactics alone would not be enough. In mid-2015, the ITF began work to share information about Chevron’s tax affairs in Australia and more broadly challenge the global oil gaint’s social license to operate. Chevron had another large offshore gas project and several other offshore projects were being developed. If Chevron -when confronted with a strong militant, well organised union- could respond this way in Australia then workers’ rights everywhere would be at risk. Other multinationals would be emboldened by Chevron’s approach. Through intensive research, strategic campaigning and working with a broad coalition, the ITF took the union fight where it could not...

A Lean Sigma Approach to Well Stimulation on Barrow Island, Australia

Summary Barrow Island (BWI), 56 km from the coast of Western Australia (WA), is home to several mature reservoirs that have produced oil since 1965. The main reservoir is the Windalia Sandstone, and it has been waterflooded since 1967, whereas all the other reservoirs are under primary depletion. Because of the maturity of the asset, it is economically critical to continue to maximize oil-production rates from the 430 online, artificially lifted wells. It is not an easy task to rank well-stimulation opportunities and streamline their execution. To this end, the BWI Subsurface Team applied the Lean Sigma processes to identify opportunities, increase efficiency, and reduce waste relating to well stimulation and well-performance improvement. The Lean Sigma methodology is a combination of Lean Production and Six Sigma, which are methods used to minimize waste and reduce variability, respectively. The methods are used globally in many industries, especially those involved in manufacturing. In this asset, we applied the processes specifically to well-performance improvement through stimulation and other means. The team broadly focused on categorizing opportunities in both production and injection wells and ranking them—specifically, descaling wells, matrix acidizing, sucker-rod optimization, reperforating, and proactive workovers. The process for performing each type of job was mapped, and bottlenecks in each process were isolated. Upon entering the “control” phase, several opportunities had been identified and put in place. Substantial improvements were made to the procurement, logistics, and storage of hydrochloric acid (HCl) and associated additives, enabling quicker execution of stimulation work. A new program was also developed to stimulate wells that had recently failed and were already awaiting workover (AWO), which reduced costs. A database containing the stimulation opportunities available at each individual well assisted with this process. The project resulted in the stimulation of several wells in the asset, with sizable oil-rate increases in each. This case study will extend the information available within the oil-industry literature regarding the application of Lean Sigma to producing assets. It will assist other operators when evaluating well-stimulation opportunities in their fields. Technical information will be shared regarding feasibility studies (laboratory-compatibility work and well-transient-testing results) for acid stimulation and steps that can be taken to streamline the execution of such work. Some insights will also be shared regarding the most-efficient manner to plan rig work regarding stimulation workovers.

Marine heatwave causes unprecedented regional mass bleaching of thermally resistant corals in northwestern Australia

In 2015/16, a marine heatwave associated with a record El Niño led to the third global mass bleaching event documented to date. This event impacted coral reefs around the world, including in Western Australia (WA), although WA reefs had largely escaped bleaching during previous strong El Niño years. Coral health surveys were conducted during the austral summer of 2016 in four bioregions along the WA coast (~17 degrees of latitude), ranging from tropical to temperate locations. Here we report the first El Niño-related regional-scale mass bleaching event in WA. The heatwave primarily affected the macrotidal Kimberley region in northwest WA (~16°S), where 4.5–9.3 degree heating weeks (DHW) resulted in 56.6–80.6% bleaching, demonstrating that even heat-tolerant corals from naturally extreme, thermally variable reef environments are threatened by heatwaves. Some heat stress (2.4 DHW) and bleaching (<30%) also occurred at Rottnest Island (32°01’S), whereas coral communities at Ningaloo Reef (23°9’S) and Bremer Bay (34°25’S) were not impacted. The only other major mass bleaching in WA occurred during a strong La Niña event in 2010/11 and primarily affected reefs along the central-to-southern coast. This suggests that WA reefs are now at risk of severe bleaching during both El Niño and La Niña years.

The impact of fire on sand dune stability: Surface coverage and biomass recovery after fires on Western Australian coastal dune systems from 1988 to 2016

This study aims to determine the common response of coastal sand dunes in Western Australia (WA) to fire on decadal time-scales, in terms of ecological-geomorphic-climatic interactions to test the hypothesis that fire plays a role in coastal dune destabilisation. Fires are commonly suggested to have contributed to widespread dune reactivation in Australia and globally, a hypothesis that is relatively untested. We used data from the Landsat Thematic Mapper, Enhanced Thematic Mapper Plus, and Operational Land Imager missions to monitor changes in surface coverage on coastal sand dunes in south-west WA after fires. We analysed 31 fire scars from 1988 to 2016 in two Landsat scenes on the west and south coast of WA. Recovery ratios derived from the Normalised Difference Vegetation Index (NDVI) were used to monitor patterns in post-fire biomass and surface cover. Recovery ratios are correlated with indices of burn severity, and meteorological data to investigate relationships. We also used Maximum Likelihood Classification to monitor changes in bare sand area. Results suggest that recovery followed a strongly consistent pattern, and is characterised by rapid vegetation cover re-establishment within six to twelve months. Prior to this, some aeolian activity may have occurred but without substantial surface changes. Initial germination and/or resprouting were followed by steady growth up to seven years, where NDVI typically neared pre-fire values. Some variation in early recovery occurred between the west and south coast, possibly owing to relative proportions of reseeding and resprouting plants. A log regression explained 75% of the recovery pattern (79% on the south coast). Precipitation had some ability to explain recovery up to nine months post-fire (r2=0.29 to 0.54). No relationships were observed between estimates of burn severity and recovery. After nine months, the biggest cause of spatial variation in recovery was the pre-fire community composition and related seedbank or resprouting density. Image classification did not identify any new blowout features except where fires were not the primary cause. Results suggest that fires are not presently contributing to the destabilisation of coastal dunes in south-west WA.

Taxonomy of the Sand Sliders of Western Australia’s central coast (genus Lerista, Squamata: Scincidae): recognition of Lerista miopus (Günther, 1867)

The Dotted-Line Robust Slider, Lerista lineopunctulata (Duméril &amp; Bibron, 1839), is widely distributed along the western coast of Western Australia. An investigation of diversity within this taxon showed a clear split between northern and southern populations in the vicinity of Jurien. Accordingly, Lerista lineopunctulata is restricted to the southern population while the northern is recognised as Lerista miopus (Günther, 1867). Both taxa are redescribed and diagnosed and a neotype for L. miopus is designated.

Continental‐scale hotspots of pelagic fish abundance inferred from commercial catch records

AbstractAimProtected areas have become pivotal to the modern conservation planning toolbox, but a limited understanding of marine macroecology is hampering their efficient design and implementation in pelagic environments. We explored the respective contributions of environmental factors and human impacts in capturing the distribution of an assemblage of commercially valuable, large‐bodied, open‐water predators (tunas, marlins and mackerels).LocationWestern Australia.Time period1997–2006.Major taxa studiedPelagic fishes.MethodsWe compiled 10 years of commercial fishing records from the Sea Around Us Project and derived relative abundance indices from standardized catch rates while accounting for confounding effects of effort, year and gear type. We used these indices to map pelagic hotspots over a 0.5°‐resolution grid and built random forests to estimate the importance of 33 geophysical, oceanographic and anthropogenic predictors in explaining their locations. We additionally examined the spatial congruence between these hotspots and an extensive network of marine reserves and determined whether patterns of co‐occurrence deviated from random expectations using null model simulations.ResultsFirst, we identified several pelagic hotspots off the coast of Western Australia. Second, geomorphometrics explained up to 50% of the variance in relative abundance of pelagic fishes, and submarine canyon presence ranked as the most influential variable in the North bioregion. Seafloor complexity, geodiversity, salinity, temperature variability, primary production, ocean energy, current regimes and human impacts were also identified as important predictors. Third, spatial overlap between hotspots and marine reserves was limited, with most high‐abundance areas primarily found in zones where anthropogenic activities are subject to few regulations.Main conclusionsThis study reveals geomorphometrics as valuable indicators of the distribution of mobile fish species and highlights the relevance of harnessing static topography as a key element in any blueprint for ocean zoning and spatial management.

Automatic fish species classification in underwater videos: exploiting pre-trained deep neural network models to compensate for limited labelled data

Abstract There is a need for automatic systems that can reliably detect, track and classify fish and other marine species in underwater videos without human intervention. Conventional computer vision techniques do not perform well in underwater conditions where the background is complex and the shape and textural features of fish are subtle. Data-driven classification models like neural networks require a huge amount of labelled data, otherwise they tend to over-fit to the training data and fail on unseen test data which is not involved in training. We present a state-of-the-art computer vision method for fine-grained fish species classification based on deep learning techniques. A cross-layer pooling algorithm using a pre-trained Convolutional Neural Network as a generalized feature detector is proposed, thus avoiding the need for a large amount of training data. Classification on test data is performed by a SVM on the features computed through the proposed method, resulting in classification accuracy of 94.3% for fish species from typical underwater video imagery captured off the coast of Western Australia. This research advocates that the development of automated classification systems which can identify fish from underwater video imagery is feasible and a cost-effective alternative to manual identification by humans.

Large scale variability in the structure of sessile invertebrate assemblages in artificial habitats reveals the importance of local-scale processes

Natural communities are structured by a complex suite of interacting physical and biological processes that operate across multiple spatial and temporal scales. Documenting spatiotemporal variability in ecological patterns can yield insights into the key processes influencing the distributions of species and structure of communities. Many previous studies conducted in natural habitats have recorded systematic shifts in assemblage structure along broad-scale latitudinal gradients, largely because of individual species' thermal affinities. However, it remains unclear as to whether similar patterns occur in artificial habitats, where patterns could be decoupled from natural processes. In this study, we examined patterns of spatial variability in the structure of sessile invertebrate assemblages in coastal infrastructure at multiple scales, including along a large-scale latitudinal gradient in Western Australia (WA). We deployed settlement panel arrays to sample invertebrate assemblages at 5 regions (in 2 seasons) along a latitudinal gradient spanning about 16° and >2000km along the coast of WA. As sea temperature co-varies predictably with latitude in this system, the study also encompassed a temperature gradient of about 10°C. We examined spatiotemporal variability in several assemblage-level metrics, including total biomass, total cover, taxonomic richness and multivariate structure, as well as variability patterns for individual taxa. Unlike assemblages associated with natural habitats along the WA coastline, sessile invertebrate assemblages on coastal infrastructure did not vary systematically with latitude/temperature. Assemblage structure demonstrated little predictability at the regional scale, driven by processes including variability in temperature and adjacent species pools. Rather local-scale variability (and presumably processes and conditions acting at this scale) was far more important. This is an important consideration for coastal managers as local factors (e.g. the design of coastal infrastructure, human activities, hydrodynamic processes and propagule pressure) are likely to be important determinants of ecological pattern, with implications for the spread and establishment of non-indigenous species, biofouling and general ecological structure and functioning.

Calanoides natalis Brady, 1914 (Copepoda: Calanoida: Calanidae): identity and distribution in relation to coastal oceanography of the eastern Atlantic and western Indian Oceans

ABSTRACTUntil recently, Calanoides carinatus s.l. was assumed to be very widespread in the upwelling systems of the Atlantic, Indian and western Pacific Oceans. Molecular data, reported here, show that Calanoides from the eastern Atlantic and Arabian Sea are one species and distinct from C. carinatus s.s. The name Calanoides natalis Brady, 1914 is available for this species, which is fully re-described. The illustration by Brady of the male fifth leg and the currently reported genetic data lead us to conclude that C. natalis is distributed from the Bay of Biscay southwards along the eastern Atlantic, around the Cape of Good Hope, and northwards along the western boundary of the Indian Ocean as far as the Arabian Sea. A by-product of this study is the recognition that Calanoides macrocarinatus is a junior synonym of Calanoides brevicornis. Females of C. natalis are easy to distinguish morphologically from C. carinatus s.s. but are more similar to C. brevicornis, apart from size differences. From physical oceanographic evidence we conclude that the Indian Ocean is currently the upstream part of the distribution of C. natalis. Calanoides philippinensis is known to extend into the eastern Indian Ocean at tropical latitudes. It is not known if it is C. philippinensis that has been recorded along the western coast of Australia. An apparently undescribed species of Calanoides occurs on the eastern Australian coast.