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Marine artificial structures provide substrates on which organisms can settle and grow. These structures facilitate establishment and spread of non-indigenous species, in part due to their distinct physical features (substrate material, movement, orientation) compared to natural habitat analogues such as rocky shores, and because following construction, they have abundant resources (space) for species to colonise. Despite the perceived importance of these habitat features, few studies have directly compared distributions of native and non-indigenous species or considered how functional identity and associated environmental preferences drive associations. We undertook a meta-analysis to investigate whether colonisation of native and non-indigenous species varies between artificial structures with features most closely resembling natural habitats (natural substrates, fixed structures, surfaces oriented upwards) and those least resembling natural habitats (artificial materials, floating structures, downfacing or vertical surfaces), or whether functional identity is the primary driver of differences. Analyses were done at global and more local (SE Australia) scales to investigate if patterns held regardless of scale. Our results suggest that functional group (i.e., algae, ascidians. barnacles, bryozoans, polychaetes) rather than species classification (i.e., native or non-indigenous) are the main drivers of differences in communities between different types of artificial structures. Specifically, there were differences in the abundance of ascidians, barnacles, and polychaetes between (1) upfacing and downfacing/vertical surfaces, and (2) floating and fixed substrates. When differences were detected, taxa were most abundant on features least resembling natural habitats. Results varied between global and SE Australian analyses, potentially due to reduced variability across studies in the SE Australian dataset. Thus, the functional group and associated preferences of the highest threat NIS in the area should be considered in design strategies (e.g., ecological engineering) to limit their establishment on newly built infrastructure. [Display omitted] • We assessed effects of habitat features on colonisation by marine biota. • Abundances did not vary between native and non-indigenous species. • Abundance of functional groups varied between features. • Ecologically informed design strategies are important to reduce invasion risk. [ABSTRACT FROM AUTHOR]

Habitat management is an ecologically based approach to suppress pest densities, utilising properties of non‐crop vegetation to improve the impact of natural enemies or to directly affect pest behaviour. Research in this approach has escalated dramatically this century, extending to uptake in some crops, but adoption in Australia has been lower than overseas. Here, we address the need of the Australian vegetable sector to reduce reliance on insecticides by assessing the scope for habitat management in brassica (Brassicaceae), lettuce (Lactuca sativa) (Asteraceae), capsicum (Capsicum annuum) (Solanaceae), carrot (Daucus carota) (Apiaceae), French bean (Phaseolus vulgaris) (Fabaceae) and sweetcorn (Zea mays) (Poaceae) crops. Each crop is of major economic importance, and together, they represent contrasting botanical families and production systems that are associated with different arthropod complexes. We review studies of habitat management that are based on provision of shelter, nectar, alternative prey or pollen for natural enemies (top‐down effects) or changing pest behaviour (bottom‐up effects) through intercropping or trap crops. The likely utility of these approaches under Australian conditions is assessed, and recommendations are made to promote adoption and for adaptive research. Nectar‐ and pollen‐providing plants, such as alyssum (Lobularia maritima) (Brassicaceae), offer strong potential to promote natural enemies in multiple crops whilst trap crops, especially yellow rocket (Barbarea vulgaris) (Brassicaceae), have more targeted utility against diamondback moth, Plutella xylostella (Lepidoptera: Plutellidae), the most serious pest of brassicas. Opportunities for intercrops and banker plant species are also identified. Our recommendations serve as a platform for researchers and for farmer‐led studies to help realise the full potential of habitat management approaches in Australian vegetable production systems. [ABSTRACT FROM AUTHOR]

Hybrid living shorelines use a combination of engineered structures with natural ecosystems to achieve coastal protection and habitat restoration outcomes, with added co-benefits such as carbon sequestration. Rock fillets constructed along eroding estuarine banks are designed to accumulate sediment, establish mangroves, and stabilise the shoreline. There is, however, a lack of data to support whether rock fillets are achieving these goals. We used a chronosequence of rock fillets to determine their effect on mangrove development, bank stabilisation and carbon sequestration in four estuaries in New South Wales, Australia. Aboveground biomass and adult density increased with age of rock fillets, and mangrove structure was similar to a natural fringing mangrove after 15 years. The rock fillets accumulated sediment, which reduced the eroded estuary bank height, however, little effect of the fillets on bank slope was observed. Sediment carbon stocks were not different between rock fillets, eroding estuary banks and natural fringing mangroves. Rock fillet design had a significant effect on mangrove structure and coastal protection function, with greater wave transmission through lower rock fillets, suggesting design optimisation is needed. As the construction cost of the rock fillets was equal or less than traditional rock revetments, where suitable they present a more economic and environmentally sustainable solution to estuarine erosion management. • Hybrid living shorelines can provide coastal protection and habitat restoration outcomes. • Rock fillets were successful at accumulating sediment and establishing mangroves. • Mangrove structure within rock fillets was similar to natural mangroves after 15 years. • There was no effect of the rock fillets on blue carbon accumulation. • Technical guidance can inform large-scale application of rock fillets for nature-based coastal defence. [ABSTRACT FROM AUTHOR]

The modern day seascape is a mix of natural habitats (saltmarsh, mangroves, seagrass, unvegetated beaches), but increasingly is being replaced with hard engineering structures (e.g. floating pontoons) that have resulted in novel habitats available for flora and fauna. While these engineered structures provide new marine habitat resources, from the viewpoint of biodiversity, they effectively support a sub-set of species found in natural habitats. Unlike previous studies that have used divers for fish visual census, we used a remotely operated vessel with an underwater camera to examine the fish community using floating pontoons in a marina facility in tropical central Queensland, Australia. The camera filmed continuously the edge and underside of pontoons (both surveys covered similar pontoon linear distances – July (winter) 430m; November (summer) 485m; 2021). Fifteen fish species representing 14 families were recorded, with more species observed during summer compared to the winter survey. Remarkably, across both surveys of the 243 fishes individuals that were recorded, 166 (68%) appeared upside-down in videos (i.e., oriented to the underside of the pontoon). Engaging a behaviour of swimming upside-down has been acknowledged in natural habitats elsewhere; some coral reef species living in caves or reef ledges orientate themselves to the cave ceiling or overhanging ledge to increase prey capture rate. However, this is the first study to record fishes exhibiting the same behaviour. We conclude that our less invasive video survey approach provided the opportunity to observe fishes in a state of natural behaviour, orientating themselves towards the pontoon substrate, which is probably simply a response of adhering to basic characteristic modes, i.e., it is the orientation relative to the substrate that is important, rather than their orientation in space per se. Indeed marina pontoons provide an additional feature in already habitat complex estuaries; these data add to why we need to consider the ecosystem services offered by marine infrastructure, and the plasticity of fish to adapt to new environments in an expanding blue economy. [Display omitted] • Pontoons in marinas are an obvious marine habitat in modern day seascape. • ROV revealed nearly all fish were upside-down, orientated to the pontoon substrate. • This behavior could be a response of adhering to basic characteristic modes, such as accessing food and shelter. • The placidity of fish to adopt to new marine environments is demonstrated here. [ABSTRACT FROM AUTHOR]

There is growing demand for novel coastal protection approaches that also provide co-benefits such as enhanced biodiversity. Rock-fillets, which are used to stabilise eroding banks in estuaries, can be colonised by mangroves, and may provide habitat for estuarine fauna. However, it is unknown whether hybrid mangrove/rock-fillet habitats are functionally equivalent to natural mangroves, for estuarine fauna. To determine whether hybrid mangrove habitats are functionally equivalent to natural mangroves, we used δ13C and δ15N stable isotope analyses to describe the isotopic niche space and overlap of estuarine species in these two habitats across three estuaries in NSW, Australia. Using a Bayesian standard ellipse analysis of isotopic niche area, over half the 12 species observed had larger isotopic niche areas in natural mangroves compared to hybrid habitats, however there were no clear patterns for species between habitats. Natural mangroves and hybrid rock-fillet habitats were isotopically distinct for all species sampled (low proportional overlap, 0–19%) suggesting they are not, at present, wholistically functionally equivalent. Estuarine communities from the two habitat types, however, had similar isotopic niches. Hybrid communities displayed a broader range of δ13C values compared to natural mangroves, suggesting mangrove/rock-fillet habitats have a more diverse range of basal food sources. These findings demonstrate the potential for defence solutions to provide unique co-benefits by supporting food webs, but also that natural habitats provide unique ecosystem services that should be protected and rehabilitated where possible. Future modelling and monitoring of habitat utilisation and species performance could provide further insight into the co-benefits and trade-offs of hybrid habitats. • Species isotopic niche size varied for natural mangrove and rock-fillet habitats. • Minimal isotopic niche overlap of natural mangrove and rock-fillet habitats. • Rock-fillet communities have broader δ13C range suggesting more basal food sources. • Natural mangroves and rock-fillet habitats are isotopically distinct. • The two habitats provide equally complex but novel and divergent niches. [ABSTRACT FROM AUTHOR]