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Estuaries are crucial feeding, nursery and resting sites for fish but can also be subject to the impacts of severe flooding. The environmental features of estuaries can mediate how they respond to these impacts. For example, the size, configuration, and context of estuarine habitats across seascapes affects the value of patches for fish, and so fish assemblages at sites with a greater habitat extent or closer to the mouth of an estuary may rebound more quickly from flooding. We investigated how a once in 100-year flood event affected fish assemblages at approximately 600 sites across 13 estuaries and six estuarine habitats (bare sediments, log snags, mangrove forests, rocky structures, saltmarsh and seagrass meadows) in southeast Queensland, Australia, and determined whether flood impacts were mediated by the position of sites within the broader estuarine seascape. Sites were surveyed annually in 2020/2021 (pre-flood) and 2022 (6 months post-flood) using underwater videography. Flooding modified the structure of the fish community and reduced the abundance of fish targeted by local fisheries in all six habitats. Crucially, flood effects on fish were greater at sites near more expansive urbanisation in some ecosystems, but lower at sites nearer to the estuary mouth. Maximising the extent of natural habitats across estuaries can mediate the effects of floods and should be priorities for restoration and management plans seeking to maintain biodiversity and fisheries productivity in the face of increasing climate-related disturbances. [ABSTRACT FROM AUTHOR]

Early indicators of restoration success can inform adaptive management strategies and maintain community interest and financial investment. Coastal wetland restoration projects prioritize monitoring the succession of habitat forming communities. However, these communities often expand slowly. In contrast, fish and crustaceans can quickly occupy newly available habitats and therefore, may be early indicators of restoration success. Here, we compared the short‐term responses of fish and crustacean communities and landcover area to restoration actions at a restoring wetland and three reference wetlands in the Maroochy River in eastern Australia. Fish and crustacean communities and landcover area were surveyed every 6 months between Spring 2017 and Spring 2019 (n = 5), with two sampling events conducted before restoration actions commenced in May 2018 and three after. Fish and crustaceans were surveyed using baited underwater video stations and fyke nets. Landcover was remotely sensed using a combination of Worldview‐2 satellite imagery, object‐based image analysis, and random forest classification. Fish and crustaceans make viable indicators for early restoration success, as our findings show the composition, diversity, and abundance of species targeted in fisheries of these communities can resemble assemblages at reference sites within 1 year of restoration actions. The area of tidal inundation significantly increased overtime, but the recovery of mangroves and saltmarsh communities did not. These findings support the notion that coastal wetland restoration can promote immediate recruitment by fish and crustacean communities, thus making these taxa useful indicators for communicating early success of restoration projects. [ABSTRACT FROM AUTHOR]

Roost selection and diet are fundamentally important to bats and can vary geographically and with habitat. The greater broad-nosed bat (Scoteanax rueppellii) is infrequently captured and poorly known, meaning appropriate conservation actions are difficult to determine. To assess variation across different habitats, we collected faecal samples for dietary analysis and radio-tracked individuals to identify roost trees at four different sites across New South Wales, Australia. Analysis of droppings verified beetles as the main prey in each study area except one dominated by mangroves, and confirmed for the first time carnivory in wild-caught individuals from the presence of hair from other bat species in its droppings. Very large, hollow trees were used as maternity roosts, being typically larger than neighbouring trees. Roosting habitat varied from wet sclerophyll forest in gullies to old-growth mangroves, and tree species used as roosts also varied. Colony size at maternity roosts was often 50–100 bats and fidelity to the maternity roost varied, with some being switched almost daily and others occupied for at least several days. One maternity roost was re-used 2 years later. Both the importance of beetles in the diet and roosts located in more productive landscapes suggest coastal plains and foothills may represent key habitat. Understanding a species' ecology across different geographic regions provides a sound basis for improving its conservation. Greater broad-nosed bats were captured and radio-tracked in different regions to describe roosts used and diet. Beetles were the main prey in each study area except one dominated by mangroves, and for the first time carnivory in wild-caught individuals was documented. Very large, hollow trees were used as maternity roosts, but vegetation associations and tree species varied. [ABSTRACT FROM AUTHOR]

The ecosystem services concept has been slow to integrate into written law and policy in Australia. We sought to examine whether the concept has permeated deeper into practice, focusing on the coastal wetland protection, management and restoration context. We conducted a Delphi study involving 16 key informants. Over two rounds of interviews we found confirmation that the ecosystem services concept is not a central part of practice, and a strong consensus support for integrating and mainstreaming ecosystem services into law and policy through law reform. Our informants also provided additional new insights on how reform should proceed: (1) integration may occur through consolidated or interconnected law and policy instruments, (2) decision-maker discretion should be retained but subject to constraints, especially regarding (3) trade-offs between different ecosystem services and ecosystem services and other land uses. Our informants also called for (4) more effective and targeted policy to facilitate restoration projects, (5) incentivised protection and restoration across land tenure types, especially on privately-owned land and (6) caution in dealing with trade-offs and financial valuations of ecosystem services. The insights provided through this Delphi study will be instructive for law and policy reform in Australia and other jurisdictions grappling with fragmented management, protection and restoration of coastal wetlands. • Practice shows that the ecosystem services concept is not central to law, policy or decision-making about coastal wetlands. • There is strong consensus support for incorporating the ecosystem services concept into law and policy. • However care should be taken when dealing with trade-offs and financial valuations of ecosystem services. [ABSTRACT FROM AUTHOR]

In the conventional view, species are separate gene pools delineated by reproductive isolation (RI). In an alternative view, species may also be delineated by a small set of 'speciation genes' without full RI, a view that has gained broad acceptance. A recent survey, however, suggested that the extensive literature on 'speciation with gene flow' is mostly (if not all) about exchanges in the early stages of speciation. There is no definitive evidence that the observed gene flow actually happened after speciation is completed. Here, we wish to know whether 'good species' (defined by the 'secondary sympatry' test) do continue to exchange genes and, importantly, under what conditions such exchanges can be observed. De novo whole-genome assembly and re-sequencing of individuals across the range of two closely related mangrove species (Rhizophora mucronata and R. stylosa) reveal the genomes to be well delineated in allopatry. They became sympatric in northeastern Australia but remain distinct species. Nevertheless, their genomes harbor ∼4000–10   000 introgression blocks averaging only about 3–4 Kb. These fine-grained introgressions indicate continual gene flow long after speciation as non-introgressable 'genomic islets,' ∼1.4 Kb in size, often harbor diverging genes of flower or gamete development. The fine-grained introgression in secondary sympatry may help settle the debate about sympatric vs. micro-allopatric speciation. In conclusion, true 'good species' may often continue to exchange genes but the opportunity for detection is highly constrained. [ABSTRACT FROM AUTHOR]

Connectivity between land and sea through the movement of species, energy and nutrients means that land-based impacts can affect the structure and functioning of nearby coastal ecosystems. As the interface between land and sea, estuaries are often faced with increasing pressures from catchment modifications (e.g. the removal of terrestrial vegetation) which can alter the overall health of estuaries (e.g. the degradation of coastal water quality due to an increase in terrestrial runoff) and change the value of habitat for many marine species. These landscape-scale impacts can, however, be mediated through variations in the context and connectivity of seascapes (e.g. greater extent of vegetated ecosystems help to filter nutrients). We surveyed fish across five estuaries over four years using underwater videography and sought correlations between fish biodiversity and abundance with variables indexing catchment land use, seascape connectivity, and coastal water quality. Fish assemblages were more abundant and diverse at sites which had lower chlorophyll-a concentrations and were nearer to the estuary mouth, in conjunction with catchments containing higher percent of natural land and heterogenous seascapes. Sites with lower concentrations of chlorophyll-a supported indicator species from more diverse functional groups that had greater fisheries values, in comparison to indicator species from sites with high concentrations of chlorophyll-a. This research can help direct coastal management to better prioritise management in coastal ecosystems, thereby enhancing fish richness and abundance, functional group richness and fisheries value. • Estuaries connect land to sea and are facing impacts from multiple spatial scales. • Coastal management requires quantitative data to disentangle multi-scaled impacts. • Sites with lower chlorophyll-a concentrations had more abundant and diverse fish. • Catchments with higher nature and conservation land had more diverse fish species. • Disentangling combined multi-scaled impacts can help prioritise coastal management. [ABSTRACT FROM AUTHOR]

Australia's Great Barrier Reef (GBR) catchments include some of the world's most intact coastal wetlands comprising diverse mangrove, seagrass and tidal marsh ecosystems. Although these ecosystems are highly efficient at storing carbon in marine sediments, their soil organic carbon (SOC) stocks and the potential changes resulting from climate impacts, including sea level rise are not well understood. For the first time, we estimated SOC stocks and their drivers within the range of coastal wetlands of GBR catchments using boosted regression trees (i.e. a machine learning approach and ensemble method for modelling the relationship between response and explanatory variables) and identified the potential changes in future stocks due to sea level rise. We found levels of SOC stocks of mangrove and seagrass meadows have different drivers, with climatic variables such as temperature, rainfall and solar radiation, showing significant contributions in accounting for variation in SOC stocks in mangroves. In contrast, soil type accounted for most of the variability in seagrass meadows. Total SOC stock in the GBR catchments, including mangroves, seagrass meadows and tidal marshes, is approximately 137 Tg C, which represents 9%–13% of Australia's total SOC stock while encompassing only 4%–6% of the total extent of Australian coastal wetlands. In a global context, this could represent 0.5%–1.4% of global SOC stock. Our study suggests that landward migration due to projected sea level rise has the potential to enhance carbon accumulation with total carbon gains between 0.16 and 0.46 Tg C and provides an opportunity for future restoration to enhance blue carbon. [ABSTRACT FROM AUTHOR]

Ecological restoration is increasingly being upscaled to larger spatial scales of tens to hundreds of kilometers. Yet the complex logistics and high costs of ecological restoration mean that actions must be placed strategically at local scales of tens of meters to maximize ecological benefits and reduce socioeconomic costs. Despite the purported use of systematic planning tools for allocating restoration effort, the uptake and implementation of data‐driven restoration planning and ecological goal setting remains poor in many restoration programs. Here we demonstrate how the sequential workflows of systematic conservation planning can be translated to restoration at two spatial scales to enhance estuarine fisheries in eastern Australia. We select estuaries where restoration is feasible and recommended based on quantitative regional ecological goals (i.e. regional‐scale prioritization), and then identify potential restoration sites at smaller spatial scales within estuaries based on the principles of spatial ecology to ensure that the success and benefits of restoration are maximized (i.e. local‐scale prioritization). At the regional scale, we identified four levels of restoration priorities (very high, high, intermediate, and low) using quantitative ecological goals and the current ecological understanding of each system. At the local scale, we used spatially explicit Bayesian belief networks to identify sites that maximize restoration outcomes based on the environmental niche of habitat‐forming species and the spatial configuration of habitats that maximizes their use by fish. We show that using systematic frameworks can become an essential tool to optimize restoration investments at multiple scales as efforts upscale globally. [ABSTRACT FROM AUTHOR]

Human pressures on ecosystems from landscape transformation and harvesting can result in changes to body size and functional traits of affected species. However, these effects remain very poorly understood in many settings. Here we examine whether and how fishing and the attributes of coastal seascapes can operate in concert to change the body size and functional traits of the giant mud crab, Scylla serrata; a prized fisheries species. We captured 65 legal sized (> 15 cm carapace width) male giant mud crabs from 13 estuaries in southeast Queensland, Australia. These estuaries span a wide range of fishing and catchment landscape transformation intensity. We made a total of 9000 external morphometric measurements in the study. There was a distinct effect of estuarine landscape context on body size, with the largest individuals captured from systems with bigger inlets and lower extent of intertidal flats. Variation in functional traits was most often associated with variation in fishing pressure and human population size in the catchment. Crabs from areas with less commercial fishing pressure and lower human populations in the catchment had the largest chelipeds. We also found effects of urbanisation (negative correlations), intertidal flats (inconsistent effects) and mangrove extent (positive correlations) on the size of some functional traits. Our results show that human pressures can have sublethal effects on animals in estuaries that alter body size and functional traits. These phenotypic responses might have consequences for the fitness and ecological roles of targeted species, and the yields of fisheries catches. [ABSTRACT FROM AUTHOR]

Plastic pollution in the marine environment is a pervasive and increasing threat to global biodiversity. Prioritising management actions that target marine plastic pollution require spatial information on the dispersal and settlement of plastics from both local and external sources. However, there is a mismatch between the scale of most plastic dispersal studies (regional, national and global) and the scale relevant to management action (local). We use a fine-resolution hydrodynamic model to predict the potential exposure of coastal habitats and species (mangroves, coral reefs and marine turtles) to plastic pollution at the local scale of a management region (the 1,700 km2 Whitsunday Islands, Queensland, Australia). We assessed the potential exposure of mangroves, coral reefs and marine turtles to plastics during the two dominant wind conditions of the region; the trade wind and monsoon wind seasons. We found that in the trade wind season (April to September) all habitats and species had lower exposure than during the monsoon wind season (October to March). In both wind seasons we found a small proportion of coral reef habitat and large area of turtle habitat were in high potential exposure categories. Unlike coral reefs or marine turtles, mangroves had consistent hotspots of high exposure across wind seasons. Local scale management requires data at fine resolution to capture the variability that occurs at this scale. The outputs of our study can inform the development of conservation resources and local scale management action. Image 1 • Weather conditions strongly dictate plastic exposure patterns. • Variable winds in the monsoon season lead to higher exposure of plastic. • Strong south-easterly trade winds lead to plastic removal, therefore lower exposure. • Plastic types have different accumulation patterns at a small geographic scale. [ABSTRACT FROM AUTHOR]

The seascape context of coastal ecosystems plays a pivotal role in shaping patterns in fish recruitment, abundance, and diversity. It might also be a principal determinant in structuring the recruitment of fish assemblages to restored habitats, but the trajectories of these relationships require further testing. In this study, we surveyed fish assemblages from 14 restored oyster reefs and 14 control sites in the Noosa River, Queensland, Australia, that differed in the presence or absence of seagrass within 500 m, over four periods using baited cameras. Fish assemblages at oyster reefs differed from those at control sites, with higher species richness (1.4 times) and more individuals of taxa that are harvested by fishers (1.8 times). The presence or absence of seagrass nearby affected the abundance of a key harvestable fish species (yellowfin bream Acanthopagrus australis) on oyster reefs, but not the overall composition of fish assemblages, species richness, or the total abundance of harvestable fishes overall. These findings highlight the importance of considering species-specific patterns in seascape utilization when selecting restoration sites and setting restoration goals, and suggest that the effects of restoration on fish assemblages might be optimized by focusing efforts in prime positions in coastal seascapes. [ABSTRACT FROM AUTHOR]

The ecosystem services paradigm is a widely recognised concept in ecology and environmental management, but one that is not uniformly incorporated into environmental law. This article argues that the integration of this paradigm into law can assist with protection of critical environmental resources, using mangrove ecosystems as an example. This article commences with a defence of the ecosystem services paradigm, followed by a discussion of the ecosystem services provided by mangroves. It argues that a comprehensive analysis of existing laws is a necessary first step towards legal reform, and to this end, it proposes a rubric for assessment of laws and legal frameworks. This rubric is applied to laws in Queensland, Australia, as a case study. It concludes by identifying major deficiencies in the recognition of mangrove ecosystem services in existing laws, and calling for reform in this area. [ABSTRACT FROM AUTHOR]

Cyclones are significant drivers of change within mangrove ecosystems with the extent of initial damage determined by storm severity, location and distribution (exposure), and influenced by species composition and structure (e.g., height). The long‐term recovery of mangroves is often dependent upon hydrological regimes, as well as the frequency of storm events. On February 3, 2011, Tropical Cyclone Yasi (Category 5) made landfall on the coast of north Queensland Australia with its path crossing the extensive mangroves within and surrounding Hinchinbrook Island National Park. Based on a combination of Landsat‐derived foliage projective cover (FPC), Queensland Globe aerial imagery, and RapidEye imagery, 16% of the 13,795 ha of mangroves experienced severe windthrow during the storm. The greatest damage from the cyclone was inflicted on mangrove forests dominated primarily by Rhizophora stylosa, whose large prop roots were unable to support them as wind speeds exceeded 280 km/hr. Classification of 2016 RapidEye data indicated that many areas of damage had experienced no or very limited recovery in the period following the cyclone, with this confirmed by a rapid decline in Landsat‐derived FPC (from levels > 90% from 1986 to just prior to the cyclone to < 20% postcyclone) and no noticeable increase in subsequent years. Advanced Land Observing Satellite (ALOS‐1) Phased Arrayed L‐band Synthetic Aperture Radar (SAR) L‐band HH backscatter also increased initially and rapidly to 5 ± 2 dB (2007–2011) due to the increase in woody debris but then decreased subsequently to −20 ± 2 dB (postcyclone), as this decomposed or was removed. The lack of recovery in affected areas was attributed to the inability of mangrove species, particularly R. stylosa, to resprout from remaining plant material and persistent inundation due to a decrease in sediment elevation thereby preventing propagule establishment. This study indicates that increases in storm intensity predicted with changes in global climate may lead to a reduction in the area, diversity, and abundance of mangroves surrounding Hinchinbrook Island. On February 3, 2011, Tropical Cyclone Yasi (Category 5) struck the coast of north Queensland Australia with its path crossing the extensive mangroves within and surrounding Hinchinbrook Island National Park. Based on a combination of remote sensing data, 16% of the 13,795 ha of mangroves experienced severe windthrow, primarily Rhizophora stylosa. The data also revealed that many areas of damage had experienced no or very limited recovery. [ABSTRACT FROM AUTHOR]

Across their range, mangroves are responding to coastal environmental change. However, separating the influence of human activities from natural events and processes (including that associated with climatic fluctuation) is often difficult. In the Gulf of Carpentaria, northern Australia (Leichhardt, Nicholson, Mornington Inlet, and Flinders River catchments), changes in mangroves are assumed to be the result of natural drivers as human impacts are minimal. By comparing classifications from time series of Landsat sensor data for the period 1987-2014, mangroves were observed to have extended seawards by up to 1.9 km (perpendicular to the coastline), with inland intrusion occurring along many of the rivers and rivulets in the tidal reaches. Seaward expansion was particularly evident near the mouth of the Leichhardt River, and was associated with peaks in river discharge with Li DAR data indicating distinct structural zones developing following each large rainfall and discharge event. However, along the Gulf coast, and particularly within the Mornington Inlet catchment, the expansion was more gradual and linked to inundation and regular sediment supply through freshwater input. Landward expansion along the Mornington Inlet catchment was attributed to the combined effects of sea level rise and prolonged periods of tidal and freshwater inundation on coastal lowlands. The study concluded that increased amounts of rainfall and associated flooding and sea level rise were responsible for recent seaward and landward extension of mangroves in this region. [ABSTRACT FROM AUTHOR]

Industrial activities and urbanization have had a major consequence for estuarine ecosystem health and water quality globally. Likewise, Sydney estuary has been significantly impacted by widespread, poor industrial practices in the past, and remediation of legacy contaminants have been undertaken in limited parts of this waterway. The objective of the present investigation was to determine the effectiveness of remediation of a former Pb-contaminated industrial site in Homebush Bay on Sydney estuary (Australia) through sampling of inter-tidal sediments and mangrove ( Avicennia marina) tissue (fine nutritive roots, pneumatophores, and leaves). Results indicate that since remediation 6 years previously, Pb and other metals (Cu, Ni and Zn) in surficial sediment have increased to concentrations that approach pre-remediation levels and that they were considerably higher than pre-settlement levels (3-30 times), as well as at the reference site. Most metals were compartmentalized in fine nutritive roots with bio-concentration factors greater than unity, while tissues of pneumatophores and leaves contained low metal concentrations. Lead concentrations in fine nutritive root, pneumatophore, and leaf tissue of mangroves from the remediated site were similar to trees in un-remediated sites of the estuary and were substantially higher than plants at the reference site. The situation for Zn in fine nutritive root tissue was similar. The source of the metals was either surface/subsurface water from the catchment or more likely remobilized contaminated sediment from un-remediated parts of Homebush Bay. Results of this study demonstrate the problems facing management in attempting to reduce contamination in small parts of a large impacted area to concentrations below local base level. [ABSTRACT FROM AUTHOR]

Globally, sea-level rise (SLR) is a major environmental challenge for coastal ecosystems. Of particular concern are the impacts on intertidal wetlands, the loss of which would have detrimental consequences for both human and ecological communities. On the south-east Australian coast, case studies suggest that the future of intertidal wetlands will greatly depend on landward migration as surface accretion may not keep up with the predicted SLR in many estuaries. However, due to differences in geomorphological settings and land-use, estuaries vary in their capacity to accommodate lateral migration. Regional scale assessment of the lateral accommodation space is therefore critical for pre-emptive planning to conserve these valuable coastal ecosystems. In this study, we analysed wetland lateral accommodation space distribution within 110 estuaries under three SLR scenarios and three land management options on the New South Wales coast, south-east Australia. From the wetland distribution predictions, we calculated and mapped the lateral accommodation space in each estuary associated with each sea level and land use scenario. We further investigated the relationships between wetland migration capacity, intertidal hypsometry represented by elevation skewness, and estuary type within a Bayesian analysis framework. Our results showed that while a few large riverine estuaries dominated the state's total accommodation space, saline wetlands were at risk of disappearing from most intermittently closed-open estuaries if they cannot vertically accrete at the pace of SLR. These distinct responses to SLR are due to different elevation distributions. Furthermore, our assessment of land use adaptation options suggested that the promotion of landward migration without impairing other important ecosystems could be achieved by making low intensity land uses available within several riverine estuaries and barrier (open entrance) estuaries. Through identifying migration opportunities and barriers, the findings of the study could support regional scale adaptation strategies to ensure the sustainability of wetland-associated ecosystem goods and services., Competing Interests: Declaration of competing interest We confirm that the manuscript has been read and approved by all named authors and that there are no other persons who satisfied the criteria for authorship but are not listed. We further confirm that the order of authors listed in the manuscript has been approved by all of us., (Crown Copyright © 2022. Published by Elsevier B.V. All rights reserved.)

In light of the global extent and cascading effect of our impact on the environment, we design and manage reserves to restore biodiversity and the functioning of ecosystems. Mobile organisms link important processes across ecosystems, however, their roles in providing these services are often overlooked and we need to know how they influence ecosystem functions in reserves. Herbivorous fish play a key role in coral reef seascapes. By removing algae, they promote coral growth and recruitment, and help to increase resilience., We examined how connectivity with mangroves affected herbivore populations and benthic succession on reefs in eastern Australia. We surveyed fish assemblages, examined reef composition and characterised benthic recruitment on reefs at multiple levels of connectivity with mangroves, in a no-take reserve and areas open to fishing., Our results show that connectivity enhanced herbivore biomass and richness in reserves, and that these connectivity and reserve effects interacted to promote herbivory on protected reefs near mangroves., Connectivity and reserve protection combined to double the biomass of roving herbivorous fish on protected reefs near mangroves. The increase in grazing intensity drove a trophic cascade that reduced algal cover and enhanced coral recruitment and reef resilience., Synthesis and applications. Our findings demonstrate that ecosystem resilience can be improved by managing both reefs and adjacent habitats together as functional seascape units. By understanding how landscapes influence resilience, and explicitly incorporating these effects into conservation decision-making, we may have greater success with environmental restoration and preservation actions. [ABSTRACT FROM AUTHOR]

Recognising both the importance of intertidal wetlands and their role in mosquito-borne disease we discuss wise management to conserve wetland values and to reduce vector borne disease health risks. First we summarise the mosquito-borne diseases associated with intertidal wetlands in sub-tropical and tropical Australia. We consider the Ramsar Strategic Plan, its reflection in some key Australian statutes and the relationship between environment-focussed legislation and health legislation. This is followed by a brief overview of mosquito control and its impact on human health. Using a salt marsh example of an integrated process, we describe the development of what was, in the 1980s in Australia, a novel method of habitat modification (runnelling) for mosquito control. Runnelling modifies the tidal water flow on salt marshes, reducing mosquito larval numbers and minimising environmental impacts. The approach is related to two of the Ramsar goals (wise use and institutional capacity and effectiveness). We then describe the extension of its rationale to a complex mangrove system. Finally, with a concept model, we consider the convergence between minimal habitat modification for wetland conservation and human health protection using an interdisicplinary approach involving multiple stakeholders. [ABSTRACT FROM AUTHOR]

In Kakadu National Park, a World Heritage property in the Australian monsoon tropics 250 km to the east of Darwin, a number of recent studies have shown that woody encroachment (expansion of woody communities) and densification (increased biomass in woody communities) has occurred in the last 40 years. The cause of this increase in woody biomass is poorly understood, but possibly associated with the control of invasive Asian water buffalo, trend to higher rainfall, and increased frequency of fires. Mangroves provide an important context to understand these landscape changes, given that they are unaffected by fire or feral water buffalo. We examine change in mangrove distribution in a series of coastal tropical swamps fringing Darwin, Northern Territory, Australia over a 30-year period using a series of 7 aerial photographs spanning 23 years from 1974 and a 2004 high-resolution satellite image. In late 1974, Darwin was impacted by an intense tropical cyclone. Vegetation at 3,000 randomly placed points was manually classified, and a multinomial logistic model was used to asses the impact of landscape position (coastal, intertidal, and upper-tidal) and swamp on mangrove change between 1974 and 2004. Over the study period, there was instability and slight mangrove loss at the coast, stability in the intertidal zone, and mangrove gain in the upper-tidal zone, with an overall increase in mangrove presence of 16.2% above the pre-cyclone distribution. A swamp that was impacted by drainage works for mosquito control and the construction of a sewage treatment plant showed a greater mangrove increase than the two unmodified swamps. The mangrove expansion is consistent with woody encroachment observed in nearby but ecologically distinct systems. Plausible causes for this change include changed local hydrology, changes in sea level, and elevated atmospheric CO concentrations. [ABSTRACT FROM AUTHOR]

Land use/cover and mangrove spatial changes were assessed for ten sites and their sub-catchments in Southeast Queensland, Australia. Two time periods were involved: 1972–1990, a period of relatively high rainfall, and 1990–2004, which was significantly drier. Aerial photographs and Landsat satellite imagery were used to map the inter-tidal wetlands and classify the land use/cover in the sub-catchments. A Maximum Likelihood Classification was used to map three types of land cover: agriculture, built-up and plantation forest. Mangroves (mainly Avicennia marina) were the focus as they have been recorded over recent decades encroaching into salt marsh. The Mangrove-Salt marsh Interface (MSI) Index was developed to quantify the relative opportunity for mangroves to expand into salt marshes, based on the shared boundary between them. The index showed a consistent relationship with mangrove expansion and change. To address problems of high dimensionality and multi-collinearity of predictor variables, a Partial Least Squares Regression (PLSR) model was used. A key finding of this research was that the contribution of environmental variables to spatial changes in the mangroves was altered following a reduction in rainfall. For example, agriculture had more influence on mangrove expansion and change during the wet period than during the dry period. [Copyright &y& Elsevier]

The notion that the widespread mangrove genus Ceriops consists of three species, C. australis (White) Ballment, Smith & Stoddart, C. decandra (Griff.) Ding Hou and C. tagal (Perr.) C. B. Rob., is still widely accepted. However, our recent studies have shown that the previously recognized species Ceriops decandra can be separated into three species, C. decandra, C. zippeliana Blume and Ceriops pseudodecandra sp. nov. Sheue, Liu, Tsai & Yang based on morphological and molecular evidence. The last entity is newly described in this treatment, which has been misapplied with the name C. decandra for several decades in Australia, Papua New Guinea and Seram, New Guinea (Irian Jaya) of Indonesia. Morphologically, the new species is more similar to C. decandra and C. zippeliana than to C. australis and C. tagal. Furthermore, molecular phylogenetic analysis also supports the notion that C. pseudodecandra is distinctly a new species. Here, the botanical descriptions with an illustration and the distribution ranges of the related species are provided. A key to differentiate species of Ceriops and a comparison with an emphasis on these three morphologically similar species are given as well. [ABSTRACT FROM AUTHOR]

Effects of salinity and nutrients on carbon gain in relation to water use were studied in the grey mangrove, Avicennia marina, growing along a natural salinity gradient in south-eastern Australia. Tall trees characterized areas of seawater salinities (fringe zone) and stunted trees dominated landward hypersaline areas (scrub zone). Trees were fertilized with nitrogen (+N) or phosphorus (+P) or unfertilized. There was no significant effect of +P on shoot growth, whereas +N enhanced canopy development, particularly in scrub trees. Scrub trees maintained greater CO2 assimilation per unit water transpired (water-use efficiency, WUE) and had lower nitrogen-use efficiency (NUE; CO2 assimilation rate per unit leaf nitrogen) than fringe trees. The CO2 assimilation rates of +N trees were similar to those in other treatments, but were achieved at lower transpiration rates, stomatal conductance and intercellular CO2 concentrations. Maintaining comparable assimilation rates at lower stomatal conductance requires greater ribulose 1·5-bisphosphate carboxylase/oxygenase activity, consistent with greater N content per unit leaf area in +N trees. Hence, +N enhanced WUE at the expense of NUE. Instantaneous WUE estimates were supported by less negative foliar δ13C values for +N trees and scrub control trees. Thus, nutrient enrichment may alter the structure and function of mangrove forests along salinity gradients. [ABSTRACT FROM AUTHOR]

Abstract: The aim was to explore the use of Light Detection and Ranging (LiDAR) data to map the micro-topography of an intertidal wetland in southeast Queensland Australia. The driver for this was the need to identify and map the habitats of the immature stages of an aedine disease vector mosquito (Aedes vigilax (Skuse)). We derived a high resolution digital elevation model (DEM) data set at a vertical resolution of 0.05m from LiDAR data. The relative accuracy of the DEM across the site was tested by comparing water depth predictions derived from the DEM against in-situ water depth readings from pressure sensors over a 10-day tidal cycle, which included high spring tides. We found that the field observations of micro-topographic units important for mosquito management matched those delineated from the DEM. The micro-topography included a low berm or central ridge that was more or less continuous across the site, a shallow back basin and fringing mangroves. The fringing mangroves had unimpeded connection to the tidal source, however the central ridge blocked tidal water from the back basin for all but the highest tides. Eggshell survey indicated that the back basin was the area suitable for immature mosquitoes. We conclude that LiDAR data has application for understanding and mapping the structure of mangrove wetlands. We have also demonstrated (in a small area) that LiDAR is useful for modelling the effect of sea level changes on the coastal fringe. LiDAR may be the only method to inform research on changes to land use and ecosystems caused by sea level change. [Copyright &y& Elsevier]

Abstract: Changes in rainfall pattern have been suggested as a mechanism for the landward incursion of mangrove into salt marsh. The aim of the research was to assess the relationship between rainfall patterns and the spatial distribution of mangrove forests at study sites in Moreton Bay, Southeast Queensland, Australia, over a 32-year period from 1972 to 2004. To identify periods of relatively consistent rainfall patterns points at which rainfall patterns changed (change-points) were identified using the non-parametric Pettitt–Mann–Whitney-Statistic and the cumulative sum technique. The change-points were then used to define the temporal periods over which changes to mangrove area were assessed. Both mangrove and salt marsh area were measured by digitizing aerial photographs acquired in 1972, 1990 (the year with the most significant change-point), and 2004. The rates of change in mangrove area pre-1990 (a wetter period) and post-1990 (a drier period) were estimated. A significant positive relationship was demonstrated between rainfall variables and landward mangrove expansion, but not for seaward expansion. We concluded that rainfall variability is one of the principal factors influencing the rate of upslope encroachment of mangrove. However, the rate of expansion may vary from site to site due to site-specific geomorphological and hydrological characteristics and the level of disturbance in the catchment. [Copyright &y& Elsevier]

The article presents a study which investigates the effect of the fucalean macroalga Hormosira banksii on molluscan species abundance in mangroves and the influence of morphology to the outcome of its interspecific interactions. The study conducted a sampling of 3 mangrove sites and 3 rocky shores along the east coast of Australia, which exposes that patches of H. banksii supports a greater species abundance of molluscs than adjacent substratum. Result shows that the transfer of H. banksii from estuarine tidal flats and rocky shores into the mangrove suggests that the source of the algae scalped the magnitude of impact. Conclusion shows that it is important to understand the conditions and mechanics that influence community-level effects of foundation species to conserve biodiversity.

The northeastern shore of Gulf St Vincent, South Australia is a mesotidal, low-wave-energy coastline, characterised by tidal-dominated bioclastic carbonate sedimentation. Distinctive assemblages of subtidal, intertidal and supratidal marine plants and invertebrate animals have resulted in well defined, adjacent bio- and litho-facies that lie parallel to each other across broad areas of coastal sedimentation. At Port Gawler, the intertidal zone is bounded by a landward high-tide beach and a subtidal Posidonia australis seagrass meadow seaward. Thirty years ago, within the immediate study area, this intertidal zone comprised an inner sandflat and an outer muddy seagrass meadow dominated by Zostera muelleri, the two areas separated by a shallow tidal distributary. Avicennia marina is a species of mangrove that has colonised much of the protected, tidal-dominated coasts of South Australia. Propagules of this tree readily take root in intertidal mud, with a natural ecological succession of Z. muelleri followed by A. marina. Over the time of observation, juvenile mangroves have progressively colonised a narrow zone along the landward side of the muddy seagrass meadow; they appear unable to colonise a sandy substrate. Juveniles advanced rapidly southward from mature woodland in the north towards equally mature woodland in the south. From the initial tap root, juvenile plants send out radial roots from which project, snorkel-like, an array of vertical pneumatophores. Redistributed algal, seagrass and other organic flotsam collect around these vertically protruding pneumatophores, promoting accumulation of organic sediment. Within the newly forming mangrove woodland, there has been pronounced sediment aggradation of >0.5 m, greatly altering the dynamics of tidal flow. Tidal flow is now largely constrained to a channel between the mature southern woodland and that formed most recently. Higher velocity flows through this channel have exhumed populations of infaunal bivalves, and floodtide and ebbtide deltas of coarse bioclastic sediments are a consequence. The aggraded sediment of the new woodland shelters the area landward. Consequently, more muddy sediments are now covering what was formerly bare sandflat, thus providing new areas for mangrove colonisation. Migration of mangroves towards the high-tide beach is inevitable and will be limited only by their need for regular flushing of accumulated salt from their roots by seawater at high tide. Thus, A. marina drives rapid geomorphic change in the tidal-dominated coasts of the South Australian gulfs. In similar coastal areas of southeast Asia, where intertidal muddy sediments predominate, this species appears to be an ideal candidate for reforestation projects. Juvenile plants should grow successfully and rapidly, so preparing coastal environments for the establishment of more ecologically diverse mangrove communities. [ABSTRACT FROM AUTHOR]

Abstract: We present results from a series of piezometers installed in the foreshore flat and mangrove environments of the Gillman Marshes, South Australia in an interdisciplinary study of the propagation of the ocean tide into the coastal aquifers. A unique feature of the analysis is that all water level records were harmonically analysed so that the behaviour of the four major tidal constituents could be independently examined. The main findings were that: (1) the decay of the groundwater tide in the coastal aquifers was greater than that predicted by the Ferris solution. A theoretical model has been developed and applied to the study site. The model suggests that this behaviour is due to the occurrence of a time delay in the Darcian response in the shelly and muddy sand substrate; (2) when the tide is incident over a gently sloping bank, the time delay in response gives rise to a spiked signal in which high water is confined to a small fraction of the tidal cycle; and (3) at the coastal interface tidal propagation across a sloping bank causes a rise in the water table relative to mean sea level which is proportional to the variance of tidal elevation and inversely proportional to the decay constant of the groundwater tide. The model developed in this study is also applicable to other coastal groundwater systems with tidal influence. [Copyright &y& Elsevier]

Abstract: The aim of this work was to quantify the soil carbon storage and sequestration rates of undisturbed natural wetlands and disturbed wetlands subject to restriction of tidal flow and subsequent rehabilitation in an Australian estuary. Disturbed and undisturbed estuarine wetlands of the Hunter estuary, New South Wales, Australia were selected as the study sites for this research. Vertical accretion rates of estuarine substrates were combined with soil carbon concentrations and bulk densities to determine the carbon store and carbon sequestration rates of the substrates tested. Relationships between estuary water level, soil evolution and vertical accretion were also examined. The carbon sequestration rate of undisturbed wetlands was lower (15% for mangrove and 55% for saltmarsh) than disturbed wetlands, but the carbon store was higher (65% for mangrove and 60% for saltmarsh). The increased carbon sequestration rate of the disturbed wetlands was driven by substantially higher rates of vertical accretion (95% for mangrove and 345% for saltmarsh). Estuarine wetland carbon stores were estimated at 700–1000GgC for the Hunter estuary and 3900–5600GgC for New South Wales. Vertical accretion and carbon sequestration rates of estuarine wetlands in the Hunter are at the lower end of the range reported in the literature. The comparatively high carbon sequestration rates reported for the disturbed wetlands in this study indicate that wetland rehabilitation has positive benefits for regulation of atmospheric carbon concentrations, in addition to more broadly accepted ecosystem services. [Copyright &y& Elsevier]

Abstract: Carbon and nitrogen isotopic composition was used to identify the main sources of carbon and describe the main trophic pathways in Deluge Inlet, a near-pristine mangrove estuary in tropical north Queensland, Australia. Producers'' δ 13C varied from −28.9‰ for mangroves to −18.6‰ for seagrass. Animals were also well separated in δ 13C (−25.4‰ to −16.3‰ for invertebrates and −25.2‰ to −17.2‰ for fish), suggesting considerable differences in ultimate sources of carbon, from a substantial reliance on mangrove carbon to an almost exclusive reliance on seagrass. In general, invertebrates had lower δ 15N than fish, indicating lower trophic levels. Among fish, δ 15N values reflected well the assumed trophic levels, as species from lower trophic levels had lower δ 15N than species from higher trophic levels. Trophic levels and trophic length were estimated based on δ 15N of invertebrate primary consumers (6.1‰), with results suggesting a food web with four trophic levels. There was also evidence of a high level of diet overlap between fish species, as indicated by similarities in δ 13C for fish species of higher trophic levels. Stable isotope data was also useful to construct a general model for this food web, where five main trophic pathways were identified: one based on both mangrove and microphytobenthos, one on plankton, two on both microphytobenthos and seagrass, and one based mainly on seagrass. This model again suggested the presence of four trophic levels, in agreement with the value calculated based on the difference in δ 15N between invertebrate primary consumers and top piscivores. [Copyright &y& Elsevier]

• A multi-layer radiative transfer model is extended for mangroves • Plant area index, woody material and fractional cover are considered • Clumping corrections are added for canopies and the submerged understory • Model parameterisation and verification using field measurements and Sentinel-2 pixels • Increased wood proportion reduces NIR reflectance and increases SWIR reflectance Mangroves are essential coastal wetland vegetation and their extent and leaf area index (LAI) have been mapped using remotely sensed Earth Observation images. However, the physics-based relationship between biophysical properties of mangroves, tidal height, and their spectral values remains underexplored. In order to quantitatively evaluate the impact of woody material on mangrove spectra from optical imagery, a canopy reflectance model (CRM) was extended to simulate and analyse the reflectance of mangroves. The fractional cover, leaf-to-total area ratio and water depth were included as model parameters, increasing the fidelity of the canopy architecture in the CRM. A mangrove study area in South East Queensland, Australia, was chosen for model parameterisation and verification using field and satellite data. Simulated Sentinel-2 reflectance spectra of the mangrove plots closely matched the observed pixel reflectance spectra, with their coefficient of determination (R 2) values higher than 0.98 and root mean square error values lower than 0.01, which was better than the performance of the original CRM omitting the fractional cover and woody material. The inverted plant area index and fractional cover values from the satellite imagery closely matched the field-derived reference values (R 2 = 0.78 and 0.97, respectively). Simulation results revealed that a higher proportion of woody material in crowns reduced the canopy reflectance of mangroves in the near infrared region and increased the reflectance in the shortwave infrared region. Moreover, the simulated reflectance of the Sentinel-2 red edge 1 (695–714 nm) was not sensitive to the wood proportion for the examined cases. The modelling framework may be used to evaluate the impact of woody material for estimating mangrove LAI from optical imagery. The model may also be used to quantitatively analyse the mangrove reflectance spectra when including other important factors such as tidal height. [ABSTRACT FROM AUTHOR]

In January 2006, 25tonnes of heavy fuel oil spilled into the Port of Gladstone in Queensland, Australia, from the breached hull of a bulk carrier ship. Over the following days, approximately 18tonnes of the oil was recovered, however a certain amount of oil was deposited in the intertidal areas of Port Curtis leaving a highly visible, viscous residue. The objectives of this research were to assess the immediate impacts on the intertidal habitat and to gain baseline information for future comparative assessments. Sediment PAH and metal concentrations, mangrove communities and intertidal macroinvertebrates were assessed within one month post-spill at oil-impacted sites; adjacent sites which were not visibly impacted; and reference sites which were located outside the recorded distribution of the oil spill. Highest PAH concentrations were found at the impacted sites, with concentrations of some PAHs exceeding Australian and New Zealand Sediment Quality Guidelines (). These sites contained very few or no crab holes in the high intertidal area, indicating a low crab density in comparison to reference sites. Little immediate impact was evident on the mangrove and macrobenthic communities, however future surveys may show evidence of longer-term impacts on these communities. [Copyright &y& Elsevier]

Rates of nest predation have frequently been shown to differ between fragmented and unfragmented habitats, but have rarely been compared among natural habitats in the same geographic region. In this study, artificial nests of two types (open cup and domed) were placed in four habitats (mangroves, monsoon rainforests, eucalypt woodlands and paperbark swamps) over 12 months in three localities near Darwin in the Australian monsoon tropics to determine the effects of habitat, season and nest type on the rate of nest predation. A quail egg and a similarly coloured plasticine egg were placed in each nest. Habitat had a strong effect on nest predation rates, with nests in mangroves experiencing predation rates more than four times higher than those in eucalypt woodlands and paperbark swamps. Despite the strong rainfall seasonality of the region, there was no consistent seasonal variation in nest predation rates. Nest type also had little influence on predation rates, except in paperbark swamps where open cup nests suffered a higher predation rate than domed nests. The study indicates that generalised nest predation rates for tropical regions, even for small areas (e.g. <17 km radius), might overlook substantial variation between habitats. Such variation confounds purported differences in nest predation rates between tropical and temperate regions. [ABSTRACT FROM AUTHOR]

Abstract: Tidal flooding and surface drainage patterns have often been used to describe mangrove species zonation. However, in mangrove forests exhibiting little topography, ambiguous species distributions and/or few species, such approaches are ineffective. We identified four physiognomic mangrove forest types (Riverine, Fringing, Overwash and Basin) at Coombabah Lake, a tidal lake in southeast Queensland, Australia and investigated tidal flooding patterns using synoptic surveys of tidal observations at the local Standard Port combined with local water depth observation. Subsequently three sub-types of the basin forest type were identified: (1) Deep Basin Forest with mature trees, ∼50cm standing water and ∼3 tides per year; (2) Medium Depth Basin Forest with intermediate tree development, ∼15–30cm standing water and 20–40 tides per year; and (3) Shallow Basin Forest with relatively recent mangrove establishment, 5–15cm standing water and ∼80 tides per year. These three basin sub-types were found to flood at different tide heights with the Shallow Basin flooding for tides above mean high water springs and the Deep Basin flooding only for tide heights approaching the highest astronomical tide. We propose that these basin types represent a succession in mangrove forest development that corresponds with increasing water depth and tree maturation over time. The succession not only represents increasing age but also change in basin substrate composition. This is manifest as increasing pneumatophore density and an increasing area of basin surface occupied by contiguous pneumatophore cover. As a result, it seems that mangrove development is able to modify tidal flooding into the basin by increasingly impeding water movement. [Copyright &y& Elsevier]

The effect of human disturbance on mangrove forest may be substantially different from the effects of natural disturbances. This paper describes differences in vegetation composition and structure of five vegetation types in two mangrove areas near Darwin, Australia, 25 years after disturbance. The vegetation in clear-felled forest showed more adult Avicennia marina than in the hurricane-affected forest, and a virtual absence of A. marina juveniles and saplings. This indicates that A. marina will be replaced by other species in the canopy, showing a multi-phase vegetation development in mangrove forest after human disturbance. The mechanism of disturbance and the conditions after clearing therefore affects the vegetation composition for at least 25 years after this disturbance took place. [ABSTRACT FROM AUTHOR]

1. Using colour aerial photography, a set of fine (∼1 m) spatial resolution orthomosaics and accompanying Digital Elevation Models (DEMs) were generated for the majority of mangroves in Kakadu National Park, Northern Australia, from which their extent and canopy height have been mapped. 2. The orthomosaics and DEMs, which were based on 68 stereo pairs acquired in 1991, cover an area of approximately 742 km² and a coastal distance of 86km. The DEMs have a height resolution of approximately ± 1 m. 3. The entire mosaic represents a key historical baseline data set of the extent and height of mangroves within the Park against which to observe and quantify changes in response to, for example, sea-level rise. 4. The data sets will be available to assist management of the coastal environment and also to provide a unique insight into the distribution, dynamics and condition of mangroves. The techniques used are applicable to mangroves and other forested wetlands in other regions of Australia and elsewhere. [ABSTRACT FROM AUTHOR]

We analyzed a time series of aerial photographs and Landsat satellite imagery of the Pioneer River Estuary (near Mackay, Queensland, Australia) to document both natural and anthropogenic changes in the area of mangroves available to filter river runoff between 1948 and 2002. Over 54 years, there was a net loss of 137 ha (22%) of tidal mangroves during four successive periods that were characterized by different driving mechanisms: (1) little net change (1948–1962); (2) net gain from rapid mangrove expansion (1962–1972); (3) net loss from clearing and tidal isolation (1972–1991); and (4) net loss from a severe species-specific dieback affecting over 50% of remaining mangrove cover (1991–2002). Manual digitization of aerial photographs was accurate for mapping changes in the boundaries of mangrove distributions, but this technique underestimated the total loss due to dieback. Regions of mangrove dieback were identified and mapped more accurately and efficiently after applying the Normalized Difference Vegetation Index (NDVI) to Landsat Thematic Mapper satellite imagery, and then monitoring changes to the index over time. These remote sensing techniques to map and monitor mangrove changes are important for identifying habitat degradation, both spatially and temporally, in order to prioritize restoration for management of estuarine and adjacent marine ecosystems. [ABSTRACT FROM AUTHOR]

Grapsid crabs are one of the most common, and potentially important, elements of the mangrove fauna but relatively little information is available on patterns in their distribution and abundance. In part, this may be due to difficulties in estimating the abundance of burrowing species. By not having reliable methods of estimating changes in distribution and abundance of crabs, ecological impacts of crabs may be greatly underestimated. We tested several methods for estimating the apparent abundance of eight species of grapsids in a north Australian mangrove forest. These methods included continuous and instantaneous visual counts at two distances, two types of pitfall traps and photography. We also excavated crabs to test the reliability of the best of these methods. Overall, pitfall traps equipped with funnels proved most useful, although these did preferentially capture larger crabs. An exception was the large crab, Neosarmatium meinerti, which was rarely captured and more reliably estimated by burrow counts. Traps proved to be most useful in this study and may be for long term studies of grapsid species, however, the selection of a method should be made after careful evaluation of the questions and relevant information required for any particular study. Finally, these methods may also prove to be useful in other environments such as salt marshes. [ABSTRACT FROM AUTHOR]

Abstract: The paradigm that mangroves are critical for sustaining production in coastal fisheries is widely accepted, but empirical evidence has been tenuous. This study showed that links between mangrove extent and coastal fisheries production could be detected for some species at a broad regional scale (1000s of kilometres) on the east coast of Queensland, Australia. The relationships between catch-per-unit-effort for different commercially caught species in four fisheries (trawl, line, net and pot fisheries) and mangrove characteristics, estimated from Landsat images were examined using multiple regression analyses. The species were categorised into three groups based on information on their life history characteristics, namely mangrove-related species (banana prawns Penaeus merguiensis, mud crabs Scylla serrata and barramundi Lates calcarifer), estuarine species (tiger prawns Penaeus esculentus and Penaeus semisulcatus, blue swimmer crabs Portunus pelagicus and blue threadfin Eleutheronema tetradactylum) and offshore species (coral trout Plectropomus spp.). For the mangrove-related species, mangrove characteristics such as area and perimeter accounted for most of the variation in the model; for the non-mangrove estuarine species, latitude was the dominant parameter but some mangrove characteristics (e.g. mangrove perimeter) also made significant contributions to the models. In contrast, for the offshore species, latitude was the dominant variable, with no contribution from mangrove characteristics. This study also identified that finer scale spatial data for the fisheries, to enable catch information to be attributed to a particular catchment, would help to improve our understanding of relationships between mangroves and fisheries production. [Copyright &y& Elsevier]

Abstract: Herbicides, particularly diuron, were correlated with severe and widespread dieback of the dominant mangrove, Avicennia marina (Forsk.) Vierh. var. eucalyptifolia (Val.) N.C. Duke (Avicenniaceae), its reduced canopy condition, and declines in seedling health within three neighbouring estuaries in the Mackay region of NE Australia. This unusual species-specific dieback, first observed in the early 1990s, had gotten notably worse by 2002 to affect >30km2 of mangroves in at least five adjacent estuaries in the region. Over the past century, agricultural production has responded well to the demands of increasing population with improvements in farm efficiency assisted by significant increases in the use of agricultural chemicals. However, with regular and episodic river flow events, these chemicals have sometimes found their way into estuarine and nearshore water and sediments where their effects on marine habitats have been largely unquantified. Investigations over the last three years in the Mackay region provide compelling evidence of diuron, and possibly other agricultural herbicides, as the most likely cause of the severe and widespread mangrove dieback. The likely consequences of such dieback included declines in coastal water quality with increased turbidity, nutrients and sediment deposition, as well as further dispersal of the toxic chemicals. The implications of such findings are immense since they describe not only the serious deterioration of protected and beneficial mangrove habitat but also the potential for significant direct and indirect effects on other highly-valued estuarine and marine habitats in the region, including seagrass beds and coral reefs of the Great Barrier Reef lagoon. This article reviews all key findings and observations to date and describes the essential correlative and causative evidence. [Copyright &y& Elsevier]

An examination was made of the genetic variation with age in mangrove populations in two estuaries in south-east Australia, one contaminated, the other uncontaminated. Sediment nutrient and metal levels, and isozyme/allozyme complements were measured in three age-classes in four stands in each estuary, to identify site and intergenerational genetic composition, and influences of sediment contamination. Within each river, there were greater genetic distances among the age-classes than among sampling sites. A downstream gradient of genetic distance was found in the uncontaminated river, but not the contaminated one, where genetic distances seemed to reflect site-specific factors, though apparently not the present sediment metal or nutrient levels. It appears that genetic distances in the polluted river may reflect past fluctuations in pollution pressures. In both rivers, genetic distances indicate that the mangroves within one estuary form one population, with `neighbourhood'' differentiation. [Copyright &y& Elsevier]

Chytrids are common microfungi in soils, but their distribution and diversity in Australian soils is poorly described. In this study we analyzed chytrid distribution and diversity in soils from four collection sites representing a subtropical rain forest, wet sclerophyll forest, dry sclerophyll forest, and open heath, using a defined and reproducible sampling protocol. The greatest number of chytrid species was observed from dry sclerophyll forest soils, while the least number of species occurred in the open heath soils, although each soil sample of the open heath harbored more species per sample. Differences in patterns of distribution of chytrid species were statistically significant between subtropical rain forest and open heath. Patterns in other habitats differed but could not be verified statistically to be significant at the 5% level. Observed differences in chytrid distribution, diversity, and freqency indicate that their ecological strategies may be in response to environmental cues such as specific edaphic conditions and substrate availability, and their capacity to respond to the environment. [ABSTRACT FROM AUTHOR]

The distribution of juvenile Penaeus (Fenneropenaeus) merguiensis de Man and other epibenthic crustaceans in different microhabitats within a riverine mangrove forest was examined in subtropical eastern Australia. Catches in vegetated and cleared microhabitats were compared at sites located in mangroves on the creek edge (1–2 m into the forest) and the inner forest (a further 14–22 m into the forest). Crustaceans were sampled using 3×3 m lift nets that were activated at the top of spring flood tides between March and May 2000. The abundance of P. merguiensis in the adjacent creek was also monitored during both high and low tides using a small beam trawl. A large size range of P. merguiensis was caught in the mangrove forest (2–13.5 mm carapace length) and the maximum density recorded was 1 prawn m−2. Catches of P. merguiensis were significantly higher at the creek edge than at the inner forest sites. Catches did not differ significantly between vegetated and cleared microhabitats, but catches were highly variable within microhabitats. This result was attributed to the very high activity levels of P. merguiensis and suggests that detecting differences between microhabitats used by prawns in the field would require a large number of samples. Substantial numbers of Acetes sibogae australis (Hansen), Macrobrachium novaehollandiae (de Man) and Metapenaeus bennettae (Racek and Dall) also entered the forest and catches of these species followed a similar pattern to those for P. merguiensis, i.e. catches were higher at the creek edge than the inner forest, did not differ between microhabitats and were highly variable within a microhabitat. [Copyright &y& Elsevier]

Contemporary foraminiferal samples and associated environmental information were collected from Cocoa Creek, a mesotidal fringing mangrove environment on the Great Barrier Reef (GBR) coastline, Australia, to elucidate the relationship of the foraminiferal assemblages with elevation and environment. There is a strong and highly significant relationship between elevation and the foraminiferal assemblages, supporting the intertidal vertical zonation concept, which suggests that the distribution of foraminifera in the intertidal zone is usually a direct function of elevation, with the most important controlling factors being the duration and frequency of subaerial exposure. Multivariate analyses separate the intertidal foraminiferal assemblages into three elevational zones, with Zone I the highest and Zone III the lowest: Zones I and II are dominated by agglutinated species Trochammina inflata and Miliammina fusca, respectively; and Zone III is dominated by calcareous species, notably Ammonia tepida and Elphidium discoidale multiloculum. These assemblage zones are similar to those found in both tropical and temperate intertidal environments. A predictive transfer function has been developed to allow reconstruction of former sea levels for tropical environments, based upon the relationship between foraminiferal assemblage and elevation. Results suggest that a precision of ±0.07 m should be attainable, superior to most similar studies from temperate, mid latitude environments. Our work has produced the first foraminifera-based transfer function for environmental interpretations for tropical Australia, and allows the potential development of a new generation of high-resolution sea-level reconstructions for the post-glacial sequences of the GBR shelf. [Copyright &y& Elsevier]

Although the life history–environment relationship for juvenile Penaeus merguiensis in tropical regions has been well documented, little is known about the species towards the subtropical limits of its range. Seasonal patterns of abundances of juvenile and postlarval P. merguiensis were studied in the Logan River, a subtropical estuary in eastern Australia from January 1998 to July 2000. Prawns were sampled using a small beam trawl at fortnightly intervals when they were abundant and monthly intervals at other times. The prawns ranged in size from 1.8 to 22 mm in carapace length (CL), with a mean size (±1 SE) of 6.7±0.1 mm CL and were caught at densities of up to 14.2±3.3 prawns m−2. Postlarvae were caught from January to July, with peaks in April and May; and juveniles were abundant from December to June, although this varied between years. The numbers of postlarvae, temperature and rainfall explained 23% of the overall variation in juvenile catches. Temperature and rainfall also explained some of the variation in postlarval catches (9.9%). Recruitment varied considerably between years, and was the highest in years when rainfall was low (1998 and 2000). In general, both the seasonal patterns of catches of postlarval and juvenile P. merguiensis, and environmental processes affecting their abundance were similar to tropical areas. However, one notable difference was that recruitment occurred over a more restricted time period in the Logan River than in tropical regions. [Copyright &y& Elsevier]

In tide-dominated sedimentary systems, close relationships exist between tidal hydrodynamics, sediment transport and geomorphology. Tropical coastlines contain many tide-dominated mangrove creeks, yet few studies to date have examined the detail of such relationships for these environments. Time-series observations of tidal height, currents and suspended sediment concentrations were taken between 1992 and 1996 in Cocoa Creek, a mangrove creek system near Townsville, NE Australia. The creek and surrounding mangrove swamps and salt flats were surveyed with an echo-sounder and total survey station, respectively. For ‘within-channel’ tides, the flood tide is always the fastest, at up to 0.5 m s−1. In contrast, for overbank tides (i.e. tidal height > + 1.5 m Australian Height Datum, AHD) ebb currents are fastest in July, December and January, but flood currents are fastest in August and September, at up to 1 m s−1 in both cases. The tidal asymmetry of overbank tides in Cocoa Creek is controlled by the interaction between offshore tidal forcing and the intertidal storage effect of the mangrove swamps and salt flats, with the result being that during certain periods of the year there tends to be a predominance of either faster flood or ebb velocities on overbank tides. Significant tidal suspended sediment transport in the channel is only initiated at overbank height. On overbank tides, measured net suspended sediment fluxes in the channel are mostly seaward-directed (up to 180 t per tidal cycle). However, the net flux measured over a neap–spring period may be either landwards or seawards (up to 465 and 60 t, respectively). Furthermore, on the larger overbank tides (where the maximum tidal height >+1.85 m AHD) net sediment fluxes may be reduced because of a limited supply of available material. Thus hydrodynamic and sediment sampling durations of up to a month may not be representative of long-term trends. Given that our large dataset has not identified a clear long-term net transport direction within the creek system, we conclude tentatively that the geomorphology of Cocoa Creek may be near a long-term equilibrium. [Copyright &y& Elsevier]

The study investigated the use of aerial photographs, acquired in 1950 and 1991, for assessing the temporal dynamics of mangroves along the West Alligator River in Australia's Northern Territory. For both years, mangrove extent was mapped using an unsupervised classification of the digital orthomosaic and Digital Elevation Models (DEMs), or height maps, of the mangrove canopy were derived from stereo pairs. Helicopter and field observations in 1998 and 1999 respectively provided ground truth for interpreting the derived datasets. The comparison of mangrove extent revealed a substantial movement over the 41-year period, perhaps in response to hydrological changes that have resulted in a landward extension of saline conditions. Changes in the height of mangroves were observed but were difficult to quantify due to the reduced quality of the 1950 DEM. The study demonstrated the viability of using time-series of aerial photography for monitoring and understanding the long-term response of mangroves to environmental change, including hydrological variations and sea level rise. [ABSTRACT FROM AUTHOR]

The decline of saltmarsh in Currambene Creek and Cararma Inlet, in Jervis Bay, eastern Australia, in the period 1944–1999 has been documented through photogrammetric analysis. The area of saltmarsh has declined in Currambene Creek by approximately 52.5% and in Cararma Inlet by approximately 35%. In Currambene Creek the decline of saltmarsh is primarily due to the landward encroachment of mangroves, while in Cararma Creek the seaward encroachment of Melaleuca and Casuarina have more significantly contributed to losses of saltmarsh. Regional sea-level rise is excluded as a primary cause of this transgression. A more plausible hypothesis involves an increase in the delivery of freshwater and nutrients to the intertidal environments in response to higher rainfall and catchment modifications. [ABSTRACT FROM AUTHOR]

Most mangrove swamp/salt flat systems have tidal currents that are ebb dominated, however, some systems show only slight ebb dominance despite having a very large swamp volume relative to the creek volume. Cocoa Ck in northern Australia is such a system. Results are presented from a simple analytical model for flow in Cocoa creek together with detailed water level observations in the swamps. It was found that the primary factor reducing the ebb dominance of this system was the very low slope of the swamp surface. During rising tides, water floods as sheet flow; however, on ebb tides, the surface water slope in the swamp becomes greater than the swamp surface slope, with the result that areas of swamp closest to the main feeder creek (Cocoa Ck) dry before areas furthest from the creek. Thus, about an hour after ebb tide commences, there is a large quantity of water perched on the salt flats/mangroves, tens of centimetres higher than the water in the creek. This water cannot leave the swamp via sheet flow, but must leave through a very small and shallow creek which is also highly constricted by vegetation. This effectively increases the friction on ebb tides and results in a delay in water leaving the swamps and salt flats, reducing any tendency towards ebb dominance. [ABSTRACT FROM AUTHOR]

This study assessed the appropriate sampling design required for quantifying variability in metal accumulation in the leaf tissues of A. marina, a dominant mangrove inhabiting Australian estuaries, by applying a hierarchical nested sampling design to sample mangroves at various levels of biological and spatial hierarchies (leaf, branch, tree, site). It was revealed that most variation in metal accumulation occurred among trees and branches, with insignificant variation between sites and among leaves. We also examined the accumulation of metal (loid)s in the leaf tissues collected from six locations across the Georges River estuary in southern Sydney, which differ in metal contamination history. Prospect Creek and Salt Pan Creek were the most contaminated locations, which exceeded sediment quality guideline values for Cu (66.71 ± 2.18 μg/g), Zn (317.14 ± 46.14 μg/g) and Pb (81.02 ± 2.79 μg/g). All metal(loid) concentrations in leaf tissues were much lower than their concentrations in sediment, but essential metals exhibited greater mobility. Out of 10 metal(loid)s, Mn, Co and Pb in leaves showed linear relationships (R 2  = 0.28-0.47) with sediment, indicating that mangrove leaves may be used as a bioindicator of environmental loads for these metals., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Restoration of coastal and marine ecosystems is essential to meet both national and global conservation targets and to counteract declines in coastal marine ecosystems. However, despite its status as a world leader in marine protection, Australia is lagging behind other countries in the implementation of coastal and marine restoration. Effective legislative frameworks that support the implementation of coastal and marine restoration as a management tool remains a key barrier to large-scale implementation of coastal and marine restoration in Australia and many other regions. We analyzed restoration projects and their policy frameworks in Australia, North America and Europe to identify the range of policy approaches for marine and coastal restoration. We then evaluated the legislative frameworks for coastal and marine restoration in two states in Australia (Queensland and New South Wales), to assess the current restoration permitting process and identify how different legislative and policy approaches could facilitate coastal and marine restoration projects. We identified two specific areas where improvements could be made to facilitate marine coastal restoration in Australia: increased transparency and better integration into coastal policy. Coastal and marine restoration in Australia is undertaken without appropriate and effective policy at the local, regional and national levels, which likely impedes its broader use as a management strategy. The policy and legislative changes and amendments outlined in this article can streamline the coastal and marine restoration process and thereby improve uptake of marine and coastal restoration in Australia. • Marine ecosystem restoration in Australia faces barriers because of inadequate and uncoordinated legislative frameworks. • Marine restoration could be better facilitated through increased transparency and integration into coastal planning policy. • Policy that supports the growing field of marine restoration for climate change mitigation will improve coastal resilience. [ABSTRACT FROM AUTHOR]