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Strategies for managing biological invasions are often based on the premise that characteristics of invading species and the invaded environment are key predictors of the invader's distribution. Yet, for either biological traits or environmental characteristics to explain distribution, adequate time must have elapsed for species to spread to all potential habitats. We compiled and analyzed a database of natural history and ecological traits of 138 coastal marine invertebrate species, the environmental conditions at sites to which they have been introduced, and their date of first introduction. We found that time since introduction explained the largest fraction (20%) of the variability in non-native range size, while traits of the species and environmental variables had significant, but minimal, influence on non-native range size. The positive relationship between time since introduction and range size indicates that non-native marine invertebrate species are not at equilibrium and are still spreading, posing a major challenge for management of coastal ecosystems.

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]

The article presents a study to determine the prevalence and effects of infection with copepods and pea crabs on three mussel species at Bucklands Beach, Auckland, New Zealand. The mussel species in this study included the non-native Musculista senhousia, and two native mussels, Perna canaliculus and Xenostrobus pulex. It is noted that copepod prevalence was highest in X. pulex, while pea crab prevalence was highest in P. canaliculus. Copepods and pea crabs infected M. senhousia at a much lower prevalence. Moreover, it is inferred that infections of M. senhousia were chance encounters of the pea crabs with the introduced species rather than an active selection in response to cues from the host.

The article presents a study on the macroparasite and ectosymbiont fauna of the introduced portunid crab Charybdis japonica and its comparison with sympatric and allopatric populations of the native portunid, Ovalipes catharus in New Zealand. It discusses the collection of 468 crabs from six harbours of the country and presents the comparison on the identity, incidence and prevalence of ectosymbionts and parasites among the different populations.