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Abstract: Artificial residential waterways are now widespread in the world’s estuaries. We used the global mapping tool, Google Earth, to determine that there are nearly 4000 linear km of artificial waterways globally, covering an area of 270km2. Residential waterways constructed as open, flow-through canal estates are at their greatest extent in North America (77% of global linear extent), where systems are typically longer and narrower, with more openings and dead-ends than systems elsewhere. The remaining canal estates are spread across all other continents except Antarctica: Asia (7%), Europe (7%), Oceania (7%), South America (0.9%), and Africa (0.6%). A relatively recent design change from open canals to artificial estuarine lakes with tidal barriers has occurred on all continents except Africa, most extensively in Australia (14km2 area, 57 independent systems). The extremely large expansion in artificial residential waterways aimed at increasing opportunities for waterfront living by humans has also modified and expanded estuarine habitat available to aquatic biota. Research can best underpin planning and management of these types of waterways by focussing on their value as habitat and their provision of other goods and services. [Copyright &y& Elsevier]

Abstract: We reviewed seagrass landscape studies on nekton (fish and larger mobile crustaceans) to summarise: (1) patterns of nekton abundance in relation to patch attributes; and (2) models used to explain processes underpinning observed patterns. The response of nekton to landscape attributes is highly variable. Different taxa showed increasing densities with: increasing and decreasing patch size (12 and 11 taxa, respectively), increasing and decreasing proximity within a patch to edge (9, 14), increasing and decreasing distances from nearest seagrass patch (4, 11), and with patches perpendicular and parallel to currents (1, 2). The majority of taxa (213 out of 281, or 82%) showed no relationships. Landscape scale patterns are important for some species but evidence so far does not demonstrate major landscape effects overall. The lack of pattern might reflect the overriding importance of other factors such as within-patch characteristics, water depth or position within an estuary. It might also result from measurements at the wrong scale. The rigour of surveys can be improved by avoiding confounding of patch attributes by other factors, increasing awareness of statistical power, and more considered survey designs for attributes such as edge effects. The predation model is the most frequently invoked and tested model. Other explanatory models are based on disturbance, rates of encounter, food availability, larval supply, migration and reproductive success, but in many cases are not based on observed patterns. The best experimental work has been done on nekton species for which landscape studies have been built on a detailed understanding of the ecology of the species, such as for blue crabs (Callinectes sapidus). As this basic ecological platform is laid for more species, the landscape approach will become increasingly fruitful. [Copyright &y& Elsevier]

Extensive artificial waterways have replaced natural wetlands and created new estuarine habitats on the southern Queensland coast, Australia. Economically important fish species found in adjacent natural wetlands of mangrove, saltmarsh and seagrass also occur in the artificial waterways. Stable isotope analyses (δ13C, δ15N) were used to test whether the relative importance of basal sources of energy varied for foodwebs found in artificial (canals and tidal lakes) and natural waterways. None of the fish species differed in their isotope values between artificial waterways. In contrast, isotopic signatures of snub-nosed garfish (Arrhamphus sclerolepis; Hemiramphidae) varied greatly between natural and artificial waterways, having highly enriched δ13C values (−10.5‰) in natural wetlands, demonstrating reliance on seagrass (−11.4‰), and significantly less enriched values (−19.0‰) in artificial waterways, consistent with either local algal sources (−19.8 to −20.4‰) or a mixture of seagrass and other less enriched autotrophs from adjacent natural wetlands. Isotopic signatures of sand whiting (Sillago ciliata; Sillaginidae) were also significantly more enriched in natural (−18.2‰) than artificial (−21.0‰) habitats, but means were not far enough apart to distinguish between different sources of nutrition. δ13C values of yellowfin bream (Acanthopagrus australis; Sparidae) did not differ between artificial and natural habitats (about −20‰ in both). δ15N values of fish varied among habitats only for A. sclerolepis, which in artificial waterways had values enriched by 2‰ over those in natural waterways. This was consistent with a shift from seagrass (relatively depleted δ15N) as a source in natural habitat to algal sources (relatively enriched δ15N) in artificial habitats. This study provides some of the first evidence that at least some fish species rely on different autotrophs in artificial waterways than in adjacent natural wetlands. [Copyright &y& Elsevier]

Studying and quantifying behaviour is important to understand how animals interact with their environments. However, manually extracting and analysing behavioural data from the large volume of camera footage collected is often time consuming. Deep learning techniques have emerged as useful tools in automating the analysis of certain behaviours under controlled or laboratory conditions, but the complexities of using raw footage from the field has resulted in this technology remaining largely unexplored as a possible data analysis alternative for animals in situ. Here, we use deep learning techniques to automate the analysis of fish grazing behaviour from real-world field imagery. We collected video footage in sea grass meadows in Queensland, Australia, and trained models on a training data set of over 3000 annotations. We used a combination of dense optical flow to assess pixel movement in underwater footage, spatiotemporal filtering to increase accuracy, and deep learning algorithms to classify grazing behaviour of luderick, Girella tricuspidata. When tested on novel videos the model had not seen in training, the model correctly identified nearly all individual grazing events. Deep learning shows promise as a viable tool for determining animal behaviour from underwater videos, and with further development offers an alternative to current time-consuming manual methods of data extraction. • Deep learning and dense optical flow can automate the analysis of behaviour. • This technique has a 92% accuracy in detecting grazing behaviour events. • Using spatiotemporal filtering postprocessing significantly increases performance. • Promising results call for further study into using automation of video analysis. [ABSTRACT FROM AUTHOR]

Species surrogates, the use of particular species to index habitat condition or to represent ecological assemblages are commonly identified in many ecosystems, but are less tested, and therefore less employed in estuaries. Estuaries provide important ecosystem goods (e.g. harvestable species) and services (e.g. carbon processing, coastal armouring), but require protection from multiple human activities, meaning that finding surrogates for estuarine condition or faunal assemblages is a significant knowledge gap. In this study, we test the efficacy of the threatened estuary ray Hemitrygon fluviorum , as a suitable indicator of ecosystem condition and management umbrella surrogate species for conservation prioritisation and monitoring purposes within estuaries. We surveyed fish assemblages and ray presence at ten sites within each of 22 estuaries in southeast Queensland, Australia, using one hour deployments of baited video arrays. We then tested for correlations between ray presence, a series of environmental variables considered important to ecosystem management within estuaries (i.e. testing rays as indicator species), and the co-occurring fish species (i.e. testing rays as umbrella species). Estuary rays function as both umbrella species and ecological indicators of habitat status in subtropical Australian estuaries. As umbrellas, ray occurrence concords with elevated species richness. As ecological indicators, ray distribution concords with habitats of good water quality (especially low turbidity) and more natural vegetation remaining in the catchment. These results highlight the potential for other threatened aquatic vertebrates that are both readily detectable and that are reliable proxies for ecosystems status to be become useful management tools in estuaries. The protection of such large, threatened species in coastal seascapes allows managers to address multiple targets for conservation, especially; (1) protecting species of conservation concern; (2) maintaining diversity; and (3) protecting optimal habitats by better placing reserves. [ABSTRACT FROM AUTHOR]

In blue carbon ecosystems, biomarkers and indicators have been developed to assess soil biogeochemical processes and history. In this study, we investigate blue carbon soils to determine if geochemical characteristics can predict soil microbial characteristics, and secondly to investigate if these two indicators can reveal novel information about processes about soil formation and alteration. First, phospholipid fatty acids (PLFAs) identified soil microbial functional groups and abundances. Microbes varied strongly among the three blue carbon ecosystems – seagrass, mangrove and saltmarsh – and to a lesser extent with soil age/depth. Then, x-ray fluorescence using a core scanner (ITRAX) was used to identify geochemical traits of the soil. Lastly, statistical procedures were carried out to test the ability of ITRAX-derived geochemical characteristics to explain the variation in PLFA composition. The soil geochemical indicators for organic matter (OM) source and turnover explained most of the variability in PLFAs, followed by indicators for redox and grain size. For both indicators the saltmarsh soils were associated with relatively higher OM availability and reactivity and microbial abundance. High OM samples also supported a range of microbial functional groups, including fungi and the co-existence of prokaryotic aerobic and anaerobic metabolisms. In contrast, increased depths representing older soil ages showed decreases in OM reactivity and shifts in OM processing through reduced active microbial abundance. We suggest that x-ray fluorescence data used as an indicator in conjunction with other biomarkers can be used to assess multiple aspects of blue carbon soils (biology, provenance, physicochemistry), while also possessing opportunity for future development as rapid field technique. [Display omitted] • Dual indicators PLFA and ITRAX were used to characterise blue carbon (BC) soils. • Organic matter concentration and reactivity influenced microbial abundance. • Organic matter source and processing supported microbial metabolic diversity. • Correlative biological and geochemical indicators describe BC at multiple scales. [ABSTRACT FROM AUTHOR]

Beach and coastal dune systems are increasingly subjected to a broad range of anthropogenic pressures that on many shorelines require significant conservation and mitigation interventions. But these interventions require reliable data on the severity and frequency of adverse ecological impacts. Such evidence is often obtained by measuring the response of ‘indicator species’. Ghost crabs are the largest invertebrates inhabiting tropical and subtropical sandy shores and are frequently used to assess human impacts on ocean beaches. Here we present the first global meta-analysis of these impacts, and analyse the design properties and metrics of studies using ghost-crabs in their assessment. This was complemented by a gap analysis to identify thematic areas of anthropogenic pressures on sandy beach ecosystems that are under-represented in the published literature. Our meta-analysis demonstrates a broad geographic reach, encompassing studies on shores of the Pacific, Indian, and Atlantic Oceans, as well as the South China Sea. It also reveals what are, arguably, two major limitations: i) the near-universal use of proxies (i.e. burrow counts to estimate abundance) at the cost of directly measuring biological traits and bio-markers in the organism itself; and ii) descriptive or correlative study designs that rarely extend beyond a simple ‘compare and contrast approach’, and hence fail to identify the mechanistic cause(s) of observed contrasts. Evidence for a historically narrow range of assessed pressures (i.e., chiefly urbanisation, vehicles, beach nourishment, and recreation) is juxtaposed with rich opportunities for the broader integration of ghost crabs as a model taxon in studies of disturbance and impact assessments on ocean beaches. Tangible advances will most likely occur where ghost crabs provide foci for experiments that test specific hypotheses associated with effects of chemical, light and acoustic pollution, as well as the consequences of climate change (e.g. species range shifts). [ABSTRACT FROM AUTHOR]

Abstract: Offshore catches of banana prawns, Penaeus merguiensis, are correlated with the extent of mangrove forests. However, recent evaluation has questioned whether the apparent relationship between juvenile penaeids and mangroves reflects specific utilisation of mangroves or just the use of shallow, organically rich, muddy habitats. We investigated this by focussing on juvenile P. merguiensis within 30 mangrove estuaries spanning 650 km of the coast of north-eastern Australia. We investigated a range of hierarchically clustered spatial scales and within-estuary spatial resolutions, as well as variables representing a variety of estuary structural factors, anthropogenic impacts, and particular hypotheses about the ways in which mangroves could influence P. merguiensis catch per unit effort (CPUE). Estuary to estuary differences, rather than climatic zone or the proximity of other estuaries, was the major large scale spatial influence on CPUE. At the among-estuaries scale mangrove extent appeared to influence CPUE but was extensively confounded with the effects of two non-mangrove variables; intertidal extent and substrate type. The fact that 3 alternative measures of connectivity with mangrove forests were not influential, points to the importance of the non-mangrove variables rather than mangrove extent. At the within-estuary scale, P. merguiensis CPUE was correlated with the extent of shallow water but not with mangrove variables. The spatial and temporal extent of sampling support a strong conclusion that factors associated with mangroves alone do not drive abundances of juvenile prawns. Nevertheless, despite being the dominant habitat, mangroves are only one of a mosaic of interacting habitats occurring in the tropical estuaries inhabited by juvenile penaeids (Sheaves, 2009), so causal relationships are complex and difficult to define unambiguously. [Copyright &y& Elsevier]

Abstract: Many anthropogenic activities physically disturb urbanised coastal habitats. The functional response of ecosystems to physical disturbances remains largely unknown due to the lack of suitable quantitative tools for assessing impacts. We conducted a manipulative field experiment to investigate the short-term (i.e. temporally sensitive) response of estuarine sandflat trophodynamics to pulse anthropogenic physical disturbance, using combined chemical tracer (13C), compartmental modelling and network analysis techniques. Pulse physical disturbance, as sediment pumping for an infaunal bait species, was applied at two disturbance intensities at the commencement of the experiment, in 0.09 m2 quadrats. Six compartments and three trophic levels in the estuarine sandflat food web were sampled, including the microphytobenthos, four meiofaunal groups, and soldier crabs (Mictyris longicarpus). Compared with undisturbed controls, in the low disturbance intensity treatment: 1) carbon flow rates between compartments increased, 2) carbon cycling increased, 3) more carbon was retained in the food web, and 4) system indices reflecting ecosystem functioning and resilience were higher. Low disturbance intensity facilitated carbon transfer between organisms and apparently increased resilience. Conversely, high disturbance intensity reduced carbon flow among compartments and carbon cycling, thus lowering resilience. This is the first study with field data quantifying structural and functional changes of sandflat food webs in response to physical disturbance and showed that both ecosystem structure and processes may support the Intermediate Disturbance Hypothesis. This alternative approach to assessing the immediate functional response of estuarine trophic interactions to physical disturbances allows impact detection not possible using conventional approaches. [Copyright &y& Elsevier]

Abstract: Stable carbon isotopes were used to determine the contribution of emergent demersal zooplankton to the diet of the scyphozoan jellyfish Catostylus mosaicus at Smiths Lake, New South Wales, Australia. A preliminary study in 2004 indicated that there was no difference in the δ 13C of ectodermal tissue and mesoglea of the medusae. In 2005, medusae and zooplankton present during the day and night were sampled and isotopic signatures were modelled using IsoSource. Modelling indicated that: (1) mollusc veligers and copepods sampled during the day contributed <13% of the carbon to the jellyfish; (2) copepods sampled at night contributed up to 25%; and (3) the large, emergent decapod Lucifer sp. contributed 88–94%. We hypothesised, therefore, that medusae derive most of their carbon from emergent species of zooplankton. In 2006, sampling done in 2005 was repeated three times over a period of 4 weeks to measure short-term temporal variation in isotopic signatures of medusae and zooplankton, and emergent demersal zooplankton was specifically sampled using emergence traps. Short-term temporal variation in isotopic signatures was observed for some taxa, however, actual variations were small (<1.5‰) and the values of medusae and zooplankton remained consistent relative to each other. IsoSource modelling revealed that mysid shrimp and emergent copepods together contributed 79–100% of the carbon to the jellyfish, and that the maximum possible contribution of daytime copepods and molluscs was only 22%. Jellyfish apparently derive most of their carbon from emergent zooplankton and by capturing small numbers of relatively large taxa, such as Lucifer sp. or mysid shrimp. Small but abundantly captured zooplankton (such as mollusc veligers) contribute only minor amounts of carbon. Jellyfish have a major role in the transfer of carbon between benthic and pelagic food webs in coastal systems. [Copyright &y& Elsevier]

Abstract: The dynamics of plumes from large rivers are relatively well known. Many estuaries are small, however, and discharge directly onto exposed, open shorelines and presumably produce smaller plumes that may have different properties. Therefore this study measured traits of a small estuary on the Australian East Coast as a model system, focusing on (a) plume size, (b) distinctness of plume edges, and (c) imprints on the seafloor. Although plumes were found to be limited in spatial extent (ca. 1km offshore×2.4km longshore) and were constrained near the shore by onshore winds, they exported high nutrient loads from an urbanised watershed. The small plumes were shallow (<2m) and strongly buoyant, with sharp vertical and horizontal clines similar to much larger plumes. The edges of the plumes were highly distinct, clearly separating disparate water masses that trapped significantly higher amounts of nutrients inside the plume. Some particulate material exported from the estuary in the plumes reached the benthos of the nearshore zone, as evidenced by increases in copper concentrations in sediments under the plume. By contrast, the amount of land-sourced carbon delivered by small plumes to the seafloor was minor in comparison to larger inputs from marine sources (e.g. onshore advection of phytoplankton blooms or algae dislodged from reefs) that swamped any contribution from plumes. Overall, small plumes can be important in land–ocean coupling, but their zone of influence may be limited. [Copyright &y& Elsevier]

With the growth of smartphone usage the number of social media posts has significantly increased and represents potentially valuable information for management, including of natural resources and the environment. Already, evidence of using ‘human sensor’ in crises management suggests that collective knowledge could be used to complement traditional monitoring. This research uses Twitter data posted from the Great Barrier Reef region, Australia, to assess whether the extent and type of data could be used to Great Barrier Reef organisations as part of their monitoring program. The analysis reveals that large amounts of tweets, covering the geographic area of interest, are available and that the pool of information providers is greatly enhanced by the large number of tourists to this region. A keyword and sentiment analysis demonstrates the usefulness of the Twitter data, but also highlights that the actual number of Reef-related tweets is comparatively small and lacks specificity. Suggestions for further steps towards the development of an integrative data platform that incorporates social media are provided. [ABSTRACT FROM AUTHOR]

Birds breeding on ocean beaches are threatened globally, often requiring significant investments in species conservation and habitat management. Conservation actions typically encompass spatial and temporal threat reductions and protection of eggs and broods. Still, populations decline or recover only slowly, calling for fresh approaches in beach-bird conservation. Because energetic demands are critically high during the nesting and chick rearing phases, and chick survival is particularly low, supplementing prey to breeding birds and their offspring is theoretically attractive as a means to complement more traditional conservation measures. Prey for plovers and similar species on ocean beaches consists of invertebrates (e.g. small crustaceans, insects) many of which feed on stranded masses of plant material (e.g. kelp and seagrass) and use this ‘wrack’ as habitat. We added wrack to the upper beach where plovers nest and their chicks forage to test whether algal subsidies promote the abundance and diversity of their invertebrate prey. Adding wrack to the upper beach significantly increased the abundance and diversity of invertebrate prey items. At wrack subsidies greater than 50% of surface cover invertebrate assemblages became highly distinct compared with those that received smaller additions of wrack. Substantial (2–4 fold) increases in the abundance amphipods and isopods that are principal prey items for plovers drove these shifts. This proof-of-concept study demonstrates the feasibility of food provisioning for birds on ocean shores. Whilst novel, it is practicable, inexpensive and does not introduce further restrictions or man-made structures. Thus, it can meaningfully add to the broader arsenal of conservation tools for threatened species that are wholly reliant on sandy beaches as breeding and foraging habitats. [ABSTRACT FROM AUTHOR]

Understanding the migratory movements of fish between habitats is an important priority for fisheries management. Carbon (C) and nitrogen (N) stable isotopes were used to evaluate the degree of movement and residency for five fish species collected from coral reefs in Queensland, Australia. Isotope values of fish were measured and compared between slow-turnover muscle tissue and fast-turnover liver tissue, with isotopic agreement between liver and muscle generally indicating resident animals, and relatively low C isotope values in muscle indicating migrants. Three fish species, rabbitfish ( Siganus fuscescens ), painted sweetlips ( Diagramma labiosum ) and Guenther's wrasse ( Pseudolabrus guentheri ) showed relatively consistent carbon isotope values between muscle and liver tissue as expected for resident populations. One quarter of bream ( Acanthopagrus australis ) individuals showed much lower δ 13 C values in muscle than liver. These low values diverged from the −10 to −15‰ values of residents and were more similar to the −20‰ values of fish collected from coastal riverine habitats, the presumed migration source. Moses perch ( Lutjanus russelli ) also showed substantial differences between muscle and liver C isotopes for about a quarter of individuals, but the overall higher C values of these individuals indicated they may have switched diets within island habitats rather than migrating. Our results were consistent with previous studies of fish residency and indicate that measuring stable isotopes in multiple tissues provides a useful methodology for characterizing fish residency in inshore areas. [ABSTRACT FROM AUTHOR]

Robust ecological paradigms and theories should, ideally, hold across several ecosystems. Yet, limited testing of generalities has occurred in some habitats despite these habitats offering unique features to make them good model systems for experiments. We contend this is the case for the ocean-exposed sandy beaches. Beaches have several distinctive traits, including extreme malleability of habitats, strong environmental control of biota, intense cross-boundary exchanges, and food webs highly reliant on imported subsidies. Here we sketch broad topical themes and theoretical concepts of general ecology that are particularly well-suited for ecological studies on sandy shores. These span a broad range: the historical legacies and species traits that determine community assemblages; food-web architectures; novel ecosystems; landscape and spatial ecology and animal movements; invasive species dynamics; ecology of disturbances; ecological thresholds and ecosystem resilience; and habitat restoration and recovery. Collectively, these concepts have the potential to shape the outlook for beach ecology and they should also encourage marine ecologists to embrace, via cross-disciplinary ecological research, exposed sandy beach systems that link the oceans with the land. [ABSTRACT FROM AUTHOR]

Complexity is increasingly the hallmark in environmental management practices of sandy shorelines. This arises primarily from meeting growing public demands (e.g., real estate, recreation) whilst reconciling economic demands with expectations of coastal users who have modern conservation ethics. Ideally, shoreline management is underpinned by empirical data, but selecting ecologically-meaningful metrics to accurately measure the condition of systems, and the ecological effects of human activities, is a complex task. Here we construct a framework for metric selection, considering six categories of issues that authorities commonly address: erosion; habitat loss; recreation; fishing; pollution (litter and chemical contaminants); and wildlife conservation. Possible metrics were scored in terms of their ability to reflect environmental change, and against criteria that are widely used for judging the performance of ecological indicators (i.e., sensitivity, practicability, costs, and public appeal). From this analysis, four types of broadly applicable metrics that also performed very well against the indicator criteria emerged: 1.) traits of bird populations and assemblages (e.g., abundance, diversity, distributions, habitat use); 2.) breeding/reproductive performance sensu lato (especially relevant for birds and turtles nesting on beaches and in dunes, but equally applicable to invertebrates and plants); 3.) population parameters and distributions of vertebrates associated primarily with dunes and the supralittoral beach zone (traditionally focused on birds and turtles, but expandable to mammals); 4.) compound measurements of the abundance/cover/biomass of biota (plants, invertebrates, vertebrates) at both the population and assemblage level. Local constraints (i.e., the absence of birds in highly degraded urban settings or lack of dunes on bluff-backed beaches) and particular issues may require alternatives. Metrics - if selected and applied correctly - provide empirical evidence of environmental condition and change, but often do not reflect deeper environmental values per se. Yet, values remain poorly articulated for many beach systems; this calls for a comprehensive identification of environmental values and the development of targeted programs to conserve these values on sandy shorelines globally. [ABSTRACT FROM AUTHOR]

All fishery food webs are ultimately underpinned by organic matter produced by algae and plants, some of it supplied by primary producers at the fringes of fish habitats. This is no different in tropical and subtropical estuaries where secondary production by crustaceans and finfish may depend on coastal wetlands (e.g. mangroves, seagrass, saltmarshes) abutting channels. Coastal urbanisation is a major cause of wetland loss globally. Hypothetically, reduced wetland area may propagate to less fisheries production if wetland contributions to food webs are substantial – this is the prime question addressed here. We sampled key fisheries species in subtropical estuaries in reaches of moderate urbanisation (18–33% of shoreline hardened) and in reference locations dominated by wetlands, on the east coast of Australia. We used triple stable isotopes (C, N, S) to estimate (using mixing models) the trophic contributions of the key primary producers to regional fisheries species. Organic matter from wetland plants, particularly saltmarsh grass (Sporobolus virginicus), underpinned fishery food webs in most cases (with median contributions ranging from 18 to 88% for saltmarsh grass, followed by 6–70% for C3 wetland plants (e.g. mangroves, phragmites) and 3–36% by benthic algae). Moderate levels of urban transformation of estuarine margins did not change the dominance of wetland carbon for fish and crustaceans in settings without significant seagrass meadows. Given the demonstrated importance of saltmarshes, and other coastal wetlands, to regional fisheries production, conservation of these habitats is necessary in the face of multiple anthropogenic threats. Image 1 • Saltmarsh grass habitat supports food webs of fisheries species. • Moderate urbanisation does not reduce contributions of wetlands to fisheries. • Saltmarsh is an important but undervalued habitat for fisheries in Australia. [ABSTRACT FROM AUTHOR]