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Aim: Retrospective (pre‐ vs. post‐invasion) and cross‐sectional comparisons of ecosystems exposed to high and low bioinvasion pressure, provide an alternative approach to evaluate shifts in biological communities associated with non‐indigenous species (NIS) introductions. In this study, we aimed to examine general patterns of change in community composition, structure and function in six well‐studied and globally distributed marine ecosystems that had documented histories of biological invasions. Location: Global. Methods: By considering a range of regional datasets and different sampling approaches, we evaluated trends within and among ecosystems by comparing paired measures of community and functional structure in either space or time. Results: Our analyses revealed different patterns of structural and functional change at ecosystem scales, but direct comparisons across regions were hindered by confounding effects of study designs and other drivers of change. The most prominent shifts in community composition were observed in the retrospective studies, characterised by the greatest relative contribution of NIS. No uniform pattern of change in functional metrics was observed across study regions. However, functional evenness and dispersion showed a tendency to increase in systems under higher invasion pressure, refuting the hypothesis of selective accumulation of specific traits and functional homogenisation within ecosystems exposed to high invasion pressure. Main Conclusions: Accumulation of NIS within broader communities can be a subtle process, with inherent spatial and temporal variability. Nonetheless, not only do species' proportional contributions to communities change over time in areas subjected to high bioinvasion pressure, but trait profiles can incrementally shift, which alters the original ecology of an area. Planned, long‐term studies that incorporate a range of measures of environmental drivers and ecosystem response are crucial for better understanding of cumulative, community‐level and ecosystem‐scale change associated with biological invasions. [ABSTRACT FROM AUTHOR]

Advances in high‐throughput sequencing (HTS) are revolutionizing monitoring in marine environments by enabling rapid, accurate and holistic detection of species within complex biological samples. Research institutions worldwide increasingly employ HTS methods for biodiversity assessments. However, variance in laboratory procedures, analytical workflows and bioinformatic pipelines impede the transferability and comparability of results across research groups. An international experiment was conducted to assess the consistency of metabarcoding results derived from identical samples and primer sets using varying laboratory procedures. Homogenized biofouling samples collected from four coastal locations (Australia, Canada, New Zealand and the USA) were distributed to 12 independent laboratories. Participants were asked to follow one of two HTS library preparation workflows. While DNA extraction, primers and bioinformatic analyses were purposefully standardized to allow comparison, many other technical variables were allowed to vary among laboratories (amplification protocols, type of instrument used, etc.). Despite substantial variation observed in raw results, the primary signal in the data was consistent, with the samples grouping strongly by geographical origin for all data sets. Simple post hoc data clean‐up by removing low‐quality samples gave the best improvement in sample classification for nuclear 18S rRNA gene data, with an overall 92.81% correct group attribution. For mitochondrial COI gene data, the best classification result (95.58%) was achieved after correction for contamination errors. The identified critical methodological factors that introduced the greatest variability (preservation buffer, sample defrosting, template concentration, DNA polymerase, PCR enhancer) should be of great assistance in standardizing future biodiversity studies using metabarcoding. [ABSTRACT FROM AUTHOR]

Aim: The introduction of aquatic non‐indigenous species (ANS) has become a major driver for global changes in species biogeography. We examined spatial patterns and temporal trends of ANS detections since 1965 to inform conservation policy and management. Location: Global. Methods: We assembled an extensive dataset of first records of detection of ANS (1965–2015) across 49 aquatic ecosystems, including the (a) year of first collection, (b) population status and (c) potential pathway(s) of introduction. Data were analysed at global and regional levels to assess patterns of detection rate, richness and transport pathways. Results: An annual mean of 43 (±16 SD) primary detections of ANS occurred—one new detection every 8.4 days for 50 years. The global rate of detections was relatively stable during 1965–1995, but increased rapidly after this time, peaking at roughly 66 primary detections per year during 2005–2010 and then declining marginally. Detection rates were variable within and across regions through time. Arthropods, molluscs and fishes were the most frequently reported ANS. Most ANS were likely introduced as stowaways in ships' ballast water or biofouling, although direct evidence is typically absent. Main conclusions: This synthesis highlights the magnitude of recent ANS detections, yet almost certainly represents an underestimate as many ANS go unreported due to limited search effort and diminishing taxonomic expertise. Temporal rates of detection are also confounded by reporting lags, likely contributing to the lower detection rate observed in recent years. There is a critical need to implement standardized, repeated methods across regions and taxa to improve the quality of global‐scale comparisons and sustain core measures over longer time‐scales. It will be fundamental to fill in knowledge gaps given that invasion data representing broad regions of the world's oceans are not yet readily available and to maintain knowledge pipelines for adaptive management. [ABSTRACT FROM AUTHOR]

Incidental detection of species of concern (e.g., invasive species, pathogens, threatened and endangered species) during biodiversity assessments based on high‐throughput DNA sequencing holds significant risks in the absence of rigorous, fit‐for‐purpose data quality and reporting standards. Molecular biodiversity data are predominantly collected for ecological studies and thus are generated to common quality assurance standards. However, the detection of certain species of concern in these data would likely elicit interest from end users working in biosecurity or other surveillance contexts (e.g., pathogen detection in health‐related fields), for which more stringent quality control standards are essential to ensure that data are suitable for informing decision‐making and can withstand legal or political challenges. We suggest here that data quality and reporting criteria are urgently needed to enable clear identification of those studies that may be appropriately applied to surveillance contexts. In the interim, more pointed disclaimers on uncertainties associated with the detection and identification of species of concern may be warranted in published studies. This is not only to ensure the utility of molecular biodiversity data for consumers, but also to protect data generators from uncritical and potentially ill‐advised application of their science in decision‐making. [ABSTRACT FROM AUTHOR]

Models of the spread of invasive species in transportation networks often assume a constant probability of transport across vectors, an assumption that is known to be false. The human dimension of these pathways is an important contributor to variation in vector risks. Yet, little attempt has been made to understand the effectiveness of strategies that involve changing risky behaviours., We modelled the efficacy of management campaigns that aim to reduce the spread of invasive biofouling organisms by improving antifouling behaviour of boaters. We examined the influence of three factors on the effectiveness of the campaigns: (i) the proportion of the vessel population that is targeted by the measure, (ii) the average amount of change in behaviour made by individual boaters and (iii) the rate of uptake of the measure by the targeted population., The modelled campaigns reduced the spread of an invasive species within New Zealand's recreational boating network by 0-56% over a 10-year period. The outcome depended strongly on the combination of the three factors examined., Strategies that targeted only the 'worst offenders' caused relatively little reduction in spread unless there was very high uptake of the measure (>75% compliance) and a larger shift from current practice than could reasonably be expected. In comparison, a strategy that utilized a lower threshold for renewing the coatings and targeted a larger proportion of boaters was three times more effective, even for modest changes in current behaviour., Synthesis and applications. Vector management can be effective in reducing the spread of a marine invader, but campaigns need to be well designed if they are to be effective. Their success will be determined by the shape of the 'risk-release relationship' and where along this curve the population of vectors lies. Greatest gains are likely when measures are targeted at critical transition points, where relatively small changes in behaviour lead to a considerable reduction in risk. High uptake of measures is required to reduce spread significantly. Combined 'carrot and stick' approaches that incorporate incentives for compliance are likely to be most effective at eliciting meaningful levels of change. [ABSTRACT FROM AUTHOR]

Aim The likelihood of a species successfully passing through all stages of the human-mediated invasion process and becoming established at new locations is often determined by phenotypic characteristics. Among species, phenotypic similarity is negatively correlated with phylogenetic distance, but examples of independent evolution of traits in unrelated taxa do exist. Using marine bryozoans as model organisms we predict that, given the selectivity of the invasion process, the phylogenetic relatedness among established non-indigenous species in a region is either higher or lower than that among the native assemblage, but not the same. Location Sixteen port and marina environments around New Zealand (the principal sites of establishment of most non-indigenous bryozoans), and coastal habitats of the entire New Zealand coastline. Methods We use average taxonomic distinctness (avTD) as a measure of phylogenetic relatedness and taxonomic ‘breadth’ of species assemblages. We compare values of avTD between native and non-indigenous bryozoan assemblages at two spatial scales and examine whether assemblages in port environments represent phylogenetically restricted and morphologically distinct subsets of the regional coastal bryofauna. Results At a nationwide and a local scale, the phylogenetic relatedness among non-indigenous bryozoans was no different from that among members of the native assemblage. However, native bryozoans inhabiting port and marina environments had a significantly reduced taxonomic breadth and higher phylogenetic relatedness than the pool of ‘available’ native bryozoans from surrounding coastal habitats. Non-indigenous species were on average six times more prevalent than native species in ports. There were no differences in morphological characteristics between native and non-indigenous bryozoans from ports and natural environments. Main conclusion We found no evidence that a successful passage through the stages of the invasion process results in a taxonomically distinct non-indigenous assemblage. However, patterns of relatedness among native and among non-indigenous species may be influenced by the nature of the study environment. [ABSTRACT FROM AUTHOR]

The article discusses the study which examines the utility of habitat suitability index (HSI) and particle dispersion models for directing sampling for marine pests. HSI models are a simple way to determine suitable habitat when species distribution data are lacking. The researchers compared the performance of HSI models with statistical models from independent data from New Zealand regarding the distribution of two nonindigenous bivalves namely, Theora lubrica and Musculista senhousia. Results of the study highlight the difficulty of accurately forecasting the distribution of invasive marine species showing low habitat occupancy and patchy distributions in time and space.

The article presents a study which investigates the facilitation at an earlier stage in the invasion process of interactions between nonindigenous species (NIS) by human vectors. It offers a comparison of the recruitment of fouling organisms to mimic bryozoan Watersipora subtorquata colonies of three different sizes. Also revealed is the increase of invasion success by positive interactions between NIS that enhance the delivery of propagules by human transport vectors.

Journal of Applied Ecology (2003) 40, 1077–1089 [ABSTRACT FROM AUTHOR]

Abstract Hull fouling is a major cost for owners of small vessels and an important pathway for the spread of non-indigenous aquatic species. The extent of fouling depends on a hull's susceptibility to recruitment by aquatic organisms and the local availability of competent planktonic propagules (‘propagule pressure’). Management strategies have typically been concerned with increasing resistance of the hull to recruitment through the use of toxic paints. Here we tested the hypothesis that fouling is influenced by the design of the harbour in which the boat is moored. We compared recruitment of sessile invertebrates to available surfaces in two types of recreational boat harbours: marinas that were partially enclosed by a permanent breakwall, and marinas that lacked breakwalls. Recruitment in the marinas was compared to coastal reference sites that were not used for mooring. At each location, recruitment tiles were deployed for 4 weeks on four separate occasions over a period of 2 years. Measurements of current velocities and spatial patterns of water flow at each location showed that permanent breakwalls created complex patterns of circulation that retained water within the marina basin for up to 12 h d-1 . Despite large regional and temporal variability in fouling over time, most organisms recruited in greatest numbers to surfaces in partially enclosed marinas, and were often several orders of magnitude more abundant in the enclosed marinas than in unenclosed marinas or coastal reference locations. Harbour design has an important influence on the rate at which fouling organisms recruit to available surfaces within marinas. Entrainment of water in enclosed marinas may limit the dispersal of planktonic propagules by advective currents but effectively increases propagule pressure to available surfaces, including resident boat hulls. This is likely to accelerate the development of hull-fouling assemblages and increase the chances of... [ABSTRACT FROM AUTHOR]

The article focuses on a study which examines the patterns of impact caused by the experimental opening of two new recreational scuba diving sites in the Great Barrier Reef Marine Park in Queensland. It provides details about monitoring the changes in the abundance and condition of corals at the dive sites and two undived sites.

Abstract: Underwater trails are intended as interpretative tools in marine parks, but concentrating divers and snorkelers in defined areas may negatively affect the surrounding environment. We examined spatial and temporal patterns in the effects of use of underwater trails on coral reef flats in the Great Barrier Reef Marine Park, Australia. Changes in benthic assemblages were assessed on two new trails used by snorkelers, two unused (control) trails, and two undisturbed areas. Total percent coral cover, numbers of broken colonies, and living coral fragments were counted 6 months before and 6 months after the new trails began to be used. Spatial patterns of effects around concentrated nodes of use were determined by stratified sampling around and away from the interpretative signs within each trail. Despite comparatively low levels of use (approximately 15 snorkelers per trail per week), snorkelers caused significant damage to corals along the trails. Branching corals (non-Acropora branching corals and Millepora spp.) were most affected. More damage occurred near the interpretative signs than elsewhere on the trails. The numbers of broken branches and damaged coral colonies in the snorkeling trails increased rapidly but stabilized within 2 months of the commencement of use. There was no significant change in overall benthic assemblages within the trails after 6 months of use by snorkelers. Although concentrating snorkelers within confined trails caused increased damage to corals, the effects can be mitigated by appropriate design and placement of the trails and by managing the behavior of snorkelers. Interpretative information should warn users about the damage they may cause when swimming along the trails. Managing the behavior of snorkelers in the water is likely to be more effective in reducing damage than simply applying fixed limits to the amount of use the trails receive. [ABSTRACT FROM AUTHOR]

Presents information on a study which described patterns in the distribution of seeds of the marine angiosperm Halodule uninervis along the north-eastern coast of Queensland, Australia. Methods used in the study; Results and discussion.