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Context. Diseases have affected coral populations worldwide, leading to population declines and requiring active restoration efforts. Aims. Describe population and individual impacts of necrotising disease in the Endangered octocoral Dendronephthya australis. Methods. We quantified population loss and recruitment by using reference photos, survey and GPS mapping and described disease lesions by using histopathology. Key results. From December 2019 to January 2020, we observed polyp loss, necrotic lesions and loss of large colonies of D. australis at Botany Bay, New South Wales, Australia. By September 2020, only a few scattered recruits remained, and all large colonies were lost. Histopathology of colonies sampled in January 2020 confirmed that the disease had resulted in necrosis, gastrovascular canal collapse and internal colony integrity loss, leading to mortality. New recruits were recorded within 10 months of disease onset, and large colonies within 18 months. Conclusions. Although the necrotising disease had significant impacts on both the individual and population level, natural recruitment began quickly. As such, unlike in other populations, restoration is not currently required in the Bare Island D. australis population. Implications. The extent of disease impact at the individual and population levels suggests that monitoring for lesions should be undertaken before developing conservation and restoration strategies for this species.

Gram-negative bacteria produce outer membrane vesicles (OMVs) and contain bacterial cargo including nucleic acids and proteins. The proteome of OMVs can be altered by various factors including bacterial growth stage, growth conditions, and environmental factors. However, it is currently unknown if the mechanism of OMV biogenesis can determine their proteome. In this study, we examined whether the mechanisms of OMV biogenesis influenced the production and protein composition of Pseudomonas aeruginosa OMVs. OMVs were isolated from three P. aeruginosa strains that produced OMVs either by budding alone, by explosive cell lysis, or by both budding and explosive cell lysis. We identified that the mechanism of OMV biogenesis dictated OMV quantity. Furthermore, a global proteomic analysis comparing the proteome of OMVs to their parent bacteria showed significant differences in the identification of proteins in bacteria and OMVs. Finally, we determined that the mechanism of OMV biogenesis influenced the protein composition of OMVs, as OMVs released by distinct mechanisms of biogenesis differed significantly from one another in their proteome and functional enrichment analysis. Overall, our findings reveal that the mechanism of OMV biogenesis is a main factor that determines the OMV proteome which may affect their subsequent biological functions.

Antarctic sea-ice forms a complex and dynamic system that drives many ecological processes in the Southern Ocean. Sea-ice microalgae and their associated microbial communities are understood to influence nutrient flow and allocation in marine polar environments. Sea-ice microalgae and their microbiota can have high seasonal and regional (>1000 km2) compositional and abundance variation, driven by factors modulating their growth, symbiotic interactions and function. In contrast, our knowledge of small-scale variation in these communities is limited. Understanding variation across multiple scales and its potential drivers is critical for informing on how multiple stressors impact sea-ice communities and the functions they provide. Here, we characterized bacterial communities associated with sea-ice microalgae and the potential drivers that influence their variation across a range of spatial scales (metres to >10 kms) in a previously understudied area in Commonwealth Bay, East Antarctica where anomalous events have substantially and rapidly expanded local sea-ice coverage. We found a higher abundance and different composition of bacterial communities living in sea-ice microalgae closer to the shore compared to those further from the coast. Variation in community structure increased linearly with distance between samples. Ice thickness and depth to the seabed were found to be poor predictors of these communities. Further research on the small-scale environmental drivers influencing these communities is needed to fully understand how large-scale regional events can affect local function and ecosystem processes.

Gram-positive bacteria ubiquitously produce membrane vesicles (MVs), and although they contribute to biological functions, our knowledge regarding their composition and immunogenicity remains limited. Here we examine the morphology, contents and immunostimulatory functions of MVs produced by three Staphylococcus aureus strains; a methicillin resistant clinical isolate, a methicillin sensitive clinical isolate and a laboratory-adapted strain. We observed differences in the number and morphology of MVs produced by each strain and showed that they contain microbe-associated molecular patterns (MAMPs) including protein, nucleic acids and peptidoglycan. Analysis of MV-derived RNA indicated the presence of small RNA (sRNA). Furthermore, we detected variability in the amount and composition of protein, nucleic acid and peptidoglycan cargo carried by MVs from each S. aureus strain. S. aureus MVs activated Toll-like receptor (TLR) 2, 7, 8, 9 and nucleotide-binding oligomerization domain containing protein 2 (NOD2) signalling and promoted cytokine and chemokine release by epithelial cells, thus identifying that MV-associated MAMPs including DNA, RNA and peptidoglycan are detected by pattern recognition receptors (PRRs). Moreover, S. aureus MVs induced the formation of and colocalized with autophagosomes in epithelial cells, while inhibition of lysosomal acidification using bafilomycin A1 resulted in accumulation of autophagosomal puncta that colocalized with MVs, revealing the ability of the host to degrade MVs via autophagy. This study reveals the ability of DNA, RNA and peptidoglycan associated with MVs to activate PRRs in host epithelial cells, and their intracellular degradation via autophagy. These findings advance our understanding of the immunostimulatory roles of Gram-positive bacterial MVs in mediating pathogenesis, and their intracellular fate within the host.

Aim Topographic complexity is widely accepted as a key driver of biodiversity, but at the patch‐scale, complexity–biodiversity relationships may vary spatially and temporally according to the environmental stressors complexity mitigates, and the species richness and identity of potential colonists. Using a manipulative experiment, we assessed spatial variation in patch‐scale effects of complexity on intertidal biodiversity. Location 27 sites within 14 estuaries/bays distributed globally. Time period 2015–2017. Major taxa studied Functional groups of algae, sessile and mobile invertebrates. Methods Concrete tiles of differing complexity (flat; 2.5‐cm or 5‐cm complex) were affixed at low–high intertidal elevation on coastal defence structures, and the richness and abundance of the colonizing taxa were quantified after 12 months. Results The patch‐scale effects of complexity varied spatially and among functional groups. Complexity had neutral to positive effects on total, invertebrate and algal taxa richness, and invertebrate abundances. However, effects on the abundance of algae ranged from positive to negative, depending on location and functional group. The tidal elevation at which tiles were placed accounted for some variation. The total and invertebrate richness were greater at low or mid than at high intertidal elevations. Latitude was also an important source of spatial variation, with the effects of complexity on total richness and mobile mollusc abundance greatest at lower latitudes, whilst the cover of sessile invertebrates and sessile molluscs responded most strongly to complexity at higher latitudes. Conclusions After 12 months, patch‐scale relationships between biodiversity and habitat complexity were not universally positive. Instead, the relationship varied among functional groups and according to local abiotic and biotic conditions. This result challenges the assumption that effects of complexity on biodiversity are universally positive. The va

Coastal systems such as estuaries are threatened by multiple anthropogenic stressors worldwide. However, how these stressors and estuarine hydrology shape benthic bacterial communities and their functions remains poorly known. Here, we surveyed sediment bacterial communities in poorly flushed embayments and well flushed channels in Sydney Harbour, Australia, using 16S rRNA gene sequencing. Sediment samples were collected monthly during the Austral summer-autumn 2014 at increasing distance from a large storm drain in each channel and embayment. Bacterial communities differed significantly between sites that varied in proximity to storm drains, with a gradient of change apparent for sites within embayments. We explored this pattern for embayment sites with analysis of RNA-Seq gene expression patterns and found higher expression of multiple genes involved in bacterial stress response far from storm drains, suggesting that bacterial communities close to storm drains may be more tolerant of localised anthropogenic stressors. Several bacterial groups also differed close to and far from storm drains, suggesting their potential utility as bioindicators to monitor contaminants in estuarine sediments. Overall, our study provides useful insights into changes in the composition and functioning of benthic bacterial communities as a result of multiple anthropogenic stressors in differing hydrological conditions.

Real-world observational datasets that record and quantify pressure-stressor-response linkages between effluent discharges and natural aquatic systems are rare. With global wastewater volumes increasing at unprecedented rates, it is urgent that the present dataset is available to provide the necessary information about microbial community structure and functioning. Field studies were performed at two time-points in the Austral summer. Single-species and microbial community whole effluent toxicity (WET) testing was performed at a complete range of effluent concentrations and two salinities, with accompanying environmental data to provide new insights into nutrient and organic matter cycling, and to identify ecotoxicological tipping points. The two salinity regimes were chosen to investigate future scenarios based on a predicted salinity increase at the study site, typical of coastal regions with rising sea levels globally. Flow cytometry, amplicon sequencing of 16S and 18S rRNA genes and micro-fluidic quantitative polymerase-chain reactions (MFQPCR) were used to determine chlorophyll-a and total bacterial cell numbers and size, as well as taxonomic and functional diversity of pelagic microbial communities. This strong pilot dataset could be replicated in other regions globally and would be of high value to scientists and engineers to support the next advances in microbial ecotoxicology, environmental biomonitoring and estuarine water quality modelling.

Real-world observational datasets that record and quantify pressure-stressor-response linkages between effluent discharges and natural aquatic systems are rare. With global wastewater volumes increasing at unprecedented rates, it is urgent that the present dataset is available to provide the necessary information about microbial community structure and functioning. Field studies were performed at two time-points in the Austral summer. Single-species and microbial community whole effluent toxicity (WET) testing was performed at a complete range of effluent concentrations and two salinities, with accompanying environmental data to provide new insights into nutrient and organic matter cycling, and to identify ecotoxicological tipping points. The two salinity regimes were chosen to investigate future scenarios based on a predicted salinity increase at the study site, typical of coastal regions with rising sea levels globally. Flow cytometry, amplicon sequencing of 16S and 18S rRNA genes and micro-fluidic quantitative polymerase-chain reactions (MFQPCR) were used to determine chlorophyll-a and total bacterial cell numbers and size, as well as taxonomic and functional diversity of pelagic microbial communities. This strong pilot dataset could be replicated in other regions globally and would be of high value to scientists and engineers to support the next advances in microbial ecotoxicology, environmental biomonitoring and estuarine water quality modelling.

Population growth is driving the demand for recreational marine infrastructure, resulting in extensive coastal habitat modification. Boat moorings, for example, are popular for vessel storage and are known to damage seagrass communities, yet little is known about how they influence unvegetated sediment habitats. Here we investigate the effects of boat moorings on sediment infauna using metrics of community composition, diversity, total abundance and abundances of individual functional groups and dominant taxa. Metrics were compared at fine and larger spatial scales, to investigate how spatial variability affects the ecological assessments in soft-sedimentary environments. Fine-scale models revealed changes in community composition and mollusk abundance with the distance from moorings, while sediment grain size was also an important predictor for composition, bivalve and polychaete abundances, although the direction of effects varied. When the same metrics were compared at larger scales (i.e., boating infrastructure present or lacking) we found that spatial variability among locations was detected, but no effect for moorings. With increased urbanization and industrialization of coastal areas there is a clear need to account for the scale of potential ecological effects in investigations of coastal infrastructure developments.

Microbially mediated biogeochemical processes are crucial for climate regulation and may be disrupted by anthropogenic contaminants. To better manage contaminants, we need tools that make real-time causal links between stressors and altered microbial functions, and the potential consequences for ecosystem services such as climate regulation. In a manipulative field experiment, we used metatranscriptomics to investigate the impact of excess organic enrichment and metal contamination on the gene expression of nitrogen and sulfur metabolisms in coastal sediments. Our gene expression data suggest that excess organic enrichment results in (i) higher transcript levels of genes involved in the production of toxic ammonia and hydrogen sulfide and (ii) lower transcript levels associated with the degradation of a greenhouse gas (nitrous oxide). However, metal contamination did not have any significant impact on gene expression. We reveal the genetic mechanisms that may lead to altered productivity and greenhouse gas production in coastal sediments due to anthropogenic contaminants. Our data highlight the applicability of metatranscriptomics as a management tool that provides an immense breadth of information and can identify potentially impacted process measurements that need further investigation.

Viruses are ubiquitous, abundant and play an important role in all ecosystems. Here, we advance understanding of coastal sediment viruses by exploring links in the composition and abundance of sediment viromes to environmental stressors and sediment bacterial communities. We collected sediment from contaminated and reference sites in Sydney Harbour and used metagenomics to analyse viral community composition. The proportion of phages at contaminated sites was significantly greater than phages at reference sites, whereas eukaryotic viruses were relatively more abundant at reference sites. We observed shifts in viral and bacterial composition between contaminated and reference sites of a similar magnitude. Models based on sediment characteristics revealed that total organic carbon in the sediments explained most of the environmental stress-related variation in the viral dataset. Our results suggest that the presence of anthropogenic contaminants in coastal sediments could be influencing viral community composition with potential consequences for associated hosts and the environment.

© 2019 Elsevier B.V. Natural systems are threatened by a variety of anthropogenic stressors and so understanding the interactive threats posed by multiple stressors is essential. In this study we focused on urban stressors that are ubiquitous to urban estuarine systems worldwide: elevated nutrients, toxic chemical contaminants, built infrastructure and non-indigenous species (NIS). We investigated structural (abundance, diversity and species richness) and functional endpoints (productivity, primary production (chlorophyll-a) and metabolism) commonly used to determine responses to these selected stressors. Through a systematic review of global literature, we found 579 studies of our selected stressors; 93% measured responses to a single stressor, with few assessing the effects of multiple stressors (7%). Structural endpoints were commonly used to measure the effects of stressors (49% of the total 579 studies). Whereas, functional endpoints were rarely assessed alone (10%) but rather in combination with structural endpoints (41%). Elevated nutrients followed by NIS were the most studied single stressors (43% and 16% of the 541 single stressor studies), while elevated nutrients and toxic contaminants were overwhelmingly the most common stressor combination (79% of the 38 multiple stressor studies); with NIS and built infrastructure representing major gaps in multi-stressor research. In the meta-analysis, structural endpoints tended to decrease, while functional endpoints increased and/or decreased in response to different types of organisms or groups. We predicted an antagonistic effect of elevated nutrients and toxic contaminants based on the opposing enriching versus toxic effects of this stressor combination. Of note, biodiversity was the only endpoint that revealed such an antagonistic response. Our results highlight the continuing paucity of multiple stressor studies and provide evidence for opposing patterns in the responses to single and interacting stressors de

Anthropogenic contaminants, including nutrient enrichment, frequently alter environmental conditions in marine systems and affect the development of communities on hard-substrata. Biofilms can influence the settlement of marine invertebrates and hence impact on the structure of fouling communities. Few studies have examined bacteria, invertebrates and nutrient-rich contaminants in concert, with none yet to examine the effects of nutrient-rich contaminants on both biofilms and the recruitment of sessile invertebrate communities in-situ to ascertain the mechanistic basis behind observed impacts. Biofilm treatments were allowed to develop under manipulated environmental conditions of either ambient or enriched nutrient levels. Enrichment conditions were elevated via slow-release fertiliser and invertebrate recruitment was prevented during initial biofilm development. Biofilm treatments (including a no film control) were then subject to either ambient or enriched water-borne nutrients (in a fully-factorial design) during a period of invertebrate colonisation in the field. Effects of nutrient-rich contaminants on invertebrate recruitment were observed as changes to community composition and the abundances of taxonomic groups. Communities on no biofilm control treatments differed from those with pre-developed biofilms. Naturally developed biofilms promoted recruitment by all organisms, except barnacles, which preferred nutrient-enriched biofilms. Water-borne nutrients increased the recruitment of ascidians and barnacles, but suppressed bryozoan, serpulid polychaete and sponge recruitment. The direct and indirect impacts observed on biofilm and invertebrate communities suggest that increasing nutrient levels via nutrient-rich contaminants will result in structural community shifts that may ultimately impact ecosystem functioning within estuaries.

Microplastics and fibres occur in high concentrations along urban coastlines, but the occurrence of microplastic ingestion by fishes in these areas requires further investigation. Herein, the ingestion of debris (i.e., synthetic and natural fibres and synthetic fragments of various polymer types) by three benthic-foraging fish species Acanthopagrus australis (yellowfin bream), Mugil cephalus (sea mullet) and Gerres subfasciatus (silverbiddy) in Sydney Harbour, Australia has been quantified and chemically speciated by vibrational spectroscopy to identify the polymer type. Ingested debris were quantified using gut content analysis, and identified using attenuated total reflectance Fourier transform infrared (ATR-FTIR) and Raman microspectroscopies in combination with principal component analysis (PCA). The occurrence of debris ingestion at the time of sampling ranged from 21 to 64% for the three species, and the debris number ranged from 0.2 to 4.6 items per fish for the different species, with ∼53% of debris being microplastic. There was a significant difference in the amount of debris ingested among species; however, there was no difference among species when debris counts were standardised to fish weight or gut content weight, indicating that these species ingest a similar concentration of debris relative to their ingestion rate of other material. ATR-FTIR microspectroscopy successfully identified 72% of debris. Raman spectroscopy contributed an additional 1% of successful identification. In addition, PCA was used to non-subjectively classify the ATR-FTIR spectra resulting in the identification of an additional 9% of the debris. The most common microplastics found were polyester (PET), acrylic-polyester blend, and rayon (semi-synthetic) fibres. The potential of using Raman microspectroscopy for debris identification was investigated and provided additional information about the nature of the debris as well as the presence of specific dyes (and hence potential toxic

© 2018 Scanes, Kutti, Fang, Johnston, Ross and Bannister. There is the potential for climate change to interact with pollution in all of the Earth's oceans. In the fjords of Norway, mine tailings are released into fjords generating suspended sediment plumes that impact deep-sea ecosystems. These same deep-sea ecosystems are expected to undergo periodic warming as climate change increases the frequency of down-welling events in fjords. It remains unknown how a polluted deep-sea ecosystem would respond to down-welling because multiple stressors will often interact in unpredictable ways. Here, we exposed two deep-sea foundation species; the gorgonian coral Primnoa resedaeformis and the demosponge Geodia atlantica to suspended sediment (10 mg L -1 ) and acute warming (+5°C) in a factorial mesocosm experiment for 40 days. Physiology (respiration, nutrient flux) and cellular responses (lysosomal cell stability) were measured for both the coral and sponge. Exposure to elevated suspended sediment reduced metabolism, supressed silicate uptake and induced cellular instability of the sponge G. atlantica. However, combining sediment with warming caused G. atlantica to respire and excrete nitrogen at a greater rate. For the coral P. resedaeformis, suspended sediments reduced O:N ratios after 40 days, however, warming had a greater effect on P. resedaeformis physiology compared to sediment. Warming increased respiration, nitrogen excretion, and cellular instability which resulted in lower O:N ratios. We argue that suspended sediment and warming can act alone and also interact to cause significant harm to deep-sea biota, however responses are likely to be species-specific. Warming and pollution could interact in the deep-sea to cause mortality to the coral P. resedaeformis and to a lesser extent, the sponge G. atlantica. As foundation species, reducing the abundance of deep sea corals and sponges would likely impact the ecosystems they support.

Coastal urbanization has led to large-scale transformation of estuaries, with artificial structures now commonplace. Boat moorings are known to reduce seagrass cover, but little is known about their effect on fish communities. We used underwater video to quantify abundance, diversity, composition and feeding behaviour of fish assemblages on two scales: with increasing distance from moorings on fine scales, and among locations where moorings were present or absent. Fish were less abundant in close proximity to boat moorings, and the species composition varied on fine scales, leading to lower predation pressure near moorings. There was no relationship at the location with seagrass. On larger scales, we detected no differences in abundance or community composition among locations where moorings were present or absent. These findings show a clear impact of moorings on fish and highlight the importance of fine-scale assessments over location-scale comparisons in the detection of the effects of artificial structures.

Sandy beaches are unique ecosystems increasingly exposed to human-induced pressures. Consistent with emerging frameworks promoting this holistic approach towards beach management, is the need to improve the integration of social data into management practices. This paper aims to increase understanding of links between demographics and community values and preferred beach activities, as key components of the social dimension of the beach environment. A mixed method approach was adopted to elucidate users' opinions on beach preferences and community values through a survey carried out in Manly Local Government Area in Sydney Harbour, Australia. A proposed conceptual model was used to frame demographic models (using age, education, employment, household income and residence status) as predictors of these two community responses. All possible regression-model combinations were compared using Akaike's information criterion. Best models were then used to calculate quantitative likelihoods of the responses, presented as heat maps. Findings concur with international research indicating the relevance of social and restful activities as important social links between the community and the beach environment. Participant's age was a significant variable in the four predictive models. The use of predictive models informed by demographics could potentially increase our understanding of interactions between the social and ecological systems of the beach environment, as a prelude to integrated beach management approaches. The research represents a practical demonstration of how demographic predictive models could support proactive approaches to beach management.

Urban areas have broad ecological footprints with complex impacts on natural systems. In coastal areas, growing populations are advancing their urban footprint into the ocean through the construction of seawalls and other built infrastructure. While we have some understanding of how urbanisation might drive functional change in terrestrial ecosystems, coastal systems have been largely overlooked. This study is one of the first to directly assess how changes in diversity relate to changes in ecosystem properties and functions (e.g. productivity, filtration rates) of artificial and natural habitats in one of the largest urbanised estuaries in the world, Sydney Harbour. We complemented our surveys with an extensive literature search. We found large and important differences in the community structure and function between artificial and natural coastal habitats. However, differences in diversity and abundance of organisms do not necessarily match observed functional changes. The abundance and composition of important functional groups differed among habitats with rocky shores having 40% and 70% more grazers than seawalls or pilings, respectively. In contrast, scavengers were approximately 8 times more abundant on seawalls than on pilings or rocky shores and algae were more diverse on natural rocky shores and seawalls than on pilings. Our results confirm previous findings in the literature. Oysters were more abundant on pilings than on rocky shores, but were also smaller. Interestingly, these differences in oyster populations did not affect in situ filtration rates between habitats. Seawalls were the most invaded habitats while pilings supported greater secondary productivity than other habitats. This study highlights the complexity of the diversity-function relationship and responses to ocean sprawl in coastal systems. Importantly, we showed that functional properties should be considered independently from structural change if we are to design and manage artificial hab

Host-associated microbial communities play a fundamental role in the life of eukaryotic hosts. It is increasingly argued that hosts and their microbiota must be studied together as 'holobionts' to better understand the effects of environmental stressors on host functioning. Disruptions of host-microbiota interactions by environmental stressors can negatively affect host performance and survival. Substantial ecological impacts are likely when the affected hosts are habitat-forming species (e.g., trees, kelps) that underpin local biodiversity. In marine systems, coastal urbanisation via the addition of artificial structures is a major source of stress to habitat formers, but its effect on their associated microbial communities is unknown. We characterised kelp-associated microbial communities in two of the most common and abundant artificial structures in Sydney Harbour - pier-pilings and seawalls - and in neighbouring natural rocky reefs. The kelp Ecklonia radiata is the dominant habitat-forming species along 8000 km of the temperate Australian coast. Kelp-associated microbial communities on pilings differed significantly from those on seawalls and natural rocky reefs, possibly due to differences in abiotic (e.g., shade) and biotic (e.g., grazing) factors between habitats. Many bacteria that were more abundant on kelp on pilings belonged to taxa often associated with macroalgal diseases, including tissue bleaching in Ecklonia. There were, however, no differences in kelp photosynthetic capacity between habitats. The observed differences in microbial communities may have negative effects on the host by promoting fouling by macroorganisms or by causing and spreading disease over time. This study demonstrates that urbanisation can alter the microbiota of key habitat-forming species with potential ecological consequences.

There is growing public concern about the global expansion of harmful algal bloom species (HABs), with dinoflagellate microalgae comprising the major portion of the harmful taxa. These motile, unicellular organisms have a lifecycle involving sexual reproduction and resting cyst formation whereby cysts can germinate from sediments and ‘seed’ planktonic populations. Thus, investigation of dinoflagellate cyst (dinocyst) distribution in sediments can provide significant insights into HAB dynamics and contribute to indices of habitat quality. Species composition and abundance of dinocysts in relation to sediment characteristics were studied at 18 stations in two densely populated temperate Australian estuaries, Sydney Harbour (Parramatta River/Port Jackson; PS) and Botany Bay (including Georges River; GB). Eighteen dinocyst taxa were identified, dominated by Protoceratium reticulatum and Gonyaulax sp.1 in the PS estuary, together with Archaeperidinium minutum and Gonyaulax sp.1 in the GB estuary. Cysts of Alexandrium catenella, which is one of the causative species of paralytic shellfish poisoning (PSP), were also detected in both estuaries. Out of the measured sediment characteristics (TOC, Cd, Cr, Cu, Fe, Pb, Mn, Ni, Zn and polycyclic aromatic hydrocarbons), TOC was the parameter explaining most of the variation in dinocyst assemblages and was positively correlated to most of the heavy metals. Given the significant relationship between sediment TOC and dinocyst abundance and heavy metal concentrations, this study suggests that sediment TOC could be broadly used in risk management for potential development of algal blooms and sediment contamination in these estuaries.

Marine Protected Areas (MPAs) are a key management tool for the conservation of biodiversity and restoration of marine communities. While large, well-designed and enforced MPAs have been found to be effective, results from small MPAs vary. The Hawkesbury Shelf, a coastal bioregion in New South Wales, Australia, has ten small, near-shore MPAs known as Aquatic Reserves with a variety of protection levels from full no-take to partial protection. This study assessed the effectiveness of these MPAs and analysed how MPA age, size, protection level, wave exposure, habitat complexity, and large canopy-forming algal cover affected fish, invertebrate and benthic communities. We found aspect, protection level, complexity and algal canopy to be important predictors of communities in these MPAs. Most MPAs, however, were not effective in meeting their goals. Only full no-take protection (three out of ten MPAs) had a significant impact on fish assemblages. One no-take MPA—Cabbage Tree Bay—which is naturally sheltered from wave action and benefits from an active local community providing informal enforcement, accounted for most of the increased richness of large fish and increased biomass of targeted fish species. Our findings suggest that small MPAs can enhance biodiversity and biomass on a local scale but only if they have full no-take protection, are in sheltered locations with complex habitat, and have positive community involvement to engender support and stewardship. These results provide a baseline for robust assessment of the effectiveness of small MPAs and inform future management decisions and small MPA design in other locations.

The global sprawl of urban centres is replacing complex natural habitats with relatively flat and featureless infrastructure that supports low biodiversity. In a growing countermovement, artificial microhabitats are increasingly incorporated into designs for “Green” and “Blue” infrastructure. In order to maximise the ecological value of such interventions, we need to inform the designs with observations from natural systems and existing Green and Blue infrastructure. Here, we focussed on water retaining features mimicking intertidal rock pools, as this is a widely used intervention in coastal ecosystems. Using a meta-analysis and a qualitative literature review, we compiled information on diversity and function of rock pools on natural rocky shores and built structures to assess the potential ecological benefits of water retaining microhabitats and the design metrics of rock pools that affect diversity and function. Our meta-analysis showed higher species richness in rock pools compared to emergent surfaces on built structures, but this was variable among locations. The qualitative review revealed that rock pools on both natural and artificial shores generally hosted species that were not present on emergent rock and can also host non-indigenous species, suggesting that the addition of these features can sometimes have unwanted consequences and local ecological knowledge is essential to implement successful interventions. Relationships between species richness and design metrics, such as height on shore, volume, surface area and depth of pool were taxa-specific. For example, results from the meta-analysis suggest that building larger, deeper pools could increase diversity of fish, but not benthic organisms. Finally, this study highlights major gaps in our understanding of how the addition of rock pools and design metrics influence diversity and the variables affecting the ecological functioning of rock pools. Based on the knowledge gathered so far, recommendations f

Historical ecology can teach us valuable lessons on the processes and drivers of environmental change that can inform future monitoring priorities and management strategies. Environmental data to study environmental history, however, is often absent or of low quality. Even when studying changes occurring during the last few decades, monitoring efforts are scarce due to logistical and cost limitations, leaving large areas unassessed. The aim of this study is to evaluate the use of estuarine water colour as an indicator of historical environmental change in catchments. Water colour change was assessed in estuaries in Australia from 1987 to 2015 using satellite remote sensing. Random points were selected for each estuary and applied to the Australian Geoscience Data Cube (based on Landsat images) to obtain reflectance data through time. We propose a framework where (i) water colour is used to detect historical changes in catchments using generalised additive models, (ii) possible stressors and pressures driving those changes are evaluated using other available historical data, and (iii) lessons learned inform appropriate monitoring and management actions. This framework represents a novel approach to generate historical data for large-scale assessments of environmental change at catchment level, even in poorly studied areas.

Artificial reefs are deployed in coastal systems to meet a range of social objectives and infrastructure requirements, such as recreational diving and fisheries enhancement. Such reefs are typically deployed on soft sediments and yet we know little of their effect on the biophysical characteristics of the surrounding benthos. This study investigated the composition of benthic infauna, sediment characteristics, and demersal fish foraging activity surrounding a large, steel, designed offshore artificial reef (OAR), measuring 12 m × 16 m x 12 m (height x length x width) and weighing approximately 42 tonnes. Using a gradient approach we established four transects with sediment sampling sites located 15, 30, 60, 120 and 240 m from the OAR. Taxon richness of infauna was lower close to the OAR (15, 30 m), and abundances of total infauna elevated at 15 m, driven largely by two families of polychaete (Onuphidae and Spionidae). Sediment characteristics (grain size, total organic carbon, metals) did not vary with distance from the OAR. Using unbaited videos we established that fish foraging activity on the soft sediments was enhanced close to the OAR (15 m), with a 5–10 fold increase in total foraging time that was largely accounted for by the activity of four benthivorous fish species (blue morwong Nemadactylus douglasii, the silver trevally Pseudocaranx georgianus, and goatfishes Upeneichthys vlamingii and U. lineatus). Fish foraging may cause changes in the composition of benthic infauna due to disturbance and selective predation. The effective benthic ‘ecological halo’ or ‘footprint’ of the OAR was 15 times the area of the actual reef. We demonstrate that a single large OAR can influence the surrounding benthic invertebrate and vertebrate communities, but that the effects are highly localised.