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Climate change is causing the distribution and abundance of many organisms to change. In particular, organisms typical of the tropics are increasing in abundance in many subtropical regions, a process known as tropicalization. Here, we examine changes in coral abundance and assemblage structure in the Solitary Islands Marine Park (SIMP), over a 23-year period between 1990 and 2013–14. Total coral cover decreased at all six islands sampled with a concomitant decline in total coral cover at the regional scale (i.e. between sampling occasions). When coral taxa were classified as either cosmopolitan or subtropical, cosmopolitan corals decreased in cover at the regional scale. In contrast, subtropical coral cover did not change at the regional scale because large increases in cover at some islands, such as North Solitary Island, were matched by decreases at other islands. Of 16 common coral taxa examined at the regional level, one declined and two increased in cover with no change in the remaining 13 taxa. In particular, there was no increase in the abundance of coral taxa typically associated with tropical reefs. Similarly, multivariate analyses of coral assemblage structure using these 16 common taxa indicated changes in two of the six island assemblages but, again, provided no evidence for tropicalization. Modelling suggested very low probabilities of larval dispersal from the southern Great Barrier Reef to the SIMP suggesting that limited connectivity with tropical coral populations is one possible cause of the lack of tropicalization in the coral assemblages. We therefore conclude that, despite significant increases in mean sea surface temperature over the last few decades, there has been no tropicalization of the coral fauna in the SIMP. Furthermore, the small proportional reduction in total coral cover, despite the occasional incidence of coral bleaching, coral disease outbreaks and a number of large storms, suggest that the reefs of the SIMP were in reasonably good health at the time of the final survey in 2014. Our results suggest that factors other than temperature, in particular, a lack of dispersal, are limiting the expansion of tropical corals along the east coast of Australia.

Reef-building corals show a marked decrease in total species richness from the tropics to high latitude regions. Several hypotheses have been proposed to account for this pattern in the context of abiotic and biotic factors, including temperature thresholds, light limitation, aragonite saturation, nutrient or sediment loads, larval dispersal constraints, competition with macro-algae or other invertebrates, and availability of suitable settlement cues or micro-algal symbionts. Surprisingly, there is a paucity of data supporting several of these hypotheses. Given the immense pressures faced by corals in the Anthropocene, it is critical to understand the factors limiting their distribution in order to predict potential range expansions and the role that high latitude reefs can play as refuges from climate change. This review examines these factors and outlines critical research areas to address knowledge gaps in our understanding of light/temperature interactions, coral-Symbiodiniaceae associations, settlement cues, and competition in high latitude reefs.

The Sea Slug Census program in Australia engages with citizen scientists to record the diversity and distribution of sea slugs across multiple locations. The program has consistently recorded shifts in distribution patterns but a recent, nine-day census in subtropical eastern Australia recorded unprecedented range extensions of tropical species. Seven species (six chromodorids and one polycerid) were found further south of their previously known distribution with Hypselodoris bertschi being recorded for the first time in Australia. These observations suggested the recent transport of larvae via the East Australian Current with recruitment to coastal sites possibly promoted by a protracted period of strong onshore winds associated with the 2021/22 La Niña in the western Pacific. With the increasing frequency of poleward range extensions of marine taxa, citizen science programs such as the Sea Slug Census provide the opportunity to substantially increase monitoring efforts. Linking with iNaturalist strengthens the value of the observations through online peer review to confirm species identities as well as the incorporation of substantiated (Research Grade) records into international biodiversity databases such as GBIF.

In 2017, the New South Wales (NSW) Office of Environment and Heritage (OEH) initiated a state-wide mapping program, SeaBed NSW, which systematically acquires high-resolution (2–5 m cell size) multibeam echosounder (MBES) and marine LiDAR data along more than 2000 km of the subtropical-to-temperate southeast Australian continental shelf. This program considerably expands upon existing efforts by OEH to date, which have mapped approximately 15% of NSW waters with these technologies. The delivery of high volumes of new data, together with the vast repository of existing data, highlights the need for a standardised, automated approach to classify seabed data. Here we present a methodological approach with new procedures to semi-automate the classification of high-resolution bathymetry and intensity (backscatter and reflectivity) data into a suite of data products including classifications of seabed morphology (landforms) and composition (substrates, habitats, geomorphology). These methodologies are applied to two case study areas representing newer (Wollongong, NSW) and older (South Solitary Islands, NSW) MBES datasets to assess the transferability of classification techniques across input data of varied quality. The suite of seabed classifications produced by this study provide fundamental baseline data on seabed shape, complexity, and composition which will inform regional risk assessments and provide insights into biodiversity and geodiversity.

Being able to tie their body into a knot is beneficial to some moray eels and other cylindrical vertebrates for various reasons, although not all morays’ tie knots. Knot tying can generate leverage for feeding activity by moving the knot up the body, and this leverage may be affected by knot type. Three types of knots are known to have been used by morays’ and this study further elucidates this behaviour and ability. Baited Remote Underwater Videos (BRUVs) were used to compare knot tying between the moray eels Gymnothorax prasinus and Gymnothorax prionodon in the Solitary Islands region, eastern Australia. Gymnothorax prasinus tied more knots overall and more types of knot than G. prionodon (five types vs one type, respectively). Both tied the overhand knot and this was the most common knot used by G. prasinus . The figure of eight knot was used two times more than the double overhand knot, being relatively wider and likely easier to move up the body. Gymnothorax prasinus also tied two undescribed knots, now called the ‘moray knot’ and the ‘morays banana knot’, which have more crossings and are bulkier, increasing potential for generating leverage. However, their uncommon use indicates costs may outweigh benefits of these more complex knots. Lower habitat complexity in deeper waters may influence differences in knot tying as G. prasinus were only recorded shallower than 40 m and G. prionodon mainly deeper. These findings further reveal the utility and complexity of knot tying in moray species and cylindrical vertebrates generally.

Malcolm, H.A., Jordan, A., Schultz, A.L., Smith, S.D.A., Ingleton, T., Foulsham, E., Linklater, M., Davies, P., Ferrari, R., Hill, N., and Lucieer, V., 2016. Integrating seafloor habitat mapping and fish assemblage patterns improves spatial management planning in a marine park. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 1292 - 1296. Coconut Creek (Florida), ISSN 0749-0208. Marine Protected Areas (MPAs) are important spatial mechanisms for managing human activities, if effectively planned. The Solitary Islands Marine Park (SIMP), covering 720 km2 of coastal waters in New South Wales, Australia, includes reef and unconsolidated habitats up to 17 km from shore and 75 m depth. When established in 1991, there was limited knowledge of biotic patterns, seafloor habitats and habitat-biotic relationships in the multiple-use SIMP, which constrained effective conservation planning. Subsequent mapping of sub-tidal habitats from aerial photography and single-beam acoustics improved habitat representation following rezoning in 2002 using Comprehensive, Adequate, Representative (CAR) principles and assisted site selection for diver surveys of fishes, a key surrogate taxon. In 2006, a swath acoustic mapping program commenced, which mapped ~35% of the MPA. This has produced high-resolution data on seafloor habitats, including depths >50 m. Bathymetry and backscatter layers have facilitated targeted deployment of Baited Remote Underwater Video (BRUV) to test hypotheses about associations between fishes and physical habitat characteristics. Strong and persistent patterns in fish assemblage composition in relation to particular habitat characteristics provided the basis for a Habitat Classification Scheme (HCS) to be refined with the following categories: substratum (consolidated, unconsolidated), cross-shelf position (inshore, mid, offshore) and depth (shallow, intermediate, deep). Further refinement of unconsolidated substratum into gravel and sand habitats, which were mapped using backscatter layers, improves this classification. The HCS, which integrates habitat and biotic patterns, greatly increases the potential for effective spatial management planning in the SIMP when used with spatial planning tools (e.g. Marxan).

Transition zones have complex patterns of biogeography and biodiversity which require consideration in conservation planning. Cross-shelf patterns of reef fish assemblage structure and biogeographic representation were determined for the Solitary Islands Marine Park (SIMP), positioned in a tropical-temperate overlap on the east coast of Australia. Sixty-eight sites were surveyed on shallow (<25 m) reefs across an inshore–offshore gradient, using timed counts. Tropical taxa were most prevalent, comprising 50% of the 254 species recorded. Australian endemics accounted for 23% of species, with east coast endemics (14%) predominating. There was a strong cross-shelf gradient, with species richness increasing offshore. There was also a distinct biogeographical gradient with the proportion of temperate species decreasing and tropical species increasing with increasing distance from shore. This gradient was similar for endemic and cosmopolitan species as many of the endemics were temperate or subtropical, and many of the tropical species were widespread Indo-Pacific taxa. These patterns are consistent with sites further offshore being more frequently exposed to the tropical East Australian Current (EAC). Patterns on reefs further inshore are consistent with the high levels of endemism previously reported for temperate and subtropical Australian waters. The complex cross-shelf arrangement of tropical, subtropical and temperate species results in high regional biodiversity and needs to be recognised in marine-park planning.

The presence of large-amplitude Internal Solitary Waves (ISWs or solitons) is quite common in the Andaman Sea, located in the north-eastern Indian Ocean basin. ISWs are known to induce strong vertical velocities which can play an essential role in the mixing transport of nutrients and are proven hazardous to offshore oil platforms. The surface signatures of ISWs can be detected using remote sensing instruments like Synthetic Aperture Radar (SAR) and sunglint true-colour images. The present study makes an effort to delineate as well as detect the possible potential generation locations of mode-1 long living ISWs in the Andaman Sea using remote sensing observations. To accomplish this, the Moderate Resolution Imaging Spectroradiometer (MODIS) true-colour images of Terra/Aqua satellites for the months of March and April during 2014–2016 are used to map the distribution and propagation characteristics of ISWs. These maps along with SAR imgaes from ENVISAT and TerraSAR-X are used to detect the possible generation locations of ISWs. The study considers the possible generation location of ISW as the circumcentre of each wave packet as they radially propagate along a two-dimensional frame. The analysis reveals five potential ISW generation hotspots that are distributed along the Northern Andaman Sea, as well as locations in the discontinuities off the Nicobar Islands and the great passage. The ISWs that form over these regions are hitting the continental shelf within the Andaman Sea. Interestingly, the waves from two potential generation sites between the Nicobar Islands appear to radiate waves in two opposite directions, towards the Andaman Sea and the southern Bay of Bengal.

Strong bidirectional internal solitary waves (ISWs) generate from a shallow channel between Car Nicobar and Chowra Islands of Nicobar Islands, India, and propagate toward the Andaman Sea (eastward) and Bay of Bengal (westward). Batti Malv Island separates this shallow channel into two ridges, north of Batti Malv (NBM) and south of Batti Malv (SBM). First, this study identifies the prominent mode-1 and mode-2 ISWs emerging from NBM and SBM using synthetic aperture radar images and then explores their generation mechanism(s) using a nonlinear, unstructured, and nonhydrostatic model, SUNTANS. During spring tide, flow over NBM is supercritical with respect to mode-1 internal wave. Model simulations reveal that mode-1 ISWs are generated at NBM by a “lee wave mechanism” and propagate both in the east and west directions depending on the tidal phases. However, the flow over SBM is subcritical with respect to mode-1 internal wave. The bidirectional propagating mode-1 ISWs evolve from a long-wave disturbance induced by “upstream influence.” But, during spring tide, with an increased tidal flow over SBM, it is observed that the westward propagating ISWs are formed by a dispersed hydraulic jump observed over the ridge. Moreover, the bidirectional mode-2 waves from SBM are generated by a lee wave mechanism. An energy budget comparison reveals that the region surrounding NBM is efficient in radiating low-mode baroclinic energy (0.98 GW), while SBM is highly efficient in converting barotropic to baroclinic energy (4.1 GW).

Multiple DNA methylation changes in the cancer methylome are associated with the acquisition of drug resistance; however it remains uncertain how many represent critical DNA methylation drivers of chemoresistance. Using isogenic, cisplatin-sensitive/resistant ovarian cancer cell lines and inducing resensitizaton with demethylating agents, we aimed to identify consistent methylation and expression changes associated with chemoresistance. Using genome-wide DNA methylation profiling across 27 578 CpG sites, we identified loci at 4092 genes becoming hypermethylated in chemoresistant A2780/cp70 compared with the parental-sensitive A2780 cell line. Hypermethylation at gene promoter regions is often associated with transcriptional silencing; however, expression of only 245 of these hypermethylated genes becomes downregulated in A2780/cp70 as measured by microarray expression profiling. Treatment of A2780/cp70 with the demethylating agent 2-deoxy-5′-azacytidine induces resensitization to cisplatin and re-expression of 41 of the downregulated genes. A total of 13/41 genes were consistently hypermethylated in further independent cisplatin-resistant A2780 cell derivatives. CpG sites at 9 of the 13 genes ( ARHGDIB , ARMCX2 , COL1A, FLNA , FLNC , MEST , MLH1 , NTS and PSMB9 ) acquired methylation in ovarian tumours at relapse following chemotherapy or chemoresistant cell lines derived at the time of patient relapse. Furthermore, 5/13 genes ( ARMCX2 , COL1A1 , MDK , MEST and MLH1 ) acquired methylation in drug-resistant ovarian cancer-sustaining (side population) cells. MLH1 has a direct role in conferring cisplatin sensitivity when reintroduced into cells in vitro . This combined genomics approach has identified further potential key drivers of chemoresistance whose expression is silenced by DNA methylation that should be further evaluated as clinical biomarkers of drug resistance.